Pass correct search path to DllImportResolver for default flags on Mono#129831
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elinor-fung merged 1 commit intoJun 25, 2026
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When neither the P/Invoke nor the assembly has a DefaultDllImportSearchPaths attribute, Mono passed DllImportSearchPath.AssemblyDirectory to a registered DllImportResolver instead of null. lookup_pinvoke_call_impl defaults the flags to ASSEMBLY_DIRECTORY for the built-in probing logic, and netcore_resolve_with_dll_import_resolver derived "has search flags" from (flags != 0), so the defaulted value leaked to the resolver. Combined with dotnet#114756 - which made an explicit AssemblyDirectory no longer fall back to the OS search - this broke resolvers that forward the search path to NativeLibrary.Load, such as loading iOS @rpath frameworks. Thread the existing user_specified_flags signal through to the resolver so it receives the attribute value, or null when none was specified, matching CoreCLR and NativeAOT. Fixes dotnet#129798 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Pull request overview
This PR fixes Mono’s DllImportResolver searchPath reporting so that the resolver receives null when no DefaultDllImportSearchPaths attribute is present, instead of receiving Mono’s internal default (AssemblyDirectory). This brings Mono behavior in line with the documented DllImportResolver contract and with CoreCLR/NativeAOT.
Changes:
- Mono: thread through and use
user_specified_flagsto decide whether to pass search flags to the resolver (instead offlags != 0). - Tests: add an interop test validating that the resolver observes
AssemblyDirectory,System32,LegacyBehavior, andnullbased on attribute presence/value.
Show a summary per file
| File | Description |
|---|---|
| src/mono/mono/metadata/native-library.c | Uses the existing user_specified_flags signal to decide whether the resolver should receive a non-null searchPath. |
| src/tests/Interop/DllImportSearchPaths/DllImportSearchPathsTest.cs | Adds coverage to assert the resolver’s observed searchPath matches DefaultDllImportSearchPaths (or null when absent). |
Copilot's findings
- Files reviewed: 2/2 changed files
- Comments generated: 2
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/backport to release/10.0 |
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Started backporting to |
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On Mono, when no search flags are user-specified,
lookup_pinvoke_call_impldefaults the flags toDLLIMPORTSEARCHPATH_ASSEMBLY_DIRECTORYfor the built-in probing logic.netcore_resolve_with_dll_import_resolverthen derived whether to report search flags to the resolver fromflags != 0, so the explicitAssemblyDirectoryvalue was passed to the resolver instead ofnull. The expectedDllImportResolvercontract is thatsearchPathis the attribute value, ornullwhen neither the P/Invoke nor the assembly has the attribute.After #114756, specifying only
AssemblyDirectorymeant only assembly directory. This means that when a resolver that forwards the (wrongly non-null)AssemblyDirectorytoNativeLibrary.Load, it no longer does the default search (baredlopen/LoadLibrary).This change passes the
user_specified_flagsvalue through to the resolver invocation and uses it for "has search flags", so the resolver receives the attribute value ornullfor non-user-specified.cc @dotnet/appmodel @AaronRobinsonMSFT
See #129798. We should backport to 10.
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This pull request was created with GitHub Copilot.