tree 3b43ece8ac5dfda49235c6b158d1c473b2a348eb
parent b356f7b676342b30b533efa3c84f301c53ce98a5
author Xing Xue <xingxue@outlook.com> 1659993690 -0400
committer Copybara-Service <copybara-worker@google.com> 1659993962 -0700

[libunwind][AIX] Save/restore errno before/after system calls dlopen/dlsym/dlclose

Summary:
libunwind on AIX calls dlopen()/dlsym()/dlclose() to dynamically load libc++abi and get the personality for state table EH when it is running against the legacy xlcang++ compiler genereated applications. dlopen() sets errno to 0 when it is successful, which clobbers the value in errno from the user code. This seems to be an AIX bug that it should not set errno to 0 according to POSIX. We will open a bug report to AIX but in the mean time there won't be time line when AIX will have a fix and even AIX does fix it, it won't help earlier AIX releases in the field. This patch saves and restores errno before and after these calls so that user code can work as expected.

Reviewed by: compnerd, libunwind

Differential Revision: https://reviews.llvm.org/D131292

GitOrigin-RevId: cc8edbea7a5f26906ae3d1f7ba0dc5da8fc5afb5