1/* Subprocesses with pipes.
2
3   Copyright (C) 2002, 2004, 2005, 2006 Free Software Foundation, Inc.
4
5   This program is free software; you can redistribute it and/or modify
6   it under the terms of the GNU General Public License as published by
7   the Free Software Foundation; either version 2, or (at your option)
8   any later version.
9
10   This program is distributed in the hope that it will be useful,
11   but WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13   GNU General Public License for more details.
14
15   You should have received a copy of the GNU General Public License
16   along with this program; if not, write to the Free Software Foundation,
17   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
18
19/* Written by Paul Eggert <eggert@twinsun.com>
20   and Florian Krohm <florian@edamail.fishkill.ibm.com>.  */
21
22#ifdef HAVE_CONFIG_H
23# include <config.h>
24#endif
25
26#include "subpipe.h"
27
28#include <errno.h>
29
30#include <signal.h>
31#if ! defined SIGCHLD && defined SIGCLD
32# define SIGCHLD SIGCLD
33#endif
34
35#include <stdlib.h>
36
37#if HAVE_UNISTD_H
38# include <unistd.h>
39#endif
40#ifndef STDIN_FILENO
41# define STDIN_FILENO 0
42#endif
43#ifndef STDOUT_FILENO
44# define STDOUT_FILENO 1
45#endif
46#if ! HAVE_DUP2 && ! defined dup2
47# include <fcntl.h>
48# define dup2(f, t) (close (t), fcntl (f, F_DUPFD, t))
49#endif
50
51#if HAVE_SYS_WAIT_H
52# include <sys/wait.h>
53#endif
54#ifndef WEXITSTATUS
55# define WEXITSTATUS(stat_val) ((unsigned int) (stat_val) >> 8)
56#endif
57#ifndef WIFEXITED
58# define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
59#endif
60
61#if HAVE_VFORK_H
62# include <vfork.h>
63#endif
64#if ! HAVE_WORKING_VFORK
65# define vfork fork
66#endif
67
68#include "error.h"
69#include "unistd-safer.h"
70
71#include "gettext.h"
72#define _(Msgid)  gettext (Msgid)
73
74#ifndef __attribute__
75/* This feature is available in gcc versions 2.5 and later.  */
76# if ! defined __GNUC__ || __GNUC__ < 2 || \
77(__GNUC__ == 2 && __GNUC_MINOR__ < 5) || __STRICT_ANSI__
78#  define __attribute__(Spec) /* empty */
79# endif
80#endif
81
82#ifndef ATTRIBUTE_UNUSED
83# define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
84#endif
85
86
87/* Initialize this module.  */
88
89void
90init_subpipe (void)
91{
92#ifdef SIGCHLD
93  /* System V fork+wait does not work if SIGCHLD is ignored.  */
94  signal (SIGCHLD, SIG_DFL);
95#endif
96}
97
98
99/* Create a subprocess that is run as a filter.  ARGV is the
100   NULL-terminated argument vector for the subprocess.  Store read and
101   write file descriptors for communication with the subprocess into
102   FD[0] and FD[1]: input meant for the process can be written into
103   FD[0], and output from the process can be read from FD[1].  Return
104   the subprocess id.
105
106   To avoid deadlock, the invoker must not let incoming data pile up
107   in FD[1] while writing data to FD[0].  */
108
109pid_t
110create_subpipe (char const * const *argv, int fd[2])
111{
112  int pipe_fd[2];
113  int child_fd[2];
114  pid_t pid;
115
116  if (pipe (child_fd) != 0
117      || (child_fd[0] = fd_safer (child_fd[0])) < 0
118      || (fd[0] = fd_safer (child_fd[1])) < 0
119      || pipe (pipe_fd) != 0
120      || (fd[1] = fd_safer (pipe_fd[0])) < 0
121      || (child_fd[1] = fd_safer (pipe_fd[1])) < 0)
122    error (EXIT_FAILURE, errno,
123	   "pipe");
124
125  pid = vfork ();
126  if (pid < 0)
127    error (EXIT_FAILURE, errno,
128	   "fork");
129
130  if (! pid)
131    {
132      /* Child.  */
133      close (fd[0]);
134      close (fd[1]);
135      dup2 (child_fd[0], STDIN_FILENO);
136      close (child_fd[0]);
137      dup2 (child_fd[1], STDOUT_FILENO);
138      close (child_fd[1]);
139
140      /* The cast to (char **) rather than (char * const *) is needed
141	 for portability to older hosts with a nonstandard prototype
142	 for execvp.  */
143      execvp (argv[0], (char **) argv);
144
145      _exit (errno == ENOENT ? 127 : 126);
146    }
147
148  /* Parent.  */
149  close (child_fd[0]);
150  close (child_fd[1]);
151  return pid;
152}
153
154
155/* Wait for the subprocess to exit.  */
156
157void
158reap_subpipe (pid_t pid, char const *program)
159{
160#if HAVE_WAITPID || defined waitpid
161  int wstatus;
162  if (waitpid (pid, &wstatus, 0) < 0)
163    error (EXIT_FAILURE, errno,
164	   "waitpid");
165  else
166    {
167      int status = WIFEXITED (wstatus) ? WEXITSTATUS (wstatus) : -1;
168      if (status)
169	error (EXIT_FAILURE, 0,
170	       _(status == 126
171		 ? "subsidiary program `%s' could not be invoked"
172		 : status == 127
173		 ? "subsidiary program `%s' not found"
174		 : status < 0
175		 ? "subsidiary program `%s' failed"
176		 : "subsidiary program `%s' failed (exit status %d)"),
177	       program, status);
178    }
179#endif
180}
181
182void
183end_of_output_subpipe (pid_t pid ATTRIBUTE_UNUSED,
184		       int fd[2] ATTRIBUTE_UNUSED)
185{
186}
187