regression: false positive from `clang-analyzer-unix.StdCLibraryFunctions` with `getcwd()`

[seanm]

clang-tidy / clang static analyzer tells me:

warning: The 1st argument to 'getcwd' is NULL but should not be NULL [clang-analyzer-unix.StdCLibraryFunctions]

         char* currentPath = getcwd(nullptr, 0);
                             ^

But the macOS man page for getcwd says:

"If buf is NULL [1st param], space is allocated as necessary to store the pathname and size [2nd param] is ignored. This space may later be free(3)'d."

Looks like the responsible line is : https://github.com/llvm/llvm-project/blob/defe43bbffb0d25ec468f0e54b20548ec192ff90/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp#L2662C1-L2662C46

from this commit: 7dd2063

from this PR: #77040

@benshi001

[llvmbot]

@llvm/issue-subscribers-clang-static-analyzer

Author: Sean McBride (seanm)

clang-tidy / clang static analyzer tells me:

warning: The 1st argument to 'getcwd' is NULL but should not be NULL [clang-analyzer-unix.StdCLibraryFunctions]

         char* currentPath = getcwd(nullptr, 0);
                             ^

But the macOS man page for getcwd says:

"If buf is NULL [1st param], space is allocated as necessary to store the pathname and size [2nd param] is ignored. This space may later be free(3)'d."

Looks like the responsible line is : https://github.com/llvm/llvm-project/blob/defe43bbffb0d25ec468f0e54b20548ec192ff90/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp#L2662C1-L2662C46

from this commit: 7dd2063

from this PR: #77040

@benshi001

[llvmbot]

Hi!

This issue may be a good introductory issue for people new to working on LLVM. If you would like to work on this issue, your first steps are:

1. Check that no other contributor has already been assigned to this issue. If you believe that no one is actually working on it despite an assignment, ping the person. After one week without a response, the assignee may be changed.
2. In the comments of this issue, request for it to be assigned to you, or just create a pull request after following the steps below. Mention this issue in the description of the pull request.
3. Fix the issue locally.
4. Run the test suite locally. Remember that the subdirectories under test/ create fine-grained testing targets, so you can e.g. use make check-clang-ast to only run Clang's AST tests.
5. Create a Git commit.
6. Run git clang-format HEAD~1 to format your changes.
7. Open a pull request to the upstream repository on GitHub. Detailed instructions can be found in GitHub's documentation. Mention this issue in the description of the pull request.

If you have any further questions about this issue, don't hesitate to ask via a comment in the thread below.

[llvmbot]

@llvm/issue-subscribers-good-first-issue

Author: Sean McBride (seanm)

clang-tidy / clang static analyzer tells me:

warning: The 1st argument to 'getcwd' is NULL but should not be NULL [clang-analyzer-unix.StdCLibraryFunctions]

         char* currentPath = getcwd(nullptr, 0);
                             ^

But the macOS man page for getcwd says:

"If buf is NULL [1st param], space is allocated as necessary to store the pathname and size [2nd param] is ignored. This space may later be free(3)'d."

Looks like the responsible line is : https://github.com/llvm/llvm-project/blob/defe43bbffb0d25ec468f0e54b20548ec192ff90/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp#L2662C1-L2662C46

from this commit: 7dd2063

from this PR: #77040

@benshi001

[FantasqueX]

i want to work on this, please assign me.

[seanm]

@FantasqueX are you going to work on this soon? If not, I will, because it looks pretty trivial to fix...

[FantasqueX]

Sorry, I'm a bit busy these days. May not be able to fix this.

[seanm]

Patch: #135720

@FantasqueX maybe you could review?