[NFC][sanitizer] Extract ScopedBlockSignals

vitalybuka · vitalybuka · commit 84b8dc710c2d · 2021-11-09T18:23:55.000-08:00
Differential Revision: https://reviews.llvm.org/D113452
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
@@ -842,6 +842,26 @@ uptr internal_sigprocmask(int how, __sanitizer_sigset_t *set,
 #endif
 }
 
+void SetSigProcMask(__sanitizer_sigset_t *set, __sanitizer_sigset_t *old) {
+  CHECK_EQ(0, internal_sigprocmask(SIG_SETMASK, set, old));
+}
+
+ScopedBlockSignals::ScopedBlockSignals(__sanitizer_sigset_t *copy) {
+  __sanitizer_sigset_t set;
+  internal_sigfillset(&set);
+#    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);
+#    endif
+  SetSigProcMask(&set, &saved_);
+  if (copy)
+    internal_memcpy(copy, &saved_, sizeof(saved_));
+}
+
+ScopedBlockSignals::~ScopedBlockSignals() { SetSigProcMask(&saved_, nullptr); }
+
 void internal_sigfillset(__sanitizer_sigset_t *set) {
   internal_memset(set, 0xff, sizeof(*set));
 }
@@ -1741,18 +1761,9 @@ HandleSignalMode GetHandleSignalMode(int signum) {
 #if !SANITIZER_GO
 void *internal_start_thread(void *(*func)(void *arg), void *arg) {
   // Start the thread with signals blocked, otherwise it can steal user signals.
-  __sanitizer_sigset_t set, old;
-  internal_sigfillset(&set);
-#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);
-#endif
-  internal_sigprocmask(SIG_SETMASK, &set, &old);
+  ScopedBlockSignals block(nullptr);
   void *th;
   real_pthread_create(&th, nullptr, func, arg);
-  internal_sigprocmask(SIG_SETMASK, &old, nullptr);
   return th;
 }
 
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_linux.h b/compiler-rt/lib/sanitizer_common/sanitizer_linux.h
@@ -49,7 +49,17 @@ uptr internal_getdents(fd_t fd, struct linux_dirent *dirp, unsigned int count);
 uptr internal_sigaltstack(const void* ss, void* oss);
 uptr internal_sigprocmask(int how, __sanitizer_sigset_t *set,
     __sanitizer_sigset_t *oldset);
-#if SANITIZER_GLIBC
+
+void SetSigProcMask(__sanitizer_sigset_t *set, __sanitizer_sigset_t *oldset);
+struct ScopedBlockSignals {
+  explicit ScopedBlockSignals(__sanitizer_sigset_t *copy);
+  ~ScopedBlockSignals();
+
+ private:
+  __sanitizer_sigset_t saved_;
+};
+
+#  if SANITIZER_GLIBC
 uptr internal_clock_gettime(__sanitizer_clockid_t clk_id, void *tp);
 #endif
 
