Reject file lengths that do not fit in usize - #21
Merged
Conversation
Previously on 32 bit platforms we'd end up potentially accepting the size initially, even if it was wrong, and then either returning errors or panicking. Now we just return the same consistent error that the upstream mmap crate gives when the requested size is too large. The problem of always relying on mmap is that it's limited to 2GiB for 32 bit platforms anyway. So there should be a better fallback here. But for now this just makes the errors more consistent, since for any size under 4GiB but above 2GiB on 32 bit we'd give this error, with any truncated size which fell outside this range getting incorrectly accepted with no error.
zanieb
approved these changes
Aug 28, 2026
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Previously on 32 bit platforms we'd end up potentially accepting the size initially, even if it was wrong, and then either returning errors or panicking.
Now we just return the same consistent error that the upstream mmap crate gives when the requested size is too large.
The problem of always relying on mmap is that it's limited to 2GiB for 32 bit platforms anyway. So there should be a better fallback here.
But for now this just makes the errors more consistent, since for any size under 4GiB but above 2GiB on 32 bit we'd give this error, with any truncated size which fell outside this range getting incorrectly accepted with no error.