Initial implementation for a linux crashlog

Author: NicksWorld

library/CMakeLists.txt

@@ -136,6 +136,7 @@ endif()
 
 set(MAIN_SOURCES_LINUX
     ${CONSOLE_SOURCES}
+    Crashlog.cpp
 )
 
 set(MAIN_SOURCES_DARWIN

library/Core.cpp

@@ -1540,6 +1540,11 @@ bool Core::InitMainThread() {
 
     Filesystem::init();
 
+    #ifdef LINUX_BUILD
+        extern void dfhack_crashlog_init();
+        dfhack_crashlog_init();
+    #endif
+
     // Re-route stdout and stderr again - DF seems to set up stdout and
     // stderr.txt on Windows as of 0.43.05. Also, log before switching files to
     // make it obvious what's going on if someone checks the *.txt files.
@@ -2375,6 +2380,11 @@ void Core::onStateChange(color_ostream &out, state_change_event event)
 
 int Core::Shutdown ( void )
 {
+    #ifdef LINUX_BUILD
+        extern void dfhack_crashlog_shutdown();
+        dfhack_crashlog_shutdown();
+    #endif
+
     if(errorstate)
         return true;
     errorstate = 1;

library/Crashlog.cpp

@@ -0,0 +1,81 @@
+#include "DFHackVersion.h"
+#include <csignal>
+#include <thread>
+#include <semaphore>
+#include <filesystem>
+#include <fstream>
+
+#include <execinfo.h>
+
+const int BT_ENTRY_MAX = 25;
+int bt_entries = 0;
+void* bt[BT_ENTRY_MAX];
+int crash_signal = 0;
+
+std::binary_semaphore crashlog_ready{0};
+std::binary_semaphore crashlog_complete{0};
+
+std::thread crashlog_thread;
+volatile bool shutdown = false;
+
+extern "C" void dfhack_crashlog_handle_signal(int sig) {
+    crash_signal = sig;
+    bt_entries = backtrace(bt, BT_ENTRY_MAX);
+    
+    // Signal saving of crashlog and wait for completion
+    crashlog_ready.release();
+    crashlog_complete.acquire();
+    std::quick_exit(1);
+}
+
+void dfhack_save_crashlog() {
+    char** backtrace_strings = backtrace_symbols(bt, bt_entries);
+    if (!backtrace_strings) {
+        // Something has gone terribly wrong
+        return;
+    }
+    std::filesystem::path crashlog_path = "./crash.txt";
+    std::ofstream crashlog(crashlog_path);
+
+    crashlog << "Dwarf Fortress has crashed!" << "\n";
+    crashlog << "DwarfFortress Version " << DFHack::Version::df_version() << "\n";
+    crashlog << "DFHack Version " << DFHack::Version::dfhack_version() << "\n\n";
+
+    for (int i = 0; i < bt_entries; i++) {
+        crashlog << i << "> " << backtrace_strings[i] << "\n";
+    }
+
+    free(backtrace_strings);
+}
+
+void dfhack_crashlog_thread() {
+    // Wait for crash or shutdown signal
+    crashlog_ready.acquire();
+    if (shutdown)
+        return;
+
+    dfhack_save_crashlog();
+    crashlog_complete.release();
+    std::quick_exit(1);
+}
+
+const int desired_signals[3] = {SIGSEGV,SIGILL,SIGABRT};
+namespace DFHack {
+void dfhack_crashlog_init() {
+    for (int signal : desired_signals) {
+        std::signal(signal, dfhack_crashlog_handle_signal);
+    }
+
+    // Ensure the library is initialized to avoid AsyncSignal-Unsafe init during crash
+    int _ = backtrace(bt, 1);
+
+    crashlog_thread = std::thread(dfhack_crashlog_thread);
+}
+
+void dfhack_crashlog_shutdown() {
+    shutdown = true;
+    crashlog_ready.release();
+    crashlog_thread.join();
+    return;
+}
+}