Rick Adams for Bill Scherlis, the night that MilNet died

[unix-history] / 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     5.3 (Berkeley) %G%";
#endif /* not lint */

#include <sys/types.h>
#include <sys/signal.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 uid_t *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();

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

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

       /* 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);
}

pclose(iop)
       FILE *iop;
{
       register int fdes;
       long omask;
       int pid, stat_loc;
       u_int waitpid();

       /*
        * pclose returns -1 if stream is not associated with a
        * `popened' command, or, if already `pclosed'.
        */
       if (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(stat_loc);
}