BSD 4_4_Lite2 release

[unix-history] / usr / src / lib / libc / gen / popen.c

/*
* Copyright (c) 1988, 1993
*      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.
* 3. All advertising materials mentioning features or use of this software
*    must display the following acknowledgement:
*      This product includes software developed by the University of
*      California, Berkeley and its contributors.
* 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.
*/

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)popen.c     8.3 (Berkeley) 5/3/95";
#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>
#include <sys/wait.h>
#include <sys/socket.h>

#include <signal.h>
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <paths.h>

static struct pid {
       struct pid *next;
       FILE *fp;
       pid_t pid;
} *pidlist; 
       
FILE *
popen(command, type)
       const char *command, *type;
{
       struct pid *cur;
       FILE *iop;
       int pdes[2], pid, twoway;

       if (strchr(type, '+')) {
               twoway = 1;
               type = "r+";
               if (socketpair(AF_UNIX, SOCK_STREAM, 0, pdes) < 0)
                       return (NULL);
       } else  {
               twoway = 0;
               if (*type != 'r' && *type != 'w' || type[1] ||
                   (pipe(pdes) < 0))
                       return (NULL);
       }

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

       switch (pid = vfork()) {
       case -1:                        /* Error. */
               (void)close(pdes[0]);
               (void)close(pdes[1]);
               (void)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]);
                               pdes[1] = STDOUT_FILENO;
                       }
                       (void) close(pdes[0]);
                       if (twoway && (pdes[1] != STDIN_FILENO))
                               (void)dup2(pdes[1], STDIN_FILENO);
               } else {
                       if (pdes[0] != STDIN_FILENO) {
                               (void)dup2(pdes[0], STDIN_FILENO);
                               (void)close(pdes[0]);
                       }
                       (void)close(pdes[1]);
               }
               execl(_PATH_BSHELL, "sh", "-c", command, 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]);
       }

       /* 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
pclose(iop)
       FILE *iop;
{
       register struct pid *cur, *last;
       int omask;
       int pstat;
       pid_t pid;

       /* 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);

       (void)fclose(iop);

       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);
}