[ASan] Move the sigaltstack() bits to sanitizer_common.

This change is a part of refactoring intended to have common signal handling behavior in all tools.
Note that this particular change doesn't enable use_sigaltstack support in every tool.



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@200310 91177308-0d34-0410-b5e6-96231b3b80d8

lib/asan/asan_internal.h

@@ -74,8 +74,6 @@ void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp);
 
 void MaybeReexec();
 bool AsanInterceptsSignal(int signum);
-void SetAlternateSignalStack();
-void UnsetAlternateSignalStack();
 void InstallSignalHandlers();
 void ReadContextStack(void *context, uptr *stack, uptr *ssize);
 void AsanPlatformThreadInit();

lib/asan/asan_posix.cc

@@ -56,33 +56,6 @@ static void     ASAN_OnSIGSEGV(int, siginfo_t *siginfo, void *context) {
   ReportSIGSEGV(pc, sp, bp, addr);
 }
 
-void SetAlternateSignalStack() {
-  stack_t altstack, oldstack;
-  CHECK_EQ(0, sigaltstack(0, &oldstack));
-  // If the alternate stack is already in place, do nothing.
-  if ((oldstack.ss_flags & SS_DISABLE) == 0) return;
-  // TODO(glider): the mapped stack should have the MAP_STACK flag in the
-  // future. It is not required by man 2 sigaltstack now (they're using
-  // malloc()).
-  void* base = MmapOrDie(kAltStackSize, __FUNCTION__);
-  altstack.ss_sp = base;
-  altstack.ss_flags = 0;
-  altstack.ss_size = kAltStackSize;
-  CHECK_EQ(0, sigaltstack(&altstack, 0));
-  VReport(1, "Alternative stack for T%d set: [%p,%p)\n",
-          GetCurrentTidOrInvalid(), altstack.ss_sp,
-          (char *)altstack.ss_sp + altstack.ss_size);
-}
-
-void UnsetAlternateSignalStack() {
-  stack_t altstack, oldstack;
-  altstack.ss_sp = 0;
-  altstack.ss_flags = SS_DISABLE;
-  altstack.ss_size = 0;
-  CHECK_EQ(0, sigaltstack(&altstack, &oldstack));
-  UnmapOrDie(oldstack.ss_sp, oldstack.ss_size);
-}
-
 void InstallSignalHandlers() {
   // Set the alternate signal stack for the main thread.
   // This will cause SetAlternateSignalStack to be called twice, but the stack

lib/asan/asan_win.cc

@@ -70,14 +70,6 @@ void *AsanDoesNotSupportStaticLinkage() {
   return 0;
 }
 
-void SetAlternateSignalStack() {
-  // FIXME: Decide what to do on Windows.
-}
-
-void UnsetAlternateSignalStack() {
-  // FIXME: Decide what to do on Windows.
-}
-
 void InstallSignalHandlers() {
   // FIXME: Decide what to do on Windows.
 }

lib/sanitizer_common/sanitizer_common.h

@@ -213,6 +213,10 @@ typedef void (*CheckFailedCallbackType)(const char *, int, const char *,
                                        u64, u64);
 void SetCheckFailedCallback(CheckFailedCallbackType callback);
 
+// Functions related to signal handling.
+void SetAlternateSignalStack();
+void UnsetAlternateSignalStack();
+
 // We don't want a summary too long.
 const int kMaxSummaryLength = 1024;
 // Construct a one-line string:

lib/sanitizer_common/sanitizer_posix.cc

@@ -21,6 +21,7 @@
 #include "sanitizer_stacktrace.h"
 
 #include <sys/mman.h>
+#include <signal.h>
 
 namespace __sanitizer {
 

lib/sanitizer_common/sanitizer_posix_libcdep.cc

@@ -20,6 +20,7 @@
 
 #include <errno.h>
 #include <pthread.h>
+#include <signal.h>
 #include <stdlib.h>
 #include <sys/mman.h>
 #include <sys/resource.h>
@@ -89,6 +90,33 @@ int internal_isatty(fd_t fd) {
   return isatty(fd);
 }
 
+// TODO(glider): different tools may require different altstack size.
+static const uptr kAltStackSize = SIGSTKSZ * 4;  // SIGSTKSZ is not enough.
+
+void SetAlternateSignalStack() {
+  stack_t altstack, oldstack;
+  CHECK_EQ(0, sigaltstack(0, &oldstack));
+  // If the alternate stack is already in place, do nothing.
+  if ((oldstack.ss_flags & SS_DISABLE) == 0) return;
+  // TODO(glider): the mapped stack should have the MAP_STACK flag in the
+  // future. It is not required by man 2 sigaltstack now (they're using
+  // malloc()).
+  void* base = MmapOrDie(kAltStackSize, __FUNCTION__);
+  altstack.ss_sp = base;
+  altstack.ss_flags = 0;
+  altstack.ss_size = kAltStackSize;
+  CHECK_EQ(0, sigaltstack(&altstack, 0));
+}
+
+void UnsetAlternateSignalStack() {
+  stack_t altstack, oldstack;
+  altstack.ss_sp = 0;
+  altstack.ss_flags = SS_DISABLE;
+  altstack.ss_size = 0;
+  CHECK_EQ(0, sigaltstack(&altstack, &oldstack));
+  UnmapOrDie(oldstack.ss_sp, oldstack.ss_size);
+}
+
 }  // namespace __sanitizer
 
 #endif

lib/sanitizer_common/sanitizer_win.cc

@@ -413,6 +413,14 @@ void RawWrite(const char *buffer) {
   }
 }
 
+void SetAlternateSignalStack() {
+  // FIXME: Decide what to do on Windows.
+}
+
+void UnsetAlternateSignalStack() {
+  // FIXME: Decide what to do on Windows.
+}
+
 }  // namespace __sanitizer
 
 #endif  // _WIN32