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  */
  21
  22 /* this came out of the ftpd sources; it's been modified to avoid the
  23  * globbing stuff since we don't need it.  also execvp instead of execv.
  24  */
  25
  26 #ifndef lint
  27 #if 0
  28 static char sccsid[] = "@(#)popen.c     5.7 (Berkeley) 2/14/89";
  29 #endif
  30 static const char rcsid[] =
  31   "$FreeBSD: src/usr.sbin/cron/cron/popen.c,v 1.7.2.3 2000/12/11 01:03:31 obrien Exp $";
  32 #endif /* not lint */
  33
  34 #include "cron.h"
  35 #include <sys/signal.h>
  36 #include <fcntl.h>
  37 #include <paths.h>
  38 #if defined(SYSLOG)
  39 # include <syslog.h>
  40 #endif
  41 #if defined(LOGIN_CAP)
  42 # include <login_cap.h>
  43 #endif
  44
  45
  46 #define MAX_ARGS 100
  47 #define WANT_GLOBBING 0
  48
  49 /*
  50  * Special version of popen which avoids call to shell.  This insures noone
  51  * may create a pipe to a hidden program as a side effect of a list or dir
  52  * command.
  53  */
  54 static PID_T *pids;
  55 static int fds;
  56
  57 FILE *
  58 cron_popen(program, type, e)
  59         char *program, *type;
  60         entry *e;
  61 {
  62         register char *cp;
  63         FILE *iop;
  64         int argc, pdes[2];
  65         PID_T pid;
  66         char *usernm;
  67         char *argv[MAX_ARGS + 1];
  68 # if defined(LOGIN_CAP)
  69         struct passwd   *pwd;
  70         login_cap_t *lc;
  71 # endif
  72 #if WANT_GLOBBING
  73         char **pop, *vv[2];
  74         int gargc;
  75         char *gargv[1000];
  76         extern char **glob(), **copyblk();
  77 #endif
  78
  79         if ((*type != 'r' && *type != 'w') || type[1])
  80                 return(NULL);
  81
  82         if (!pids) {
  83                 if ((fds = getdtablesize()) <= 0)
  84                         return(NULL);
  85                 if (!(pids = (PID_T *)malloc((u_int)(fds * sizeof(PID_T)))))
  86                         return(NULL);
  87                 bzero((char *)pids, fds * sizeof(PID_T));
  88         }
  89         if (pipe(pdes) < 0)
  90                 return(NULL);
  91
  92         /* break up string into pieces */
  93         for (argc = 0, cp = program; argc < MAX_ARGS; cp = NULL)
  94                 if (!(argv[argc++] = strtok(cp, " \t\n")))
  95                         break;
  96         argv[MAX_ARGS] = NULL;
  97
  98 #if WANT_GLOBBING
  99         /* glob each piece */
 100         gargv[0] = argv[0];
 101         for (gargc = argc = 1; argv[argc]; argc++) {
 102                 if (!(pop = glob(argv[argc]))) {        /* globbing failed */
 103                         vv[0] = argv[argc];
 104                         vv[1] = NULL;
 105                         pop = copyblk(vv);
 106                 }
 107                 argv[argc] = (char *)pop;               /* save to free later */
 108                 while (*pop && gargc < 1000)
 109                         gargv[gargc++] = *pop++;
 110         }
 111         gargv[gargc] = NULL;
 112 #endif
 113
 114         iop = NULL;
 115         switch(pid = vfork()) {
 116         case -1:                        /* error */
 117                 (void)close(pdes[0]);
 118                 (void)close(pdes[1]);
 119                 goto pfree;
 120                 /* NOTREACHED */
 121         case 0:                         /* child */
 122                 if (e != NULL) {
 123 #ifdef SYSLOG
 124                         closelog();
 125 #endif
 126
 127                         /* get new pgrp, void tty, etc.
 128                          */
 129                         (void) setsid();
 130                 }
 131                 if (*type == 'r') {
 132                         /* Do not share our parent's stdin */
 133                         (void)close(0);
 134                         (void)open(_PATH_DEVNULL, O_RDWR);
 135                         if (pdes[1] != 1) {
 136                                 dup2(pdes[1], 1);
 137                                 dup2(pdes[1], 2);       /* stderr, too! */
 138                                 (void)close(pdes[1]);
 139                         }
 140                         (void)close(pdes[0]);
 141                 } else {
 142                         if (pdes[0] != 0) {
 143                                 dup2(pdes[0], 0);
 144                                 (void)close(pdes[0]);
 145                         }
 146                         /* Hack: stdout gets revoked */
 147                         (void)close(1);
 148                         (void)open(_PATH_DEVNULL, O_RDWR);
 149                         (void)close(2);
 150                         (void)open(_PATH_DEVNULL, O_RDWR);
 151                         (void)close(pdes[1]);
 152                 }
 153 # if defined(LOGIN_CAP)
 154                 if (e != NULL) {
 155                         /* Set user's entire context, but skip the environment
 156                          * as cron provides a separate interface for this
 157                          */
 158                         usernm = env_get("LOGNAME", e->envp);
 159                         if ((pwd = getpwnam(usernm)) == NULL)
 160                                 pwd = getpwuid(e->uid);
 161                         lc = NULL;
 162                         if (pwd != NULL) {
 163                                 pwd->pw_gid = e->gid;
 164                                 if (e->class != NULL)
 165                                         lc = login_getclass(e->class);
 166                         }
 167                         if (pwd &&
 168                             setusercontext(lc, pwd, e->uid,
 169                                     LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETENV)) == 0)
 170                                 (void) endpwent();
 171                         else {
 172                                 /* fall back to the old method */
 173                                 (void) endpwent();
 174 # endif
 175                                 /* set our directory, uid and gid.  Set gid first,
 176                                  * since once we set uid, we've lost root privledges.
 177                                  */
 178                                 setgid(e->gid);
 179 # if defined(BSD)
 180                                 initgroups(usernm, e->gid);
 181 # endif
 182                                 setlogin(usernm);
 183                                 setuid(e->uid);         /* we aren't root after this..*/
 184 #if defined(LOGIN_CAP)
 185                         }
 186                         if (lc != NULL)
 187                                 login_close(lc);
 188 #endif
 189                         chdir(env_get("HOME", e->envp));
 190                 }
 191 #if WANT_GLOBBING
 192                 execvp(gargv[0], gargv);
 193 #else
 194                 execvp(argv[0], argv);
 195 #endif
 196                 _exit(1);
 197         }
 198         /* parent; assume fdopen can't fail...  */
 199         if (*type == 'r') {
 200                 iop = fdopen(pdes[0], type);
 201                 (void)close(pdes[1]);
 202         } else {
 203                 iop = fdopen(pdes[1], type);
 204                 (void)close(pdes[0]);
 205         }
 206         pids[fileno(iop)] = pid;
 207
 208 pfree:
 209 #if WANT_GLOBBING
 210         for (argc = 1; argv[argc] != NULL; argc++) {
 211 /*              blkfree((char **)argv[argc]);   */
 212                 free((char *)argv[argc]);
 213         }
 214 #endif
 215         return(iop);
 216 }
 217
 218 int
 219 cron_pclose(iop)
 220         FILE *iop;
 221 {
 222         register int fdes;
 223         int omask;
 224         WAIT_T stat_loc;
 225         PID_T pid;
 226
 227         /*
 228          * pclose returns -1 if stream is not associated with a
 229          * `popened' command, or, if already `pclosed'.
 230          */
 231         if (pids == 0 || pids[fdes = fileno(iop)] == 0)
 232                 return(-1);
 233         (void)fclose(iop);
 234         omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
 235         while ((pid = wait(&stat_loc)) != pids[fdes] && pid != -1)
 236                 ;
 237         (void)sigsetmask(omask);
 238         pids[fdes] = 0;
 239         return (pid == -1 ? -1 : WEXITSTATUS(stat_loc));
 240 }