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Exclude signal handler from linux crashlogs #5672

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Merged
ab9rf merged 2 commits into from
Dec 6, 2025
+16 −8
Merged

Exclude signal handler from linux crashlogs #5672

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d6eaea1
Ensure the dfhack signal handler doesn't appear in crashlogs
NicksWorld Nov 29, 2025
5687f5c
Make a failure to obtain relevant crash backtrace obvious
NicksWorld Dec 4, 2025
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24 changes: 16 additions & 8 deletions library/Crashlog.cpp
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
#include "DFHackVersion.h"

#include <csignal>
#include <iomanip>
#include <filesystem>
Expand Down Expand Up @@ -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.
Expand All @@ -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) {
Expand Down Expand Up @@ -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);
Expand All @@ -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 (...) {}

Expand Down