cp: force mode: try to open destination for write to check if delete is required #8496
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GNU testsuite comparison: |
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ok, this does not work (related GNU test fails). I'll further investigate. |
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GNU testsuite comparison: |
sylvestre
reviewed
Aug 20, 2025
| is_symlink_loop(dest) || fs::metadata(dest)?.permissions().readonly() | ||
| is_symlink_loop(dest) | ||
| || fs::metadata(dest)?.permissions().readonly() | ||
| || (dest.is_file() && OpenOptions::new().write(true).open(dest).is_err()) |
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The condition dest.is_file() check seems redundant since
OpenOptions::new().write(true).open(dest) will fail on non-files anyway, and this creates an unnecessary extra syscall
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I tried that first, but the open(dest) gets stuck when the destination is a FIFO. It does not return.
sylvestre
reviewed
Aug 20, 2025
sylvestre
reviewed
Aug 20, 2025
So far cp only checked if the metadata of the destination file indicates read-only permissions. In order to handle the case where the destination file is in use, we try to open the destination file for writing. Also other cases which prevent overwriting can be detected that way. For the test case we copy the coreutils binary to a test directory. Then use the copy to try to copy a file over itself. This should fail in non-force mode, but succeed in force mode.
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@sylvestre thank you for your review. I addressed the findings. Please check. |
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fails here: |
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GNU testsuite comparison: |
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ok, this needs more investigations. I'll change the PR back to draft. |
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So far cp only checked if the metadata of the destination file indicates
read-only permissions. In order to handle the case where the destination
file is in use, we try to open the destination file for writing. Also
other cases which prevent overwriting can be detected that way.
For the test case we copy the coreutils binary to a test directory. Then
use the copy to try to copy a file over itself. This should fail in
non-force mode, but succeed in force mode.
this fixes #8261