Merge pull request #5672 from NicksWorld/crashlog/hide_signal_handler

Exclude signal handler from linux crashlogs

Author: ab9rf

library/Crashlog.cpp

@@ -1,4 +1,5 @@
 #include "DFHackVersion.h"
+
 #include <csignal>
 #include <iomanip>
 #include <filesystem>
@@ -42,7 +43,8 @@ void signal_crashlog_complete() {
 
 std::thread crashlog_thread;
 
-extern "C" void dfhack_crashlog_handle_signal(int sig) {
+// Force this method to be inlined so that it doesn't create a stack frame
+[[gnu::always_inline]] inline void handle_signal_internal(int sig) {
     if (shutdown.load() || crashed.exchange(true) || crashlog_ready.load()) {
         // Ensure the signal handler doesn't try to write a crashlog
         // whilst the crashlog thread is unavailable.
@@ -61,8 +63,12 @@ extern "C" void dfhack_crashlog_handle_signal(int sig) {
     std::quick_exit(1);
 }
 
+extern "C" void dfhack_crashlog_handle_signal(int sig) {
+    handle_signal_internal(sig);
+}
+
 void dfhack_crashlog_handle_terminate() {
-    dfhack_crashlog_handle_signal(0);
+    handle_signal_internal(0);
 }
 
 std::string signal_name(int sig) {
@@ -105,10 +111,6 @@ std::filesystem::path get_crashlog_path() {
 
 void dfhack_save_crashlog() {
     char** backtrace_strings = backtrace_symbols(crash_info.backtrace, crash_info.backtrace_entries);
-    if (!backtrace_strings) {
-        // Allocation failed, give up
-        return;
-    }
     try {
         std::filesystem::path crashlog_path = get_crashlog_path();
         std::ofstream crashlog(crashlog_path);
@@ -122,8 +124,14 @@ void dfhack_save_crashlog() {
             crashlog << "Signal " << signal << "\n";
         }
 
-        for (int i = 0; i < crash_info.backtrace_entries; i++) {
-            crashlog << i << "> " << backtrace_strings[i] << "\n";
+        if (crash_info.backtrace_entries >= 2 && backtrace_strings != nullptr) {
+            // Skip the first backtrace entry as it will always be dfhack_crashlog_handle_(signal|terminate)
+            for (int i = 1; i < crash_info.backtrace_entries; i++) {
+                crashlog << i - 1 << "> " << backtrace_strings[i] << "\n";
+            }
+        } else {
+            // Make it clear if no relevant backtrace was able to be obtained
+            crashlog << "Failed to obtain relevant backtrace\n";
         }
     } catch (...) {}