From bf3531de81c1815becd45be7247965b0347e454b Mon Sep 17 00:00:00 2001
From: Justine Tunney <jtunney@gmail.com>
Date: Thu, 23 May 2024 19:23:42 -0700
Subject: [PATCH] Make crash reports reliable in multithreaded case

---
 libc/log/oncrash_amd64.c    |  2 ++
 libc/log/oncrash_arm64.c    |  2 ++
 libc/log/showcrashreports.c | 12 ++++++------
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/libc/log/oncrash_amd64.c b/libc/log/oncrash_amd64.c
index 0c965faec..66fdd4b81 100644
--- a/libc/log/oncrash_amd64.c
+++ b/libc/log/oncrash_amd64.c
@@ -192,6 +192,8 @@ void ShowCrashReportHook(int, int, int, struct siginfo *, ucontext_t *);
 
 static relegated void ShowCrashReport(int err, int sig, struct siginfo *si,
                                       ucontext_t *ctx) {
+  if (sig != SIGTRAP && sig != SIGQUIT)
+    sigaddset(&ctx->uc_sigmask, sig);
 #pragma GCC push_options
 #pragma GCC diagnostic ignored "-Walloca-larger-than="
   long size = __get_safe_size(8192, 4096);
diff --git a/libc/log/oncrash_arm64.c b/libc/log/oncrash_arm64.c
index 2ab6d31a1..59d02f12c 100644
--- a/libc/log/oncrash_arm64.c
+++ b/libc/log/oncrash_arm64.c
@@ -191,6 +191,8 @@ static relegated char *GetSymbolName(struct SymbolTable *st, int symbol) {
 
 static relegated void __oncrash_impl(int sig, struct siginfo *si,
                                      ucontext_t *ctx) {
+  if (sig != SIGTRAP && sig != SIGQUIT)
+    sigaddset(&ctx->uc_sigmask, sig);
 #pragma GCC push_options
 #pragma GCC diagnostic ignored "-Walloca-larger-than="
   long size = __get_safe_size(10000, 4096);
diff --git a/libc/log/showcrashreports.c b/libc/log/showcrashreports.c
index 1ee46c6b4..da63e3136 100644
--- a/libc/log/showcrashreports.c
+++ b/libc/log/showcrashreports.c
@@ -85,13 +85,13 @@ void ShowCrashReports(void) {
 #ifdef __x86_64__
   InstallCrashHandler(SIGTRAP, 0);
 #else
-  InstallCrashHandler(SIGTRAP, SA_RESETHAND);
+  InstallCrashHandler(SIGTRAP, 0);
 #endif
-  InstallCrashHandler(SIGFPE, SA_RESETHAND);
-  InstallCrashHandler(SIGILL, SA_RESETHAND);
-  InstallCrashHandler(SIGBUS, SA_RESETHAND);
-  InstallCrashHandler(SIGABRT, SA_RESETHAND);
-  InstallCrashHandler(SIGSEGV, SA_RESETHAND | SA_ONSTACK);
+  InstallCrashHandler(SIGFPE, 0);
+  InstallCrashHandler(SIGILL, 0);
+  InstallCrashHandler(SIGBUS, 0);
+  InstallCrashHandler(SIGABRT, 0);
+  InstallCrashHandler(SIGSEGV, SA_ONSTACK);
 }
 
 IGNORE_LEAKS(ShowCrashReports)