Bug 1837907 [Linux] Enable AppShell SIGTERM signal handler for Firefox r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D194183

browser/app/nsBrowserApp.cpp

@@ -431,6 +431,10 @@ int main(int argc, char* argv[], char* envp[]) {
   mozilla::CreateAndStorePreXULSkeletonUI(GetModuleHandle(nullptr), argc, argv);
 #endif
 
+#if defined(XP_UNIX)
+  setenv("MOZ_ENABLE_APPSHELL_SIG_HANDLER", "1", true);
+#endif
+
   nsresult rv = InitXPCOMGlue(LibLoadingStrategy::ReadAhead);
   if (NS_FAILED(rv)) {
     return 255;

widget/gtk/nsAppShell.cpp

@@ -332,6 +332,15 @@ void nsAppShell::TermSignalHandler(int signo) {
 }
 
 void nsAppShell::InstallTermSignalHandler() {
+  if (!PR_GetEnv("MOZ_ENABLE_APPSHELL_SIG_HANDLER")) {
+    return;
+  }
+  unsetenv("MOZ_ENABLE_APPSHELL_SIG_HANDLER");
+
+  if (!XRE_IsParentProcess() || PR_GetEnv("MOZ_DISABLE_SIG_HANDLER")) {
+    return;
+  }
+
   struct sigaction act = {}, oldact;
   act.sa_handler = TermSignalHandler;
   sigfillset(&act.sa_mask);
@@ -446,9 +455,7 @@ nsresult nsAppShell::Init() {
   mTag = g_source_attach(source, nullptr);
   g_source_unref(source);
 
-  if (XRE_IsParentProcess() && !PR_GetEnv("MOZ_DISABLE_SIG_HANDLER")) {
-    InstallTermSignalHandler();
-  }
+  InstallTermSignalHandler();
 
   return nsBaseAppShell::Init();
 failed:
@@ -476,6 +483,11 @@ void nsAppShell::ScheduleNativeEventCallback() {
   Unused << write(mPipeFDs[1], buf, 1);
 }
 
+void nsAppShell::ScheduleQuitEvent() {
+  unsigned char buf[] = {QUIT_TOKEN};
+  Unused << write(mPipeFDs[1], buf, 1);
+}
+
 bool nsAppShell::ProcessNextNativeEvent(bool mayWait) {
   if (mSuspendNativeCount) {
     return false;
@@ -483,8 +495,3 @@ bool nsAppShell::ProcessNextNativeEvent(bool mayWait) {
   bool didProcessEvent = g_main_context_iteration(nullptr, mayWait);
   return didProcessEvent;
 }
-
-void nsAppShell::ScheduleQuitEvent() {
-  unsigned char buf[] = {QUIT_TOKEN};
-  Unused << write(mPipeFDs[1], buf, 1);
-}