pkg/strip: handle read-only input #4450
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racket/collects/pkg/strip.rkt
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| (define old-mode | ||
| (file-or-directory-permissions pth 'bits)) | ||
| (define new-mode | ||
| (bitwise-ior old-mode user-write-bit)) |
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I think this won't work on Windows, where the only thing you can control via file-or-directory-permissions is whether writing is allowed for everyone (i.e., no user vs. group vs. other distinction).
So, (if (eq? (system-type) 'windows) (bitwise-ior user-write-bit group-write-bit other-write-bit) user-write-bit)?
Also, maybe it would be better to try to change permissions only if user-write-bit is not already set.
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Oh, I bet this is also the reason why tests for #4126 failed on Windows. I had seen in the documentation that Windows doesn't have a user/group/other distinction, but I guess I must have thought the non-user bits were just ignored or managed automatically somehow: I didn't realize the user of file-or-directory-permissions was responsible for keeping the bits consistent.
From the linked issues there, it seems like I got it wrong in the same way in 55b6cbd: I'll try to fix that, too.
A package directory supplied to the functions from `pkg/strip` might have had all of its write permission bits unset. Since `copy-file` preserves the permissions of the source file, we may end up with a read-only file that we want to overwrite (e.g. an `info.rkt` file). Explicitly setting `user-write-bit` before writing avoids this problem. Conservatively, we only set the permissions when actually needed, and we restore the original permissions when we are done.
This is a follow-up to 55b6cbd. On Windows, you can't set just something like `user-write-bit` using `file-or-directory-permissions`: you have to supply a new mode where the `user-`, `group-`, and `other-` bits are consistent, because Windows does not distinguish permissions that way. See <https://github.com/racket/racket/pull/4450/files#r990709739>.
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I've pushed a revised commit with the fix, plus a commit fixing 55b6cbd the same way. |
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@mflatt could you take another look at this? I'm happy to make other changes if needed! |
A package directory supplied to the functions from
pkg/stripmight have had all of its write permission bits unset. Sincecopy-filepreserves the permissions of the source file, we may end up with a read-only file that we want to overwrite (e.g. aninfo.rktfile). Explicitly settinguser-write-bitbefore writing avoids this problem. Conservatively, we restore the original permissions when we are done.