gdb/ser-pipe.c

   1 /* Serial interface for a pipe to a separate program
   2    Copyright (C) 1999-2023 Free Software Foundation, Inc.
   3
   4    Contributed by Cygnus Solutions.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "defs.h"
  22 #include "serial.h"
  23 #include "ser-base.h"
  24 #include "ser-unix.h"
  25
  26 #include "gdb_vfork.h"
  27
  28 #include <sys/types.h>
  29 #include <sys/socket.h>
  30 #include "gdbsupport/gdb_sys_time.h"
  31 #include <fcntl.h>
  32 #include "gdbsupport/filestuff.h"
  33 #include "gdbsupport/pathstuff.h"
  34
  35 #include <signal.h>
  36
  37 static int pipe_open (struct serial *scb, const char *name);
  38 static void pipe_close (struct serial *scb);
  39
  40 struct pipe_state
  41   {
  42     int pid;
  43   };
  44
  45 /* Open up a raw pipe.  */
  46
  47 static int
  48 pipe_open (struct serial *scb, const char *name)
  49 {
  50 #if !HAVE_SOCKETPAIR
  51   return -1;
  52 #else
  53   struct pipe_state *state;
  54   /* This chunk: */
  55   /* Copyright (c) 1988, 1993
  56    *      The Regents of the University of California.  All rights reserved.
  57    *
  58    * This code is derived from software written by Ken Arnold and
  59    * published in UNIX Review, Vol. 6, No. 8.
  60    */
  61   int pdes[2];
  62   int err_pdes[2];
  63   int pid;
  64
  65   if (*name == '|')
  66     {
  67       name++;
  68       name = skip_spaces (name);
  69     }
  70
  71   if (gdb_socketpair_cloexec (AF_UNIX, SOCK_STREAM, 0, pdes) < 0)
  72     return -1;
  73   if (gdb_socketpair_cloexec (AF_UNIX, SOCK_STREAM, 0, err_pdes) < 0)
  74     {
  75       close (pdes[0]);
  76       close (pdes[1]);
  77       return -1;
  78     }
  79
  80   /* Create the child process to run the command in.  Note that the
  81      apparent call to vfork() below *might* actually be a call to
  82      fork() due to the fact that autoconf will ``#define vfork fork''
  83      on certain platforms.  */
  84   pid = vfork ();
  85
  86   /* Error.  */
  87   if (pid == -1)
  88     {
  89       close (pdes[0]);
  90       close (pdes[1]);
  91       close (err_pdes[0]);
  92       close (err_pdes[1]);
  93       return -1;
  94     }
  95
  96   if (fcntl (err_pdes[0], F_SETFL, O_NONBLOCK) == -1)
  97     {
  98       close (err_pdes[0]);
  99       close (err_pdes[1]);
 100       err_pdes[0] = err_pdes[1] = -1;
 101     }
 102
 103   /* Child.  */
 104   if (pid == 0)
 105     {
 106       /* We don't want ^c to kill the connection.  */
 107 #ifdef HAVE_SETSID
 108       pid_t sid = setsid ();
 109       if (sid == -1)
 110         signal (SIGINT, SIG_IGN);
 111 #else
 112       signal (SIGINT, SIG_IGN);
 113 #endif
 114
 115       /* Re-wire pdes[1] to stdin/stdout.  */
 116       close (pdes[0]);
 117       if (pdes[1] != STDOUT_FILENO)
 118         {
 119           dup2 (pdes[1], STDOUT_FILENO);
 120           close (pdes[1]);
 121         }
 122       dup2 (STDOUT_FILENO, STDIN_FILENO);
 123
 124       if (err_pdes[0] != -1)
 125         {
 126           close (err_pdes[0]);
 127           dup2 (err_pdes[1], STDERR_FILENO);
 128           close (err_pdes[1]);
 129         }
 130
 131       close_most_fds ();
 132
 133       const char *shellfile = get_shell ();
 134       execl (shellfile, shellfile, "-c", name, (char *) 0);
 135       _exit (127);
 136     }
 137
 138   /* Parent.  */
 139   close (pdes[1]);
 140   if (err_pdes[1] != -1)
 141     close (err_pdes[1]);
 142   /* :end chunk */
 143   state = XNEW (struct pipe_state);
 144   state->pid = pid;
 145   scb->fd = pdes[0];
 146   scb->error_fd = err_pdes[0];
 147   scb->state = state;
 148
 149   /* If we don't do this, GDB simply exits when the remote side dies.  */
 150   signal (SIGPIPE, SIG_IGN);
 151   return 0;
 152 #endif
 153 }
 154
 155 static void
 156 pipe_close (struct serial *scb)
 157 {
 158   struct pipe_state *state = (struct pipe_state *) scb->state;
 159
 160   close (scb->fd);
 161   scb->fd = -1;
 162
 163   if (state != NULL)
 164     {
 165       int wait_result, status;
 166
 167       /* Don't kill the task right away, give it a chance to shut down cleanly.
 168          But don't wait forever though.  */
 169 #define PIPE_CLOSE_TIMEOUT 5
 170
 171       /* Assume the program will exit after SIGTERM.  Might be
 172          useful to print any remaining stderr output from
 173          scb->error_fd while waiting.  */
 174 #define SIGTERM_TIMEOUT INT_MAX
 175
 176       wait_result = -1;
 177 #ifdef HAVE_WAITPID
 178       wait_result = wait_to_die_with_timeout (state->pid, &status,
 179                                               PIPE_CLOSE_TIMEOUT);
 180 #endif
 181       if (wait_result == -1)
 182         {
 183           kill (state->pid, SIGTERM);
 184 #ifdef HAVE_WAITPID
 185           wait_to_die_with_timeout (state->pid, &status, SIGTERM_TIMEOUT);
 186 #endif
 187         }
 188
 189       if (scb->error_fd != -1)
 190         close (scb->error_fd);
 191       scb->error_fd = -1;
 192       xfree (state);
 193       scb->state = NULL;
 194     }
 195 }
 196
 197 int
 198 gdb_pipe (int pdes[2])
 199 {
 200 #if !HAVE_SOCKETPAIR
 201   errno = ENOSYS;
 202   return -1;
 203 #else
 204
 205   if (gdb_socketpair_cloexec (AF_UNIX, SOCK_STREAM, 0, pdes) < 0)
 206     return -1;
 207
 208   /* If we don't do this, GDB simply exits when the remote side
 209      dies.  */
 210   signal (SIGPIPE, SIG_IGN);
 211   return 0;
 212 #endif
 213 }
 214
 215 static const struct serial_ops pipe_ops =
 216 {
 217   "pipe",
 218   pipe_open,
 219   pipe_close,
 220   NULL,
 221   ser_base_readchar,
 222   ser_base_write,
 223   ser_base_flush_output,
 224   ser_base_flush_input,
 225   ser_base_send_break,
 226   ser_base_raw,
 227   ser_base_get_tty_state,
 228   ser_base_copy_tty_state,
 229   ser_base_set_tty_state,
 230   ser_base_print_tty_state,
 231   ser_base_setbaudrate,
 232   ser_base_setstopbits,
 233   ser_base_setparity,
 234   ser_base_drain_output,
 235   ser_base_async,
 236   ser_unix_read_prim,
 237   ser_unix_write_prim
 238 };
 239
 240 void _initialize_ser_pipe ();
 241 void
 242 _initialize_ser_pipe ()
 243 {
 244   serial_add_interface (&pipe_ops);
 245 }