[5.9] [stdlib] Fix String.reserveCapacity underallocation (#65902) #65977
Conversation
This file contains 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
When called on a string that is not uniquely referenced, `String.reserveCapacity(_:)` ignores the current capacity, using the passed-in capacity for the size of its new storage. This can result in an underallocation and write past the end of the new buffer. This fix changes the new size calculation to use the current UTF-8 count as the minimum. Non-native or non-unique strings now allocate the requested capacity (or space enough for the current contents, if that's larger than what's requested). rdar://109275875 Fixes apple#53483
|
@swift-ci Please test |
|
cc @apple/swift5-branch-managers |
stephentyrone
approved these changes
Jun 1, 2023
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
This is a cherry-pick of #65902.
When called on a string that is not uniquely referenced,
String.reserveCapacity(_:)ignores the current capacity, using the passed-in capacity for the size of its new storage. This can result in an underallocation and write past the end of the new buffer.This fix changes the new size calculation to use the current UTF-8 count as the minimum. Non-native or non-unique strings now allocate the requested capacity (or space enough for the current contents, if that's larger than what's requested).
rdar://109275875
Fixes #53483