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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 3 of the License, or
8 (at your option) 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, see <http://www.gnu.org/licenses/>. */
17
18 /* Written by Paul Eggert <eggert@twinsun.com>
19 and Florian Krohm <florian@edamail.fishkill.ibm.com>. */
20
21 #include <config.h>
22
23 #include "subpipe.h"
24
25 #include <errno.h>
26
27 #include <signal.h>
28 #if ! defined SIGCHLD && defined SIGCLD
29 # define SIGCHLD SIGCLD
30 #endif
31
32 #include <stdlib.h>
33
34 #include <unistd.h>
35 #ifndef STDIN_FILENO
36 # define STDIN_FILENO 0
37 #endif
38 #ifndef STDOUT_FILENO
39 # define STDOUT_FILENO 1
40 #endif
41 #if ! HAVE_DUP2 && ! defined dup2
42 # include <fcntl.h>
43 # define dup2(f, t) (close (t), fcntl (f, F_DUPFD, t))
44 #endif
45
46 #if HAVE_SYS_WAIT_H
47 # include <sys/wait.h>
48 #endif
49 #ifndef WEXITSTATUS
50 # define WEXITSTATUS(stat_val) ((unsigned int) (stat_val) >> 8)
51 #endif
52 #ifndef WIFEXITED
53 # define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
54 #endif
55
56 #if HAVE_VFORK_H
57 # include <vfork.h>
58 #endif
59 #if ! HAVE_WORKING_VFORK
60 # define vfork fork
61 #endif
62
63 #include "error.h"
64 #include "unistd-safer.h"
65
66 #include "gettext.h"
67 #define _(Msgid) gettext (Msgid)
68
69 #ifndef __attribute__
70 /* This feature is available in gcc versions 2.5 and later. */
71 # if ! defined __GNUC__ || __GNUC__ < 2 || \
72 (__GNUC__ == 2 && __GNUC_MINOR__ < 5) || __STRICT_ANSI__
73 # define __attribute__(Spec) /* empty */
74 # endif
75 #endif
76
77 #ifndef ATTRIBUTE_UNUSED
78 # define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
79 #endif
80
81
82 /* Initialize this module. */
83
84 void
85 init_subpipe (void)
86 {
87 #ifdef SIGCHLD
88 /* System V fork+wait does not work if SIGCHLD is ignored. */
89 signal (SIGCHLD, SIG_DFL);
90 #endif
91 }
92
93
94 /* Create a subprocess that is run as a filter. ARGV is the
95 NULL-terminated argument vector for the subprocess. Store read and
96 write file descriptors for communication with the subprocess into
97 FD[0] and FD[1]: input meant for the process can be written into
98 FD[0], and output from the process can be read from FD[1]. Return
99 the subprocess id.
100
101 To avoid deadlock, the invoker must not let incoming data pile up
102 in FD[1] while writing data to FD[0]. */
103
104 pid_t
105 create_subpipe (char const * const *argv, int fd[2])
106 {
107 int pipe_fd[2];
108 int child_fd[2];
109 pid_t pid;
110
111 if (pipe_safer (child_fd) != 0 || pipe_safer (pipe_fd) != 0)
112 error (EXIT_FAILURE, errno, "pipe");
113 fd[0] = child_fd[1];
114 fd[1] = pipe_fd[0];
115 child_fd[1] = pipe_fd[1];
116
117 pid = vfork ();
118 if (pid < 0)
119 error (EXIT_FAILURE, errno, "fork");
120
121 if (! pid)
122 {
123 /* Child. */
124 close (fd[0]);
125 close (fd[1]);
126 dup2 (child_fd[0], STDIN_FILENO);
127 close (child_fd[0]);
128 dup2 (child_fd[1], STDOUT_FILENO);
129 close (child_fd[1]);
130
131 /* The cast to (char **) rather than (char * const *) is needed
132 for portability to older hosts with a nonstandard prototype
133 for execvp. */
134 execvp (argv[0], (char **) argv);
135
136 _exit (errno == ENOENT ? 127 : 126);
137 }
138
139 /* Parent. */
140 close (child_fd[0]);
141 close (child_fd[1]);
142 return pid;
143 }
144
145
146 /* Wait for the subprocess to exit. */
147
148 void
149 reap_subpipe (pid_t pid, char const *program)
150 {
151 #if HAVE_WAITPID || defined waitpid
152 int wstatus;
153 if (waitpid (pid, &wstatus, 0) < 0)
154 error (EXIT_FAILURE, errno, "waitpid");
155 else
156 {
157 int status = WIFEXITED (wstatus) ? WEXITSTATUS (wstatus) : -1;
158 if (status)
159 error (EXIT_FAILURE, 0,
160 _(status == 126
161 ? "subsidiary program `%s' could not be invoked"
162 : status == 127
163 ? "subsidiary program `%s' not found"
164 : status < 0
165 ? "subsidiary program `%s' failed"
166 : "subsidiary program `%s' failed (exit status %d)"),
167 program, status);
168 }
169 #endif
170 }
171
172 void
173 end_of_output_subpipe (pid_t pid ATTRIBUTE_UNUSED,
174 int fd[2] ATTRIBUTE_UNUSED)
175 {
176 }