From 676a190308b1492bdb6c1f8889247d4dfedefaf1 Mon Sep 17 00:00:00 2001
From: Joshua Peraza <jperaza@chromium.org>
Date: Mon, 30 Sep 2019 13:56:12 -0700
Subject: [PATCH] linux: fix --monitor-self

The metrics recording signal handler doesn't need to be re-installed
on Linux because the handler installed by StartHandler() restores the
previously installed handler by default. Reinstalling the metrics
handler results in a crash dump loop in which each signal handler
restores the other.

Change-Id: Ieef40c74bfc69f6e0caef9809f33cfcaa10f0d03
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/1832153
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Joshua Peraza <jperaza@chromium.org>
---
 client/crashpad_client_linux.cc |  1 -
 handler/handler_main.cc         | 29 ++++++-----------------------
 2 files changed, 6 insertions(+), 24 deletions(-)

diff --git a/client/crashpad_client_linux.cc b/client/crashpad_client_linux.cc
index c3ebbd4c..f1368ec7 100644
--- a/client/crashpad_client_linux.cc
+++ b/client/crashpad_client_linux.cc
@@ -352,7 +352,6 @@ bool CrashpadClient::StartHandler(
     const std::vector<std::string>& arguments,
     bool restartable,
     bool asynchronous_start) {
-  DCHECK(!restartable);
   DCHECK(!asynchronous_start);
 
   ScopedFileHandle client_sock, handler_sock;
diff --git a/handler/handler_main.cc b/handler/handler_main.cc
index 9fce9fc1..7d9701c0 100644
--- a/handler/handler_main.cc
+++ b/handler/handler_main.cc
@@ -263,8 +263,6 @@ class CallMetricsRecordNormalExit {
 
 #if defined(OS_MACOSX) || defined(OS_LINUX) || defined(OS_ANDROID)
 
-Signals::OldActions g_old_crash_signal_handlers;
-
 void HandleCrashSignal(int sig, siginfo_t* siginfo, void* context) {
   MetricsRecordExit(Metrics::LifetimeMilestone::kCrashed);
 
@@ -299,9 +297,7 @@ void HandleCrashSignal(int sig, siginfo_t* siginfo, void* context) {
   }
   Metrics::HandlerCrashed(metrics_code);
 
-  struct sigaction* old_action =
-      g_old_crash_signal_handlers.ActionForSignal(sig);
-  Signals::RestoreHandlerAndReraiseSignalOnReturn(siginfo, old_action);
+  Signals::RestoreHandlerAndReraiseSignalOnReturn(siginfo, nullptr);
 }
 
 void HandleTerminateSignal(int sig, siginfo_t* siginfo, void* context) {
@@ -309,13 +305,13 @@ void HandleTerminateSignal(int sig, siginfo_t* siginfo, void* context) {
   Signals::RestoreHandlerAndReraiseSignalOnReturn(siginfo, nullptr);
 }
 
-#if defined(OS_MACOSX)
-
 void ReinstallCrashHandler() {
   // This is used to re-enable the metrics-recording crash handler after
   // MonitorSelf() sets up a Crashpad exception handler. On macOS, the
   // metrics-recording handler uses signals and the Crashpad handler uses Mach
   // exceptions, so there’s nothing to re-enable.
+  // On Linux, the signal handler installed by StartHandler() restores the
+  // previously installed signal handler by default.
 }
 
 void InstallCrashHandler() {
@@ -325,6 +321,8 @@ void InstallCrashHandler() {
   Signals::InstallTerminateHandlers(HandleTerminateSignal, 0, nullptr);
 }
 
+#if defined(OS_MACOSX)
+
 struct ResetSIGTERMTraits {
   static struct sigaction* InvalidValue() {
     return nullptr;
@@ -349,21 +347,6 @@ void HandleSIGTERM(int sig, siginfo_t* siginfo, void* context) {
   g_exception_handler_server->Stop();
 }
 
-#else
-
-void ReinstallCrashHandler() {
-  // This is used to re-enable the metrics-recording crash handler after
-  // MonitorSelf() sets up a Crashpad signal handler.
-  Signals::InstallCrashHandlers(
-      HandleCrashSignal, 0, &g_old_crash_signal_handlers);
-}
-
-void InstallCrashHandler() {
-  ReinstallCrashHandler();
-
-  Signals::InstallTerminateHandlers(HandleTerminateSignal, 0, nullptr);
-}
-
 #endif  // OS_MACOSX
 
 #elif defined(OS_WIN)
@@ -473,7 +456,7 @@ void MonitorSelf(const Options& options) {
   // instance of crashpad_handler to be writing metrics at a time, and it should
   // be the primary instance.
   CrashpadClient crashpad_client;
-#if defined(OS_LINUX) || defined(OS_ANDROID)
+#if defined(OS_ANDROID)
   if (!crashpad_client.StartHandlerAtCrash(executable_path,
                                            options.database,
                                            base::FilePath(),