[release/6.0] Make sure that shared memory object name meets the length requiremens #64266
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
dotnet#64099) Co-authored-by: Stephen Toub <stoub@microsoft.com> # Conflicts: # src/libraries/System.IO.MemoryMappedFiles/tests/MemoryMappedFile.CreateNew.Tests.cs # src/libraries/System.IO.MemoryMappedFiles/tests/MemoryMappedViewAccessor.Tests.cs # src/libraries/System.IO.MemoryMappedFiles/tests/MemoryMappedViewStream.Tests.cs # src/libraries/System.IO.MemoryMappedFiles/tests/MemoryMappedViewStreamConformanceTests.cs
|
Tagging subscribers to this area: @dotnet/area-system-io Issue DetailsA manual backport of #64099
|
|
/azp run runtime-extra-platforms |
|
Azure Pipelines could not run because the pipeline triggers exclude this branch/path. |
stephentoub
reviewed
Jan 25, 2022
| return null; | ||
| } | ||
| Interop.ErrorInfo errorInfo = Interop.Sys.GetLastErrorInfo(); | ||
| fd.Dispose(); |
There was a problem hiding this comment.
FWIW, it's a little weird to Dispose of the SafeHandle and then continue to use it, but technically in this case it's ok to do so, given how it's being used. It's just unusual to see and thus a little disconcerting.
There was a problem hiding this comment.
Maybe a comment here would help clarify the unusual usage?
stephentoub
approved these changes
Jan 25, 2022
|
Could you add a template we could review, before tactics mail? |
Done |
|
Template looks good. I added that its customer reported. Feel free to send mail.. |
leecow
added
Servicing-approved
ghost
locked as resolved and limited conversation to collaborators
Sign up for free
to subscribe to this conversation on GitHub.
Already have an account?
Sign in.
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Outdated suggestions cannot be applied.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.
A manual backport of #64099
The sys-call that we use to create shared memory mapped objects (
shm_open) has distro-specific map name length requirements. On most Unix-like Operating Systems it'sPATH_MAX(4096), while on macOS it'sSHM_NAME_MAXwhich for the arm64 version currently maps to 32. The code has been simply generating a string that is too long.Customer Impact
Customer reported #63240 in 6.0. macOS arm64 users can't create a memory mapped file which is not backed by a real file (
MemoryMappedFile.CreateNew(mapName: null)) . There is no workaround.Testing
The tests have been.. re-enabled. Yes, we had failing tests that were clearly saying that there is a bug but they got disabled rather than fixed.
Risk
Low. By reducing the map name length we have reduced the entropy so chances for generating a name that is already in use have increased. However, a simple retry logic was added and it ensures that even if a shared map object with a given name already exists, a new name is generated and the process is repeated until it succeeds (or fails for other reasons).