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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.
 *
 */

/* 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[] = "$Id: popen.c,v 1.5 1994/01/15 20:43:43 vixie Exp $";
static char sccsid[] = "@(#)popen.c 5.7 (Berkeley) 2/14/89";
#endif /* not lint */

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

#if defined(BSD) || defined(POSIX)
#  include <grp.h>
#endif


#define MAX_ARGS 100
#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, e)
      char *program, *type;
      entry *e;
{
      register char *cp;
      FILE *iop;
      int argc, pdes[2];
      PID_T pid;
      char *argv[MAX_ARGS + 1];
#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; argc < MAX_ARGS; cp = NULL)
            if (!(argv[argc++] = strtok(cp, " \t\n")))
                  break;
    argv[MAX_ARGS] = NULL;

#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]);
            }
            /* Lose root privilege */
            setgid(e->gid);
# if defined(BSD) || defined(POSIX)
            if (initgroups(env_get("LOGNAME", e->envp), e->gid) !=0) {
              char msg[256];
              snprintf(msg, 256, "do_command:initgroups(%lu) failed: %s",
                     (unsigned long) e->gid, strerror(errno));
              log_it("CRON",getpid(),"error",msg);
              exit(ERROR_EXIT);
                }
# endif
            if (setuid(e->uid) !=0) {
              char msg[256];
              snprintf(msg, 256, "popen: setuid(%lu) failed: %s",
                     (unsigned long) e->uid, strerror(errno)); 
              log_it("CRON",getpid(),"error",msg);
              exit(ERROR_EXIT);
            }     
            chdir(env_get("HOME", e->envp));

#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));
}

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