usr.sbin/cron/popen.c

   1 /*      $NetBSD: popen.c,v 1.10 2005/07/31 17:52:01 christos Exp $      */
   2
   3 /*
   4  * Copyright (c) 1988, 1993, 1994
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software written by Ken Arnold and
   8  * published in UNIX Review, Vol. 6, No. 8.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  *
  31  */
  32
  33 #include <sys/cdefs.h>
  34 #ifndef lint
  35 #if 0
  36 static char rcsid[] = "Id: popen.c,v 1.5 1994/01/15 20:43:43 vixie Exp";
  37 static char sccsid[] = "@(#)popen.c     5.7 (Berkeley) 2/14/89";
  38 #else
  39 __RCSID("$NetBSD: popen.c,v 1.10 2005/07/31 17:52:01 christos Exp $");
  40 #endif
  41 #endif /* not lint */
  42
  43 #include "cron.h"
  44 #include <signal.h>
  45
  46 /*
  47  * Special version of popen which avoids call to shell.  This insures noone
  48  * may create a pipe to a hidden program as a side effect of a list or dir
  49  * command.
  50  */
  51 static PID_T *pids;
  52 static int fds;
  53
  54 #define MAX_ARGS 1024
  55
  56 FILE *
  57 cron_popen(char *program, const char *type)
  58 {
  59         char *cp;
  60         FILE *iop;
  61         int argc, pdes[2];
  62         PID_T pid;
  63         char *argv[MAX_ARGS];
  64
  65         if ((*type != 'r' && *type != 'w') || type[1])
  66                 return(NULL);
  67
  68         if (!pids) {
  69                 if ((fds = getdtablesize()) <= 0)
  70                         return(NULL);
  71                 if (!(pids = (PID_T *)malloc((u_int)(fds * sizeof(PID_T)))))
  72                         return(NULL);
  73                 bzero((char *)pids, fds * sizeof(PID_T));
  74         }
  75         if (pipe(pdes) < 0)
  76                 return(NULL);
  77
  78         /* break up string into pieces */
  79         for (argc = 0, cp = program; argc < MAX_ARGS; cp = NULL)
  80                 if (!(argv[argc++] = strtok(cp, " \t\n")))
  81                         break;
  82
  83         switch(pid = vfork()) {
  84         case -1:                        /* error */
  85                 (void)close(pdes[0]);
  86                 (void)close(pdes[1]);
  87                 return NULL;
  88         case 0:                         /* child */
  89                 if (*type == 'r') {
  90                         if (pdes[1] != 1) {
  91                                 (void)dup2(pdes[1], 1);
  92                                 (void)dup2(pdes[1], 2); /* stderr, too! */
  93                                 (void)close(pdes[1]);
  94                         }
  95                         (void)close(pdes[0]);
  96                 } else {
  97                         if (pdes[0] != 0) {
  98                                 (void)dup2(pdes[0], 0);
  99                                 (void)close(pdes[0]);
 100                         }
 101                         (void)close(pdes[1]);
 102                 }
 103                 (void)execvp(argv[0], argv);
 104                 _exit(1);
 105         }
 106         /* parent; assume fdopen can't fail...  */
 107         if (*type == 'r') {
 108                 iop = fdopen(pdes[0], type);
 109                 (void)close(pdes[1]);
 110         } else {
 111                 iop = fdopen(pdes[1], type);
 112                 (void)close(pdes[0]);
 113         }
 114         pids[fileno(iop)] = pid;
 115         return(iop);
 116 }
 117
 118 int
 119 cron_pclose(FILE *iop)
 120 {
 121         int fdes;
 122         sigset_t oset, nset;
 123         WAIT_T status;
 124         PID_T pid;
 125
 126         /*
 127          * pclose returns -1 if stream is not associated with a
 128          * `popened' command, or, if already `pclosed'.
 129          */
 130         if (pids == 0 || pids[fdes = fileno(iop)] == 0)
 131                 return -1;
 132         (void)fclose(iop);
 133
 134         sigemptyset(&nset);
 135         sigaddset(&nset, SIGINT);
 136         sigaddset(&nset, SIGQUIT);
 137         sigaddset(&nset, SIGHUP);
 138         (void)sigprocmask(SIG_BLOCK, &nset, &oset);
 139         pid = waitpid(pids[fdes], &status, 0);
 140         (void)sigprocmask(SIG_SETMASK, &oset, NULL);
 141         pids[fdes] = 0;
 142         if (pid == -1)
 143                 return -1;
 144         return WIFEXITED(status) ? WEXITSTATUS(status) : WTERMSIG(status);
 145 }