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/*      $NetBSD: popen.c,v 1.11 1995/06/16 07:05:33 jtc Exp $   */

/*

 * Copyright (c) 1988, 1993, 2006

 *      The Regents of the University of California.  All rights reserved.

 *

 * This code is derived from software written by Ken Arnold and

 * published in UNIX Review, Vol. 6, No. 8.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 4. Neither the name of the University nor the names of its contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 */

/*

FUNCTION

<<popen>>, <<pclose>>---tie a stream to a command string

INDEX

        popen

INDEX

        pclose

ANSI_SYNOPSIS

        #include <stdio.h>

        FILE *popen(const char *<[s]>, const char *<[mode]>);

        int pclose(FILE *<[f]>);

DESCRIPTION

Use <<popen>> to create a stream to a child process executing a

command string <<*<[s]>>> as processed by <</bin/sh>> on your system.

The argument <[mode]> must start with either `<<r>>', where the stream

reads from the child's <<stdout>>, or `<<w>>', where the stream writes

to the child's <<stdin>>.  As an extension, <[mode]> may also contain

`<<e>>' to set the close-on-exec bit of the parent's file descriptor.

The stream created by <<popen>> must be closed by <<pclose>> to avoid

resource leaks.

Streams created by prior calls to <<popen>> are not visible in

subsequent <<popen>> children, regardless of the close-on-exec bit.

Use ``<<system(NULL)>>'' to test whether your system has <</bin/sh>>

available.

RETURNS

<<popen>> returns a file stream opened with the specified <[mode]>,

or <<NULL>> if a child process could not be created.  <<pclose>>

returns -1 if the stream was not created by <<popen>> or if the

application used <<wait>> or similar to steal the status; otherwise

it returns the exit status of the child which can be interpreted

in the same manner as a status obtained by <<waitpid>>.

PORTABILITY

POSIX.2 requires <<popen>> and <<pclose>>, but only specifies a mode

of just <<r>> or <<w>>.  Where <<sh>> is found is left unspecified.

Supporting OS subroutines required: <<_exit>>, <<_execve>>, <<_fork_r>>,

<<_wait_r>>, <<pipe>>, <<fcntl>>, <<sbrk>>.

*/

#ifndef _NO_POPEN

#if defined(LIBC_SCCS) && !defined(lint)

#if 0

static char sccsid[] = "@(#)popen.c     8.1 (Berkeley) 6/4/93";

#else

static char rcsid[] = "$NetBSD: popen.c,v 1.11 1995/06/16 07:05:33 jtc Exp $";

#endif

#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>

#include <sys/types.h>

#include <sys/wait.h>

#include <signal.h>

#include <errno.h>

#include <unistd.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <paths.h>

#include <fcntl.h>

static struct pid {

        struct pid *next;

        FILE *fp;

        pid_t pid;

} *pidlist;

FILE *

_DEFUN(popen, (program, type),

        const char *program _AND

        const char *type)

{

        struct pid *cur, *last;

        FILE *iop;

        int pdes[2], pid;

       if ((*type != 'r' && *type != 'w')

           || (type[1]

#ifdef HAVE_FCNTL

               && (type[2] || (type[1] != 'e'))

#endif

                               )) {

                errno = EINVAL;

                return (NULL);

        }

        if ((cur = malloc(sizeof(struct pid))) == NULL)

                return (NULL);

        if (pipe(pdes) < 0) {

                free(cur);

                return (NULL);

        }

        switch (pid = vfork()) {

        case -1:                        /* Error. */

                (void)close(pdes[0]);

                (void)close(pdes[1]);

                free(cur);

                return (NULL);

                /* NOTREACHED */

        case 0:                          /* Child. */

                if (*type == 'r') {

                        if (pdes[1] != STDOUT_FILENO) {

                                (void)dup2(pdes[1], STDOUT_FILENO);

                                (void)close(pdes[1]);

                        }

                        if (pdes[0] != STDOUT_FILENO) {

                                (void) close(pdes[0]);

                        }

                } else {

                        if (pdes[0] != STDIN_FILENO) {

                                (void)dup2(pdes[0], STDIN_FILENO);

                                (void)close(pdes[0]);

                        }

                        (void)close(pdes[1]);

                }

                /* Close all fd's created by prior popen.  */

                for (last = NULL, cur = pidlist; cur;

                     last = cur, cur = cur->next)

                        (void)close (fileno (cur->fp));

                execl(_PATH_BSHELL, "sh", "-c", program, NULL);

                _exit(127);

                /* NOTREACHED */

        }

        /* Parent; assume fdopen can't fail. */

        if (*type == 'r') {

                iop = fdopen(pdes[0], type);

                (void)close(pdes[1]);

        } else {

                iop = fdopen(pdes[1], type);

                (void)close(pdes[0]);

        }

#ifdef HAVE_FCNTL

        /* Mark pipe cloexec if requested.  */

        if (type[1] == 'e')

                fcntl (fileno (iop), F_SETFD,

                       fcntl (fileno (iop), F_GETFD, 0) | FD_CLOEXEC);

#endif /* HAVE_FCNTL */

        /* Link into list of file descriptors. */

        cur->fp = iop;

        cur->pid =  pid;

        cur->next = pidlist;

        pidlist = cur;

        return (iop);

}

/*

 * pclose --

 *      Pclose returns -1 if stream is not associated with a `popened' command,

 *      if already `pclosed', or waitpid returns an error.

 */

int

_DEFUN(pclose, (iop),

        FILE *iop)

{

        register struct pid *cur, *last;

        int pstat;

        pid_t pid;

        (void)fclose(iop);

        /* Find the appropriate file pointer. */

        for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)

                if (cur->fp == iop)

                        break;

        if (cur == NULL)

                return (-1);

        do {

                pid = waitpid(cur->pid, &pstat, 0);

        } while (pid == -1 && errno == EINTR);

        /* Remove the entry from the linked list. */

        if (last == NULL)

                pidlist = cur->next;

        else

                last->next = cur->next;

        free(cur);

        return (pid == -1 ? -1 : pstat);

}

#endif  /* !_NO_POPEN  */