gdb/ser-pipe.c

   1 /* Serial interface for a pipe to a separate program
   2    Copyright (C) 1999-2024 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 "serial.h"
  22 #include "ser-base.h"
  23 #include "ser-unix.h"
  24
  25 #include "gdb_vfork.h"
  26
  27 #include <sys/types.h>
  28 #include <sys/socket.h>
  29 #include "gdbsupport/gdb_sys_time.h"
  30 #include <fcntl.h>
  31 #include "gdbsupport/filestuff.h"
  32 #include "gdbsupport/pathstuff.h"
  33
  34 #include <signal.h>
  35
  36 static void pipe_close (struct serial *scb);
  37
  38 struct pipe_state
  39   {
  40     int pid;
  41   };
  42
  43 /* Open up a raw pipe.  */
  44
  45 static void
  46 pipe_open (struct serial *scb, const char *name)
  47 {
  48 #if !HAVE_SOCKETPAIR
  49   return -1;
  50 #else
  51   struct pipe_state *state;
  52   /* This chunk: */
  53   /* Copyright (c) 1988, 1993
  54    *      The Regents of the University of California.  All rights reserved.
  55    *
  56    * This code is derived from software written by Ken Arnold and
  57    * published in UNIX Review, Vol. 6, No. 8.
  58    */
  59   int pdes[2];
  60   int err_pdes[2];
  61   int pid;
  62
  63   if (*name == '|')
  64     {
  65       name++;
  66       name = skip_spaces (name);
  67     }
  68
  69   if (gdb_socketpair_cloexec (AF_UNIX, SOCK_STREAM, 0, pdes) < 0)
  70     perror_with_name (_("could not open socket pair"));
  71   if (gdb_socketpair_cloexec (AF_UNIX, SOCK_STREAM, 0, err_pdes) < 0)
  72     {
  73       int save = errno;
  74       close (pdes[0]);
  75       close (pdes[1]);
  76       perror_with_name (_("could not open socket pair"), save);
  77     }
  78
  79   /* Create the child process to run the command in.  Note that the
  80      apparent call to vfork() below *might* actually be a call to
  81      fork() due to the fact that autoconf will ``#define vfork fork''
  82      on certain platforms.  */
  83   pid = vfork ();
  84
  85   /* Error.  */
  86   if (pid == -1)
  87     {
  88       int save = errno;
  89       close (pdes[0]);
  90       close (pdes[1]);
  91       close (err_pdes[0]);
  92       close (err_pdes[1]);
  93       perror_with_name (_("could not vfork"), save);
  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 #endif
 152 }
 153
 154 static void
 155 pipe_close (struct serial *scb)
 156 {
 157   struct pipe_state *state = (struct pipe_state *) scb->state;
 158
 159   close (scb->fd);
 160   scb->fd = -1;
 161
 162   if (state != NULL)
 163     {
 164       int wait_result, status;
 165
 166       /* Don't kill the task right away, give it a chance to shut down cleanly.
 167          But don't wait forever though.  */
 168 #define PIPE_CLOSE_TIMEOUT 5
 169
 170       /* Assume the program will exit after SIGTERM.  Might be
 171          useful to print any remaining stderr output from
 172          scb->error_fd while waiting.  */
 173 #define SIGTERM_TIMEOUT INT_MAX
 174
 175       wait_result = -1;
 176 #ifdef HAVE_WAITPID
 177       wait_result = wait_to_die_with_timeout (state->pid, &status,
 178                                               PIPE_CLOSE_TIMEOUT);
 179 #endif
 180       if (wait_result == -1)
 181         {
 182           kill (state->pid, SIGTERM);
 183 #ifdef HAVE_WAITPID
 184           wait_to_die_with_timeout (state->pid, &status, SIGTERM_TIMEOUT);
 185 #endif
 186         }
 187
 188       if (scb->error_fd != -1)
 189         close (scb->error_fd);
 190       scb->error_fd = -1;
 191       xfree (state);
 192       scb->state = NULL;
 193     }
 194 }
 195
 196 int
 197 gdb_pipe (int pdes[2])
 198 {
 199 #if !HAVE_SOCKETPAIR
 200   errno = ENOSYS;
 201   return -1;
 202 #else
 203
 204   if (gdb_socketpair_cloexec (AF_UNIX, SOCK_STREAM, 0, pdes) < 0)
 205     return -1;
 206
 207   /* If we don't do this, GDB simply exits when the remote side
 208      dies.  */
 209   signal (SIGPIPE, SIG_IGN);
 210   return 0;
 211 #endif
 212 }
 213
 214 static const struct serial_ops pipe_ops =
 215 {
 216   "pipe",
 217   pipe_open,
 218   pipe_close,
 219   NULL,
 220   ser_base_readchar,
 221   ser_base_write,
 222   ser_base_flush_output,
 223   ser_base_flush_input,
 224   ser_base_send_break,
 225   ser_base_raw,
 226   ser_base_get_tty_state,
 227   ser_base_copy_tty_state,
 228   ser_base_set_tty_state,
 229   ser_base_print_tty_state,
 230   ser_base_setbaudrate,
 231   ser_base_setstopbits,
 232   ser_base_setparity,
 233   ser_base_drain_output,
 234   ser_base_async,
 235   ser_unix_read_prim,
 236   ser_unix_write_prim
 237 };
 238
 239 void _initialize_ser_pipe ();
 240 void
 241 _initialize_ser_pipe ()
 242 {
 243   serial_add_interface (&pipe_ops);
 244 }