[NFC][sanitizer] Extract ScopedBlockSignals

[vitalybuka]

rebase

[eugenis]

LGTM

[vitalybuka]

rebase

[ro]

This patch broke the Solaris/amd64 buildbot:

[71/467] Generating I386SunOSConfig/Asan-i386-calls-Noinst-Test
FAILED: projects/compiler-rt/lib/asan/tests/I386SunOSConfig/Asan-i386-calls-Noinst-Test 
cd /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/projects/compiler-rt/lib/asan/tests && /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/./bin/clang++ ASAN_NOINST_TEST_OBJECTS.gtest-all.cc.i386-calls.o ASAN_NOINST_TEST_OBJECTS.asan_fake_stack_test.cpp.i386-calls.o ASAN_NOINST_TEST_OBJECTS.asan_noinst_test.cpp.i386-calls.o ASAN_NOINST_TEST_OBJECTS.asan_test_main.cpp.i386-calls.o /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/projects/compiler-rt/lib/asan/tests/libRTAsanTest.i386.a -o /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/projects/compiler-rt/lib/asan/tests/I386SunOSConfig/./Asan-i386-calls-Noinst-Test -Wthread-safety -Wthread-safety-reference -Wthread-safety-beta -g --driver-mode=g++ -lm -ldl -lrt -pthread -m32
Undefined			first referenced
 symbol  			    in file
_ZN11__sanitizer18ScopedBlockSignalsD1Ev /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/projects/compiler-rt/lib/asan/tests/libRTAsanTest.i386.a(sanitizer_linux.cpp.o)
_ZN11__sanitizer18ScopedBlockSignalsC1EPNS_20__sanitizer_sigset_tE /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/projects/compiler-rt/lib/asan/tests/libRTAsanTest.i386.a(sanitizer_linux.cpp.o)
ld: fatal: symbol referencing errors

The definitions are within a !SANITIZER_SOLARIS && !SANITIZER_NETBSD block.

[vitalybuka]

In D113452#3120755, @ro wrote:

This patch broke the Solaris/amd64 buildbot:

Sorry, 3330a6670ee8d725f16c61fa127ba93613f1fc1f should fix.

[ro]

In D113452#3123634, @vitalybuka wrote:

Sorry, 3330a6670ee8d725f16c61fa127ba93613f1fc1f should fix.

It did indeed: the buildbot is (mostly) green again. Thanks.

compiler-rt/lib/sanitizer_common/sanitizer_linux.h

 
 void ReadProcMaps(ProcSelfMapsBuff *proc_maps);
 
 // Syscall wrappers.
 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
 
 // Linux-only syscalls.
 #if SANITIZER_LINUX
 uptr internal_prctl(int option, uptr arg2, uptr arg3, uptr arg4, uptr arg5);
 // Used only by sanitizer_stoptheworld. Signal handlers that are actually used
 // (like the process-wide error reporting SEGV handler) must use

compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

 #else
   __sanitizer_kernel_sigset_t *k_set = (__sanitizer_kernel_sigset_t *)set;
   __sanitizer_kernel_sigset_t *k_oldset = (__sanitizer_kernel_sigset_t *)oldset;
   return internal_syscall(SYSCALL(rt_sigprocmask), (uptr)how, (uptr)k_set,
                           (uptr)k_oldset, sizeof(__sanitizer_kernel_sigset_t));
 #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));
 }
 
 void internal_sigemptyset(__sanitizer_sigset_t *set) {
   internal_memset(set, 0, sizeof(*set));
 }
 
HandleSignalMode GetHandleSignalMode(int signum) {
   if (result == kHandleSignalYes && !common_flags()->allow_user_segv_handler)
     return kHandleSignalExclusive;
   return result;
 }
 
 #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;
 }
 
 void internal_join_thread(void *th) {
   real_pthread_join(th, nullptr);
 }
 #else
 void *internal_start_thread(void *(*func)(void *), void *arg) { return 0; }