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`copy(src, dst)` copies a single file into the repository (or the working directory of a module extension) and preserves its executable bit. On file systems that support it, the copy is created as a copy-on-write clone of the source (`clonefile` on macOS, `copy_file_range` on Linux), so it doesn't take up additional disk space. The source is watched by default, which can be controlled via `watch_src`. Unlike a symlink to a file in the main repo or in another repo, a copy doesn't prevent a reproducible repo from being stored in the local and remote repo contents caches. Emulating a copy via `ctx.file(dst, ctx.read(src))` loads the file into memory and loses the executable bit. Contrary to `symlink`, `copy` is also available on `module_ctx` since it watches the source in the same way on all platforms and thus doesn't result in platform-specific lockfiles. Work towards bazelbuild#31434 and bazelbuild#31456.
`repository_ctx.copy` and `module_ctx.copy` now also accept a directory as `src`. It is copied as if each file in it were copied individually: * Symlinks to files and directories are followed, so the copy doesn't contain any symlinks. * Existing files below `dst` are overwritten and all other files below `dst` are kept, which matches `extract`. * Executable bits are preserved and the copied files are writable. The source directory is watched in the same way as by `repository_ctx.watch_tree`, which also follows symlinks. Symlink cycles, dangling symlinks and overlapping `src` and `dst` are errors.
repository_ctx.copy preserves executable bits. Include executable bits in regular FileStateValue comparisons, directory-tree digests and copied file inputs so chmod invalidates cached copies. Keep ordinary reads and watches content-only. Use FILE_CONTENTS for content-only records and include the executable bit in FILE records. Old FILE records revalidate once, including affected module lockfiles.
dzbarsky
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lberki and
meteorcloudy
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October 15, 2026 22:56
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Depends on #31461.
repository_ctx.copypreserves executable bits, but its recorded inputscurrently only check file contents. Changing a source from 0644 to 0755 can
therefore reuse a stale, non-executable copy.
Include executable bits in
FileStateValuecomparisons, directory-treedigests and copied-file records. Regular reads and watches still record only
contents. Old
FILErecords revalidate once; new content-only records useFILE_CONTENTS, so affected module lockfiles need regeneration.