Skip to content

Fix background process creation on macOS #15834

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
jtainer wants to merge 1 commit into
base: main
Choose a base branch
from
+19 −7
Open

Fix background process creation on macOS #15834

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
26 changes: 19 additions & 7 deletions src/process/posix/SDL_posixprocess.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -340,16 +340,14 @@ bool SDL_SYS_CreateProcessWithProperties(SDL_Process *process, SDL_PropertiesID
// Spawn the new process
if (process->background) {
int status = -1;
#ifdef SDL_PLATFORM_APPLE // Apple has vfork marked as deprecated and (as of macOS 10.12) is almost identical to calling fork() anyhow.
int pid_pipe[2];
if (!CreatePipe(pid_pipe)) {
goto posix_spawn_fail_all;
}
const pid_t pid = fork();
const char *forkname = "fork";
#else
const pid_t pid = vfork();
const char *forkname = "vfork";
#endif
switch (pid) {
case -1:
SDL_SetError("%s() failed: %s", forkname, strerror(errno));
SDL_SetError("fork() failed: %s", strerror(errno));
goto posix_spawn_fail_all;

case 0:
Expand All @@ -358,9 +356,23 @@ bool SDL_SYS_CreateProcessWithProperties(SDL_Process *process, SDL_PropertiesID
if (posix_spawnp(&data->pid, args[0], &fa, &attr, args, envp) != 0) {
_exit(errno);
}
// Write the PID back to the parent so it can be waited on
close(pid_pipe[READ_END]);
if (write(pid_pipe[WRITE_END], &data->pid, sizeof(data->pid)) != sizeof(data->pid)) {
_exit(errno);
}
close(pid_pipe[WRITE_END]);
_exit(0);

default:
// Wait for the child to launch and report the PID back
close(pid_pipe[WRITE_END]);
ssize_t bytes_read = read(pid_pipe[READ_END], &data->pid, sizeof(data->pid));
close(pid_pipe[READ_END]);
if ((size_t)bytes_read != sizeof(data->pid)) {
SDL_SetError("Failed to read child PID from pipe: %s", strerror(errno));
goto posix_spawn_fail_all;
}
if (waitpid(pid, &status, 0) < 0) {
SDL_SetError("waitpid() failed: %s", strerror(errno));
goto posix_spawn_fail_all;
Expand Down
Loading