$NetBSD$

--- src/arch/netbsd/async/debug.c.orig	2017-11-02 06:34:33.813702898 +0000
+++ src/arch/netbsd/async/debug.c
@@ -0,0 +1,216 @@
+#include "emu.h"
+#include "dosemu_config.h"
+#include "debug.h"
+#include "sig.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <assert.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <execinfo.h>
+
+static FILE *gdb_f = NULL;
+
+static void gdb_command(char *cmd)
+{
+  printf("%s", cmd);
+  fflush(stdout);
+  fprintf(gdb_f, "%s", cmd);
+  fflush(gdb_f);
+}
+
+static int start_gdb(pid_t dosemu_pid)
+{
+  char *buf;
+  int ret;
+
+  printf("Debug info:\n");
+  fflush(stdout);
+
+  ret = asprintf(&buf, "gdb %s", dosemu_proc_self_exe);
+  assert(ret != -1);
+
+  printf("%s", buf);
+  putchar('\n');
+  fflush(stdout);
+
+  if (!(gdb_f = popen(buf, "w"))) {
+    free(buf);
+    return 0;
+  }
+  free(buf);
+
+  ret = asprintf(&buf, "attach %i\n", dosemu_pid);
+  assert(ret != -1);
+
+  gdb_command(buf);
+  free(buf);
+
+  return 1;
+}
+
+static void do_debug(void)
+{
+  char *cmd1 = "info registers\n";
+//  char *cmd2 = "backtrace\n";
+  char *cmd3 = "thread apply all backtrace full\n";
+
+  gdb_command(cmd1);
+//  gdb_command(cmd2);
+  gdb_command(cmd3);
+}
+
+static int stop_gdb(void)
+{
+  char *cmd1 = "detach\n";
+  char *cmd2 = "quit\n";
+  int status;
+
+  gdb_command(cmd1);
+  gdb_command(cmd2);
+  wait(&status);
+  pclose(gdb_f);
+  putchar('\n');
+  fflush(stdout);
+  return !WEXITSTATUS(status);
+}
+
+/* disable as this crashes under DPMI trying to trace through DOS stack */
+/* ... and re-enable because people fuck up instead of installing gdb.
+ * But run this only if the gdb trace fails. */
+#if 1
+/* Obtain a backtrace and print it to `stdout'.
+   (derived from 'info libc')
+ */
+static void print_trace (void)
+{
+#define MAX_FRAMES 256
+  void *array[MAX_FRAMES];
+  int size;
+  char **strings;
+  size_t i;
+
+  size = backtrace (array, MAX_FRAMES);
+  strings = backtrace_symbols (array, size);
+  fprintf(dbg_fd, "Obtained %d stack frames.\n", size);
+
+  for (i = 0; i < size; i++)
+    fprintf(dbg_fd, "%s\n", strings[i]);
+
+  free (strings);
+  fprintf(dbg_fd, "Backtrace finished\n");
+}
+#endif
+
+static void collect_info(pid_t pid)
+{
+  char *cmd0 = "ldd %s";
+  char *cmd1 = "getconf GNU_LIBC_VERSION";
+  char *cmd2 = "getconf GNU_LIBPTHREAD_VERSION";
+  char *cmd3 = "cat /proc/%i/maps";
+  char *tmp;
+  int ret;
+
+  printf("System info:\n");
+  fflush(stdout);
+
+  ret = asprintf(&tmp, cmd0, dosemu_proc_self_exe);
+  assert(ret != -1);
+
+  if(system(tmp)) {
+    printf("command '%s' failed\n", tmp);
+  }
+  free(tmp);
+
+  if(system(cmd1)) {
+    printf("command '%s' failed\n", cmd1);
+  }
+
+  if(system(cmd2)) {
+    printf("command '%s' failed\n", cmd2);
+  }
+
+  ret = asprintf(&tmp, cmd3, pid);
+  assert(ret != -1);
+
+  if(system(tmp)) {
+    printf("command '%s' failed\n", tmp);
+  }
+  free(tmp);
+
+  fflush(stdout);
+}
+
+static int do_gdb_debug(void)
+{
+  int ret = 0;
+  pid_t dosemu_pid = getpid();
+  pid_t dbg_pid;
+  int status;
+  sigset_t set, oset;
+
+  if (getuid() != geteuid())
+    return 0;
+
+  sigemptyset(&set);
+  sigaddset(&set, SIGIO);
+  sigaddset(&set, SIGALRM);
+  sigprocmask(SIG_BLOCK, &set, &oset);
+  switch ((dbg_pid = fork())) {
+    case 0:
+      ioselect_done();
+      signal_done();
+      sigprocmask(SIG_SETMASK, &oset, NULL);
+
+      dup2(fileno(dbg_fd), STDOUT_FILENO);
+      dup2(fileno(dbg_fd), STDERR_FILENO);
+
+      collect_info(dosemu_pid);
+
+      if (!start_gdb(dosemu_pid))
+        _exit(1);
+      do_debug();
+      if (!stop_gdb())
+        _exit(1);
+      _exit(0);
+      break;
+    case -1:
+      error("fork failed, %s\n", strerror(errno));
+      break;
+    default:
+      waitpid(dbg_pid, &status, 0);
+      if (WEXITSTATUS(status)) {
+        dbug_printf("backtrace failure\n");
+      } else {
+        ret = 1;
+        dbug_printf("done backtrace\n");
+      }
+      break;
+  }
+  sigprocmask(SIG_SETMASK, &oset, NULL);
+  return ret;
+}
+
+void gdb_debug(void)
+{
+    int ret = do_gdb_debug();
+#if 0
+    if (!ret) {
+        print_trace();
+        error("Please install gdb!\n");
+    }
+#else
+    /* the problem with the above is that gdb usually doesn't work
+     * because of the security restrictions */
+    if (!ret)
+        error("Please install gdb!\n");
+    print_trace();
+#endif
+
+    fprintf(dbg_fd, "\n");
+    fflush(dbg_fd);
+    dump_state();
+}