Bug 804828 - Talagent trips ValidWriteAssert (when Firefox tries to restart in safe mode due to previous crashes). r=ted.

--HG--
extra : rebase_source : dd4a3dec5204181a4c421d84daccf9ea172757c8

toolkit/xre/nsAppRunner.cpp

@@ -129,6 +129,7 @@ using mozilla::unused;
 #include "nsINIParser.h"
 #include "mozilla/Omnijar.h"
 #include "mozilla/StartupTimeline.h"
+#include "mozilla/mozPoisonWrite.h"
 
 #include <stdlib.h>
 
@@ -3874,6 +3875,10 @@ XREMain::XRE_main(int argc, char* argv[], const nsXREAppData* aAppData)
   // corresponds to nsIAppStartup.quit(eRestart)
   if (rv == NS_SUCCESS_RESTART_APP) {
     appInitiatedRestart = true;
+  } else {
+    // We will have a real shutdown, let ShutdownXPCOM poison writes to
+    // find any late ones.
+    mozilla::EnableWritePoisoning();
   }
 
   if (!mShuttingDown) {

xpcom/build/mozPoisonWrite.h

@@ -17,5 +17,6 @@ MOZ_END_EXTERN_C
 namespace mozilla {
 void PoisonWrite();
 void DisableWritePoisoning();
+void EnableWritePoisoning();
 }
 #endif

xpcom/build/mozPoisonWriteMac.cpp

@@ -276,7 +276,14 @@ public:
     }
 };
 
-bool PoisoningDisabled = false;
+// This variable being true has two consequences
+// * It prevents PoisonWrite from patching the write functions.
+// * If the patching has already been done, it prevents AbortOnBadWrite from
+//   asserting. Note that not all writes use AbortOnBadWrite at this point
+//   (aio_write for example), so disabling writes after patching doesn't
+//   completely undo it.
+bool PoisoningDisabled = true;
+
 void AbortOnBadWrite(int fd, const void *wbuf, size_t count) {
     if (PoisoningDisabled)
         return;
@@ -375,7 +382,15 @@ extern "C" {
 
 namespace mozilla {
 void PoisonWrite() {
-    PoisoningDisabled = false;
+    // Quick sanity check that we don't poison twice.
+    static bool WritesArePoisoned = false;
+    MOZ_ASSERT(!WritesArePoisoned);
+    if (WritesArePoisoned)
+        return;
+    WritesArePoisoned = true;
+
+    if (PoisoningDisabled)
+        return;
 
     nsCOMPtr<nsIFile> mozFile;
     NS_GetSpecialDirectory(NS_APP_USER_PROFILE_50_DIR, getter_AddRefs(mozFile));
@@ -404,4 +419,7 @@ void PoisonWrite() {
 void DisableWritePoisoning() {
     PoisoningDisabled = true;
 }
+void EnableWritePoisoning() {
+    PoisoningDisabled = false;
+}
 }

xpcom/build/mozPoisonWriteStub.cpp

@@ -10,6 +10,8 @@ void PoisonWrite() {
 }
 void DisableWritePoisoning() {
 }
+void EnableWritePoisoning() {
+}
 }
 extern "C" {
     void MozillaRegisterDebugFD(int fd) {