diff --git a/src/services/file-safety/__tests__/safeWriteText.integration.spec.ts b/src/services/file-safety/__tests__/safeWriteText.integration.spec.ts new file mode 100644 index 0000000000..d0730d1254 --- /dev/null +++ b/src/services/file-safety/__tests__/safeWriteText.integration.spec.ts @@ -0,0 +1,58 @@ +import * as fs from "fs/promises" +import * as os from "os" +import * as path from "path" + +import { safeWriteText } from "../safeWriteText" + +// No fs mocks in this file: the point is to assert what a real filesystem ends up +// holding after a publish attempt, which the mocked spec cannot show. The failure is +// provoked with real filesystem semantics rather than with a stubbed call. +describe("safeWriteText against a real filesystem", () => { + let dir: string + + beforeEach(async () => { + dir = await fs.mkdtemp(path.join(os.tmpdir(), "safe-write-text-int-")) + }) + + afterEach(async () => { + await fs.rm(dir, { recursive: true, force: true }) + }) + + // The commit-rename failure mode is covered deterministically in safeWriteText.spec.ts + // ('a failed commit does not move the target, so nothing has to be rolled back'): on a real + // filesystem there is no portable way to make only the rename fail - the ESM fs namespace + // cannot be spied, and read-only-parent / sticky-bit / cross-device setups are not portable. + it("publishes the new bytes and leaves no staging or backup residue", async () => { + const targetPath = path.join(dir, "target.txt") + await fs.writeFile(targetPath, "old bytes") + + // No platform override: the real platform's own durability and ACL steps run, and this + // case is the successful restore. A failed restore now throws DaclRestoreError after the + // commit rename has already happened (the focused unit test "win32 DACL: a failed restore + // is an error and the dump is still unlinked" covers that path), so on a machine where + // icacls cannot put a saved ACL back into a throwaway temp directory this publish + // reports that error instead of resolving, and the residue assertions below are reached + // only where the restore worked. + await safeWriteText(targetPath, "new bytes", { backup: true }) + + expect(await fs.readFile(targetPath, "utf8")).toBe("new bytes") + expect(await fs.readdir(dir)).toEqual(["target.txt"]) + }) + + it("leaves the target bytes untouched when the backup copy cannot be made", async () => { + // A regular file cannot be renamed over a directory, so the step-3 backup copy fails + // on a real filesystem with no mocking. Note what this case does NOT cover: the commit + // rename is never reached, because the backup failure aborts the write first. + const targetPath = path.join(dir, "target-dir") + await fs.mkdir(targetPath) + const inside = path.join(targetPath, "payload.txt") + await fs.writeFile(inside, "original bytes") + + await expect(safeWriteText(targetPath, "new data", { backup: true })).rejects.toThrow() + + // The directory and its content are exactly as they were, and no backup copy + // or staging directory was left behind next to them. + expect(await fs.readFile(inside, "utf8")).toBe("original bytes") + expect(await fs.readdir(dir)).toEqual(["target-dir"]) + }) +}) diff --git a/src/services/file-safety/__tests__/safeWriteText.spec.ts b/src/services/file-safety/__tests__/safeWriteText.spec.ts new file mode 100644 index 0000000000..37f1a5234c --- /dev/null +++ b/src/services/file-safety/__tests__/safeWriteText.spec.ts @@ -0,0 +1,1813 @@ +import * as fs from "fs/promises" +import * as fsSync from "fs" +import type { BigIntStats } from "fs" +import { execFile } from "child_process" +import type { ChildProcess } from "child_process" +import * as path from "path" + +import { + DaclInspectionError, + DaclRestoreError, + OrphanedBackupError, + PostCommitDurabilityError, + resolveLockKey, + safeWriteText, + StagingPathError, + type PublishResidue, + type SafeWriteTextOptions, +} from "../safeWriteText" + +// Full mock for fs/promises — all methods are vi.fn() stubs +vi.mock("fs/promises", () => ({ + copyFile: vi.fn(), + chmod: vi.fn(), + mkdir: vi.fn(), + access: vi.fn(), + rename: vi.fn(), + unlink: vi.fn(), + rmdir: vi.fn(), + realpath: vi.fn(), + lstat: vi.fn(), + readlink: vi.fn(), +})) + +// Full mock for fs — all sync methods are vi.fn() stubs. Stats is a bare +// class stub so tests can build minimal Stats stand-ins via its prototype. +vi.mock("fs", () => ({ + openSync: vi.fn(), + writeSync: vi.fn(), + closeSync: vi.fn(), + mkdirSync: vi.fn(), + fsyncSync: vi.fn(), + chmodSync: vi.fn(), + fchmodSync: vi.fn(), + statSync: vi.fn(), + Stats: class Stats {}, +})) + +// Mock child_process.execFile (callback-based — must invoke callback to resolve) +vi.mock("child_process", () => ({ + execFile: vi.fn((cmd, args, opts, cb) => { + if (typeof cb === "function") cb(null) + }), +})) + +// Minimal stand-in for the ChildProcess that callback-form execFile returns. +const fakeChild = { kill: () => true } as unknown as ChildProcess + +// Helper that mirrors safeWriteText's path resolution exactly +function _resolvedTarget(filePath: string): string { + return path.resolve(filePath) +} +function _dirPath(filePath: string): string { + return path.dirname(_resolvedTarget(filePath)) +} +// Minimal Stats stand-in: the SUT only reads `.mode` from it. +// Async lstat stand-in: the SUT only asks whether the path is a link or a file. +// Built on the Stats prototype so the mock value still satisfies fsSync.Stats. +function _fileStats(isLink: boolean): fsSync.Stats { + const s = Object.create(fsSync.Stats.prototype) as fsSync.Stats + s.isSymbolicLink = () => isLink + s.isFile = () => !isLink + return s +} + +// fs.BigIntStats is a type-only export (fs.BigIntStats is undefined at runtime), so the stand-in is +// a Stats object carrying bigint ino/dev - exactly what fs.lstat(path, { bigint: true }) hands +// back at runtime. +function _fileStatsWithIdentity(ino: bigint, dev: bigint): fsSync.BigIntStats { + // Double assertion: the runtime value is the Stats stand-in, the type is the bigint variant. + const s = _fileStats(false) as unknown as fsSync.BigIntStats + s.ino = ino + s.dev = dev + return s +} + +function mockDefaults(): void { + vi.resetAllMocks() + // After resetAllMocks, vi.fn() returns undefined — restore promise defaults. + vi.mocked(fs.mkdir).mockResolvedValue(undefined) + vi.mocked(fs.access).mockResolvedValue(undefined) + vi.mocked(fs.rename).mockResolvedValue(undefined) + vi.mocked(fs.unlink).mockResolvedValue(undefined) + vi.mocked(fs.rmdir).mockResolvedValue(undefined) + // Existing-target default: a regular 0o644 file. + vi.mocked(fsSync.statSync).mockReturnValue(_stats(0o644)) + // Staged-file default: a regular file, not a link, so a caller-supplied + // tempPath passes the location and file-type check by default. + vi.mocked(fs.lstat).mockResolvedValue(_fileStats(false)) +} +function _stats(mode: number): fsSync.Stats { + const s = Object.create(fsSync.Stats.prototype) as fsSync.Stats + Object.assign(s, { mode }) + return s +} + +// ── Test 1: staging file created then cleaned after success ──────────────── + +describe("safeWriteText", () => { + beforeEach(() => { + mockDefaults() + // Default sync-write behaviour: report that all requested bytes were + // written. The Buffer overload passes (fd, buffer, offset, length), + // so the fourth argument is the requested length. + vi.mocked(fsSync.writeSync).mockImplementation((...args: unknown[]) => + typeof args[3] === "number" ? args[3] : 0, + ) + }) + + describe("staging and cleanup", () => { + it("creates a temp file in the staging dir, fsyncs it, renames to target, and cleans up on success", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) // fd=1 + vi.mocked(fsSync.closeSync).mockReturnValue(undefined) + + await safeWriteText(targetPath, "hello world", { platform: "linux" }) + + // staging dir was created with private permissions — use + // stringContaining to handle Windows path resolution + expect(fsSync.mkdirSync).toHaveBeenCalledWith(expect.stringContaining(".file-safety-staging"), { + recursive: true, + mode: 0o700, + }) + // a pre-existing staging dir is repaired to private permissions too + expect(fsSync.chmodSync).toHaveBeenCalledWith(expect.stringContaining(".file-safety-staging"), 0o700) + + // temp file was opened for writing with the existing target's mode + // (default 0o644 from the statSync default mock) + expect(fsSync.openSync).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), "w", 0o644) + + // content was written as a buffer (partial-write loop, full write) + expect(fsSync.writeSync).toHaveBeenCalledWith(1, Buffer.from("hello world", "utf8"), 0, 11) + + // fsync (sync form) was called on the fd + expect(fsSync.fsyncSync).toHaveBeenCalledWith(1) + + // file was closed + expect(fsSync.closeSync).toHaveBeenCalledWith(1) + + // atomic rename happened — realpath mock returns targetPath, so that's the dest + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), targetPath) + + // no unlink of temp (it's now the committed file; DACL skipped via platform:linux) + expect(fs.unlink).not.toHaveBeenCalled() + }) + + it("removes the now-empty staging directory after a successful self-staged commit", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + await safeWriteText(targetPath, "hello", { platform: "linux" }) + + // the staging subdir is removed best-effort after the commit rename + // (stringContaining: the SUT and the test helper resolve Windows + // drive-relative paths differently, as in the existing staging tests) + expect(fs.rmdir).toHaveBeenCalledTimes(1) + expect(fs.rmdir).toHaveBeenCalledWith(expect.stringContaining(".file-safety-staging")) + // the win32 DACL restore gate must stay closed on other platforms: + // no icacls save or restore is attempted + expect(execFile).not.toHaveBeenCalled() + }) + + it("still removes the staging directory when no options are supplied at all", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + // options is undefined: the self-staged check and the optional-chained + // DACL runner lookup must not dereference it + await expect(safeWriteText(targetPath, "hello")).resolves.toEqual({ leftoverPaths: [] }) + + expect(fs.rmdir).toHaveBeenCalledTimes(1) + expect(fs.rmdir).toHaveBeenCalledWith(expect.stringContaining(".file-safety-staging")) + if (process.platform === "win32") { + // default platform is win32: the DACL save + restore still ran + // through the default icacls path (options?.execFileRunner must + // not throw when options is undefined) + expect(vi.mocked(execFile)).toHaveBeenCalledTimes(2) + expect(vi.mocked(fs.unlink)).toHaveBeenCalledWith(expect.stringContaining("safeWriteText.acl")) + } + }) + + it("does not remove the staging directory when the caller supplies its own tempPath", async () => { + const targetPath = "/tmp/test-dir/target.txt" + const callerTemp = "/tmp/test-dir/caller-staged.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + await safeWriteText(targetPath, "hello", { platform: "linux", tempPath: callerTemp }) + + // the caller owns its temp file's directory; safeWriteText must not + // rmdir a directory it did not create + expect(fs.rmdir).not.toHaveBeenCalled() + }) + + it("a failed staging-dir removal never fails the committed write", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + vi.mocked(fs.rmdir).mockRejectedValue(Object.assign(new Error("ENOTEMPTY"), { code: "ENOTEMPTY" })) + + const result = await safeWriteText(targetPath, "hello", { platform: "linux" }) + + // The commit rename still happened: a directory this write created is a leftover to clean + // up, not a failed save. It is reported rather than swallowed, because the caller is the + // only party that can sweep it and an empty list claims there is nothing left to sweep. + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining(".file-safety-staging"), targetPath) + const stagingDir = vi.mocked(fsSync.mkdirSync).mock.calls.map((call) => String(call[0]))[0] + expect(result).toEqual({ leftoverPaths: [stagingDir] }) + + // One retry: a directory can still be reported busy by the OS while the handle of the + // file it held is being released, so a single failure is not evidence it is stuck. + expect(fs.rmdir).toHaveBeenCalledTimes(2) + expect(fs.rmdir).toHaveBeenCalledWith(expect.stringContaining(".file-safety-staging")) + }) + + it("gives each self-staged write its own staging directory so a concurrent write cannot remove it", async () => { + const targetA = "/tmp/test-dir/target-a.txt" + const targetB = "/tmp/test-dir/target-b.txt" + vi.mocked(fs.realpath).mockImplementation((p) => Promise.resolve(p as string)) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + await safeWriteText(targetA, "a", { platform: "linux" }) + await safeWriteText(targetB, "b", { platform: "linux" }) + + // Two self-staged writes in the same directory must not share one staging + // directory: the first write's best-effort rmdir would otherwise delete the + // directory the second write had created but not yet opened (ENOENT on openSync). + const created = vi.mocked(fsSync.mkdirSync).mock.calls.map((c) => String(c[0])) + const staging = created.filter((p) => p.includes(".file-safety-staging_")) + expect(staging).toHaveLength(2) + expect(staging[0]).not.toBe(staging[1]) + // Uniqueness comes from the documented name shape + // /.file-safety-staging__: pinning the shape + // keeps the separator and the random suffix meaningful, not just the prefix. + for (const dir of staging) { + expect(dir).toMatch(/\.file-safety-staging_\d+_[a-z0-9]+$/) + } + const removed = vi.mocked(fs.rmdir).mock.calls.map((c) => String(c[0])) + expect(removed).toEqual([staging[0], staging[1]]) + }) + + it("removes its own staging directory when a self-staged write fails", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + vi.mocked(fs.rename).mockRejectedValue(Object.assign(new Error("EACCES"), { code: "EACCES" })) + + await expect(safeWriteText(targetPath, "hello", { platform: "linux" })).rejects.toThrow("EACCES") + + // The failed write's temp file is unlinked, then the directory it + // created is removed — a failed write must not leave an empty + // .file-safety-staging directory behind. + // mkdirSync created this write's staging directory; the temp file lives + // inside it, so the unlink targets a path under that directory. + const staging = vi.mocked(fsSync.mkdirSync).mock.calls.map((c) => String(c[0])) + expect(staging).toHaveLength(1) + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining(staging[0])) + expect(fs.rmdir).toHaveBeenCalledWith(staging[0]) + // The directory is only empty after its temp file is gone, so the + // unlink must happen before the rmdir. + expect(vi.mocked(fs.unlink).mock.invocationCallOrder[0]).toBeLessThan( + vi.mocked(fs.rmdir).mock.invocationCallOrder[0], + ) + }) + + it("does not remove a staging directory it did not create when a caller-staged write fails", async () => { + const targetPath = "/tmp/test-dir/target.txt" + const callerTemp = "/tmp/test-dir/caller-staged.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + vi.mocked(fs.rename).mockRejectedValue(Object.assign(new Error("EACCES"), { code: "EACCES" })) + + await expect( + safeWriteText(targetPath, "hello", { platform: "linux", tempPath: callerTemp }), + ).rejects.toThrow("EACCES") + + // The caller owns that directory: only the caller's temp file is cleaned, + // never a rmdir of a directory safeWriteText never created. + expect(fs.unlink).toHaveBeenCalledWith(callerTemp) + expect(fs.rmdir).not.toHaveBeenCalled() + }) + }) + + it("win32: a rejecting async onWarning does not abort the write or leak an unhandled rejection", async () => { + // TypeScript accepts an async sink where a void callback is expected, so the + // wrapper has to attach a handler to the returned promise: an unhandled + // rejection can end the process under Node's default mode, after a write that + // already succeeded. + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + // The DACL save succeeds: the notice this test needs has to come from a warning that + // still exists, and the DACL-save notice became a refusal. + vi.mocked(execFile).mockImplementation((_cmd, _args, _opts, cb) => { + if (typeof cb === "function") cb(null, "", "") + return fakeChild + }) + // The surviving notice is the leftover one, emitted after the commit. + vi.mocked(fs.unlink).mockImplementation(async (p) => { + if (String(p).includes("safeWriteText.bak_")) { + throw Object.assign(new Error("EPERM: operation not permitted"), { code: "EPERM" }) + } + }) + const consoleWarn = vi.spyOn(console, "warn").mockImplementation(() => {}) + + await expect( + safeWriteText(targetPath, "data", { + backup: true, + platform: "win32", + onWarning: async () => { + throw new Error("async sink down") + }, + }), + ).resolves.toEqual({ leftoverPaths: [expect.stringContaining("safeWriteText.bak_")] }) + + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining(".file-safety-staging"), targetPath) + // The rejection is reported through the fallback sink rather than surfacing as an + // unhandled rejection. + expect(consoleWarn).toHaveBeenCalledWith(expect.stringContaining("onWarning callback rejected")) + consoleWarn.mockRestore() + }) + + // ── Test 2: fsync ordering ─────────────────────────────────────────────── + + describe("fsync ordering", () => { + it("calls fsync on the fd before close, and rename after close", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + await safeWriteText(targetPath, "data", { platform: "linux" }) + + // Verify call order: openSync(temp) → writeSync → fsyncSync(temp) + // → closeSync(temp) → rename. On POSIX the parent directory is then + // opened and fsynced after the commit rename, so openSync/fsyncSync/ + // closeSync each have a second (directory) call. + expect(vi.mocked(fsSync.openSync).mock.calls.length).toBe(2) + expect(vi.mocked(fsSync.writeSync).mock.calls.length).toBe(1) + expect(vi.mocked(fsSync.fsyncSync).mock.calls.length).toBe(2) + expect(vi.mocked(fsSync.closeSync).mock.calls.length).toBe(2) + + // the temp file was fully closed before the commit rename + expect(vi.mocked(fsSync.closeSync).mock.calls[0][0]).toBe(1) + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), targetPath) + // The title promises the order, so compare the invocations rather than + // only count them: a rename before closeSync, or a close before fsync, + // would not be a durable commit. + const fsyncOrder = vi.mocked(fsSync.fsyncSync).mock.invocationCallOrder[0] + const closeOrder = vi.mocked(fsSync.closeSync).mock.invocationCallOrder[0] + const renameOrder = vi.mocked(fs.rename).mock.invocationCallOrder[0] + expect(fsyncOrder).toBeLessThan(closeOrder) + expect(closeOrder).toBeLessThan(renameOrder) + }) + }) + + // ── Test 3: simulated failure between write and rename leaves target intact ── + + describe("crash/torn-write safety", () => { + it("simulated failure between fsync and rename leaves the target byte-identical and no temp left behind", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + vi.mocked(fs.rename).mockRejectedValue(new Error("ENOSPC")) + + await expect(safeWriteText(targetPath, "new data", { platform: "linux" })).rejects.toThrow("ENOSPC") + + // rename was attempted (the failure point) + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), targetPath) + + // temp file was cleaned up on failure + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_")) + + // backup was NOT created (backup:false by default), so target is untouched + // The only rename call was temp→target, not a rollback rename + expect(fs.rename).toHaveBeenCalledTimes(1) + }) + + it("a post-commit backup cleanup failure is non-fatal: the target stays committed and no temp is left behind", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + // The post-commit backup unlink (SUT step 6) fails — the write must + // still succeed; an orphaned backup is the documented acceptable + // outcome, so the failure is swallowed instead of rolling back. + vi.mocked(fs.unlink).mockRejectedValueOnce(new Error("EPERM")) + + await safeWriteText(targetPath, "data", { backup: true, platform: "linux" }) + + // the commit rename (temp -> target) still happened; it is the only rename + expect(fs.rename).toHaveBeenCalledTimes(1) + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), targetPath) + + // the failing cleanup was the post-commit backup unlink + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining("safeWriteText.bak_")) + + // the staging temp was already committed by the rename; nothing + // temp-shaped is unlinked afterwards + expect(fs.unlink).not.toHaveBeenCalledWith(expect.stringContaining("safeWriteText_")) + }) + + it("a failed post-commit directory fsync does not roll the backup back over the published content", async () => { + const targetPath = "/tmp/test-dir/target.txt" + const dirPath = path.dirname(targetPath) + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + // The file fd opens normally; the parent-directory open after the commit + // rename fails, which is the post-commit durability failure. + vi.mocked(fsSync.openSync).mockImplementation((target) => { + if (String(target) === dirPath) throw new Error("EBADF") + return 1 + }) + + await expect(safeWriteText(targetPath, "new data", { backup: true, platform: "linux" })).rejects.toThrow( + PostCommitDurabilityError, + ) + + // The commit rename already published the new content, and the backup was only + // ever a copy: the target was never moved, so there is nothing to rename back. + expect(fs.copyFile).toHaveBeenCalledWith(targetPath, expect.stringContaining("safeWriteText.bak_")) + expect(fs.rename).toHaveBeenCalledTimes(1) + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), targetPath) + + // The durability failure is reported, not swallowed - and the backup copy is not + // left beside the target where no caller could find it. + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining("safeWriteText.bak_")) + }) + }) + + // ── Test 4: backup:true keeps old safeWriteJson semantics, copy-based ── + + describe("backup:true", () => { + it("copies target -> backup before commit without moving the target, deletes the copy on success", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + await safeWriteText(targetPath, "new data", { backup: true }) + + // target was accessed (exists check) + expect(fs.access).toHaveBeenCalledWith(targetPath) + + // The backup is a copy: the canonical target is never moved away, so readers + // never see a missing file and no later step can clobber a concurrent publish. + expect(fs.copyFile).toHaveBeenCalledWith(targetPath, expect.stringContaining("safeWriteText.bak_")) + expect(fs.rename).not.toHaveBeenCalledWith(targetPath, expect.stringContaining("safeWriteText.bak_")) + + // the only rename is the atomic commit temp -> target + expect(fs.rename).toHaveBeenCalledTimes(1) + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), targetPath) + + // backup copy was deleted on success + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining("safeWriteText.bak_")) + }) + + it("a failed commit does not move the target, so nothing has to be rolled back", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + // The commit rename is the only rename in the flow and it fails. + vi.mocked(fs.rename).mockRejectedValue(new Error("ENOSPC")) + + await expect(safeWriteText(targetPath, "new data", { backup: true })).rejects.toThrow("ENOSPC") + + // The target never left its path, so there is no restore rename and the + // pre-write content is still what a reader sees at targetPath. + expect(fs.rename).toHaveBeenCalledTimes(1) + expect(fs.copyFile).toHaveBeenCalledWith(targetPath, expect.stringContaining("safeWriteText.bak_")) + + // Both the backup copy and the staging temp are cleaned up on failure. + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining("safeWriteText.bak_")) + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_")) + }) + + it("creates the backup privately before its content exists, then fsyncs it", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + await safeWriteText(targetPath, "new data", { backup: true }) + + // The destination must exist with a private mode before copyFile writes anything + // into it: copyFile chooses the destination mode itself, so a restrictive target + // could otherwise leave a group/world-readable copy that a later chmod cannot + // undo. "wx" also means a pre-existing path is never silently reused. + const seedOpen = vi.mocked(fsSync.openSync).mock.calls.find(function (call) { + return String(call[0]).includes("safeWriteText.bak_") && call[1] === "wx" + }) + expect(seedOpen).toBeDefined() + expect(seedOpen?.[2]).toBe(0o600) + const seedOrder = vi.mocked(fsSync.openSync).mock.invocationCallOrder[ + vi.mocked(fsSync.openSync).mock.calls.indexOf(seedOpen!) + ] + expect(seedOrder).toBeLessThan(vi.mocked(fs.copyFile).mock.invocationCallOrder[0]) + + // The chmod keeps a copied read-only attribute (Windows) from breaking the fsync + // open, and keeps a backup of a permissive file private. + expect(fs.copyFile).toHaveBeenCalledWith(targetPath, expect.stringContaining("safeWriteText.bak_")) + expect(fs.chmod).toHaveBeenCalledWith(expect.stringContaining("safeWriteText.bak_"), 0o600) + expect(vi.mocked(fs.chmod).mock.invocationCallOrder[0]).toBeGreaterThan( + vi.mocked(fs.copyFile).mock.invocationCallOrder[0], + ) + + // The copy is then opened for fsync with the writable flag. + const backupOpen = vi.mocked(fsSync.openSync).mock.calls.find(function (call) { + return String(call[0]).includes("safeWriteText.bak_") && call[1] === "r+" + }) + expect(backupOpen).toBeDefined() + }) + + it("a failed backup flush is reported and leaves no partial backup behind", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + // The copy lands, but the fsync of the copy fails: the retained content is not + // known to be durable, so the write must not proceed on a half-written backup. + // The staged temp is fsynced earlier with a different handle, so target the + // backup's fd specifically. + vi.mocked(fsSync.openSync).mockImplementation((p: unknown) => + String(p).includes("safeWriteText.bak_") ? 7 : 1, + ) + vi.mocked(fsSync.fsyncSync).mockImplementation((fd: unknown) => { + if (fd === 7) { + throw new Error("EIO") + } + }) + + await expect(safeWriteText(targetPath, "new data", { backup: true, platform: "linux" })).rejects.toThrow( + "EIO", + ) + + // Nothing was published, and the incomplete copy is removed rather than left + // next to the target looking like a usable backup. + expect(fs.rename).not.toHaveBeenCalled() + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining("safeWriteText.bak_")) + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_")) + }) + + it("carries the leftover path when the partial backup cannot be removed either", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockImplementation((p: unknown) => + String(p).includes("safeWriteText.bak_") ? 7 : 1, + ) + vi.mocked(fsSync.fsyncSync).mockImplementation((fd: unknown) => { + if (fd === 7) { + throw new Error("EIO") + } + }) + let unlinkAttempts = 0 + vi.mocked(fs.unlink).mockImplementation(async (p: unknown) => { + if (String(p).includes("safeWriteText.bak_")) { + unlinkAttempts++ + } + throw Object.assign(new Error("EPERM"), { code: "EPERM" }) + }) + + // The copy failed and the locked leftover could not be unlinked even after the + // retry. Dropping the path would leave a partial copy of the previous content on + // disk with no reference to it anywhere, so the error carries it. + const error = await safeWriteText(targetPath, "new data", { + backup: true, + platform: "linux", + }).catch((caught: unknown) => caught) + + expect(error).toBeInstanceOf(OrphanedBackupError) + const orphan = error as OrphanedBackupError + expect(orphan.orphanedBackupPath).toContain("safeWriteText.bak_") + expect(orphan.message).toContain("safeWriteText.bak_") + expect(orphan.message).toContain("EPERM") + expect(orphan.originalError).toBeInstanceOf(Error) + expect((orphan.originalError as Error).message).toBe("EIO") + expect(orphan.cause).toBe(orphan.originalError) + expect(unlinkAttempts).toBe(2) + expect(fs.rename).not.toHaveBeenCalled() + + // The dedicated orphan field names the copy, and the residue lists every path this write + // left on disk: the partial copy first, then the staged file the failure handler could not + // remove either. The throw discards the structured result, so without these the caller + // would have to work out for itself which of its paths are still on disk. + expect(orphan).toMatchObject({ + leftoverPaths: [ + expect.stringContaining("safeWriteText.bak_"), + expect.stringContaining("safeWriteText_"), + ], + cleanupErrors: [expect.objectContaining({ code: "EPERM" }), expect.objectContaining({ code: "EPERM" })], + }) + }) + + it("a failed staging-file flush rejects and publishes nothing", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + // The staged file's own fsync fails. The bytes are not known to have reached the + // disk, so the commit rename must not happen at all - this is the durability gate + // the staging fsync exists for. + vi.mocked(fsSync.fsyncSync).mockImplementation(() => { + throw new Error("EIO") + }) + + await expect(safeWriteText(targetPath, "new data", { platform: "linux" })).rejects.toThrow("EIO") + + expect(fs.rename).not.toHaveBeenCalled() + // The fd is closed despite the throw, and neither the staged file nor its private + // staging directory survives the failure. + expect(fsSync.closeSync).toHaveBeenCalledWith(1) + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_")) + expect(fs.rmdir).toHaveBeenCalledWith(expect.stringContaining(".file-safety-staging")) + }) + + it("retries a failed backup cleanup and removes the copy", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + const warnings: string[] = [] + let backupUnlinkAttempts = 0 + // Windows commonly reports EPERM for a file whose handle has not been released yet, + // so the first failure must not end the cleanup. + vi.mocked(fs.unlink).mockImplementation(async (p: unknown) => { + if (String(p).includes("safeWriteText.bak_")) { + backupUnlinkAttempts++ + if (backupUnlinkAttempts === 1) { + throw Object.assign(new Error("EPERM"), { code: "EPERM" }) + } + } + }) + + await safeWriteText(targetPath, "new data", { + backup: true, + platform: "linux", + onWarning: (message: string) => { + warnings.push(message) + }, + }) + + expect(backupUnlinkAttempts).toBe(2) + expect(warnings).toHaveLength(0) + }) + + it("reports a backup it cannot remove instead of dropping the path", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + const warnings: string[] = [] + let backupUnlinkAttempts = 0 + vi.mocked(fs.unlink).mockImplementation(async (p: unknown) => { + if (String(p).includes("safeWriteText.bak_")) { + backupUnlinkAttempts++ + throw Object.assign(new Error("EPERM"), { code: "EPERM" }) + } + }) + + // The publish succeeded, so a leftover backup must not fail the write; but the copy + // of the previous content is still on disk, so its path has to be reported rather + // than dropped where no caller can act on it. + await safeWriteText(targetPath, "new data", { + backup: true, + platform: "linux", + onWarning: (message: string) => { + warnings.push(message) + }, + }) + + expect(fs.rename).toHaveBeenCalledTimes(1) + expect(backupUnlinkAttempts).toBe(2) + expect(warnings).toHaveLength(1) + expect(warnings[0]).toContain("safeWriteText.bak_") + expect(warnings[0]).toContain("EPERM") + }) + + it("backup:true when target does not exist: no backup created, just commit", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + // fs.access resolves for dirPath check, but rejects for target check (backup path) + vi.mocked(fs.access).mockImplementation(async (p) => { + if (typeof p === "string" && p.endsWith("target.txt")) throw { code: "ENOENT" } + }) + + await safeWriteText(targetPath, "new data", { backup: true, platform: "linux" }) + + // no backup rename (target didn't exist) + expect(fs.access).toHaveBeenCalledWith(targetPath) + + // only one rename: temp -> target + expect(fs.rename).toHaveBeenCalledTimes(1) + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), targetPath) + + // no unlink (no backup to delete; DACL skipped via platform:linux) + expect(fs.unlink).not.toHaveBeenCalled() + }) + }) + + it("treats an already-absent post-commit backup as cleaned up, without a second unlink", async () => { + const targetPath = "/tmp/test-dir/target.txt" + const onWarning = vi.fn() + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + vi.mocked(fsSync.closeSync).mockReturnValue(undefined) + // Step 6 removes the backup copy after the commit; something else removed it first. + vi.mocked(fs.unlink).mockRejectedValueOnce(Object.assign(new Error("ENOENT"), { code: "ENOENT" })) + + await safeWriteText(targetPath, "data", { backup: true, platform: "linux", onWarning }) + + // ENOENT means the cleanup goal is already met: the write resolves, nothing is reported + // as a leftover, and the retry loop stops instead of unlinking the same path twice. + const backupUnlinks = vi.mocked(fs.unlink).mock.calls.filter(function (call) { + return String(call[0]).includes("safeWriteText.bak") + }) + expect(backupUnlinks.length).toBe(1) + expect(onWarning).not.toHaveBeenCalled() + }) + + it("propagates a seed-descriptor close failure and runs the backup cleanup", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + // The seed open is the only "wx" open; give its descriptor a distinguishable fd. + vi.mocked(fsSync.openSync).mockImplementation(((p: fsSync.PathLike, flags?: fsSync.OpenMode) => + flags === "wx" ? 42 : 1) as typeof fsSync.openSync) + let seedCloseAttempts = 0 + vi.mocked(fsSync.closeSync).mockImplementation((fd: number) => { + if (fd === 42) { + seedCloseAttempts++ + throw new Error("close failed") + } + return undefined + }) + + await expect(safeWriteText(targetPath, "data", { backup: true, platform: "linux" })).rejects.toThrow( + "close failed", + ) + + // Exactly one close attempt: POSIX close(2) may have released the descriptor before it + // reported the error, so a retry could release a descriptor another operation reused. + expect(seedCloseAttempts).toBe(1) + // The seeded backup must not outlive the failed write. + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining("safeWriteText.bak")) + }) + + // ── Test 5: win32 DACL path ────────────────────────────────────────────── + + describe("win32 DACL", () => { + it.skipIf(process.platform !== "win32")( + "copies target DACL onto staging file via icacls before rename on Windows", + async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + await safeWriteText(targetPath, "data", { platform: "win32" }) + + // icacls dump + restore were called (execFile is callback-based mock) + expect(execFile).toHaveBeenCalledTimes(2) + }, + ) + + it("non-win32: DACL path is unreachable when platform is not win32", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + await safeWriteText(targetPath, "data", { platform: "linux" }) + + // icacls was NOT called on non-win32 + expect(execFile).not.toHaveBeenCalled() + }) + + it("win32 DACL failure refuses the publish instead of renaming over the target", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + // icacls dump fails — the callback-based mock must invoke cb with an error. + vi.mocked(execFile).mockImplementation((_cmd, _args, _opts, cb) => { + if (typeof cb === "function") cb(new Error("icacls error"), "", "") + return fakeChild + }) + + // Captured once: calling safeWriteText twice here would double-count the single icacls + // attempt asserted below. + const refusal = await safeWriteText(targetPath, "data", { platform: "win32" }).catch( + (error: unknown) => error, + ) + + expect(refusal).toBeInstanceOf(DaclInspectionError) + // The class alone does not pin the contract: swapping the phase or dropping the target path + // still satisfies toBeInstanceOf, and both are caller-visible - the phase says which check + // refused, the path says which file the caller must not assume was saved. + expect(refusal).toMatchObject({ + name: "DaclInspectionError", + phase: "save", + targetPath, + message: expect.stringContaining("its DACL could not be saved"), + }) + + // Contract change (Security Boundaries row): a target whose DACL could not be saved is + // no longer replaced by a file that inherits different rights. Nothing is committed. + expect(fs.rename).not.toHaveBeenCalled() + // one icacls attempt only: a failed DACL apply must not try to restore + expect(execFile).toHaveBeenCalledTimes(1) + }) + + it("win32: refuses the publish without an onWarning notice when the DACL cannot be saved", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + vi.mocked(execFile).mockImplementation((_cmd, _args, _opts, cb) => { + if (typeof cb === "function") cb(new Error("icacls error"), "", "") + return fakeChild + }) + const warnings: string[] = [] + + await expect( + safeWriteText(targetPath, "data", { platform: "win32", onWarning: (m) => warnings.push(m) }), + ).rejects.toBeInstanceOf(DaclInspectionError) + + // Contract change: the refusal replaces the warning. There is no replacement whose access + // rights could have changed, so no notice is emitted for a write that did not happen. + expect(fs.rename).not.toHaveBeenCalled() + expect(warnings).toHaveLength(0) + }) + + it("win32: refuses the publish when the target cannot be checked for DACL preservation", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + // The target exists but is not readable: that is not "absent", and skipping DACL + // preservation has to be visible. + vi.mocked(fs.access).mockImplementation(async (p) => { + if (String(p) === targetPath) { + throw Object.assign(new Error("EACCES"), { code: "EACCES" }) + } + }) + const warnings: string[] = [] + + // Captured once: a second call would double-count the assertions below. + const refusal = await safeWriteText(targetPath, "data", { + platform: "win32", + onWarning: (m) => warnings.push(m), + }).catch((error: unknown) => error) + + expect(refusal).toBeInstanceOf(DaclInspectionError) + // The class alone does not pin the contract: swapping the phase or dropping the target path + // still satisfies toBeInstanceOf, and both are caller-visible - the phase says which check + // refused, the path says which file the caller must not assume was saved. + expect(refusal).toMatchObject({ + name: "DaclInspectionError", + phase: "inspect", + targetPath, + message: expect.stringContaining("its access rights could not be checked"), + }) + + // Contract change: "there but unreadable" is no longer a reason to publish blind. The + // publish is refused before any icacls runs, and nothing is warned about a write that did + // not happen. + expect(execFile).not.toHaveBeenCalled() + expect(fs.rename).not.toHaveBeenCalled() + expect(warnings).toHaveLength(0) + }) + + // The DACL refusals sit inside the try whose catch performs the cleanup, so a refused publish is + // cleaned up by that handler and by nothing else. Counted, not matched with toHaveBeenCalledWith: + // that matcher passes however many times the same path is passed, so it cannot see a cleanup + // that runs twice. + it("win32: a refused publish removes its staged file and staging directory exactly once", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + vi.mocked(execFile).mockImplementation((_cmd, _args, _opts, cb) => { + if (typeof cb === "function") cb(new Error("icacls error"), "", "") + return fakeChild + }) + + await expect(safeWriteText(targetPath, "data", { platform: "win32" })).rejects.toBeInstanceOf( + DaclInspectionError, + ) + + const unlinkCalls = vi.mocked(fs.unlink).mock.calls.map((call) => String(call[0])) + const rmdirCalls = vi.mocked(fs.rmdir).mock.calls.map((call) => String(call[0])) + expect(unlinkCalls.filter((p) => p.includes("safeWriteText_"))).toHaveLength(1) + expect(rmdirCalls.filter((p) => p.includes(".file-safety-staging"))).toHaveLength(1) + }) + + // Warning delivery is advisory: it must not be able to fail the save it is reporting on. + it("win32: a throwing onWarning does not abort the write", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + // The DACL save succeeds here: the warning this test exercises has to come from a notice + // that still exists, and the DACL-save notice became a refusal. + vi.mocked(execFile).mockImplementation((_cmd, _args, _opts, cb) => { + if (typeof cb === "function") cb(null, "", "") + return fakeChild + }) + // The surviving notice is the leftover one: the publish committed and the copy of the + // previous content could not be removed (Windows reports EPERM while a handle is open). + vi.mocked(fs.unlink).mockImplementation(async (p) => { + if (String(p).includes("safeWriteText.bak_")) { + throw Object.assign(new Error("EPERM: operation not permitted"), { code: "EPERM" }) + } + }) + + await expect( + safeWriteText(targetPath, "data", { + backup: true, + platform: "win32", + onWarning: () => { + throw new Error("callback down") + }, + }), + ).resolves.toEqual({ leftoverPaths: [expect.stringContaining("safeWriteText.bak_")] }) + + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining(".file-safety-staging"), targetPath) + }) + + it("win32 DACL: a partial dump left by a failed save is removed and never restored", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + // icacls save fails — a real icacls may have written a partial dump + // before erroring, so the dump path must be cleaned up and must never + // be used for a restore. + vi.mocked(execFile).mockImplementation((_cmd, _args, _opts, cb) => { + if (typeof cb === "function") cb(new Error("icacls save error"), "", "") + return fakeChild + }) + + await expect(safeWriteText(targetPath, "data", { platform: "win32" })).rejects.toBeInstanceOf( + DaclInspectionError, + ) + + // Contract change: the publish is refused, so nothing is renamed. Only the save was + // attempted, and the partial dump is still removed below. + expect(fs.rename).not.toHaveBeenCalled() + expect(execFile).toHaveBeenCalledTimes(1) + const saveArgs = vi.mocked(execFile).mock.calls[0]?.[1] + expect(saveArgs?.[1]).toBe("/save") + // the dump path (possibly partially created by icacls) was unlinked + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining("safeWriteText.acl")) + }) + + it("win32 DACL save args are [targetPath, /save, dumpPath, /T] before backup rename", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + await safeWriteText(targetPath, "data", { backup: true, platform: "win32" }) + + // icacls was called twice (save + restore) + expect(execFile).toHaveBeenCalledTimes(2) + + // First call: save DACL from target before backup rename + const firstCall = vi.mocked(execFile).mock.calls[0] + expect(firstCall[0]).toBe("icacls") + expect(firstCall[1]).toEqual([targetPath, "/save", expect.stringContaining("safeWriteText.acl"), "/T"]) + + // Second call: restore DACL onto directory after commit rename + const secondCall = vi.mocked(execFile).mock.calls[1] + expect(secondCall[0]).toBe("icacls") + expect(secondCall[1]).toEqual([ + expect.stringContaining("/tmp/test-dir"), + "/restore", + expect.stringContaining("safeWriteText.acl"), + ]) + + // dump file was unlinked after restore + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining("safeWriteText.acl")) + }) + + it("win32 DACL save runs before the backup copy, not after it", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + // The title is about order, so assert the order the mocks were actually + // called in. If the save ran after the backup copy the dump could describe a + // file that a concurrent publish had already replaced. + await safeWriteText(targetPath, "data", { backup: true, platform: "win32" }) + + const callOrder = vi.mocked(execFile).mock.invocationCallOrder + const copyOrder = vi.mocked(fs.copyFile).mock.invocationCallOrder + const renameOrder = vi.mocked(fs.rename).mock.invocationCallOrder + const saveCall = callOrder[0] + const restoreCall = callOrder[1] + const backupCopy = copyOrder[0] + const commitRename = renameOrder[0] + + expect(saveCall).toBeLessThan(backupCopy) + expect(backupCopy).toBeLessThan(commitRename) + expect(commitRename).toBeLessThan(restoreCall) + }) + + it("win32 DACL: a failed restore is an error and the dump is still unlinked", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {}) + + // icacls save succeeds, restore fails + let callCount = 0 + vi.mocked(execFile).mockImplementation((_cmd, _args, _opts, cb) => { + callCount++ + if (typeof cb === "function") { + cb(callCount === 1 ? null : new Error("icacls restore error"), "", "") + } + return fakeChild + }) + + await expect(safeWriteText(targetPath, "data", { platform: "win32" })).rejects.toBeInstanceOf( + DaclRestoreError, + ) + + // The content did commit before the restore failed, so the rename happened exactly once + // even though the publish reports an error. + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), targetPath) + expect(fs.rename).toHaveBeenCalledTimes(1) + + // Contract change: the changed access rights are an error the caller receives, not a + // warning beside a write that resolved. + expect(warnSpy.mock.calls.flat().join(" ")).not.toContain("could not be restored") + warnSpy.mockRestore() + + // dump file was still unlinked in finally + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining("safeWriteText.acl")) + }) + + it("win32 DACL: when target does not exist, no save/restore/dump", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + // fs.access rejects for targetPath (ENOENT), but resolves for dirPath + vi.mocked(fs.access).mockImplementation(async (p) => { + if (typeof p === "string" && p.endsWith("target.txt")) throw { code: "ENOENT" } + return undefined + }) + + await safeWriteText(targetPath, "data", { platform: "win32" }) + + // icacls was NOT called (target absent → skip DACL entirely) + expect(execFile).not.toHaveBeenCalled() + + // no dump file created or unlinked + expect(fs.unlink).not.toHaveBeenCalled() + }) + }) + + // ── Test 6: pre-written temp path (tempPath option) ────────────────────── + + describe("pre-written temp path", () => { + it("uses the provided tempPath, fsyncs it, and renames to target", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + const customTempPath = "/tmp/test-dir/custom-temp.tmp" + + // platform:linux skips DACL entirely so this test focuses on tempPath only + await safeWriteText(targetPath, "", { tempPath: customTempPath, platform: "linux" }) + + // openSync was called on the custom temp path (r+ mode for fsync) + expect(fsSync.openSync).toHaveBeenCalledWith(customTempPath, "r+") + + // fsync was called + expect(fsSync.fsyncSync).toHaveBeenCalledWith(1) + + // rename happened — realpath mock returns targetPath + expect(fs.rename).toHaveBeenCalledWith(customTempPath, targetPath) + + // no unlink of custom temp (caller's concern; DACL skipped via platform:linux) + expect(fs.unlink).not.toHaveBeenCalled() + + // a caller-supplied tempPath must not create the staging directory + expect(fsSync.mkdirSync).not.toHaveBeenCalled() + }) + + it("applies the existing target's mode to a caller-supplied tempPath before publishing", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.statSync).mockReturnValue(_stats(0o600)) + vi.mocked(fsSync.openSync).mockReturnValue(2) + + const customTempPath = "/tmp/test-dir/custom-temp.tmp" + + await safeWriteText(targetPath, "", { tempPath: customTempPath, platform: "linux" }) + + // the caller-staged temp is fchmod'd to the restrictive target mode so + // the atomic rename cannot widen a 0o600 target (CWE-732 regression) + expect(fsSync.fchmodSync).toHaveBeenCalledWith(2, 0o600) + expect(fsSync.openSync).toHaveBeenCalledWith(customTempPath, "r+") + expect(fs.rename).toHaveBeenCalledWith(customTempPath, targetPath) + }) + + it("keeps the temp's default mode when the target does not exist yet (ENOENT)", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + const enoent = Object.assign(new Error("ENOENT: no such file or directory"), { code: "ENOENT" }) + vi.mocked(fsSync.statSync).mockImplementation(() => { + throw enoent + }) + vi.mocked(fsSync.openSync).mockReturnValue(2) + + const customTempPath = "/tmp/test-dir/custom-temp.tmp" + + await safeWriteText(targetPath, "", { tempPath: customTempPath, platform: "linux" }) + + // no existing target, so nothing to preserve and no fchmod on the temp + expect(fsSync.fchmodSync).not.toHaveBeenCalled() + expect(fs.rename).toHaveBeenCalledWith(customTempPath, targetPath) + }) + + it("propagates a non-ENOENT stat failure rather than defaulting the mode (caller-staged)", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + const eacces = Object.assign(new Error("EACCES: permission denied"), { code: "EACCES" }) + vi.mocked(fsSync.statSync).mockImplementation(() => { + throw eacces + }) + vi.mocked(fsSync.openSync).mockReturnValue(2) + + const customTempPath = "/tmp/test-dir/custom-temp.tmp" + + // A target that cannot be stat'd is not a fresh target: publishing with + // the default mode would widen a restrictive target through the rename. + await expect( + safeWriteText(targetPath, "", { tempPath: customTempPath, platform: "linux" }), + ).rejects.toThrow("EACCES") + expect(fsSync.fchmodSync).not.toHaveBeenCalled() + expect(fs.rename).not.toHaveBeenCalled() + }) + + it("propagates a non-ENOENT stat failure rather than defaulting the mode (self-staged)", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + const eio = Object.assign(new Error("EIO: i/o error"), { code: "EIO" }) + vi.mocked(fsSync.statSync).mockImplementation(() => { + throw eio + }) + + // The mode is read before the temp is opened, so a real I/O failure stops + // the write before anything is staged. + await expect(safeWriteText(targetPath, "hello world", { platform: "linux" })).rejects.toThrow("EIO") + expect(fsSync.openSync).not.toHaveBeenCalled() + expect(fs.rename).not.toHaveBeenCalled() + }) + + it("opens the temp before applying a read-only target's mode (0o444 does not block the open)", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.statSync).mockReturnValue(_stats(0o444)) + vi.mocked(fsSync.openSync).mockReturnValue(3) + + const customTempPath = "/tmp/test-dir/custom-temp.tmp" + + await safeWriteText(targetPath, "", { tempPath: customTempPath, platform: "linux" }) + + // a 0o444 target must not make openSync(tempPath, "r+") fail: the mode + // is applied with fchmodSync on the already-open fd, after the open + expect(fsSync.openSync).toHaveBeenCalledWith(customTempPath, "r+") + expect(fsSync.fchmodSync).toHaveBeenCalledWith(3, 0o444) + const openIdx = vi.mocked(fsSync.openSync).mock.invocationCallOrder[0] + const fchmodIdx = vi.mocked(fsSync.fchmodSync).mock.invocationCallOrder[0] + expect(openIdx).toBeLessThan(fchmodIdx) + expect(fs.rename).toHaveBeenCalledWith(customTempPath, targetPath) + }) + + it("applies the existing target's exact mode to the self-staged temp (umask must not narrow it)", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.statSync).mockReturnValue(_stats(0o664)) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + await safeWriteText(targetPath, "data", { platform: "linux" }) + + // openSync's creation mode is narrowed by the process umask (0o664 -> 0o644 with + // the common 0o022), and the rename publishes the temp's mode onto the target, + // so the existing target's mode must be applied on the fd before the commit. + expect(fsSync.fchmodSync).toHaveBeenCalledWith(1, 0o664) + const openIdx = vi.mocked(fsSync.openSync).mock.invocationCallOrder[0] + const fchmodIdx = vi.mocked(fsSync.fchmodSync).mock.invocationCallOrder[0] + expect(openIdx).toBeLessThan(fchmodIdx) + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), targetPath) + }) + + it("does not fchmod the self-staged temp for a fresh target", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + const enoent = Object.assign(new Error("ENOENT: no such file or directory"), { code: "ENOENT" }) + vi.mocked(fsSync.statSync).mockImplementation(() => { + throw enoent + }) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + await safeWriteText(targetPath, "data", { platform: "linux" }) + + // Nothing exists to preserve: the default creation mode is the intended one. + expect(fsSync.fchmodSync).not.toHaveBeenCalled() + }) + }) + + // ── Test 7: symlink handling (Finding 4 regression test) ───────────────── + + describe("symlink handling", () => { + it("a write through a symlink commits onto the resolved referent, never the link path", async () => { + const linkPath = "/tmp/links/link.txt" + const referentPath = "/tmp/targets/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(referentPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + await safeWriteText(linkPath, "new-content", { platform: "linux" }) + + // The commit rename must target the realpath result (the referent), never the link itself — + // that is what guarantees a write through a symlink replaces the referent's content + // and preserves the link. + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), referentPath) + expect(fs.rename).not.toHaveBeenCalledWith(expect.anything(), linkPath) + }) + + it("when realpath reports ENOENT (target absent), uses the given path as-is", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockRejectedValue(Object.assign(new Error("ENOENT"), { code: "ENOENT" })) + // lstat reports the path itself as absent, so this is a new target and + // the fallback is allowed. + vi.mocked(fs.lstat).mockRejectedValue(Object.assign(new Error("ENOENT"), { code: "ENOENT" })) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + await safeWriteText(targetPath, "data", { platform: "linux" }) + + // rename still happened with the fallback path (path.resolve on /tmp → C:\tmp) + const resolvedFallback = _resolvedTarget(targetPath) + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), resolvedFallback) + }) + + it("propagates a dangling symlink instead of writing through the link path", async () => { + // realpath resolves the referent, so a link whose target is missing reports + // ENOENT. Falling back to the link path would replace the symlink with a + // regular file, so the error must propagate and nothing may be committed. + const linkPath = "/tmp/test-dir/dangling-link.txt" + vi.mocked(fs.realpath).mockRejectedValue(Object.assign(new Error("ENOENT"), { code: "ENOENT" })) + const linkStats = Object.create(fsSync.Stats.prototype) as fsSync.Stats + linkStats.isSymbolicLink = () => true + vi.mocked(fs.lstat).mockResolvedValue(linkStats) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + await expect(safeWriteText(linkPath, "data", { platform: "linux" })).rejects.toThrow("ENOENT") + + expect(fs.rename).not.toHaveBeenCalled() + }) + }) + + // ── Test 8: review fixes (permissions, partial writes, resolution, durability) ── + + describe("review fixes", () => { + it("preserves the target's restrictive mode and tolerates a failed staging-dir permission repair", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + vi.mocked(fsSync.statSync).mockReturnValue(_stats(0o600)) + // a pre-existing staging dir may fail its best-effort permission repair + vi.mocked(fsSync.chmodSync).mockImplementationOnce(() => { + throw new Error("EACCES") + }) + + await safeWriteText(targetPath, "secret", { platform: "linux" }) + + // the staging file inherits the target's 0o600 mode and the write commits + expect(fsSync.openSync).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), "w", 0o600) + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), targetPath) + }) + + it("falls back to the 0o644 default when the target does not exist yet", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + vi.mocked(fsSync.statSync).mockImplementation(() => { + throw Object.assign(new Error("ENOENT"), { code: "ENOENT" }) + }) + + await safeWriteText(targetPath, "fresh", { platform: "linux" }) + + expect(fsSync.openSync).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), "w", 0o644) + }) + + it("loops on short writes until the full content is durable before fsync", async () => { + const targetPath = "/tmp/test-dir/target.txt" + const content = "0123456789" // 10 bytes + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + const buffer = Buffer.from(content, "utf8") + // first write (offset 0) reports 4 bytes (short write); the loop continues + vi.mocked(fsSync.writeSync).mockImplementation((...args: unknown[]) => + args[2] === 0 ? 4 : typeof args[3] === "number" ? args[3] : 0, + ) + + await safeWriteText(targetPath, content, { platform: "linux" }) + + // [0,10) reports 4 bytes, then [4,10) writes the remaining 6 + expect(fsSync.writeSync).toHaveBeenCalledTimes(2) + expect(fsSync.writeSync).toHaveBeenNthCalledWith(1, 1, buffer, 0, 10) + expect(fsSync.writeSync).toHaveBeenNthCalledWith(2, 1, buffer, 4, 6) + expect(fsSync.fsyncSync).toHaveBeenCalledWith(1) + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), targetPath) + }) + + it("fsyncs the parent directory after the commit rename on POSIX", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + // temp fd=1 then parent-dir fd=2 - distinct fds prove the ordering + vi.mocked(fsSync.openSync).mockReturnValueOnce(1).mockReturnValue(2) + + await safeWriteText(targetPath, "data", { platform: "linux" }) + + // the directory fsync (fd 2) happens only after the file fsync (fd 1); + // the dir path assertion is path-agnostic (stringContaining) because + // path.dirname renders the same input differently on Windows + expect(fsSync.openSync).toHaveBeenCalledWith(expect.stringContaining("test-dir"), "r") + expect(fsSync.fsyncSync).toHaveBeenNthCalledWith(1, 1) + expect(fsSync.fsyncSync).toHaveBeenNthCalledWith(2, 2) + expect(fsSync.closeSync).toHaveBeenCalledWith(2) + }) + + it("reports a failed parent-directory fsync instead of claiming a durable write", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync) + .mockReturnValueOnce(1) + .mockImplementationOnce(() => { + throw new Error("EBADF") + }) + + // The content rename committed, so the caller can still find the data at + // the target; what the write cannot claim is that the directory entry + // reached the disk. Returning success here would claim durability the + // filesystem did not grant. + await expect(safeWriteText(targetPath, "data", { platform: "linux" })).rejects.toThrow( + PostCommitDurabilityError, + ) + + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), targetPath) + }) + + it("propagates realpath errors (EACCES and code-less) instead of the fallback path", async () => { + const targetPath = "/tmp/test-dir/target.txt" + const eacces = Object.assign(new Error("EACCES: permission denied"), { code: "EACCES" }) + vi.mocked(fs.realpath).mockRejectedValueOnce(eacces) + await expect(safeWriteText(targetPath, "data", { platform: "linux" })).rejects.toBe(eacces) + expect(fs.rename).not.toHaveBeenCalled() + + const plain = new Error("resolution failed") + vi.mocked(fs.realpath).mockRejectedValueOnce(plain) + await expect(safeWriteText(targetPath, "data", { platform: "linux" })).rejects.toBe(plain) + expect(fs.rename).not.toHaveBeenCalled() + }) + + it("backup:true propagates access errors (EACCES and code-less) instead of skipping the backup", async () => { + const targetPath = "/tmp/test-dir/target.txt" + const eacces = Object.assign(new Error("EACCES"), { code: "EACCES" }) + const plain = new Error("access failed") + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + // each write accesses dirPath then target; only the target access rejects + const rejectTarget = (error: Error) => async (p: unknown) => { + if (typeof p === "string" && p.endsWith("target.txt")) throw error + } + vi.mocked(fs.access) + .mockImplementationOnce(rejectTarget(eacces)) + .mockImplementationOnce(rejectTarget(eacces)) + .mockImplementationOnce(rejectTarget(plain)) + .mockImplementationOnce(rejectTarget(plain)) + + await expect(safeWriteText(targetPath, "data", { backup: true, platform: "linux" })).rejects.toEqual( + expect.objectContaining({ code: "EACCES" }), + ) + await expect(safeWriteText(targetPath, "data", { backup: true, platform: "linux" })).rejects.toThrow( + "access failed", + ) + expect(fs.rename).not.toHaveBeenCalled() + }) + }) + describe("content bytes", () => { + const targetPath = "/tmp/enc-dir/target.txt" + + beforeEach(() => { + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + }) + + it("stages UTF-8 bytes for string content", async () => { + await safeWriteText(targetPath, "héllo", { platform: "linux" }) + expect(fsSync.writeSync).toHaveBeenCalledWith(1, Buffer.from("héllo", "utf8"), 0, 6) + }) + + it("publishes caller-supplied bytes unchanged instead of re-encoding them", async () => { + // The extension host encodes a document with VS Code's own codec, which + // covers the legacy code pages and BOMs Node cannot represent, and hands + // the result over: those bytes must reach the commit rename exactly as + // they were given. + const bytes = Buffer.from([0x00, 0x68, 0x00, 0x69]) + await safeWriteText(targetPath, bytes, { platform: "linux" }) + expect(fsSync.writeSync).toHaveBeenCalledWith(1, bytes, 0, 4) + }) + }) +}) + +// ── Test 12: lock key, staging path, and post-commit durability ───────────── + +describe("resolveLockKey", () => { + beforeEach(() => mockDefaults()) + + it("canonicalizes the parent directory, not just the file", async () => { + vi.mocked(fs.realpath).mockImplementation(async (target) => { + const key = String(target) + if (key === "/tmp/linkdir/file.json") return "/real/dir/file.json" + if (key === "/real/dir") return "/real/dir" + return key + }) + + // The key is the canonical directory plus the basename, so a symlinked + // ancestor and its referent share one lock. + await expect(resolveLockKey("/tmp/linkdir/file.json")).resolves.toBe(path.join("/real/dir", "file.json")) + }) + + it("computes a key for a dangling link, which resolvePublishTarget refuses", async () => { + const enoent = Object.assign(new Error("ENOENT: no such file or directory"), { code: "ENOENT" }) + vi.mocked(fs.realpath).mockRejectedValue(enoent) + vi.mocked(fs.lstat).mockResolvedValue(_fileStats(true)) + // Only the link path is read, so a single answer is enough and keeps the mock's + // return type matching fs.promises.readlink. + vi.mocked(fs.readlink).mockResolvedValue("referent.json") + + // Mid-commit a peer writer unlinks the referent and re-creates it, so the key + // must still be computable while the link dangles. + await expect(resolveLockKey("/tmp/linkdir/file.json")).resolves.toBe( + path.resolve(path.join("/tmp/linkdir", "referent.json")), + ) + }) + + it("terminates on a two-link cycle instead of walking forever", async () => { + const enoent = Object.assign(new Error("ENOENT: no such file or directory"), { code: "ENOENT" }) + vi.mocked(fs.realpath).mockRejectedValue(enoent) + vi.mocked(fs.lstat).mockResolvedValue(_fileStats(true)) + // Every readlink answers with the same link, so an unbounded walk would + // never end; the bounded walk returns the key it actually reached. + vi.mocked(fs.readlink).mockImplementation(async () => "a.json") + + await expect(resolveLockKey("/tmp/linkdir/a.json")).resolves.toBe( + path.resolve(path.join("/tmp/linkdir", "a.json")), + ) + expect(fs.readlink).toHaveBeenCalledTimes(8) + }) +}) + +describe("caller-supplied staging path", () => { + beforeEach(() => mockDefaults()) + + it("rejects a staging file outside the target's directory before writing anything", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + + // A rename across filesystems fails with EXDEV, and a path elsewhere lets + // a caller publish an unrelated file onto the target. + await expect( + safeWriteText(targetPath, "data", { tempPath: "/tmp/other-dir/x.tmp", platform: "linux" }), + ).rejects.toThrow(StagingPathError) + expect(fsSync.openSync).not.toHaveBeenCalled() + expect(fs.rename).not.toHaveBeenCalled() + }) + + it("rejects a staging path that is a symlink", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fs.lstat).mockResolvedValue(_fileStats(true)) + + // Renaming a link over the target publishes whatever the link points at. + await expect( + safeWriteText(targetPath, "data", { tempPath: "/tmp/test-dir/x.tmp", platform: "linux" }), + ).rejects.toThrow(StagingPathError) + expect(fsSync.openSync).not.toHaveBeenCalled() + expect(fs.rename).not.toHaveBeenCalled() + }) + + it("rejects a staging path that is a directory rather than a regular file", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + // A directory satisfies the location rule (it sits beside the target) and is neither a + // symlink nor a regular file. Renaming it over the target would publish a directory in + // place of the file, so the rejection has to name the file type and happen before anything + // is opened or renamed. Structural double: BigIntStats has no constructor a test can call. + vi.mocked(fs.lstat).mockResolvedValue({ + isSymbolicLink: () => false, + isFile: () => false, + } as unknown as BigIntStats) + + await expect( + safeWriteText(targetPath, "data", { tempPath: "/tmp/test-dir/x.tmp", platform: "linux" }), + ).rejects.toThrow(/another file type/) + + expect(fsSync.openSync).not.toHaveBeenCalled() + expect(fs.rename).not.toHaveBeenCalled() + }) + + it("rejects a staging path that is the target itself", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + // Same inode and device for the supplied staging path and the target: the + // failure handler would unlink the only copy of the content, so a failed + // write would delete the file it was meant to protect. + const stats = _fileStatsWithIdentity(42n, 7n) + vi.mocked(fs.lstat).mockResolvedValue(stats) + + await expect(safeWriteText(targetPath, "data", { tempPath: targetPath, platform: "linux" })).rejects.toThrow( + StagingPathError, + ) + expect(fsSync.openSync).not.toHaveBeenCalled() + expect(fs.rename).not.toHaveBeenCalled() + // The comparison is only sound when both stats are read as bigint: on NTFS/ReFS the file + // identifiers exceed Number.MAX_SAFE_INTEGER. + // Filter on the options, not the spelling: path.resolve prefixes a drive letter on Windows, + // so the two identity reads are the calls that asked for options at all. + const identityLookups = vi.mocked(fs.lstat).mock.calls.filter((c) => c[1] !== undefined) + expect(identityLookups.length).toBeGreaterThanOrEqual(2) + for (const c of identityLookups) { + expect(c[1]).toEqual({ bigint: true }) + } + expect(fs.unlink).not.toHaveBeenCalled() + }) + + it("rejects when the target identity cannot be compared for a reason other than a missing target", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + // A hard-linked staging file shares the target's inode, so the identity comparison is the only thing + // between this write and a rename onto the very file the guard protects. An EACCES from the target + // lstat must not be mistaken for "there is no target". + const stagingStats = _fileStatsWithIdentity(42n, 7n) + vi.mocked(fs.lstat).mockImplementation(async (p) => { + if (String(p) === targetPath) { + throw Object.assign(new Error("EACCES"), { code: "EACCES" }) + } + return stagingStats + }) + + await expect( + safeWriteText(targetPath, "data", { tempPath: "/tmp/test-dir/hardlink.txt", platform: "linux" }), + ).rejects.toThrow("Staging file could not be compared with the target") + expect(fsSync.openSync).not.toHaveBeenCalled() + expect(fs.rename).not.toHaveBeenCalled() + // Both identity reads must ask for bigint stats, or the comparison silently falls + // back to rounded numbers on NTFS/ReFS. + const identityLookups = vi.mocked(fs.lstat).mock.calls.filter((c) => c[1] !== undefined) + expect(identityLookups).toHaveLength(2) + for (const c of identityLookups) { + expect(c[1]).toEqual({ bigint: true }) + } + }) +}) + +describe("cleanup when a backed-up write fails before commit", () => { + beforeEach(() => mockDefaults()) + + it("releases the staged file, its copy and its own staging directory before throwing", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + // The commit rename is the only rename in this flow and it fails. + vi.mocked(fs.rename).mockRejectedValue(new Error("ENOSPC")) + + await expect(safeWriteText(targetPath, "data", { backup: true, platform: "linux" })).rejects.toThrow("ENOSPC") + + // The staging file and this write's own directory must not leak, and neither may + // the backup copy: the target still holds the pre-write content on disk. + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_")) + expect(fs.unlink).toHaveBeenCalledWith(expect.stringContaining("safeWriteText.bak_")) + const stagingDirs = vi.mocked(fsSync.mkdirSync).mock.calls.map((call) => String(call[0])) + expect(stagingDirs.length).toBe(1) + expect(fs.rmdir).toHaveBeenCalledWith(stagingDirs[0]) + + const failingRenameOrder = vi.mocked(fs.rename).mock.invocationCallOrder[0] + const unlinkOrder = vi.mocked(fs.unlink).mock.invocationCallOrder[0] + const rmdirOrder = vi.mocked(fs.rmdir).mock.invocationCallOrder[0] + expect(unlinkOrder).toBeGreaterThan(failingRenameOrder) + expect(rmdirOrder).toBeGreaterThan(failingRenameOrder) + }) +}) + +describe("resolvePublishTarget", () => { + beforeEach(() => mockDefaults()) + + it("propagates an lstat failure that is not ENOENT instead of falling back to the link path", async () => { + const targetPath = "/tmp/test-dir/target.txt" + const enoent = Object.assign(new Error("ENOENT: no such file or directory"), { code: "ENOENT" }) + const eacces = Object.assign(new Error("EACCES: permission denied"), { code: "EACCES" }) + vi.mocked(fs.realpath).mockRejectedValue(enoent) + vi.mocked(fs.lstat).mockRejectedValue(eacces) + + // A failed lstat says nothing about whether the path is a link, so the + // fallback would publish through a link we were not allowed to inspect. + await expect(safeWriteText(targetPath, "data", { platform: "linux" })).rejects.toBe(eacces) + expect(fs.rename).not.toHaveBeenCalled() + }) + + it("still falls back to the given path when lstat also reports the path as absent", async () => { + const targetPath = "/tmp/test-dir/target.txt" + const enoent = Object.assign(new Error("ENOENT: no such file or directory"), { code: "ENOENT" }) + vi.mocked(fs.realpath).mockRejectedValue(enoent) + vi.mocked(fs.lstat).mockRejectedValue(enoent) + vi.mocked(fsSync.openSync).mockReturnValue(1) + + await safeWriteText(targetPath, "data", { platform: "linux" }) + + // The fallback is the resolved path, not the string that was handed in. + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), path.resolve(targetPath)) + }) +}) + +// A publish that cannot remove something it created has to say so on whichever exit it takes: the +// resolved result carries the paths, and a rejection carries the same paths on the error, because the +// throw discards the result. Each test below names one residue kind and one exit path. + +describe("residue a publish must not lose", () => { + beforeEach(() => mockDefaults()) + + /** Make only the DACL dump unlink fail, and record every attempt at it. */ + function stuckDumpUnlink(): string[] { + const attempts: string[] = [] + vi.mocked(fs.unlink).mockImplementation(async (p: unknown) => { + if (String(p).includes("safeWriteText.acl")) { + attempts.push(String(p)) + throw Object.assign(new Error("EPERM: operation not permitted"), { code: "EPERM" }) + } + }) + return attempts + } + + it("win32 DACL: a dump the finally block cannot remove is reported on the resolved write", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + const dumpAttempts = stuckDumpUnlink() + + const result = await safeWriteText(targetPath, "data", { platform: "win32" }) + + // The publish committed and the restore ran: a dump that survives cleanup is a leftover to + // sweep, not a failed save. + expect(fs.rename).toHaveBeenCalledWith(expect.stringContaining("safeWriteText_"), targetPath) + expect(execFile).toHaveBeenCalledTimes(2) + + // The dump is retried once, and the result names the path once: recording each attempt would + // tell the caller there are two files to remove when there is one. + expect(dumpAttempts).toHaveLength(2) + expect(result).toEqual({ leftoverPaths: [dumpAttempts[0]] }) + }) + + it("win32 DACL: a partial dump that cannot be removed is reported on the refusal", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + // icacls /save fails, so a partial dump may exist, and removing it fails too. + vi.mocked(execFile).mockImplementation((_cmd, _args, _opts, cb) => { + if (typeof cb === "function") cb(new Error("icacls error"), "", "") + return fakeChild + }) + const dumpAttempts = stuckDumpUnlink() + + const refusal = await safeWriteText(targetPath, "data", { platform: "win32" }).catch( + (caught: unknown) => caught, + ) + + expect(refusal).toBeInstanceOf(DaclInspectionError) + expect(fs.rename).not.toHaveBeenCalled() + + // The refusal throws, so the structured result never reaches the caller. Without the residue + // on the error the caller holds an error naming no file while a partial DACL dump - a file + // whose contents describe access rights - stays on disk with no reference to it anywhere. + expect(refusal).toMatchObject({ + leftoverPaths: [dumpAttempts[0]], + cleanupErrors: [expect.objectContaining({ code: "EPERM" })], + }) + }) + + it("win32 DACL: a restore failure carries the dump its cleanup could not remove", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + // The save lands, the restore fails: the commit happened, so this is the exit where the + // dump's owner is the finally block and the error is DaclRestoreError. + let icaclsCalls = 0 + vi.mocked(execFile).mockImplementation((_cmd, _args, _opts, cb) => { + icaclsCalls++ + if (typeof cb === "function") cb(icaclsCalls === 1 ? null : new Error("icacls restore error"), "", "") + return fakeChild + }) + const dumpAttempts = stuckDumpUnlink() + + const failure = await safeWriteText(targetPath, "data", { platform: "win32" }).catch( + (caught: unknown) => caught, + ) + + expect(failure).toBeInstanceOf(DaclRestoreError) + expect(fs.rename).toHaveBeenCalledTimes(1) + // The original error is preserved, not replaced: its message is what tells the caller that + // the committed file answers to different access rights. + expect((failure as DaclRestoreError).message).toContain("could not be restored") + + // Previously the finally block recorded this path and the failure handler threw it away with + // the result, so a dump left by a failed restore was invisible on the only exit taken. + expect(failure).toMatchObject({ leftoverPaths: [dumpAttempts[0]] }) + }) + + it("a failed publish reports the staged file it could not remove", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + vi.mocked(fs.rename).mockRejectedValue(new Error("ENOSPC")) + const stagedAttempts: string[] = [] + vi.mocked(fs.unlink).mockImplementation(async (p: unknown) => { + if (String(p).includes("safeWriteText_")) { + stagedAttempts.push(String(p)) + throw Object.assign(new Error("EPERM: operation not permitted"), { code: "EPERM" }) + } + }) + + const failure = await safeWriteText(targetPath, "data", { platform: "linux" }).catch( + (caught: unknown) => caught, + ) + + expect((failure as Error).message).toBe("ENOSPC") + expect(stagedAttempts).toHaveLength(2) + expect(failure).toMatchObject({ leftoverPaths: [stagedAttempts[0]] }) + }) + + it("a failed publish reports the staging directory it could not remove", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + vi.mocked(fs.rename).mockRejectedValue(new Error("ENOSPC")) + vi.mocked(fs.rmdir).mockRejectedValue(Object.assign(new Error("ENOTEMPTY"), { code: "ENOTEMPTY" })) + + const failure = await safeWriteText(targetPath, "data", { platform: "linux" }).catch( + (caught: unknown) => caught, + ) + + const stagingDir = vi.mocked(fsSync.mkdirSync).mock.calls.map((call) => String(call[0]))[0] + expect(failure).toMatchObject({ leftoverPaths: [stagingDir] }) + }) + + it("a failed publish reports a backup copy it could not remove and still warns about it", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + vi.mocked(fs.rename).mockRejectedValue(new Error("ENOSPC")) + const backupAttempts: string[] = [] + vi.mocked(fs.unlink).mockImplementation(async (p: unknown) => { + if (String(p).includes("safeWriteText.bak_")) { + backupAttempts.push(String(p)) + throw Object.assign(new Error("EPERM: operation not permitted"), { code: "EPERM" }) + } + }) + const warnings: string[] = [] + + const failure = await safeWriteText(targetPath, "data", { + backup: true, + platform: "linux", + onWarning: (message) => warnings.push(message), + }).catch((caught: unknown) => caught) + + expect((failure as Error).message).toBe("ENOSPC") + // The human notice and the caller-visible list are separate channels: neither replaces the + // other, because a caller cannot parse a warning and a human cannot read a thrown array. + expect(warnings).toHaveLength(1) + expect(warnings[0]).toContain("safeWriteText.bak_") + expect(failure).toMatchObject({ leftoverPaths: [backupAttempts[0]] }) + }) + + it("a publish that cleaned everything up attaches no residue to its error", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + vi.mocked(fs.rename).mockRejectedValue(new Error("ENOSPC")) + + const failure = await safeWriteText(targetPath, "data", { platform: "linux" }).catch( + (caught: unknown) => caught, + ) + + // An empty list would make every caller ask whether "no leftovers" means it checked or that + // the field was never filled in, so nothing is attached unless something stayed on disk. + expect((failure as PublishResidue).leftoverPaths).toBeUndefined() + expect((failure as PublishResidue).cleanupErrors).toBeUndefined() + }) + + it("a thrown value that cannot carry the residue is rethrown exactly as it came", async () => { + const targetPath = "/tmp/test-dir/target.txt" + vi.mocked(fs.realpath).mockResolvedValue(targetPath) + vi.mocked(fsSync.openSync).mockReturnValue(1) + // A rejected promise can carry any value, not only an Error. Attaching the residue by + // replacing such a value would change the error the caller catches, and assigning a property + // to a primitive throws, so the failure would become a TypeError about the cleanup. + vi.mocked(fs.rename).mockRejectedValue("boom") + vi.mocked(fs.unlink).mockRejectedValue(Object.assign(new Error("EPERM"), { code: "EPERM" })) + + const failure = await safeWriteText(targetPath, "data", { platform: "linux" }).catch( + (caught: unknown) => caught, + ) + + expect(failure).toBe("boom") + }) +}) diff --git a/src/services/file-safety/safeWriteText.ts b/src/services/file-safety/safeWriteText.ts new file mode 100644 index 0000000000..17bfd08059 --- /dev/null +++ b/src/services/file-safety/safeWriteText.ts @@ -0,0 +1,779 @@ +import * as fs from "fs/promises" +import * as fsSync from "fs" +import * as path from "path" +import { execFile } from "child_process" + +export interface SafeWriteTextOptions { + /** + * When true, keep the old-file semantics without ever removing the target: the + * previous content is copied to a hidden backup path and flushed before the + * commit rename, the commit rename atomically replaces the target, and on success + * the backup copy is deleted. A failure before the commit leaves the target + * untouched (there is nothing to roll back) and removes the backup copy. When + * false (default) the atomic rename simply replaces the target. + */ + backup?: boolean + + /** + * Platform override for testing. When omitted the real process.platform + * value is used. Set to "win32" or "linux" / "darwin" from tests so that + * both branches are reachable without needing a real Windows runner. + */ + platform?: string + + /** + * Custom execFile runner for testing (e.g. vi.fn). When omitted the real + * child_process.execFile is used. + */ + execFileRunner?: typeof execFile + + /** + * Sink for non-fatal safety notices. The notices that still reach it are the leftover ones: a copy + * of the previous content this write could not remove, reported with its path whether the + * publish committed or failed. A Windows DACL that could not be captured is no longer a notice + * here - the publish is refused with DaclInspectionError before anything is committed - and a + * saved DACL that could not be put back after the commit arrives as DaclRestoreError rather + * than a warning, so neither reaches this sink. Defaults to console.warn. + */ + onWarning?: (message: string) => void + + /** + * Pre-written temp path to use for the commit phase. When provided, + * safeWriteText skips creating its own staging file and uses this path + * instead (it still fsyncs before rename). Useful when a caller has + * already written data to a temp file via a custom stream. + */ + tempPath?: string +} + +/** + * A caller-supplied staging path that is not a file this write may publish: it + * sits outside the target's directory (so the commit rename would cross + * filesystems) or is not a regular file. Rejecting it before any write keeps the + * target from being replaced by whatever the path points at. + */ +export class StagingPathError extends Error { + readonly stagingPath: string + + constructor(message: string, stagingPath: string) { + super(message) + this.name = "StagingPathError" + this.stagingPath = stagingPath + } +} + +/** + * The commit rename succeeded but the parent-directory fsync did not, so the + * directory entry is not known to be durable. The content is at the target; the + * caller cannot assume it survives a crash. Reported as its own error so a + * successful return never claims durability the filesystem did not grant. + */ +export class PostCommitDurabilityError extends Error { + readonly targetPath: string + + constructor(targetPath: string, cause: unknown) { + super( + "The rename committed but the parent directory could not be fsynced -- the content is at the target path reported on this error, and the directory entry may not be durable.", + { cause }, + ) + this.name = "PostCommitDurabilityError" + this.targetPath = targetPath + } +} + +/** + * The target exists but its access rights could not be inspected or saved, so publishing would + * replace it with a file that inherits different rights. On Windows the publish fails instead of + * warning: a successful write that silently widened who can read the file is not a save the user + * can trust, and the failure happens before the commit, so the target still holds its content. + */ +export class DaclInspectionError extends Error { + constructor( + readonly targetPath: string, + readonly phase: "inspect" | "save", + readonly causeError: unknown, + ) { + const detail = phase === "save" ? "its DACL could not be saved" : "its access rights could not be checked" + super(`safeWriteText: refusing to publish over ${targetPath} because ${detail}`) + this.name = "DaclInspectionError" + } +} + +/** + * The content is committed but the saved DACL could not be put back on it, so the file at the + * target answers to different access rights than the one it replaced. Reported as an error rather + * than a warning: the caller has to know that the publish changed who can read the file. + */ +export class DaclRestoreError extends Error { + constructor( + readonly targetPath: string, + readonly causeError: unknown, + ) { + super(`safeWriteText: content committed at ${targetPath}, but its saved access rights could not be restored`) + this.name = "DaclRestoreError" + } +} + +/** The outcome of a publish: paths this call left on disk that it could not remove. */ +export interface SafeWriteTextResult { + /** + * Every leftover this write could not clean up (a backup copy whose unlink kept failing, a DACL + * dump, a staging directory). A warning tells a human about them; this is what the caller has to + * act on - a retry, a startup sweep, or a message that names the path. + */ + leftoverPaths: string[] +} + +/** + * The residue a publish could not remove. A resolved write reports it in `SafeWriteTextResult`; a + * rejected write cannot, because the throw discards that result, so the same two lists travel on the + * error the caller catches instead. Without them a failed publish would leave a file on disk with no + * reference to it anywhere the caller can reach. + */ +export interface PublishResidue { + /** Paths this write left on disk that its own cleanup could not remove. */ + leftoverPaths: string[] + /** The failure that kept each path on disk, in the same order as `leftoverPaths`. */ + cleanupErrors: unknown[] +} + +/** + * The backup copy could not be created AND the partial copy could not be removed. + * The write failed either way, but the leftover is a copy of the previous content that + * is still on disk: its path travels on the error so the caller can remove it, instead + * of the cleanup silently discarding the only reference to it. + */ +export class OrphanedBackupError extends Error { + readonly orphanedBackupPath: string + readonly originalError: unknown + readonly cleanupError: unknown + constructor(backupPath: string, targetPath: string, cause: unknown, cleanupError: unknown) { + super(_orphanedBackupMessage(targetPath, backupPath, cause, cleanupError), { cause }) + this.name = "OrphanedBackupError" + this.orphanedBackupPath = backupPath + this.originalError = cause + this.cleanupError = cleanupError + } +} + +function _orphanedBackupMessage(targetPath: string, backupPath: string, cause: unknown, cleanupError: unknown): string { + const reason = (error: unknown): string => (error instanceof Error ? error.message : String(error)) + return ( + `safeWriteText: could not create the backup of ${targetPath} (${reason(cause)}), and the ` + + `partial copy at ${backupPath} could not be removed (${reason(cleanupError)}). The copy is ` + + `still on disk and must be deleted.` + ) +} +// -- helpers --------------------------------------------------------------- + +/** Generate a unique temp file name in the given directory. */ +function _tempName(dir: string, prefix: string): string { + return path.join(dir, "." + prefix + "_" + Date.now() + "_" + Math.random().toString(36).substring(2) + ".tmp") +} + +/** Create a private per-write staging sub-directory inside *dir*. The name is + * unique per write, so concurrent writes never collide on their temp names and + * never remove a staging directory another write is still using: with one shared + * name, one write's best-effort rmdir could delete the directory another write + * had just created but not yet opened, failing its openSync with ENOENT. */ +function _stagingDir(dir: string): string { + const sd = path.join(dir, ".file-safety-staging_" + Date.now() + "_" + Math.random().toString(36).substring(2)) + // mode:0o700 protects a freshly created staging dir; the best-effort chmod + // repairs a pre-existing one (mkdirSync with recursive:true never chmods an + // existing directory), so staged temp files are never group/world readable. + fsSync.mkdirSync(sd, { recursive: true, mode: 0o700 }) + try { + fsSync.chmodSync(sd, 0o700) + } catch { + // best-effort: chmod denied or unavailable; a fresh dir was still + // created with the requested mode + } + return sd +} + +function _fsyncFile(fd: number): void { + fsSync.fsyncSync(fd) +} + +/** Save the DACL of *srcPath* to a dump file on Windows. + * Returns true when the dump was written successfully; false otherwise. + * Never throws — callers treat failure as "skip DACL handling". */ +async function _saveDaclWindows(srcPath: string, dumpPath: string, execFileRunner?: typeof execFile): Promise { + const runner = execFileRunner ?? execFile + try { + await new Promise((resolve, reject) => { + runner("icacls", [srcPath, "/save", dumpPath, "/T"], { windowsHide: true }, (err) => + err ? reject(err) : resolve(), + ) + }) + return true + } catch { + return false + } +} + +/** Restore a DACL dump onto *dirPath* on Windows. + * Returns whether icacls succeeded; the caller reports a failure. */ +async function _restoreDaclWindows( + dirPath: string, + dumpPath: string, + execFileRunner?: typeof execFile, +): Promise { + const runner = execFileRunner ?? execFile + try { + await new Promise((resolve, reject) => { + runner("icacls", [dirPath, "/restore", dumpPath], { windowsHide: true }, (err) => + err ? reject(err) : resolve(), + ) + }) + return true + } catch { + return false + } +} + +// -- public API ------------------------------------------------------------ + +/** + * Resolve the publish target: the symlink referent when the given path is an + * existing symlink, the path itself otherwise. Only ENOENT (target absent yet) + * may fall back to the given path; any other resolution error (EACCES, EIO, ...) + * propagates so a broken or unreadable symlink is never written through its + * link path. Callers that stage a temp file themselves must stage it beside + * the resolved path: the commit is a rename onto the referent, and a rename + * across filesystems fails with EXDEV. + */ +export async function resolvePublishTarget(absoluteFilePath: string): Promise { + return fs.realpath(absoluteFilePath).catch(async (error: unknown) => { + if (errorCode(error) !== "ENOENT") throw error + // ENOENT also covers a dangling symlink, which must never be written through. + // Only a lstat that also reports the path as absent may fall back to the + // given path; a real lstat failure (EACCES, EIO) says nothing about whether + // the path is a link, so falling back would write through a link we were + // simply not allowed to inspect. + const linkStat = await fs.lstat(absoluteFilePath).catch((lstatError: unknown) => { + if (errorCode(lstatError) === "ENOENT") return undefined + throw lstatError + }) + if (linkStat?.isSymbolicLink()) throw error + return absoluteFilePath + }) +} +/** + * Distinguish "the target does not exist" from a real I/O failure (EACCES, + * EIO, ...). The mode-preservation path may only fall back to the fresh-file + * default on ENOENT; any other failure is propagated, otherwise a restrictive + * target (0o600) would be published with the default 0o644 through the rename. + */ +function errorCode(error: unknown): string | undefined { + return typeof error === "object" && error !== null && "code" in error + ? String((error as { code: unknown }).code) + : undefined +} + +/** + * Canonicalize the parent directory and re-join the basename. fs.realpath + * canonicalizes every component, including a symlinked ancestor directory or a + * Windows 8.3 short name, so a lock key must be canonical even when the file + * itself is not there yet -- otherwise the key for one file depends on whether + * the file exists when the key is computed, and two writers take two locks. + */ + +async function canonicalDirKey(absoluteFilePath: string): Promise { + const dirPath = path.dirname(absoluteFilePath) + const canonicalDir = await fs.realpath(dirPath).catch(() => dirPath) + return path.join(canonicalDir, path.basename(absoluteFilePath)) +} + +/** + * Lock key for a publish target: the symlink referent when the path is an + * existing symlink, the path itself otherwise. Unlike resolvePublishTarget this + * tolerates a dangling link, because the lock key has to be computable while a + * peer writer is mid-commit (a publish renames the staged file onto the referent, + * and backup mode keeps a copy beside it). + * The walk is bounded so a two-link cycle terminates, and every key it returns is + * canonicalized through canonicalDirKey. + */ +export async function resolveLockKey(absoluteFilePath: string): Promise { + try { + return await canonicalDirKey(await resolvePublishTarget(absoluteFilePath)) + } catch { + // A real readlink throws for anything that is not a link, so a normal chain + // ends the walk. Two links that point at each other never would, so the + // walk is bounded and callers use the key they actually reached. + let key = absoluteFilePath + for (let depth = 0; depth < 8; depth++) { + const target = await fs.readlink(key).catch(() => undefined) + if (target === undefined) return await canonicalDirKey(key) + key = await canonicalDirKey(path.resolve(path.dirname(key), target)) + } + return await canonicalDirKey(key) + } +} + +/** + * Remove one residue path this write created, retrying once: Windows reports EPERM for a path whose + * handle has not been released yet, so a single failure is not evidence that the path is stuck. + * ENOENT counts as removed - the goal is that the path is gone, not that this call performed the + * removal. `remove` is the filesystem call for this residue kind (`fs.unlink` for a file, `fs.rmdir` + * for a directory), so every residue this operation owns is removed under one set of rules rather + * than one per kind. Returns the error that kept the path on disk, or null when it is gone. + */ +async function _removeResidue(residuePath: string, remove: (residuePath: string) => Promise): Promise { + let lastError: unknown = null + for (let attempt = 0; attempt < 2; attempt++) { + try { + await remove(residuePath) + return null + } catch (error: unknown) { + if (errorCode(error) === "ENOENT") { + return null + } + lastError = error + } + } + return lastError +} + +/** + * Attach the residue of a failed publish to the error being thrown, preserving that error: the + * caller's `instanceof` checks, its message and its cause all stay exactly as they were, and the + * residue is extra information on top. A publish that cleaned everything up attaches nothing, so a + * caller never has to tell an empty list apart from no residue at all. A thrown value that is not an + * object cannot carry the lists, and replacing it with one that could would change the error the + * caller catches, so it is returned as it came. + */ +function _attachResidue(error: unknown, residue: PublishResidue): unknown { + if (residue.leftoverPaths.length === 0 || typeof error !== "object" || error === null) { + return error + } + const carrier = error as PublishResidue + carrier.leftoverPaths = residue.leftoverPaths + carrier.cleanupErrors = residue.cleanupErrors + return error +} + +export async function safeWriteText( + filePath: string, + content: string | Uint8Array, + options?: SafeWriteTextOptions, +): Promise { + const absoluteFilePath = path.resolve(filePath) + // Every leftover is recorded here as it is discovered, so a caller gets a structured result + // instead of having to parse warnings to learn that content is still on disk. A rejection cannot + // carry that result, so the same two lists are attached to the error it throws instead. + const leftoverPaths: string[] = [] + const cleanupErrors: unknown[] = [] + + /** + * Remove one residue path this write created and record it when it is still there. Every residue + * this operation owns - staged file, staging directory, DACL dump, backup copy - is removed + * through here, so a path that survives is reported the same way whichever step left it behind. + */ + const cleanResidue = async ( + residuePath: string, + remove: (residuePath: string) => Promise, + ): Promise => { + const cleanupError = await _removeResidue(residuePath, remove) + if (cleanupError !== null) { + leftoverPaths.push(residuePath) + cleanupErrors.push(cleanupError) + } + return cleanupError + } + + // Warning delivery must never abort the write: the notices below describe a + // committed-but-imperfect publish, and a caller whose callback throws (a UI sink, a logger that + // is mid-restart) must not turn that into a failed save. Declared above the try whose failure + // handler reports a leftover backup copy, so both sides can reach it. + const warn = (message: string) => { + const report = (label: string, error: unknown) => { + console.warn( + `safeWriteText: onWarning callback ${label}: ${error instanceof Error ? error.message : String(error)}`, + ) + } + try { + const sink = options?.onWarning ?? ((m: string) => console.warn(m)) + const result: unknown = sink(message) + // A sink may be async - TypeScript accepts a value-returning callback where + // a void one is expected. Awaiting it would let warning delivery delay a + // write that has already committed (and hang it if the sink never settles), + // while leaving the promise unhandled turns a rejection into an unhandled + // rejection, which under Node's default mode can end the process after a + // successful write. Attach a handler without awaiting. + if (result instanceof Promise) { + result.catch((error: unknown) => report("rejected", error)) + } + } catch (error: unknown) { + report("failed", error) + } + } + + // Resolve the symlink referent (see resolvePublishTarget). + const targetPath = await resolvePublishTarget(absoluteFilePath) + const dirPath = path.dirname(targetPath) + + // Ensure parent directory exists (mirrors safeWriteJson behaviour). + await fs.mkdir(dirPath, { recursive: true }) + await fs.access(dirPath) + + // Create the staging directory only when we generate the temp file there; + // callers supplying their own tempPath (e.g. safeWriteJson) must not be left + // with an empty .file-safety-staging directory behind. Track the directory this + // write created so its cleanup removes its own directory, not a shared one. + let stagingDir: string | null = null + let tempPath: string + if (options?.tempPath) { + // A caller-supplied staging file is only safe when it is the file this + // write is staging, not an arbitrary path. Two properties are checked: + // it must sit beside the resolved target (a rename across filesystems + // fails with EXDEV, and a path elsewhere lets a caller publish an + // unrelated file onto the target), and it must be a regular file rather + // than a link — renaming a link over the target publishes whatever the + // link points at, which is the same trust problem as writing through a + // dangling symlink in resolvePublishTarget. + const supplied = path.resolve(options.tempPath) + if (path.dirname(supplied) !== path.resolve(dirPath)) { + throw new StagingPathError( + `Staging file must sit in the target's directory (${dirPath}), got ${supplied}`, + supplied, + ) + } + // BigInt stats: on NTFS/ReFS the file identity can exceed Number.MAX_SAFE_INTEGER, and + // a rounded number makes two different files look identical (rejecting a valid staging + // file) or hides a real alias. + const stagingStat = await fs.lstat(supplied, { bigint: true }) + if (stagingStat.isSymbolicLink() || !stagingStat.isFile()) { + throw new StagingPathError( + `Staging file must be a regular file, not ${stagingStat.isSymbolicLink() ? "a symlink" : "another file type"}`, + supplied, + ) + } + // A staging path that is the target would be unlinked by the failure handler + // while it still holds the only copy of the content, so a failed write would + // delete the file it was meant to protect. Compare identities, not spellings: + // an alias of the target is the same hazard. + // Only a missing target may be skipped: an EACCES/ELOOP/ENOTDIR here means the + // identity comparison could not be made, and treating that as "no target" would let a + // staging alias reach the commit and let cleanup delete the file it was meant to + // protect. + const targetStat = await fs.lstat(targetPath, { bigint: true }).catch((error: unknown) => { + if (errorCode(error) !== "ENOENT") { + throw new StagingPathError("Staging file could not be compared with the target", supplied) + } + return null + }) + if ( + targetStat && + typeof stagingStat.ino === "bigint" && + typeof targetStat.ino === "bigint" && + stagingStat.ino === targetStat.ino && + stagingStat.dev === targetStat.dev + ) { + throw new StagingPathError("Staging file must not be the target itself", supplied) + } + // The caller's own path is used as given; only the check is canonical. + tempPath = options.tempPath + } else { + stagingDir = _stagingDir(dirPath) + tempPath = _tempName(stagingDir, "safeWriteText") + } + + let backupPath: string | null = null + let releaseBackupOnSuccess = false + // Non-null only when the win32 step-2 block saved a successful DACL dump: + // it gates the step-5 restore and is tracked for the cleanup unlinks. + let daclDumpPath: string | null = null + try { + // -- Step 1: write content to staging temp file ------------------- + if (!options?.tempPath) { + // Preserve the existing target's permissions: the staging file must + // not be published wider than the file it replaces (a 0o600 target + // must not become 0o644 through the atomic rename). + // Encode before opening the staging file: an encoding Node cannot + // represent must not leave a half-written temp file behind. + // A string is encoded as UTF-8; bytes handed in by the caller (the + // extension host encodes a document with VS Code's own codec, which + // covers the legacy code pages Node cannot represent) are published + // unchanged. + const buffer = Buffer.from(content) + let targetMode = 0o644 // default for a fresh target + let targetExists = false + try { + targetMode = fsSync.statSync(targetPath).mode & 0o777 + targetExists = true + } catch (error: unknown) { + if (errorCode(error) !== "ENOENT") throw error + // target does not exist yet - keep the default + } + // openSync's creation mode is narrowed by the process umask, so an + // existing 0o664 target would be published as 0o644 through the + // rename. Apply the existing target's exact mode on the fd, as the + // caller-staged branch does; a fresh target keeps the default mode. + const fd = fsSync.openSync(tempPath, "w", targetMode) + try { + if (targetExists) { + fsSync.fchmodSync(fd, targetMode) + } + // Loop until every byte is written: writeSync can report a short + // (partial) write, and publishing a truncated staging file would + // commit corrupt content. + let offset = 0 + while (offset < buffer.length) { + offset += fsSync.writeSync(fd, buffer, offset, buffer.length - offset) + } + _fsyncFile(fd) + } finally { + fsSync.closeSync(fd) + } + } else { + // Preserve the existing target's mode (CWE-732): the caller-staged + // temp carries its own creation mode, and publishing it as-is would + // widen a restrictive target (e.g. 0o600 -> 0o644) through rename. + // The mode is applied with fchmodSync on the open fd (AFTER openSync): + // chmodSync on the path before the open would make a read-only target + // (0o400/0o444) fail openSync(tempPath, "r+") with EACCES. + let targetMode: number | null = null + try { + targetMode = fsSync.statSync(targetPath).mode & 0o777 + } catch (error: unknown) { + if (errorCode(error) !== "ENOENT") throw error + // target does not exist yet - keep the temp's default mode + } + const fd = fsSync.openSync(tempPath, "r+") + try { + if (targetMode !== null) { + fsSync.fchmodSync(fd, targetMode) + } + _fsyncFile(fd) + } finally { + fsSync.closeSync(fd) + } + } + + // -- Step 2 (win32): save DACL BEFORE the backup copy ----------- + const platform = options?.platform ?? process.platform + if (platform === "win32") { + let accessError: unknown = null + try { + await fs.access(targetPath) // target exists? + } catch (error: unknown) { + accessError = error + } + if (accessError === null) { + const dumpPath = _tempName(dirPath, "safeWriteText.acl") + const saved = await _saveDaclWindows(targetPath, dumpPath, options?.execFileRunner) + if (saved) { + // Only a successfully saved dump may be restored onto the + // committed file (step 5). + daclDumpPath = dumpPath + } else { + // A failed icacls may have left a partial dump behind; remove it now so no partial + // dump survives and no later step can restore from it. A dump that cannot be removed is + // recorded, because the refusal below throws: without the record the caller would hold + // an error naming no file while a partial DACL dump stayed on disk. + await cleanResidue(dumpPath, fs.unlink) + // The target exists and its DACL could not be captured, so the commit rename + // would replace it with a file that inherits different access rights. Nothing here + // can verify an equivalent restrictive ACL on the replacement, so the publish is + // refused instead of warned about: a save that silently changed who can read the + // file is not a save the user can trust. Nothing is committed yet, so the target + // still holds its content, and this throw lands in the catch at the bottom of this + // try - the one place that unlinks the staged file and removes this write's own + // staging directory before rethrowing - so a refused publish strands no residue. + throw new DaclInspectionError(targetPath, "save", null) + } + } else if (errorCode(accessError) !== "ENOENT") { + // Not "absent": the target is there but its access rights could not be read (EACCES, + // ...), so publishing would replace a file whose rights this call never learned. Same + // rule as the save failure above: refuse before anything is committed, and let the + // catch at the bottom of this try remove the staged file and the staging directory. + throw new DaclInspectionError(targetPath, "inspect", accessError) + } + } + try { + // -- Step 3 (backup:true): durable copy target -> backup ---- + if (options?.backup) { + try { + await fs.access(targetPath) + backupPath = _tempName(dirPath, "safeWriteText.bak") + // Copy, never move. Renaming the target away leaves the canonical path absent for + // the whole commit window: readers see a missing file, and a concurrent + // writer can create a new target that a later rollback would destroy. A copy + // keeps the target present, so the step 4 rename is the only change to the + // canonical path. The copy is flushed so the retained content survives a crash. + try { + // Create the destination BEFORE any content exists at it, with the mode fixed + // at open time. fs.copyFile picks the destination mode itself (the platform + // creation mask subject to umask on some platforms, the source's mode - or its + // read-only attribute - on others), so letting it create the file would either + // leave a restrictive target's bytes briefly readable to others, or leave the + // copy unwritable so the fsync open below fails with EACCES. open() ignores its + // mode argument for an existing file, so this 0o600 survives the copy on POSIX; + // the chmod afterwards is what clears a copied read-only attribute on Windows + // and keeps a backup of a permissive file private. + const seedFd = fsSync.openSync(backupPath, "wx", 0o600) + // Single close, no retry: on POSIX close(2) can release the descriptor before it + // reports an error (and leaves its state unspecified after EINTR), so a second + // close could release a descriptor some other operation has meanwhile reused. + // The failure propagates; backupPath is already recorded, so the outer cleanup + // removes the seeded file instead of leaving it beside the target. + fsSync.closeSync(seedFd) + await fs.copyFile(targetPath, backupPath) + await fs.chmod(backupPath, 0o600) + // "r+" not "r": fsync on a read-only handle is EPERM on Windows, and the same + // flag the staged temp file uses above. + const backupFd = fsSync.openSync(backupPath, "r+") + try { + _fsyncFile(backupFd) + } finally { + fsSync.closeSync(backupFd) + } + } catch (backupError: unknown) { + // A partial backup must not outlive this attempt: it is not a complete copy + // of anything, and once the write fails nothing else removes it. The unlink is + // retried once (Windows reports EPERM for a file whose handle has not been + // released yet); if it still fails the path is carried on the thrown error + // instead of being dropped where no caller can act on it. + const orphanPath = backupPath + // Same rule as every other residue: one retry, ENOENT counts as removed, and a copy + // that stays is recorded so the error thrown below carries it too. + const backupCleanupError = await cleanResidue(orphanPath, fs.unlink) + backupPath = null + if (backupCleanupError !== null) { + throw new OrphanedBackupError(orphanPath, targetPath, backupError, backupCleanupError) + } + throw backupError + } + releaseBackupOnSuccess = true + } catch (err: unknown) { + if (errorCode(err) !== "ENOENT") throw err + } + } + + // -- Step 4: atomic rename temp -> target --------------------- + await fs.rename(tempPath, targetPath) + + // -- Step 4b (POSIX): fsync the parent directory so the directory entry + // changed by the commit rename is durable, not just the file content. + if (platform !== "win32") { + try { + const dirFd = fsSync.openSync(dirPath, "r") + try { + _fsyncFile(dirFd) + } finally { + fsSync.closeSync(dirFd) + } + } catch (error: unknown) { + // The content rename committed, but the directory entry that + // points at it is not known to be durable. Reporting success + // here would let a caller believe the write survives a crash, + // so the failure is surfaced as its own error: the caller can + // still find the content at the target, it just cannot rely on + // the directory entry having reached the disk. + throw new PostCommitDurabilityError(targetPath, error) + } + } + + // -- Step 5 (win32): restore DACL AFTER commit rename --------- + // daclDumpPath is non-null only when the win32 step-2 block saved a + // successful dump, so this gate is closed on every other platform + // and on every failed save. + if (daclDumpPath !== null) { + const restoredDir = path.dirname(targetPath) + const restored = await _restoreDaclWindows(restoredDir, daclDumpPath, options?.execFileRunner) + if (!restored) { + // The content is committed, but the published file answers to a different + // DACL from the one that was saved, and nothing here verified an equivalent + // restrictive ACL on the replacement. This is reported as an error rather than a + // warning: the caller has to know that the save changed who can read the file. + // Contract change - this used to warn and resolve, which let a publish that + // widened access look like an ordinary successful save. + throw new DaclRestoreError(targetPath, null) + } + } + + // -- Step 6 (backup:true): delete backup on success ----------- + if (releaseBackupOnSuccess && backupPath) { + // The backup is a full copy of the previous content sitting next to the published file. + // A failed unlink goes through the shared residue path, which retries once (Windows + // commonly reports EPERM while another handle is still being released) and records a path + // that stays. The publish itself succeeded, so this is a leftover to clean up rather than + // a failed save: the path reaches the human through onWarning and the caller through the + // structured result, because a full copy of the previous content is still beside the target. + const cleanupError = await cleanResidue(backupPath, fs.unlink) + if (cleanupError !== null) { + warn( + `safeWriteText: committed ${targetPath} but could not remove its backup copy at ${backupPath} (${ + errorCode(cleanupError) ?? "unknown error" + }); the copy of the previous content is still on disk and needs to be removed.`, + ) + } + } + } finally { + // Unlink the DACL dump on every exit from this span, success or failure, and record one that + // stays. This is the dump's only owner once a save succeeded, so what is recorded here is + // what the caller receives on either exit: a resolved write returns the list, and a rejected + // one carries the same list on its error instead of dropping it with the discarded result. + if (daclDumpPath !== null) { + await cleanResidue(daclDumpPath, fs.unlink) + } + } + + // tempPath is now the committed file; no cleanup needed. + + // Remove the now-empty staging directory through the same cleanup path as every other residue. + // Self-staged writes only, and only this write's own directory: a per-write directory cannot be + // the one another concurrent write is still using. A failure must not un-commit a published + // file, but a directory this write created and could not remove is residue the caller is told + // about rather than a failure that disappears. + if (stagingDir !== null) { + await cleanResidue(stagingDir, fs.rmdir) + } + + // The result is reported only after this call's own residue has been dealt with: a caller + // that receives an empty list knows there is nothing left for it to sweep. + return { leftoverPaths } + } catch (originalError: unknown) { + // The backup is a copy, never a restore source: whether the failure happened before + // or after the commit rename, the copy is removed below so no stale duplicate of the + // previous content survives next to the target. + if (backupPath && releaseBackupOnSuccess) { + // Nothing to restore: the backup is a copy, so the target still holds whatever + // the commit left there - before the commit that is the pre-write content, and + // after it the published content. Either way the copy has served its purpose + // and must not be left beside the target where no caller can find it. + const stuckBackup = await cleanResidue(backupPath, fs.unlink) + if (stuckBackup !== null) { + // The original error is what the caller needs, so the leftover cannot be thrown, and a + // throw means the structured result never reaches the caller either: the path is + // reported with its location through onWarning, and attached to the error below, so + // neither the human nor the caller has to parse a message to find it. + warn( + `safeWriteText: the write failed and its backup copy could not be removed from ${backupPath} (${ + errorCode(stuckBackup) ?? "unknown error" + }); a full copy of the previous content is still on disk and needs to be removed.`, + ) + } + backupPath = null + } + + // The staged file and this write's own staging directory go through the same cleanup path as + // every other residue, so a failure at either is recorded and reported on the error below + // instead of being swallowed here: a caller that catches a throw has no result to read. + await cleanResidue(tempPath, fs.unlink) + + // A failed self-staged write must not leave its staging directory behind. + // Only the directory this write created, and only after its temp file is + // gone, so the directory is empty and the removal stays best-effort. + if (stagingDir !== null) { + await cleanResidue(stagingDir, fs.rmdir) + } + + // The DACL dump is not removed here. It is non-null only once step 2 saved a dump, and every + // path from that point enters the try whose finally owns the dump, so by the time this handler + // runs the dump has already been removed or recorded. Removing it again here would compensate + // for a resource this span no longer owns and would report a surviving dump twice. + throw _attachResidue(originalError, { leftoverPaths, cleanupErrors }) + } +}