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popen.c revision 1.5 
      1 /*
      2  * Copyright (c) 1988 The Regents of the University of California.
      3  * All rights reserved.
      4  *
      5  * This code is derived from software written by Ken Arnold and
      6  * published in UNIX Review, Vol. 6, No. 8.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  * 3. All advertising materials mentioning features or use of this software
     17  *    must display the following acknowledgement:
     18  *	This product includes software developed by the University of
     19  *	California, Berkeley and its contributors.
     20  * 4. Neither the name of the University nor the names of its contributors
     21  *    may be used to endorse or promote products derived from this software
     22  *    without specific prior written permission.
     23  *
     24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     34  * SUCH DAMAGE.
     35  */
     36 
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 /*static char *sccsid = "from: @(#)popen.c	5.15 (Berkeley) 2/23/91";*/
     39 static char *rcsid = "$Id: popen.c,v 1.5 1993/08/26 00:44:55 jtc Exp $";
     40 #endif /* LIBC_SCCS and not lint */
     41 
     42 #include <sys/param.h>
     43 #include <sys/wait.h>
     44 #include <errno.h>
     45 #include <stdio.h>
     46 #include <stdlib.h>
     47 #include <string.h>
     48 #include <unistd.h>
     49 #include <paths.h>
     50 
     51 static pid_t *pids;
     52 
     53 FILE *
     54 popen(command, type)
     55 	const char *command;
     56 	const char *type;
     57 {
     58 	FILE *iop;
     59 	int pdes[2], fds, pid;
     60 
     61 	if (*type != 'r' && *type != 'w' || type[1]) {
     62 		errno = EINVAL;
     63 		return (NULL);
     64 	}
     65 
     66 	if (pids == NULL) {
     67 		if ((fds = getdtablesize()) <= 0)
     68 			return (NULL);
     69 		if ((pids = (pid_t *)malloc((u_int)(fds * sizeof(int)))) == NULL)
     70 			return (NULL);
     71 		bzero((char *)pids, fds * sizeof(pid_t));
     72 	}
     73 	if (pipe(pdes) < 0)
     74 		return (NULL);
     75 	switch (pid = vfork()) {
     76 	case -1:			/* error */
     77 		(void) close(pdes[0]);
     78 		(void) close(pdes[1]);
     79 		return (NULL);
     80 		/* NOTREACHED */
     81 	case 0:				/* child */
     82 		if (*type == 'r') {
     83 			if (pdes[1] != STDOUT_FILENO) {
     84 				(void) dup2(pdes[1], STDOUT_FILENO);
     85 				(void) close(pdes[1]);
     86 			}
     87 			(void) close(pdes[0]);
     88 		} else {
     89 			if (pdes[0] != STDIN_FILENO) {
     90 				(void) dup2(pdes[0], STDIN_FILENO);
     91 				(void) close(pdes[0]);
     92 			}
     93 			(void) close(pdes[1]);
     94 		}
     95 		execl(_PATH_BSHELL, "sh", "-c", command, (char *) 0);
     96 		_exit(127);
     97 		/* NOTREACHED */
     98 	}
     99 	/* parent; assume fdopen can't fail...  */
    100 	if (*type == 'r') {
    101 		iop = fdopen(pdes[0], type);
    102 		(void) close(pdes[1]);
    103 	} else {
    104 		iop = fdopen(pdes[1], type);
    105 		(void) close(pdes[0]);
    106 	}
    107 	pids[fileno(iop)] = pid;
    108 	return (iop);
    109 }
    110 
    111 int
    112 pclose(iop)
    113 	FILE *iop;
    114 {
    115 	register int fdes;
    116 	int omask;
    117 	int pstat;
    118 	pid_t pid;
    119 
    120 	/*
    121 	 * pclose returns -1 if stream is not associated with a
    122 	 * `popened' command, if already `pclosed', or waitpid
    123 	 * returns an error.
    124 	 */
    125 	if (pids == NULL || pids[fdes = fileno(iop)] == 0)
    126 		return (-1);
    127 	(void) fclose(iop);
    128 	do {
    129 		pid = waitpid(pids[fdes], &pstat, 0);
    130 	} while (pid == -1 && errno == EINTR);
    131 	pids[fdes] = 0;
    132 	return (pid == -1 ? -1 : pstat);
    133 }
    134