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 "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 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 void
  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 (*name == '|')
  65     {
  66       name++;
  67       name = skip_spaces (name);
  68     }
  69
  70   if (gdb_socketpair_cloexec (AF_UNIX, SOCK_STREAM, 0, pdes) < 0)
  71     perror_with_name (_("could not open socket pair"));
  72   if (gdb_socketpair_cloexec (AF_UNIX, SOCK_STREAM, 0, err_pdes) < 0)
  73     {
  74       int save = errno;
  75       close (pdes[0]);
  76       close (pdes[1]);
  77       perror_with_name (_("could not open socket pair"), save);
  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       int save = errno;
  90       close (pdes[0]);
  91       close (pdes[1]);
  92       close (err_pdes[0]);
  93       close (err_pdes[1]);
  94       perror_with_name (_("could not vfork"), save);
  95     }
  96
  97   if (fcntl (err_pdes[0], F_SETFL, O_NONBLOCK) == -1)
  98     {
  99       close (err_pdes[0]);
 100       close (err_pdes[1]);
 101       err_pdes[0] = err_pdes[1] = -1;
 102     }
 103
 104   /* Child.  */
 105   if (pid == 0)
 106     {
 107       /* We don't want ^c to kill the connection.  */
 108 #ifdef HAVE_SETSID
 109       pid_t sid = setsid ();
 110       if (sid == -1)
 111         signal (SIGINT, SIG_IGN);
 112 #else
 113       signal (SIGINT, SIG_IGN);
 114 #endif
 115
 116       /* Re-wire pdes[1] to stdin/stdout.  */
 117       close (pdes[0]);
 118       if (pdes[1] != STDOUT_FILENO)
 119         {
 120           dup2 (pdes[1], STDOUT_FILENO);
 121           close (pdes[1]);
 122         }
 123       dup2 (STDOUT_FILENO, STDIN_FILENO);
 124
 125       if (err_pdes[0] != -1)
 126         {
 127           close (err_pdes[0]);
 128           dup2 (err_pdes[1], STDERR_FILENO);
 129           close (err_pdes[1]);
 130         }
 131
 132       close_most_fds ();
 133
 134       const char *shellfile = get_shell ();
 135       execl (shellfile, shellfile, "-c", name, (char *) 0);
 136       _exit (127);
 137     }
 138
 139   /* Parent.  */
 140   close (pdes[1]);
 141   if (err_pdes[1] != -1)
 142     close (err_pdes[1]);
 143   /* :end chunk */
 144   state = XNEW (struct pipe_state);
 145   state->pid = pid;
 146   scb->fd = pdes[0];
 147   scb->error_fd = err_pdes[0];
 148   scb->state = state;
 149
 150   /* If we don't do this, GDB simply exits when the remote side dies.  */
 151   signal (SIGPIPE, SIG_IGN);
 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 }