gdb/ser-pipe.c

   1 /* Serial interface for a pipe to a separate program
   2    Copyright (C) 1999-2021 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 (gdb_socketpair_cloexec (AF_UNIX, SOCK_STREAM, 0, pdes) < 0)
  66     return -1;
  67   if (gdb_socketpair_cloexec (AF_UNIX, SOCK_STREAM, 0, err_pdes) < 0)
  68     {
  69       close (pdes[0]);
  70       close (pdes[1]);
  71       return -1;
  72     }
  73
  74   /* Create the child process to run the command in.  Note that the
  75      apparent call to vfork() below *might* actually be a call to
  76      fork() due to the fact that autoconf will ``#define vfork fork''
  77      on certain platforms.  */
  78   pid = vfork ();
  79
  80   /* Error.  */
  81   if (pid == -1)
  82     {
  83       close (pdes[0]);
  84       close (pdes[1]);
  85       close (err_pdes[0]);
  86       close (err_pdes[1]);
  87       return -1;
  88     }
  89
  90   if (fcntl (err_pdes[0], F_SETFL, O_NONBLOCK) == -1)
  91     {
  92       close (err_pdes[0]);
  93       close (err_pdes[1]);
  94       err_pdes[0] = err_pdes[1] = -1;
  95     }
  96
  97   /* Child.  */
  98   if (pid == 0)
  99     {
 100       /* We don't want ^c to kill the connection.  */
 101 #ifdef HAVE_SETSID
 102       pid_t sid = setsid ();
 103       if (sid == -1)
 104         signal (SIGINT, SIG_IGN);
 105 #else
 106       signal (SIGINT, SIG_IGN);
 107 #endif
 108
 109       /* Re-wire pdes[1] to stdin/stdout.  */
 110       close (pdes[0]);
 111       if (pdes[1] != STDOUT_FILENO)
 112         {
 113           dup2 (pdes[1], STDOUT_FILENO);
 114           close (pdes[1]);
 115         }
 116       dup2 (STDOUT_FILENO, STDIN_FILENO);
 117
 118       if (err_pdes[0] != -1)
 119         {
 120           close (err_pdes[0]);
 121           dup2 (err_pdes[1], STDERR_FILENO);
 122           close (err_pdes[1]);
 123         }
 124
 125       close_most_fds ();
 126
 127       const char *shellfile = get_shell ();
 128       execl (shellfile, shellfile, "-c", name, (char *) 0);
 129       _exit (127);
 130     }
 131
 132   /* Parent.  */
 133   close (pdes[1]);
 134   if (err_pdes[1] != -1)
 135     close (err_pdes[1]);
 136   /* :end chunk */
 137   state = XNEW (struct pipe_state);
 138   state->pid = pid;
 139   scb->fd = pdes[0];
 140   scb->error_fd = err_pdes[0];
 141   scb->state = state;
 142
 143   /* If we don't do this, GDB simply exits when the remote side dies.  */
 144   signal (SIGPIPE, SIG_IGN);
 145   return 0;
 146 #endif
 147 }
 148
 149 static void
 150 pipe_close (struct serial *scb)
 151 {
 152   struct pipe_state *state = (struct pipe_state *) scb->state;
 153
 154   close (scb->fd);
 155   scb->fd = -1;
 156
 157   if (state != NULL)
 158     {
 159       int wait_result, status;
 160
 161       /* Don't kill the task right away, give it a chance to shut down cleanly.
 162          But don't wait forever though.  */
 163 #define PIPE_CLOSE_TIMEOUT 5
 164
 165       /* Assume the program will exit after SIGTERM.  Might be
 166          useful to print any remaining stderr output from
 167          scb->error_fd while waiting.  */
 168 #define SIGTERM_TIMEOUT INT_MAX
 169
 170       wait_result = -1;
 171 #ifdef HAVE_WAITPID
 172       wait_result = wait_to_die_with_timeout (state->pid, &status,
 173                                               PIPE_CLOSE_TIMEOUT);
 174 #endif
 175       if (wait_result == -1)
 176         {
 177           kill (state->pid, SIGTERM);
 178 #ifdef HAVE_WAITPID
 179           wait_to_die_with_timeout (state->pid, &status, SIGTERM_TIMEOUT);
 180 #endif
 181         }
 182
 183       if (scb->error_fd != -1)
 184         close (scb->error_fd);
 185       scb->error_fd = -1;
 186       xfree (state);
 187       scb->state = NULL;
 188     }
 189 }
 190
 191 int
 192 gdb_pipe (int pdes[2])
 193 {
 194 #if !HAVE_SOCKETPAIR
 195   errno = ENOSYS;
 196   return -1;
 197 #else
 198
 199   if (gdb_socketpair_cloexec (AF_UNIX, SOCK_STREAM, 0, pdes) < 0)
 200     return -1;
 201
 202   /* If we don't do this, GDB simply exits when the remote side
 203      dies.  */
 204   signal (SIGPIPE, SIG_IGN);
 205   return 0;
 206 #endif
 207 }
 208
 209 static const struct serial_ops pipe_ops =
 210 {
 211   "pipe",
 212   pipe_open,
 213   pipe_close,
 214   NULL,
 215   ser_base_readchar,
 216   ser_base_write,
 217   ser_base_flush_output,
 218   ser_base_flush_input,
 219   ser_base_send_break,
 220   ser_base_raw,
 221   ser_base_get_tty_state,
 222   ser_base_copy_tty_state,
 223   ser_base_set_tty_state,
 224   ser_base_print_tty_state,
 225   ser_base_setbaudrate,
 226   ser_base_setstopbits,
 227   ser_base_setparity,
 228   ser_base_drain_output,
 229   ser_base_async,
 230   ser_unix_read_prim,
 231   ser_unix_write_prim
 232 };
 233
 234 void _initialize_ser_pipe ();
 235 void
 236 _initialize_ser_pipe ()
 237 {
 238   serial_add_interface (&pipe_ops);
 239 }