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Annotation of src/lib/libc/gen/popen.c, Revision 1.2

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)
1.2     ! mycroft    38: /*static char sccsid[] = "from: @(#)popen.c    5.15 (Berkeley) 2/23/91";*/
        !            39: static char rcsid[] = "$Id: $";
1.1       cgd        40: #endif /* LIBC_SCCS and not lint */
                     41:
                     42: #include <sys/param.h>
                     43: #include <sys/signal.h>
                     44: #include <sys/wait.h>
                     45: #include <errno.h>
                     46: #include <stdio.h>
                     47: #include <stdlib.h>
                     48: #include <string.h>
                     49: #include <unistd.h>
                     50: #include <paths.h>
                     51:
                     52: static pid_t *pids;
                     53:
                     54: FILE *
                     55: popen(program, type)
                     56:        const char *program;
                     57:        const char *type;
                     58: {
                     59:        FILE *iop;
                     60:        int pdes[2], fds, pid;
                     61:
                     62:        if (*type != 'r' && *type != 'w' || type[1])
                     63:                return (NULL);
                     64:
                     65:        if (pids == NULL) {
                     66:                if ((fds = getdtablesize()) <= 0)
                     67:                        return (NULL);
                     68:                if ((pids = (pid_t *)malloc((u_int)(fds * sizeof(int)))) == NULL)
                     69:                        return (NULL);
                     70:                bzero((char *)pids, fds * sizeof(pid_t));
                     71:        }
                     72:        if (pipe(pdes) < 0)
                     73:                return (NULL);
                     74:        switch (pid = vfork()) {
                     75:        case -1:                        /* error */
                     76:                (void) close(pdes[0]);
                     77:                (void) close(pdes[1]);
                     78:                return (NULL);
                     79:                /* NOTREACHED */
                     80:        case 0:                         /* child */
                     81:                if (*type == 'r') {
                     82:                        if (pdes[1] != STDOUT_FILENO) {
                     83:                                (void) dup2(pdes[1], STDOUT_FILENO);
                     84:                                (void) close(pdes[1]);
                     85:                        }
                     86:                        (void) close(pdes[0]);
                     87:                } else {
                     88:                        if (pdes[0] != STDIN_FILENO) {
                     89:                                (void) dup2(pdes[0], STDIN_FILENO);
                     90:                                (void) close(pdes[0]);
                     91:                        }
                     92:                        (void) close(pdes[1]);
                     93:                }
                     94:                execl(_PATH_BSHELL, "sh", "-c", program, NULL);
                     95:                _exit(127);
                     96:                /* NOTREACHED */
                     97:        }
                     98:        /* parent; assume fdopen can't fail...  */
                     99:        if (*type == 'r') {
                    100:                iop = fdopen(pdes[0], type);
                    101:                (void) close(pdes[1]);
                    102:        } else {
                    103:                iop = fdopen(pdes[1], type);
                    104:                (void) close(pdes[0]);
                    105:        }
                    106:        pids[fileno(iop)] = pid;
                    107:        return (iop);
                    108: }
                    109:
                    110: int
                    111: pclose(iop)
                    112:        FILE *iop;
                    113: {
                    114:        register int fdes;
                    115:        int omask;
                    116:        union wait pstat;
                    117:        pid_t pid;
                    118:
                    119:        /*
                    120:         * pclose returns -1 if stream is not associated with a
                    121:         * `popened' command, if already `pclosed', or waitpid
                    122:         * returns an error.
                    123:         */
                    124:        if (pids == NULL || pids[fdes = fileno(iop)] == 0)
                    125:                return (-1);
                    126:        (void) fclose(iop);
                    127:        omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
                    128:        do {
                    129:                pid = waitpid(pids[fdes], (int *) &pstat, 0);
                    130:        } while (pid == -1 && errno == EINTR);
                    131:        (void) sigsetmask(omask);
                    132:        pids[fdes] = 0;
                    133:        return (pid == -1 ? -1 : pstat.w_status);
                    134: }