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 (at) twinsun.com> 20 and Florian Krohm <florian (at) 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 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 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 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 183 end_of_output_subpipe (pid_t pid ATTRIBUTE_UNUSED, 184 int fd[2] ATTRIBUTE_UNUSED) 185 { 186 } 187
