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Annotation of 43BSDReno/lib/libc/gen/popen.c, revision 1.1

1.1     ! root        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 are permitted
        !             9:  * provided that: (1) source distributions retain this entire copyright
        !            10:  * notice and comment, and (2) distributions including binaries display
        !            11:  * the following acknowledgement:  ``This product includes software
        !            12:  * developed by the University of California, Berkeley and its contributors''
        !            13:  * in the documentation or other materials provided with the distribution
        !            14:  * and in all advertising materials mentioning features or use of this
        !            15:  * software. Neither the name of the University nor the names of its
        !            16:  * contributors may be used to endorse or promote products derived
        !            17:  * from this software without specific prior written permission.
        !            18:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
        !            19:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
        !            20:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            21:  */
        !            22: 
        !            23: #if defined(LIBC_SCCS) && !defined(lint)
        !            24: static char sccsid[] = "@(#)popen.c    5.14 (Berkeley) 6/1/90";
        !            25: #endif /* LIBC_SCCS and not lint */
        !            26: 
        !            27: #include <sys/param.h>
        !            28: #include <sys/signal.h>
        !            29: #include <sys/wait.h>
        !            30: #include <errno.h>
        !            31: #include <stdio.h>
        !            32: #include <unistd.h>
        !            33: #include <paths.h>
        !            34: 
        !            35: static pid_t *pids;
        !            36: 
        !            37: FILE *
        !            38: popen(program, type)
        !            39:        char *program, *type;
        !            40: {
        !            41:        FILE *iop;
        !            42:        int pdes[2], fds, pid;
        !            43:        char *malloc();
        !            44: 
        !            45:        if (*type != 'r' && *type != 'w' || type[1])
        !            46:                return (NULL);
        !            47: 
        !            48:        if (pids == NULL) {
        !            49:                if ((fds = getdtablesize()) <= 0)
        !            50:                        return (NULL);
        !            51:                if ((pids = (pid_t *)malloc((u_int)(fds * sizeof(int)))) == NULL)
        !            52:                        return (NULL);
        !            53:                bzero((char *)pids, fds * sizeof(pid_t));
        !            54:        }
        !            55:        if (pipe(pdes) < 0)
        !            56:                return (NULL);
        !            57:        switch (pid = vfork()) {
        !            58:        case -1:                        /* error */
        !            59:                (void) close(pdes[0]);
        !            60:                (void) close(pdes[1]);
        !            61:                return (NULL);
        !            62:                /* NOTREACHED */
        !            63:        case 0:                         /* child */
        !            64:                if (*type == 'r') {
        !            65:                        if (pdes[1] != STDOUT_FILENO) {
        !            66:                                (void) dup2(pdes[1], STDOUT_FILENO);
        !            67:                                (void) close(pdes[1]);
        !            68:                        }
        !            69:                        (void) close(pdes[0]);
        !            70:                } else {
        !            71:                        if (pdes[0] != STDIN_FILENO) {
        !            72:                                (void) dup2(pdes[0], STDIN_FILENO);
        !            73:                                (void) close(pdes[0]);
        !            74:                        }
        !            75:                        (void) close(pdes[1]);
        !            76:                }
        !            77:                execl(_PATH_BSHELL, "sh", "-c", program, NULL);
        !            78:                _exit(127);
        !            79:                /* NOTREACHED */
        !            80:        }
        !            81:        /* parent; assume fdopen can't fail...  */
        !            82:        if (*type == 'r') {
        !            83:                iop = fdopen(pdes[0], type);
        !            84:                (void) close(pdes[1]);
        !            85:        } else {
        !            86:                iop = fdopen(pdes[1], type);
        !            87:                (void) close(pdes[0]);
        !            88:        }
        !            89:        pids[fileno(iop)] = pid;
        !            90:        return (iop);
        !            91: }
        !            92: 
        !            93: pclose(iop)
        !            94:        FILE *iop;
        !            95: {
        !            96:        extern int errno;
        !            97:        register int fdes;
        !            98:        int omask;
        !            99:        union wait pstat;
        !           100:        pid_t pid, waitpid();
        !           101: 
        !           102:        /*
        !           103:         * pclose returns -1 if stream is not associated with a
        !           104:         * `popened' command, if already `pclosed', or waitpid
        !           105:         * returns an error.
        !           106:         */
        !           107:        if (pids == NULL || pids[fdes = fileno(iop)] == 0)
        !           108:                return (-1);
        !           109:        (void) fclose(iop);
        !           110:        omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
        !           111:        do {
        !           112:                pid = waitpid(pids[fdes], &pstat, 0);
        !           113:        } while (pid == -1 && errno == EINTR);
        !           114:        (void) sigsetmask(omask);
        !           115:        pids[fdes] = 0;
        !           116:        return (pid == -1 ? -1 : pstat.w_status);
        !           117: }

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