pipe2/dup3 O_CLOEXEC - #1520
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July 8, 2026 00:11
Add safeOpen / safePipe / safeDuplicate helpers on FileDescriptor that always request close-on-exec, so descriptors created by the build system are not leaked into the child processes it spawns. They route through the swift-system pipe2/dup3 wrappers where those are available: - safePipe uses FileDescriptor.pipe(options: .closeOnExec) on non-Apple platforms (including Windows), and on Apple platforms running OS 27 or later via the SDK's System framework; older Apple OSes fall back to a plain pipe(). - safeDuplicate(as:) uses FileDescriptor.duplicate(as:options:) on non-Apple platforms (dup3 is unavailable on Windows) and on Apple OS 27 or later; elsewhere it falls back to a plain dup2(). - safeDuplicate() (no target) uses fcntl(F_DUPFD_CLOEXEC) to atomically obtain the lowest-numbered unused descriptor with close-on-exec set; on Windows, which has no F_DUPFD_CLOEXEC, it falls back to a plain dup(). - safeOpen forces OpenOptions.closeOnExec. Adopt these wrappers in FSProxy, PbxCp, XCBuildDataArchive, LineReader, and the build service entry point, and require swift-system 1.7.3.
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Add
safeOpen/safePipe/safeDuplicatehelpers onFileDescriptorthat always request close-on-exec, so descriptors created by the build system are not leaked into the child processes it spawns. They route through the swift-system pipe2/dup3 wrappers where those are available:safePipeusesFileDescriptor.pipe(options: .closeOnExec)on non-Apple platforms (including Windows), and on Apple platforms running OS 27 or later via the SDK'sSystemframework; older Apple OSes fall back to a plainpipe().safeDuplicate(as:)usesFileDescriptor.duplicate(as:options:)on non-Apple platforms (dup3 is unavailable on Windows) and on Apple OS 27 or later; elsewhere it falls back to a plaindup2().safeDuplicate()(no target) usesfcntl(F_DUPFD_CLOEXEC)to atomically obtain the lowest-numbered unused descriptor with close-on-exec set; on Windows, which has noF_DUPFD_CLOEXEC, it falls back to a plaindup().safeOpenforcesOpenOptions.closeOnExec.Adopt these wrappers in
FSProxy,PbxCp,XCBuildDataArchive,LineReader, and the build service entry point, and require swift-system 1.7.3 (which exposesOpenOptions.closeOnExecon Windows).