[compiler-rt] [sanitizer] Don't TestPTrace() if SPARC; don't give up if internal_fork() fails (PR #152072)

[Vitaly Buka via llvm-commits]

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@@ -405,10 +405,16 @@ struct ScopedSetTracerPID {
 
 // This detects whether ptrace is blocked (e.g., by seccomp), by forking and
 // then attempting ptrace.
-// This separate check is necessary because StopTheWorld() creates a child
-// process with a shared virtual address space and shared TLS, and therefore
+// This separate check is necessary because StopTheWorld() creates a thread
+// with a shared virtual address space and shared TLS, and therefore
 // cannot use waitpid() due to the shared errno.
 static void TestPTrace() {
+#  if SANITIZER_SPARC
+  // internal_fork() on SPARC actually calls __fork(). We can't safely fork,
+  // because it's possible seccomp has been configured to disallow fork() but
+  // allow clone().
+  Report("WARNING: skipping TestPTrace() because this is SPARC\n");
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vitalybuka wrote:

It's better to e VPrint

spamming stderr just in case is not helpful

https://github.com/llvm/llvm-project/pull/152072