Backport "Allow WASI to open directories without O_DIRECTORY" (#6163)#6283
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jameysharp merged 2 commits intobytecodealliance:release-8.0.0from Apr 25, 2023
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…dealliance#6163) The `O_DIRECTORY` flag is a request that open should fail if the named path is not a directory. Opening a path which turns out to be a directory is not supposed to fail if this flag is not specified. However, wasi-common required callers to use it when opening directories. With this PR, we always open the path the same way whether or not the `O_DIRECTORY` flag is specified. However, after opening it, we `stat` it to check whether it turned out to be a directory, and determine which operations the file descriptor should support accordingly. In addition, we explicitly check whether the precondition defined by `O_DIRECTORY` is satisfied. On Windows, when opening a path which might be a directory using `CreateFile`, cap-primitives also removes the `FILE_SHARE_DELETE` mode. That means that if we implement WASI's `path_open` such that it always uses `CreateFile` on Windows, for both files and directories, then holding an open file handle prevents deletion of that file.
alexcrichton
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Thanks! Mind adding an entry to RELEASES.md as well?
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Sure thing. Would you review the release notes I just wrote for this too? |
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alexcrichton
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The
O_DIRECTORYflag is a request that open should fail if the named path is not a directory. Opening a path which turns out to be a directory is not supposed to fail if this flag is not specified. However, wasi-common required callers to use it when opening directories.With this PR, we always open the path the same way whether or not the
O_DIRECTORYflag is specified. However, after opening it, westatit to check whether it turned out to be a directory, and determine which operations the file descriptor should support accordingly. In addition, we explicitly check whether the precondition defined byO_DIRECTORYis satisfied.On Windows, when opening a path which might be a directory using
CreateFile, cap-primitives also removes theFILE_SHARE_DELETEmode. That means that if we implement WASI'spath_opensuch that it always usesCreateFileon Windows, for both files and directories, then holding an open file handle prevents deletion of that file.