usr.sbin/cron/cron/popen.c

   1 /*
   2  * Copyright (c) 1988 The Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * This code is derived from software written by Ken Arnold and
   6  * published in UNIX Review, Vol. 6, No. 8.
   7  *
   8  * Redistribution and use in source and binary forms are permitted
   9  * provided that the above copyright notice and this paragraph are
  10  * duplicated in all such forms and that any documentation,
  11  * advertising materials, and other materials related to such
  12  * distribution and use acknowledge that the software was developed
  13  * by the University of California, Berkeley.  The name of the
  14  * University may not be used to endorse or promote products derived
  15  * from this software without specific prior written permission.
  16  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  18  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  19  *
  20  * @(#)popen.c  5.7 (Berkeley) 2/14/89
  21  * $FreeBSD: src/usr.sbin/cron/cron/popen.c,v 1.7.2.3 2000/12/11 01:03:31 obrien Exp $
  22  * $DragonFly: src/usr.sbin/cron/cron/popen.c,v 1.2 2003/06/17 04:29:53 dillon Exp $
  23  */
  24
  25 /* this came out of the ftpd sources; it's been modified to avoid the
  26  * globbing stuff since we don't need it.  also execvp instead of execv.
  27  */
  28
  29 #include "cron.h"
  30 #include <sys/signal.h>
  31 #include <fcntl.h>
  32 #include <paths.h>
  33 #if defined(SYSLOG)
  34 # include <syslog.h>
  35 #endif
  36 #if defined(LOGIN_CAP)
  37 # include <login_cap.h>
  38 #endif
  39
  40
  41 #define MAX_ARGS 100
  42 #define WANT_GLOBBING 0
  43
  44 /*
  45  * Special version of popen which avoids call to shell.  This insures noone
  46  * may create a pipe to a hidden program as a side effect of a list or dir
  47  * command.
  48  */
  49 static PID_T *pids;
  50 static int fds;
  51
  52 FILE *
  53 cron_popen(program, type, e)
  54         char *program, *type;
  55         entry *e;
  56 {
  57         register char *cp;
  58         FILE *iop;
  59         int argc, pdes[2];
  60         PID_T pid;
  61         char *usernm;
  62         char *argv[MAX_ARGS + 1];
  63 # if defined(LOGIN_CAP)
  64         struct passwd   *pwd;
  65         login_cap_t *lc;
  66 # endif
  67 #if WANT_GLOBBING
  68         char **pop, *vv[2];
  69         int gargc;
  70         char *gargv[1000];
  71         extern char **glob(), **copyblk();
  72 #endif
  73
  74         if ((*type != 'r' && *type != 'w') || type[1])
  75                 return(NULL);
  76
  77         if (!pids) {
  78                 if ((fds = getdtablesize()) <= 0)
  79                         return(NULL);
  80                 if (!(pids = (PID_T *)malloc((u_int)(fds * sizeof(PID_T)))))
  81                         return(NULL);
  82                 bzero((char *)pids, fds * sizeof(PID_T));
  83         }
  84         if (pipe(pdes) < 0)
  85                 return(NULL);
  86
  87         /* break up string into pieces */
  88         for (argc = 0, cp = program; argc < MAX_ARGS; cp = NULL)
  89                 if (!(argv[argc++] = strtok(cp, " \t\n")))
  90                         break;
  91         argv[MAX_ARGS] = NULL;
  92
  93 #if WANT_GLOBBING
  94         /* glob each piece */
  95         gargv[0] = argv[0];
  96         for (gargc = argc = 1; argv[argc]; argc++) {
  97                 if (!(pop = glob(argv[argc]))) {        /* globbing failed */
  98                         vv[0] = argv[argc];
  99                         vv[1] = NULL;
 100                         pop = copyblk(vv);
 101                 }
 102                 argv[argc] = (char *)pop;               /* save to free later */
 103                 while (*pop && gargc < 1000)
 104                         gargv[gargc++] = *pop++;
 105         }
 106         gargv[gargc] = NULL;
 107 #endif
 108
 109         iop = NULL;
 110         switch(pid = vfork()) {
 111         case -1:                        /* error */
 112                 (void)close(pdes[0]);
 113                 (void)close(pdes[1]);
 114                 goto pfree;
 115                 /* NOTREACHED */
 116         case 0:                         /* child */
 117                 if (e != NULL) {
 118 #ifdef SYSLOG
 119                         closelog();
 120 #endif
 121
 122                         /* get new pgrp, void tty, etc.
 123                          */
 124                         (void) setsid();
 125                 }
 126                 if (*type == 'r') {
 127                         /* Do not share our parent's stdin */
 128                         (void)close(0);
 129                         (void)open(_PATH_DEVNULL, O_RDWR);
 130                         if (pdes[1] != 1) {
 131                                 dup2(pdes[1], 1);
 132                                 dup2(pdes[1], 2);       /* stderr, too! */
 133                                 (void)close(pdes[1]);
 134                         }
 135                         (void)close(pdes[0]);
 136                 } else {
 137                         if (pdes[0] != 0) {
 138                                 dup2(pdes[0], 0);
 139                                 (void)close(pdes[0]);
 140                         }
 141                         /* Hack: stdout gets revoked */
 142                         (void)close(1);
 143                         (void)open(_PATH_DEVNULL, O_RDWR);
 144                         (void)close(2);
 145                         (void)open(_PATH_DEVNULL, O_RDWR);
 146                         (void)close(pdes[1]);
 147                 }
 148 # if defined(LOGIN_CAP)
 149                 if (e != NULL) {
 150                         /* Set user's entire context, but skip the environment
 151                          * as cron provides a separate interface for this
 152                          */
 153                         usernm = env_get("LOGNAME", e->envp);
 154                         if ((pwd = getpwnam(usernm)) == NULL)
 155                                 pwd = getpwuid(e->uid);
 156                         lc = NULL;
 157                         if (pwd != NULL) {
 158                                 pwd->pw_gid = e->gid;
 159                                 if (e->class != NULL)
 160                                         lc = login_getclass(e->class);
 161                         }
 162                         if (pwd &&
 163                             setusercontext(lc, pwd, e->uid,
 164                                     LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETENV)) == 0)
 165                                 (void) endpwent();
 166                         else {
 167                                 /* fall back to the old method */
 168                                 (void) endpwent();
 169 # endif
 170                                 /* set our directory, uid and gid.  Set gid first,
 171                                  * since once we set uid, we've lost root privledges.
 172                                  */
 173                                 setgid(e->gid);
 174 # if defined(BSD)
 175                                 initgroups(usernm, e->gid);
 176 # endif
 177                                 setlogin(usernm);
 178                                 setuid(e->uid);         /* we aren't root after this..*/
 179 #if defined(LOGIN_CAP)
 180                         }
 181                         if (lc != NULL)
 182                                 login_close(lc);
 183 #endif
 184                         chdir(env_get("HOME", e->envp));
 185                 }
 186 #if WANT_GLOBBING
 187                 execvp(gargv[0], gargv);
 188 #else
 189                 execvp(argv[0], argv);
 190 #endif
 191                 _exit(1);
 192         }
 193         /* parent; assume fdopen can't fail...  */
 194         if (*type == 'r') {
 195                 iop = fdopen(pdes[0], type);
 196                 (void)close(pdes[1]);
 197         } else {
 198                 iop = fdopen(pdes[1], type);
 199                 (void)close(pdes[0]);
 200         }
 201         pids[fileno(iop)] = pid;
 202
 203 pfree:
 204 #if WANT_GLOBBING
 205         for (argc = 1; argv[argc] != NULL; argc++) {
 206 /*              blkfree((char **)argv[argc]);   */
 207                 free((char *)argv[argc]);
 208         }
 209 #endif
 210         return(iop);
 211 }
 212
 213 int
 214 cron_pclose(iop)
 215         FILE *iop;
 216 {
 217         register int fdes;
 218         int omask;
 219         WAIT_T stat_loc;
 220         PID_T pid;
 221
 222         /*
 223          * pclose returns -1 if stream is not associated with a
 224          * `popened' command, or, if already `pclosed'.
 225          */
 226         if (pids == 0 || pids[fdes = fileno(iop)] == 0)
 227                 return(-1);
 228         (void)fclose(iop);
 229         omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
 230         while ((pid = wait(&stat_loc)) != pids[fdes] && pid != -1)
 231                 ;
 232         (void)sigsetmask(omask);
 233         pids[fdes] = 0;
 234         return (pid == -1 ? -1 : WEXITSTATUS(stat_loc));
 235 }