/* Subprocesses with pipes. Copyright (C) 2002 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /* Written by Paul Eggert and Florian Krohm . */ #if HAVE_CONFIG_H # include #endif #if HAVE_SYS_TYPES_H # include #endif #include #ifndef errno extern int errno; #endif #include #if ! defined SIGCHLD && defined SIGCLD # define SIGCHLD SIGCLD #endif #if HAVE_STDLIB_H # include #endif /* The following test is to work around the gross typo in systems like Sony NEWS-OS Release 4.0C, whereby EXIT_FAILURE is defined to 0, not 1. */ #if ! EXIT_FAILURE # undef EXIT_FAILURE # define EXIT_FAILURE 1 #endif #if HAVE_UNISTD_H # include #endif #ifndef STDIN_FILENO # define STDIN_FILENO 0 #endif #ifndef STDOUT_FILENO # define STDOUT_FILENO 1 #endif #if ! HAVE_DUP2 && ! defined dup2 # if HAVE_FCNTL_H # include # endif # define dup2(f, t) (close (t), fcntl (f, F_DUPFD, t)) #endif #if HAVE_SYS_WAIT_H # include #endif #ifndef WEXITSTATUS # define WEXITSTATUS(stat_val) ((unsigned int) (stat_val) >> 8) #endif #ifndef WIFEXITED # define WIFEXITED(stat_val) (((stat_val) & 255) == 0) #endif #if HAVE_VFORK_H # include #endif #if ! HAVE_WORKING_VFORK # define vfork fork #endif #include "error.h" #include "gettext.h" #define _(Msgid) gettext (Msgid) #include "subpipe.h" /* Initialize this module. */ void init_subpipe (void) { #ifdef SIGCHLD /* System V fork+wait does not work if SIGCHLD is ignored. */ signal (SIGCHLD, SIG_DFL); #endif } /* Create a subprocess that is run as a filter. ARGV is the NULL-terminated argument vector for the subprocess. Store read and write file descriptors for communication with the subprocess into FD[0] and FD[1]: input meant for the process can be written into FD[0], and output from the process can be read from FD[1]. Return the subprocess id. To avoid deadlock, the invoker must not let incoming data pile up in FD[1] while writing data to FD[0]. */ pid_t create_subpipe (char const * const *argv, int fd[2]) { int pipe_fd[2]; int from_in_fd; int from_out_fd; int to_in_fd; int to_out_fd; pid_t pid; if (pipe (pipe_fd) != 0) error (EXIT_FAILURE, errno, "pipe"); to_in_fd = pipe_fd[0]; to_out_fd = pipe_fd[1]; if (pipe (pipe_fd) != 0) error (EXIT_FAILURE, errno, "pipe"); from_in_fd = pipe_fd[0]; from_out_fd = pipe_fd[1]; pid = vfork (); if (pid < 0) error (EXIT_FAILURE, errno, "fork"); if (! pid) { /* Child. */ close (to_out_fd); close (from_in_fd); if (to_in_fd != STDIN_FILENO) { dup2 (to_in_fd, STDIN_FILENO); close (to_in_fd); } if (from_out_fd != STDOUT_FILENO) { dup2 (from_out_fd, STDOUT_FILENO); close (from_out_fd); } /* The cast to (char **) rather than (char * const *) is needed for portability to older hosts with a nonstandard prototype for execvp. */ execvp (argv[0], (char **) argv); _exit (errno == ENOENT ? 127 : 126); } /* Parent. */ close (to_in_fd); close (from_out_fd); fd[0] = to_out_fd; fd[1] = from_in_fd; return pid; } /* Wait for the subprocess to exit. */ void reap_subpipe (pid_t pid, char const *program) { #if HAVE_WAITPID || defined waitpid int wstatus; if (waitpid (pid, &wstatus, 0) < 0) error (EXIT_FAILURE, errno, "waitpid"); else { int status = WIFEXITED (wstatus) ? WEXITSTATUS (wstatus) : -1; if (status) error (EXIT_FAILURE, 0, _(status == 126 ? "subsidiary program `%s' could not be invoked" : status == 127 ? "subsidiary program `%s' not found" : status < 0 ? "subsidiary program `%s' failed" : "subsidiary program `%s' failed (exit status %d)"), program, status); } #endif }