usr.sbin/cron/popen.c

/*
 * Copyright (c) 1988 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software written by Ken Arnold and
 * published in UNIX Review, Vol. 6, No. 8.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * From Id: popen.c,v 1.5 1994/01/15 20:43:43 vixie Exp
 */

/* this came out of the ftpd sources; it's been modified to avoid the
 * globbing stuff since we don't need it.  also execvp instead of execv.
 */

#ifndef lint
static char rcsid[] = "$Header: $";
static char sccsid[] = "@(#)popen.c     5.7 (Berkeley) 2/14/89";
#endif /* not lint */

#include "cron.h"
#include <sys/signal.h>


#define WANT_GLOBBING 0

/*
 * Special version of popen which avoids call to shell.  This insures noone
 * may create a pipe to a hidden program as a side effect of a list or dir
 * command.
 */
static PID_T *pids;
static int fds;

FILE *
cron_popen(program, type)
        char *program, *type;
{
        register char *cp;
        FILE *iop;
        int argc, pdes[2];
        PID_T pid;
        char *argv[100];
#if WANT_GLOBBING
        char **pop, *vv[2];
        int gargc;
        char *gargv[1000];
        extern char **glob(), **copyblk();
#endif

        if (*type != 'r' && *type != 'w' || type[1])
                return(NULL);

        if (!pids) {
                if ((fds = getdtablesize()) <= 0)
                        return(NULL);
                if (!(pids = (PID_T *)malloc((u_int)(fds * sizeof(PID_T)))))
                        return(NULL);
                bzero((char *)pids, fds * sizeof(PID_T));
        }
        if (pipe(pdes) < 0)
                return(NULL);

        /* break up string into pieces */
        for (argc = 0, cp = program;; cp = NULL)
                if (!(argv[argc++] = strtok(cp, " \t\n")))
                        break;

#if WANT_GLOBBING
        /* glob each piece */
        gargv[0] = argv[0];
        for (gargc = argc = 1; argv[argc]; argc++) {
                if (!(pop = glob(argv[argc]))) {        /* globbing failed */
                        vv[0] = argv[argc];
                        vv[1] = NULL;
                        pop = copyblk(vv);
                }
                argv[argc] = (char *)pop;               /* save to free later */
                while (*pop && gargc < 1000)
                        gargv[gargc++] = *pop++;
        }
        gargv[gargc] = NULL;
#endif

        iop = NULL;
        switch(pid = vfork()) {
        case -1:                        /* error */
                (void)close(pdes[0]);
                (void)close(pdes[1]);
                goto pfree;
                /* NOTREACHED */
        case 0:                         /* child */
                if (*type == 'r') {
                        if (pdes[1] != 1) {
                                dup2(pdes[1], 1);
                                dup2(pdes[1], 2);       /* stderr, too! */
                                (void)close(pdes[1]);
                        }
                        (void)close(pdes[0]);
                } else {
                        if (pdes[0] != 0) {
                                dup2(pdes[0], 0);
                                (void)close(pdes[0]);
                        }
                        (void)close(pdes[1]);
                }
#if WANT_GLOBBING
                execvp(gargv[0], gargv);
#else
                execvp(argv[0], argv);
#endif
                _exit(1);
        }
        /* parent; assume fdopen can't fail...  */
        if (*type == 'r') {
                iop = fdopen(pdes[0], type);
                (void)close(pdes[1]);
        } else {
                iop = fdopen(pdes[1], type);
                (void)close(pdes[0]);
        }
        pids[fileno(iop)] = pid;

pfree:
#if WANT_GLOBBING
        for (argc = 1; argv[argc] != NULL; argc++) {
/*              blkfree((char **)argv[argc]);   */
                free((char *)argv[argc]);
        }
#endif
        return(iop);
}

int
cron_pclose(iop)
        FILE *iop;
{
        register int fdes;
        int omask;
        WAIT_T stat_loc;
        PID_T pid;

        /*
         * pclose returns -1 if stream is not associated with a
         * `popened' command, or, if already `pclosed'.
         */
        if (pids == 0 || pids[fdes = fileno(iop)] == 0)
                return(-1);
        (void)fclose(iop);
        omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
        while ((pid = wait(&stat_loc)) != pids[fdes] && pid != -1)
                ;
        (void)sigsetmask(omask);
        pids[fdes] = 0;
        return (pid == -1 ? -1 : WEXITSTATUS(stat_loc));
}