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Annotation of src/lib/libc/gen/popen.c, Revision 1.7

1.1       cgd         1: /*
1.7     ! jtc         2:  * Copyright (c) 1988, 1993
        !             3:  *     The Regents of the University of California.  All rights reserved.
1.1       cgd         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)
1.7     ! jtc        38: /* static char sccsid[] = "from: @(#)popen.c   8.1 (Berkeley) 6/4/93"; */
        !            39: static char *rcsid = "$Id: popen.c,v 1.6 1993/11/11 19:04:30 jtc Exp $";
1.1       cgd        40: #endif /* LIBC_SCCS and not lint */
                     41:
                     42: #include <sys/param.h>
                     43: #include <sys/wait.h>
1.7     ! jtc        44:
        !            45: #include <signal.h>
1.1       cgd        46: #include <errno.h>
1.7     ! jtc        47: #include <unistd.h>
1.1       cgd        48: #include <stdio.h>
                     49: #include <stdlib.h>
                     50: #include <string.h>
                     51: #include <paths.h>
                     52:
1.7     ! jtc        53: static struct pid {
        !            54:        struct pid *next;
        !            55:        FILE *fp;
        !            56:        pid_t pid;
        !            57: } *pidlist;
        !            58:
1.1       cgd        59: FILE *
1.3       jtc        60: popen(command, type)
                     61:        const char *command;
1.1       cgd        62:        const char *type;
                     63: {
1.7     ! jtc        64:        struct pid *cur;
1.1       cgd        65:        FILE *iop;
1.7     ! jtc        66:        int pdes[2], pid;
1.1       cgd        67:
1.3       jtc        68:        if (*type != 'r' && *type != 'w' || type[1]) {
                     69:                errno = EINVAL;
1.1       cgd        70:                return (NULL);
1.3       jtc        71:        }
1.1       cgd        72:
1.7     ! jtc        73:        if ((cur = malloc(sizeof(struct pid))) == NULL)
        !            74:                return (NULL);
        !            75:
        !            76:        if (pipe(pdes) < 0) {
        !            77:                (void)free(cur);
        !            78:                return (NULL);
1.1       cgd        79:        }
1.7     ! jtc        80:
1.1       cgd        81:        switch (pid = vfork()) {
1.7     ! jtc        82:        case -1:                        /* Error. */
        !            83:                (void)close(pdes[0]);
        !            84:                (void)close(pdes[1]);
        !            85:                (void)free(cur);
1.1       cgd        86:                return (NULL);
                     87:                /* NOTREACHED */
1.7     ! jtc        88:        case 0:                         /* Child. */
1.1       cgd        89:                if (*type == 'r') {
                     90:                        if (pdes[1] != STDOUT_FILENO) {
1.7     ! jtc        91:                                (void)dup2(pdes[1], STDOUT_FILENO);
        !            92:                                (void)close(pdes[1]);
1.1       cgd        93:                        }
                     94:                        (void) close(pdes[0]);
                     95:                } else {
                     96:                        if (pdes[0] != STDIN_FILENO) {
1.7     ! jtc        97:                                (void)dup2(pdes[0], STDIN_FILENO);
        !            98:                                (void)close(pdes[0]);
1.1       cgd        99:                        }
1.7     ! jtc       100:                        (void)close(pdes[1]);
1.1       cgd       101:                }
1.3       jtc       102:                execl(_PATH_BSHELL, "sh", "-c", command, (char *) 0);
1.1       cgd       103:                _exit(127);
                    104:                /* NOTREACHED */
                    105:        }
1.7     ! jtc       106:
        !           107:        /* Parent; assume fdopen can't fail. */
1.1       cgd       108:        if (*type == 'r') {
                    109:                iop = fdopen(pdes[0], type);
1.7     ! jtc       110:                (void)close(pdes[1]);
1.1       cgd       111:        } else {
                    112:                iop = fdopen(pdes[1], type);
1.7     ! jtc       113:                (void)close(pdes[0]);
1.1       cgd       114:        }
1.7     ! jtc       115:
        !           116:        /* Link into list of file descriptors. */
        !           117:        cur->fp = iop;
        !           118:        cur->pid =  pid;
        !           119:        cur->next = pidlist;
        !           120:        pidlist = cur;
        !           121:
1.1       cgd       122:        return (iop);
                    123: }
                    124:
1.7     ! jtc       125: /*
        !           126:  * pclose --
        !           127:  *     Pclose returns -1 if stream is not associated with a `popened' command,
        !           128:  *     if already `pclosed', or waitpid returns an error.
        !           129:  */
1.1       cgd       130: int
                    131: pclose(iop)
                    132:        FILE *iop;
                    133: {
1.7     ! jtc       134:        register struct pid *cur, *last;
        !           135:        int omask;
1.3       jtc       136:        int pstat;
1.1       cgd       137:        pid_t pid;
                    138:
1.7     ! jtc       139:        /* Find the appropriate file pointer. */
        !           140:        for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
        !           141:                if (cur->fp == iop)
        !           142:                        break;
        !           143:        if (cur == NULL)
1.1       cgd       144:                return (-1);
1.7     ! jtc       145:
        !           146:        (void)fclose(iop);
        !           147:
1.1       cgd       148:        do {
1.7     ! jtc       149:                pid = waitpid(cur->pid, &pstat, 0);
1.1       cgd       150:        } while (pid == -1 && errno == EINTR);
1.7     ! jtc       151:
        !           152:        /* Remove the entry from the linked list. */
        !           153:        if (last == NULL)
        !           154:                pidlist = cur->next;
        !           155:        else
        !           156:                last->next = cur->next;
        !           157:        free(cur);
        !           158:
1.3       jtc       159:        return (pid == -1 ? -1 : pstat);
1.1       cgd       160: }

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