/* GLIB - Library of useful routines for C programming

 * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald

 *

 * SPDX-License-Identifier: LGPL-2.1-or-later

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, see <http://www.gnu.org/licenses/>.

 */

/*

 * Modified by the GLib Team and others 1997-2000.  See the AUTHORS

 * file for a list of people on the GLib Team.  See the ChangeLog

 * files for a list of changes.  These files are distributed with

 * GLib at ftp://ftp.gtk.org/pub/gtk/.

 */

/*

 * MT safe ; except for g_on_error_stack_trace, but who wants thread safety

 * then

 */

#include "config.h"

#include "glibconfig.h"

#include <signal.h>

#include <stdarg.h>

#include <stdio.h>

#include <stdlib.h>

#ifdef HAVE_SYS_TIME_H

#include <sys/time.h>

#endif

#include <sys/types.h>

#include <time.h>

#ifdef G_OS_UNIX

#include "glib-unixprivate.h"

#include <errno.h>

#include <unistd.h>

#include <sys/wait.h>

#ifdef HAVE_SYS_SELECT_H

#include <sys/select.h>

#endif /* HAVE_SYS_SELECT_H */

#endif

#include <string.h>

#ifdef G_OS_WIN32

#include <windows.h>

#else

#include <fcntl.h>

#endif

#include "gbacktrace.h"

#include "gtypes.h"

#include "gmain.h"

#include "gprintfint.h"

#include "gunicode.h"

#include "gutils.h"

#ifndef G_OS_WIN32

static void stack_trace (const char * const *args);

#endif

/* Default to using LLDB for backtraces on macOS. */

#ifdef __APPLE__

#define USE_LLDB

#endif

#ifdef USE_LLDB

#define DEBUGGER "lldb"

#else

#define DEBUGGER "gdb"

#endif

/* People want to hit this from their debugger... */

GLIB_AVAILABLE_IN_ALL volatile gboolean glib_on_error_halt;

volatile gboolean glib_on_error_halt = TRUE;

/**

 * g_on_error_query:

 * @prg_name: the program name, needed by gdb for the "[S]tack trace"

 *     option. If @prg_name is %NULL, g_get_prgname() is called to get

 *     the program name (which will work correctly if gdk_init() or

 *     gtk_init() has been called)

 *

 * Prompts the user with

 * `[E]xit, [H]alt, show [S]tack trace or [P]roceed`.

 * This function is intended to be used for debugging use only.

 * The following example shows how it can be used together with

 * the g_log() functions.

 *

 * |[<!-- language="C" -->

 * #include <glib.h>

 *

 * static void

 * log_handler (const gchar   *log_domain,

 *              GLogLevelFlags log_level,

 *              const gchar   *message,

 *              gpointer       user_data)

 * {

 *   g_log_default_handler (log_domain, log_level, message, user_data);

 *

 *   g_on_error_query (MY_PROGRAM_NAME);

 * }

 *

 * int

 * main (int argc, char *argv[])

 * {

 *   g_log_set_handler (MY_LOG_DOMAIN,

 *                      G_LOG_LEVEL_WARNING |

 *                      G_LOG_LEVEL_ERROR |

 *                      G_LOG_LEVEL_CRITICAL,

 *                      log_handler,

 *                      NULL);

 *   ...

 * ]|

 *

 * If "[E]xit" is selected, the application terminates with a call

 * to _exit(0).

 *

 * If "[S]tack" trace is selected, g_on_error_stack_trace() is called.

 * This invokes gdb, which attaches to the current process and shows

 * a stack trace. The prompt is then shown again.

 *

 * If "[P]roceed" is selected, the function returns.

 *

 * This function may cause different actions on non-UNIX platforms.

 *

 * On Windows consider using the `G_DEBUGGER` environment

 * variable (see [Running GLib Applications](running.html)) and

 * calling g_on_error_stack_trace() instead.

 */

void

g_on_error_query (const gchar *prg_name)

{

#ifndef G_OS_WIN32

  static const gchar * const query1 = "[E]xit, [H]alt";

  static const gchar * const query2 = ", show [S]tack trace";

  static const gchar * const query3 = " or [P]roceed";

  gchar buf[16];

  if (!prg_name)

    prg_name = g_get_prgname ();

 retry:

  _g_fprintf (stdout,

              "(process:%u): %s%s%s: ",

              (guint) getpid (),

              query1,

              query2,

              query3);

  fflush (stdout);

  if (isatty(0) && isatty(1))

    {

      if (fgets (buf, 8, stdin) == NULL)

        _exit (0);

    }

  else

    {

      strcpy (buf, "E\n");

    }

  if ((buf[0] == 'E' || buf[0] == 'e')

      && buf[1] == '\n')

    _exit (0);

  else if ((buf[0] == 'P' || buf[0] == 'p')

           && buf[1] == '\n')

    return;

  else if ((buf[0] == 'S' || buf[0] == 's')

           && buf[1] == '\n')

    {

      g_on_error_stack_trace (prg_name);

      goto retry;

    }

  else if ((buf[0] == 'H' || buf[0] == 'h')

           && buf[1] == '\n')

    {

      while (glib_on_error_halt)

        ;

      glib_on_error_halt = TRUE;

      return;

    }

  else

    goto retry;

#else

  if (!prg_name)

    prg_name = g_get_prgname ();

  /* MessageBox is allowed on UWP apps only when building against

   * the debug CRT, which will set -D_DEBUG */

#if defined(_DEBUG) || !defined(G_WINAPI_ONLY_APP)

  {

    WCHAR *caption = NULL;

    if (prg_name && *prg_name)

      {

        caption = g_utf8_to_utf16 (prg_name, -1, NULL, NULL, NULL);

      }

    MessageBoxW (NULL, L"g_on_error_query called, program terminating",

                 caption,

                 MB_OK|MB_ICONERROR);

    g_free (caption);

  }

#else

  printf ("g_on_error_query called, program '%s' terminating\n",

      (prg_name && *prg_name) ? prg_name : "(null)");

#endif

  _exit(0);

#endif

}

/**

 * g_on_error_stack_trace:

 * @prg_name: (nullable): the program name, needed by gdb for the

 *   "[S]tack trace" option, or `NULL` to use a default string

 *

 * Invokes gdb, which attaches to the current process and shows a

 * stack trace. Called by g_on_error_query() when the "[S]tack trace"

 * option is selected. You can get the current process's program name

 * with g_get_prgname(), assuming that you have called gtk_init() or

 * gdk_init().

 *

 * This function may cause different actions on non-UNIX platforms.

 *

 * When running on Windows, this function is *not* called by

 * g_on_error_query(). If called directly, it will raise an

 * exception, which will crash the program. If the `G_DEBUGGER` environment

 * variable is set, a debugger will be invoked to attach and

 * handle that exception (see [Running GLib Applications](running.html)).

 */

void

g_on_error_stack_trace (const gchar *prg_name)

{

#if defined(G_OS_UNIX)

  pid_t pid;

  gchar buf[16];

  gchar buf2[64];

  const gchar *args[5] = { DEBUGGER, NULL, NULL, NULL, NULL };

  int status;

  if (!prg_name)

    {

      _g_snprintf (buf2, sizeof (buf2), "/proc/%u/exe", (guint) getpid ());

      prg_name = buf2;

    }

  _g_snprintf (buf, sizeof (buf), "%u", (guint) getpid ());

#ifdef USE_LLDB

  args[1] = prg_name;

  args[2] = "-p";

  args[3] = buf;

#else

  args[1] = prg_name;

  args[2] = buf;

#endif

  pid = fork ();

  if (pid == 0)

    {

      stack_trace (args);

      _exit (0);

    }

  else if (pid == (pid_t) -1)

    {

      perror ("unable to fork " DEBUGGER);

      return;

    }

  /* Wait until the child really terminates. On Mac OS X waitpid ()

   * will also return when the child is being stopped due to tracing.

   */

  while (1)

    {

      pid_t retval = waitpid (pid, &status, 0);

      if (retval == -1)

        {

          if (errno == EAGAIN || errno == EINTR)

            continue;

          break;

        }

      else if (WIFEXITED (status) || WIFSIGNALED (status))

        break;

    }

#else

  if (IsDebuggerPresent ())

    G_BREAKPOINT ();

  else

    g_abort ();

#endif

}

#ifndef G_OS_WIN32

static gboolean stack_trace_done = FALSE;

static void

stack_trace_sigchld (int signum)

{

  stack_trace_done = TRUE;

}

#define BUFSIZE 1024

static inline const char *

get_strerror (char *buffer, gsize n)

{

#if defined(STRERROR_R_CHAR_P)

  return strerror_r (errno, buffer, n);

#elif defined(HAVE_STRERROR_R)

  int ret = strerror_r (errno, buffer, n);

  if (ret == 0 || ret == EINVAL)

    return buffer;

  return NULL;

#else

  const char *error_str = strerror (errno);

  if (!error_str)

    return NULL;

  strncpy (buffer, error_str, n);

  return buffer;

#endif

}

static gssize

checked_write (int fd, gconstpointer buf, gsize n)

{

  gssize written = write (fd, buf, n);

  if (written == -1)

    {

      char msg[BUFSIZE] = {0};

      char error_str[BUFSIZE / 2] = {0};

      get_strerror (error_str, sizeof (error_str) - 1);

      snprintf (msg, sizeof (msg) - 1, "Unable to write to fd %d: %s", fd, error_str);

      perror (msg);

      _exit (0);

    }

  return written;

}

static int

checked_dup (int fd)

{

  int new_fd = dup (fd);

  if (new_fd == -1)

    {

      char msg[BUFSIZE] = {0};

      char error_str[BUFSIZE / 2] = {0};

      get_strerror (error_str, sizeof (error_str) - 1);

      snprintf (msg, sizeof (msg) - 1, "Unable to duplicate fd %d: %s", fd, error_str);

      perror (msg);

      _exit (0);

    }

  return new_fd;

}

static void

stack_trace (const char * const *args)

{

  pid_t pid;

  int in_fd[2];

  int out_fd[2];

  fd_set fdset;

  fd_set readset;

  struct timeval tv;

  int sel, idx, state;

#ifdef USE_LLDB

  int line_idx;

#endif

  char buffer[BUFSIZE];

  char c;

  stack_trace_done = FALSE;

  signal (SIGCHLD, stack_trace_sigchld);

  if (!g_unix_open_pipe_internal (in_fd, TRUE, FALSE) ||

      !g_unix_open_pipe_internal (out_fd, TRUE, FALSE))

    {

      perror ("unable to open pipe");

      _exit (0);

    }

  pid = fork ();

  if (pid == 0)

    {

      /* Save stderr for printing failure below */

      int old_err = dup (2);

      if (old_err != -1)

  {

    int getfd = fcntl (old_err, F_GETFD);

    if (getfd != -1)

      (void) fcntl (old_err, F_SETFD, getfd | FD_CLOEXEC);

  }

      close (0);

      checked_dup (in_fd[0]);   /* set the stdin to the in pipe */

      close (1);

      checked_dup (out_fd[1]);  /* set the stdout to the out pipe */

      close (2);

      checked_dup (out_fd[1]);  /* set the stderr to the out pipe */

      execvp (args[0], (char **) args);      /* exec gdb */

      /* Print failure to original stderr */

      if (old_err != -1)

        {

          close (2);

          /* We can ignore the return value here as we're failing anyways */

          (void) !dup (old_err);

        }

      perror ("exec " DEBUGGER " failed");

      _exit (0);

    }

  else if (pid == (pid_t) -1)

    {

      perror ("unable to fork");

      _exit (0);

    }

  FD_ZERO (&fdset);

  FD_SET (out_fd[0], &fdset);

#ifdef USE_LLDB

  checked_write (in_fd[1], "bt\n", 3);

  checked_write (in_fd[1], "p x = 0\n", 8);

  checked_write (in_fd[1], "process detach\n", 15);

  checked_write (in_fd[1], "quit\n", 5);

#else

  /* Don't wrap so that lines are not truncated */

  checked_write (in_fd[1], "set width 0\n", 12);

  checked_write (in_fd[1], "set height 0\n", 13);

  checked_write (in_fd[1], "set pagination no\n", 18);

  checked_write (in_fd[1], "thread apply all backtrace\n", 27);

  checked_write (in_fd[1], "p x = 0\n", 8);

  checked_write (in_fd[1], "quit\n", 5);

#endif

  idx = 0;

#ifdef USE_LLDB

  line_idx = 0;

#endif

  state = 0;

  while (1)

    {

      readset = fdset;

      tv.tv_sec = 1;

      tv.tv_usec = 0;

      sel = select (FD_SETSIZE, &readset, NULL, NULL, &tv);

      if (sel == -1)

        break;

      if ((sel > 0) && (FD_ISSET (out_fd[0], &readset)))

        {

          if (read (out_fd[0], &c, 1))

            {

#ifdef USE_LLDB

              line_idx += 1;

#endif

              switch (state)

                {

                case 0:

#ifdef USE_LLDB

                  if (c == '*' || (c == ' ' && line_idx == 1))

#else

                  if (c == '#')

#endif

                    {

                      state = 1;

                      idx = 0;

                      buffer[idx++] = c;

                    }

                  break;

                case 1:

                  if (idx < BUFSIZE - 1)

                    buffer[idx++] = c;

                  if ((c == '\n') || (c == '\r'))

                    {

                      buffer[idx] = 0;

                      _g_fprintf (stdout, "%s", buffer);

                      state = 0;

                      idx = 0;

#ifdef USE_LLDB

                      line_idx = 0;

#endif

                    }

                  break;

                default:

                  break;

                }

            }

        }

      else if (stack_trace_done)

        break;

    }

  close (in_fd[0]);

  close (in_fd[1]);

  close (out_fd[0]);

  close (out_fd[1]);

  _exit (0);

}

#endif /* !G_OS_WIN32 */