feat: export debugging signal handlers to zig

include/thespian/backtrace.h

@@ -1,13 +1,21 @@
 #pragma once
 
 #ifdef __cplusplus
+#include <csignal>
 extern "C" {
+#else
+#include <signal.h>
 #endif
 
 void install_debugger();
+void install_remote_debugger();
 void install_backtrace();
 void install_jitdebugger();
 
+void sighdl_debugger(int no, siginfo_t * /*sigi*/, void * /*uco*/);
+void sighdl_remote_debugger(int no, siginfo_t * /*sigi*/, void * /*uco*/);
+void sighdl_backtrace(int no, siginfo_t * /*sigi*/, void * /*uco*/);
+
 #ifdef __cplusplus
 }
 #endif

src/backtrace.cpp

@@ -1,6 +1,5 @@
 #ifdef __linux__
 
-#include <csignal>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
@@ -31,7 +30,8 @@ static void get_pid_binpath() {
 }
 
 static const auto lldb{"/usr/bin/lldb"};
-static const auto default_debugger{"/usr/bin/gdbserver"};
+static const auto default_debugger{"/usr/bin/gdb"};
+static const auto default_remote_debugger{"/usr/bin/gdbserver"};
 
 static auto get_debugger() -> const char * {
   const char *debugger = secure_getenv("JITDEBUG");
@@ -47,6 +47,20 @@ static auto get_debugger() -> const char * {
 }
 const char *const debugger = get_debugger();
 
+static auto get_remote_debugger() -> const char * {
+  const char *debugger = secure_getenv("JITDEBUG");
+  if (not debugger)
+    return default_remote_debugger;
+  if (strcmp(debugger, "on") == 0)
+    return default_remote_debugger;
+  if (strcmp(debugger, "1") == 0)
+    return default_remote_debugger;
+  if (strcmp(debugger, "true") == 0)
+    return default_remote_debugger;
+  return debugger;
+}
+const char *const remote_debugger = get_remote_debugger();
+
 void start_debugger(const char *dbg, const char **argv) {
 #if defined(PR_SET_PTRACER)
   prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY, 0, 0, 0); // NOLINT
@@ -67,11 +81,21 @@ void start_debugger(const char *dbg, const char **argv) {
 extern "C" void sighdl_debugger(int no, siginfo_t * /*sigi*/, void * /*uco*/) {
   get_pid_binpath();
   const char *argv[] = {// NOLINT
-                        debugger, "--attach", "[::1]:7777", pid_s, nullptr};
+                        debugger, "--pid", pid_s, nullptr};
   start_debugger(debugger, argv);
   (void)raise(no);
 }
 
+extern "C" void sighdl_remote_debugger(int no, siginfo_t * /*sigi*/,
+                                       void * /*uco*/) {
+  get_pid_binpath();
+  const char *argv[] = {// NOLINT
+                        remote_debugger, "--attach", "[::1]:7777", pid_s,
+                        "-ex",           "continue", nullptr};
+  start_debugger(remote_debugger, argv);
+  (void)raise(no);
+}
+
 extern "C" void sighdl_backtrace(int no, siginfo_t * /*sigi*/, void * /*uco*/) {
   get_pid_binpath();
   const char *argv[] = {// NOLINT
@@ -98,6 +122,9 @@ static void install_crash_handler(void (*hdlr)(int, siginfo_t *, void *)) {
 } // namespace
 
 extern "C" void install_debugger() { install_crash_handler(sighdl_debugger); }
+extern "C" void install_remote_debugger() {
+  install_crash_handler(sighdl_remote_debugger);
+}
 extern "C" void install_backtrace() { install_crash_handler(sighdl_backtrace); }
 extern "C" void install_jitdebugger() {
   if (secure_getenv("JITDEBUG"))

src/thespian.zig

@@ -18,8 +18,14 @@ pub var stack_trace_on_errors: bool = false;
 pub const subprocess = if (builtin.os.tag == .windows) @import("subprocess_windows.zig") else @import("subprocess.zig");
 
 pub const install_debugger = c.install_debugger;
+pub const install_remote_debugger = c.install_remote_debugger;
 pub const install_backtrace = c.install_backtrace;
 pub const install_jitdebugger = c.install_jitdebugger;
+
+pub const sighdl_debugger = c.sighdl_debugger;
+pub const sighdl_remote_debugger = c.sighdl_remote_debugger;
+pub const sighdl_backtrace = c.sighdl_backtrace;
+
 pub const max_message_size = 8 * 4096;
 const message_buf_allocator = std.heap.c_allocator;
 threadlocal var message_buffer: std.ArrayList(u8) = std.ArrayList(u8).init(message_buf_allocator);