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Annotation of src/lib/libc/gen/popen.c, Revision 1.1

1.1     ! cgd         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[] = "@(#)popen.c    5.15 (Berkeley) 2/23/91";
        !            39: #endif /* LIBC_SCCS and not lint */
        !            40:
        !            41: #include <sys/param.h>
        !            42: #include <sys/signal.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(program, type)
        !            55:        const char *program;
        !            56:        const char *type;
        !            57: {
        !            58:        FILE *iop;
        !            59:        int pdes[2], fds, pid;
        !            60:
        !            61:        if (*type != 'r' && *type != 'w' || type[1])
        !            62:                return (NULL);
        !            63:
        !            64:        if (pids == NULL) {
        !            65:                if ((fds = getdtablesize()) <= 0)
        !            66:                        return (NULL);
        !            67:                if ((pids = (pid_t *)malloc((u_int)(fds * sizeof(int)))) == NULL)
        !            68:                        return (NULL);
        !            69:                bzero((char *)pids, fds * sizeof(pid_t));
        !            70:        }
        !            71:        if (pipe(pdes) < 0)
        !            72:                return (NULL);
        !            73:        switch (pid = vfork()) {
        !            74:        case -1:                        /* error */
        !            75:                (void) close(pdes[0]);
        !            76:                (void) close(pdes[1]);
        !            77:                return (NULL);
        !            78:                /* NOTREACHED */
        !            79:        case 0:                         /* child */
        !            80:                if (*type == 'r') {
        !            81:                        if (pdes[1] != STDOUT_FILENO) {
        !            82:                                (void) dup2(pdes[1], STDOUT_FILENO);
        !            83:                                (void) close(pdes[1]);
        !            84:                        }
        !            85:                        (void) close(pdes[0]);
        !            86:                } else {
        !            87:                        if (pdes[0] != STDIN_FILENO) {
        !            88:                                (void) dup2(pdes[0], STDIN_FILENO);
        !            89:                                (void) close(pdes[0]);
        !            90:                        }
        !            91:                        (void) close(pdes[1]);
        !            92:                }
        !            93:                execl(_PATH_BSHELL, "sh", "-c", program, NULL);
        !            94:                _exit(127);
        !            95:                /* NOTREACHED */
        !            96:        }
        !            97:        /* parent; assume fdopen can't fail...  */
        !            98:        if (*type == 'r') {
        !            99:                iop = fdopen(pdes[0], type);
        !           100:                (void) close(pdes[1]);
        !           101:        } else {
        !           102:                iop = fdopen(pdes[1], type);
        !           103:                (void) close(pdes[0]);
        !           104:        }
        !           105:        pids[fileno(iop)] = pid;
        !           106:        return (iop);
        !           107: }
        !           108:
        !           109: int
        !           110: pclose(iop)
        !           111:        FILE *iop;
        !           112: {
        !           113:        register int fdes;
        !           114:        int omask;
        !           115:        union wait pstat;
        !           116:        pid_t pid;
        !           117:
        !           118:        /*
        !           119:         * pclose returns -1 if stream is not associated with a
        !           120:         * `popened' command, if already `pclosed', or waitpid
        !           121:         * returns an error.
        !           122:         */
        !           123:        if (pids == NULL || pids[fdes = fileno(iop)] == 0)
        !           124:                return (-1);
        !           125:        (void) fclose(iop);
        !           126:        omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
        !           127:        do {
        !           128:                pid = waitpid(pids[fdes], (int *) &pstat, 0);
        !           129:        } while (pid == -1 && errno == EINTR);
        !           130:        (void) sigsetmask(omask);
        !           131:        pids[fdes] = 0;
        !           132:        return (pid == -1 ? -1 : pstat.w_status);
        !           133: }