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
89 void
init_subpipe(void)90 init_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
109 pid_t
create_subpipe(char const * const * argv,int fd[2])110 create_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
157 void
reap_subpipe(pid_t pid,char const * program)158 reap_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
182 void
end_of_output_subpipe(pid_t pid ATTRIBUTE_UNUSED,int fd[2]ATTRIBUTE_UNUSED)183 end_of_output_subpipe (pid_t pid ATTRIBUTE_UNUSED,
184 int fd[2] ATTRIBUTE_UNUSED)
185 {
186 }
187