gdb/ser-pipe.c

   1 /* Serial interface for a pipe to a separate program
   2    Copyright (C) 1999-2020 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
  34 #include <signal.h>
  35
  36 static int pipe_open (struct serial *scb, const char *name);
  37 static void pipe_close (struct serial *scb);
  38
  39 struct pipe_state
  40   {
  41     int pid;
  42   };
  43
  44 /* Open up a raw pipe.  */
  45
  46 static int
  47 pipe_open (struct serial *scb, const char *name)
  48 {
  49 #if !HAVE_SOCKETPAIR
  50   return -1;
  51 #else
  52   struct pipe_state *state;
  53   /* This chunk: */
  54   /* Copyright (c) 1988, 1993
  55    *      The Regents of the University of California.  All rights reserved.
  56    *
  57    * This code is derived from software written by Ken Arnold and
  58    * published in UNIX Review, Vol. 6, No. 8.
  59    */
  60   int pdes[2];
  61   int err_pdes[2];
  62   int pid;
  63
  64   if (gdb_socketpair_cloexec (AF_UNIX, SOCK_STREAM, 0, pdes) < 0)
  65     return -1;
  66   if (gdb_socketpair_cloexec (AF_UNIX, SOCK_STREAM, 0, err_pdes) < 0)
  67     {
  68       close (pdes[0]);
  69       close (pdes[1]);
  70       return -1;
  71     }
  72
  73   /* Create the child process to run the command in.  Note that the
  74      apparent call to vfork() below *might* actually be a call to
  75      fork() due to the fact that autoconf will ``#define vfork fork''
  76      on certain platforms.  */
  77   pid = vfork ();
  78
  79   /* Error.  */
  80   if (pid == -1)
  81     {
  82       close (pdes[0]);
  83       close (pdes[1]);
  84       close (err_pdes[0]);
  85       close (err_pdes[1]);
  86       return -1;
  87     }
  88
  89   if (fcntl (err_pdes[0], F_SETFL, O_NONBLOCK) == -1)
  90     {
  91       close (err_pdes[0]);
  92       close (err_pdes[1]);
  93       err_pdes[0] = err_pdes[1] = -1;
  94     }
  95
  96   /* Child.  */
  97   if (pid == 0)
  98     {
  99       /* We don't want ^c to kill the connection.  */
 100 #ifdef HAVE_SETSID
 101       pid_t sid = setsid ();
 102       if (sid == -1)
 103         signal (SIGINT, SIG_IGN);
 104 #else
 105       signal (SIGINT, SIG_IGN);
 106 #endif
 107
 108       /* Re-wire pdes[1] to stdin/stdout.  */
 109       close (pdes[0]);
 110       if (pdes[1] != STDOUT_FILENO)
 111         {
 112           dup2 (pdes[1], STDOUT_FILENO);
 113           close (pdes[1]);
 114         }
 115       dup2 (STDOUT_FILENO, STDIN_FILENO);
 116
 117       if (err_pdes[0] != -1)
 118         {
 119           close (err_pdes[0]);
 120           dup2 (err_pdes[1], STDERR_FILENO);
 121           close (err_pdes[1]);
 122         }
 123
 124       close_most_fds ();
 125       execl ("/bin/sh", "sh", "-c", name, (char *) 0);
 126       _exit (127);
 127     }
 128
 129   /* Parent.  */
 130   close (pdes[1]);
 131   if (err_pdes[1] != -1)
 132     close (err_pdes[1]);
 133   /* :end chunk */
 134   state = XNEW (struct pipe_state);
 135   state->pid = pid;
 136   scb->fd = pdes[0];
 137   scb->error_fd = err_pdes[0];
 138   scb->state = state;
 139
 140   /* If we don't do this, GDB simply exits when the remote side dies.  */
 141   signal (SIGPIPE, SIG_IGN);
 142   return 0;
 143 #endif
 144 }
 145
 146 static void
 147 pipe_close (struct serial *scb)
 148 {
 149   struct pipe_state *state = (struct pipe_state *) scb->state;
 150
 151   close (scb->fd);
 152   scb->fd = -1;
 153
 154   if (state != NULL)
 155     {
 156       int wait_result, status;
 157
 158       /* Don't kill the task right away, give it a chance to shut down cleanly.
 159          But don't wait forever though.  */
 160 #define PIPE_CLOSE_TIMEOUT 5
 161
 162       /* Assume the program will exit after SIGTERM.  Might be
 163          useful to print any remaining stderr output from
 164          scb->error_fd while waiting.  */
 165 #define SIGTERM_TIMEOUT INT_MAX
 166
 167       wait_result = -1;
 168 #ifdef HAVE_WAITPID
 169       wait_result = wait_to_die_with_timeout (state->pid, &status,
 170                                               PIPE_CLOSE_TIMEOUT);
 171 #endif
 172       if (wait_result == -1)
 173         {
 174           kill (state->pid, SIGTERM);
 175 #ifdef HAVE_WAITPID
 176           wait_to_die_with_timeout (state->pid, &status, SIGTERM_TIMEOUT);
 177 #endif
 178         }
 179
 180       if (scb->error_fd != -1)
 181         close (scb->error_fd);
 182       scb->error_fd = -1;
 183       xfree (state);
 184       scb->state = NULL;
 185     }
 186 }
 187
 188 int
 189 gdb_pipe (int pdes[2])
 190 {
 191 #if !HAVE_SOCKETPAIR
 192   errno = ENOSYS;
 193   return -1;
 194 #else
 195
 196   if (gdb_socketpair_cloexec (AF_UNIX, SOCK_STREAM, 0, pdes) < 0)
 197     return -1;
 198
 199   /* If we don't do this, GDB simply exits when the remote side
 200      dies.  */
 201   signal (SIGPIPE, SIG_IGN);
 202   return 0;
 203 #endif
 204 }
 205
 206 static const struct serial_ops pipe_ops =
 207 {
 208   "pipe",
 209   pipe_open,
 210   pipe_close,
 211   NULL,
 212   ser_base_readchar,
 213   ser_base_write,
 214   ser_base_flush_output,
 215   ser_base_flush_input,
 216   ser_base_send_break,
 217   ser_base_raw,
 218   ser_base_get_tty_state,
 219   ser_base_copy_tty_state,
 220   ser_base_set_tty_state,
 221   ser_base_print_tty_state,
 222   ser_base_setbaudrate,
 223   ser_base_setstopbits,
 224   ser_base_setparity,
 225   ser_base_drain_output,
 226   ser_base_async,
 227   ser_unix_read_prim,
 228   ser_unix_write_prim
 229 };
 230
 231 void _initialize_ser_pipe ();
 232 void
 233 _initialize_ser_pipe ()
 234 {
 235   serial_add_interface (&pipe_ops);
 236 }