[compiler-rt] [sanitizer_common] Fix TgKill on Solaris (PR #98000)

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llvmbot wrote:


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@llvm/pr-subscribers-compiler-rt-sanitizer

Author: Rainer Orth (rorth)

<details>
<summary>Changes</summary>

While working on safestack on Solaris, I noticed that the `TgKill` implementation is wrong here: `TgKill` is supposed to return `-1` on error, while `thr_kill` returns `errno` instead.  This patch compensates for that.

This went unnoticed so far since `TgKill` has been unused.

Tested on `amd64-pc-solaris2.11` and `sparcv9-sun-solaris2.11` together with a subsequent patch to make safestack actually work on Solaris.

---
Full diff: https://github.com/llvm/llvm-project/pull/98000.diff


1 Files Affected:

- (modified) compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp (+3-1) 


``````````diff
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
index 12df3ef73da4bc..eec9d652630f95 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
@@ -563,7 +563,9 @@ int TgKill(pid_t pid, tid_t tid, int sig) {
   return internal_syscall(SYSCALL(thr_kill2), pid, tid, sig);
 #    elif SANITIZER_SOLARIS
   (void)pid;
-  return thr_kill(tid, sig);
+  errno = thr_kill(tid, sig);
+  // TgKill is expected to return -1 on error, not an errno.
+  return errno != 0 ? -1 : 0;
 #    endif
 }
 #  endif

``````````

</details>


https://github.com/llvm/llvm-project/pull/98000