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Annotation of src/lib/libc/gen/popen.c, Revision 1.8

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

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