usr/src/libexec/ftpd/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 MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * static char sccsid[] = "@(#)popen.c  5.7 (Berkeley) 9/1/88";
 */

#ifndef lint
static char sccsid[] = "@(#)popen.c     5.5 (Berkeley) %G%";
#endif /* not lint */

#include <sys/types.h>
#include <sys/signal.h>
#include <sys/wait.h>
#include <stdio.h>

/*
 * 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 int *pids;
static int fds;

FILE *
ftpd_popen(program, type)
        char *program, *type;
{
        register char *cp;
        FILE *iop;
        int argc, gargc, pdes[2], pid;
        char **pop, *argv[100], *gargv[1000], *vv[2];
        extern char **glob(), **copyblk(), *strtok(), *malloc();

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

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

        /* 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;

        iop = NULL;
        switch(pid = vfork()) {
        case -1:                        /* error */
                (void)close(pdes[0]);
                (void)close(pdes[1]);
                goto free;
                /* NOTREACHED */
        case 0:                         /* child */
                if (*type == 'r') {
                        if (pdes[1] != 1) {
                                dup2(pdes[1], 1);
                                (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]);
                }
                execv(gargv[0], gargv);
                _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;

free:   for (argc = 1; argv[argc] != NULL; argc++)
                blkfree((char **)argv[argc]);
        return(iop);
}

ftpd_pclose(iop)
        FILE *iop;
{
        register int fdes;
        int omask;
        union wait stat_loc;
        int 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 : stat_loc.w_status);
}