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/* Creation of subprocesses, communicating via pipes.
Copyright (C) 2001 Free Software Foundation, Inc.
Written by Bruno Haible <haible@clisp.cons.org>, 2001.
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. */
#ifndef _PIPE_H
#define _PIPE_H
/* Get pid_t. */
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <sys/types.h>
#include <stdbool.h>
/* All these functions create a subprocess and don't wait for its termination.
They return the process id of the subprocess. They also return in fd[]
one or two file descriptors for communication with the subprocess.
If the subprocess creation fails: if exit_on_error is true, the main
process exits with an error message; otherwise, -1 is returned and fd[]
remain uninitialized.
After finishing communication, the caller should call wait_subprocess()
to get rid of the subprocess in the process table.
If exit_on_error is false, a child process id of -1 should be treated the
same way as a subprocess which accepts no input, produces no output and
terminates with exit code 127. Why? Some errors during posix_spawnp()
cause the function posix_spawnp() to return an error code; some other
errors cause the subprocess to exit with return code 127. It is
implementation dependent which error is reported which way. The caller
must treat both cases as equivalent. */
/* Open a pipe for output to a child process.
* The child's stdout goes to a file.
*
* write system read
* parent -> fd[0] -> STDIN_FILENO -> child
*
*/
extern pid_t create_pipe_out PARAMS ((const char *progname,
const char *prog_path, char **prog_argv,
const char *prog_stdout, bool null_stderr,
bool exit_on_error,
int fd[1]));
/* Open a pipe for input from a child process.
* The child's stdin comes from a file.
*
* read system write
* parent <- fd[0] <- STDOUT_FILENO <- child
*
*/
extern pid_t create_pipe_in PARAMS ((const char *progname,
const char *prog_path, char **prog_argv,
const char *prog_stdin, bool null_stderr,
bool exit_on_error,
int fd[1]));
/* Open a bidirectional pipe.
*
* write system read
* parent -> fd[1] -> STDIN_FILENO -> child
* parent <- fd[0] <- STDOUT_FILENO <- child
* read system write
*
*/
extern pid_t create_pipe_bidi PARAMS ((const char *progname,
const char *prog_path, char **prog_argv,
bool null_stderr,
bool exit_on_error,
int fd[2]));
#endif /* _PIPE_H */
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