[compiler-rt] [sanitizer_common] AND signals in BlockSignals instead of deleting (PR #113443)

[Vitaly Buka via llvm-commits]

================
@@ -164,33 +164,45 @@ void SetSigProcMask(__sanitizer_sigset_t *set, __sanitizer_sigset_t *oldset) {
   CHECK_EQ(0, internal_sigprocmask(SIG_SETMASK, set, oldset));
 }
 
+// Deletes the specified signal from newset, if it is not present in oldset
+// Equivalently: newset[signum] = newset[signum] & oldset[signum]
+static void KeepUnblocked(__sanitizer_sigset_t &newset,
+                          __sanitizer_sigset_t &oldset, int signum) {
+  if (!internal_sigismember(oldset, signum))
+    internal_sigdelset(newset, signum);
+}
+
 // Block asynchronous signals
 void BlockSignals(__sanitizer_sigset_t *oldset) {
-  __sanitizer_sigset_t set;
-  internal_sigfillset(&set);
+  __sanitizer_sigset_t currentset;
+  SetSigProcMask(NULL, &currentset);
+
+  __sanitizer_sigset_t newset;
+  internal_sigfillset(&newset);
 #  if SANITIZER_LINUX && !SANITIZER_ANDROID
   // Glibc uses SIGSETXID signal during setuid call. If this signal is blocked
   // on any thread, setuid call hangs.
   // See test/sanitizer_common/TestCases/Linux/setuid.c.
-  internal_sigdelset(&set, 33);
+  KeepUnblocked(&newset, &currentset, 33);
----------------
vitalybuka wrote:

It should apply to all of them

https://github.com/llvm/llvm-project/pull/113443