usr.sbin/cron/cron/database.c

   1 /* Copyright 1988,1990,1993,1994 by Paul Vixie
   2  * All rights reserved
   3  *
   4  * Distribute freely, except: don't remove my name from the source or
   5  * documentation (don't take credit for my work), mark your changes (don't
   6  * get me blamed for your possible bugs), don't alter or remove this
   7  * notice.  May be sold if buildable source is provided to buyer.  No
   8  * warrantee of any kind, express or implied, is included with this
   9  * software; use at your own risk, responsibility for damages (if any) to
  10  * anyone resulting from the use of this software rests entirely with the
  11  * user.
  12  *
  13  * Send bug reports, bug fixes, enhancements, requests, flames, etc., and
  14  * I'll try to keep a version up to date.  I can be reached as follows:
  15  * Paul Vixie          <paul@vix.com>          uunet!decwrl!vixie!paul
  16  *
  17  * $FreeBSD: src/usr.sbin/cron/cron/database.c,v 1.8 1999/08/28 01:15:50 peter Exp $
  18  * $DragonFly: src/usr.sbin/cron/cron/database.c,v 1.7 2008/01/07 14:11:23 matthias Exp $
  19  */
  20
  21 /* vix 26jan87 [RCS has the log]
  22  */
  23
  24
  25 #include "cron.h"
  26 #include <fcntl.h>
  27 #include <sys/stat.h>
  28 #include <sys/file.h>
  29
  30
  31 #define TMAX(a,b) ((a)>(b)?(a):(b))
  32
  33
  34 static  void            process_crontab(char *, char *, char *,
  35                                              struct stat *,
  36                                              cron_db *, cron_db *);
  37
  38
  39 void
  40 load_database(cron_db *old_db)
  41 {
  42         DIR             *dir;
  43         struct stat     statbuf;
  44         struct stat     syscron_stat;
  45         DIR_T           *dp;
  46         cron_db         new_db;
  47         user            *u, *nu;
  48
  49         Debug(DLOAD, ("[%d] load_database()\n", getpid()))
  50
  51         /* before we start loading any data, do a stat on SPOOL_DIR
  52          * so that if anything changes as of this moment (i.e., before we've
  53          * cached any of the database), we'll see the changes next time.
  54          */
  55         if (stat(SPOOL_DIR, &statbuf) < OK) {
  56                 log_it("CRON", getpid(), "STAT FAILED", SPOOL_DIR);
  57                 exit(ERROR_EXIT);
  58         }
  59
  60         /* track system crontab file
  61          */
  62         if (stat(SYSCRONTAB, &syscron_stat) < OK)
  63                 syscron_stat.st_mtime = 0;
  64
  65         /* if spooldir's mtime has not changed, we don't need to fiddle with
  66          * the database.
  67          *
  68          * Note that old_db->mtime is initialized to 0 in main(), and
  69          * so is guaranteed to be different than the stat() mtime the first
  70          * time this function is called.
  71          */
  72         if (old_db->mtime == TMAX(statbuf.st_mtime, syscron_stat.st_mtime)) {
  73                 Debug(DLOAD, ("[%d] spool dir mtime unch, no load needed.\n",
  74                               getpid()))
  75                 return;
  76         }
  77
  78         /* something's different.  make a new database, moving unchanged
  79          * elements from the old database, reloading elements that have
  80          * actually changed.  Whatever is left in the old database when
  81          * we're done is chaff -- crontabs that disappeared.
  82          */
  83         new_db.mtime = TMAX(statbuf.st_mtime, syscron_stat.st_mtime);
  84         new_db.head = new_db.tail = NULL;
  85
  86         if (syscron_stat.st_mtime) {
  87                 process_crontab("root", SYS_NAME,
  88                                 SYSCRONTAB, &syscron_stat,
  89                                 &new_db, old_db);
  90         }
  91
  92         /* we used to keep this dir open all the time, for the sake of
  93          * efficiency.  however, we need to close it in every fork, and
  94          * we fork a lot more often than the mtime of the dir changes.
  95          */
  96         if (!(dir = opendir(SPOOL_DIR))) {
  97                 log_it("CRON", getpid(), "OPENDIR FAILED", SPOOL_DIR);
  98                 exit(ERROR_EXIT);
  99         }
 100
 101         while (NULL != (dp = readdir(dir))) {
 102                 char    fname[NAME_MAX + 1], tabname[NAME_MAX + 1];
 103
 104                 /* avoid file names beginning with ".".  this is good
 105                  * because we would otherwise waste two guaranteed calls
 106                  * to getpwnam() for . and .., and also because user names
 107                  * starting with a period are just too nasty to consider.
 108                  */
 109                 if (dp->d_name[0] == '.')
 110                         continue;
 111
 112                 strlcpy(fname, dp->d_name, sizeof(fname));
 113                 snprintf(tabname, sizeof tabname, CRON_TAB(fname));
 114
 115                 process_crontab(fname, fname, tabname,
 116                                 &statbuf, &new_db, old_db);
 117         }
 118         closedir(dir);
 119
 120         /* if we don't do this, then when our children eventually call
 121          * getpwnam() in do_command.c's child_process to verify MAILTO=,
 122          * they will screw us up (and v-v).
 123          */
 124         endpwent();
 125
 126         /* whatever's left in the old database is now junk.
 127          */
 128         Debug(DLOAD, ("unlinking old database:\n"))
 129         for (u = old_db->head;  u != NULL;  u = nu) {
 130                 Debug(DLOAD, ("\t%s\n", u->name))
 131                 nu = u->next;
 132                 unlink_user(old_db, u);
 133                 free_user(u);
 134         }
 135
 136         /* overwrite the database control block with the new one.
 137          */
 138         *old_db = new_db;
 139         Debug(DLOAD, ("load_database is done\n"))
 140 }
 141
 142
 143 void
 144 link_user(cron_db *db, user *u)
 145 {
 146         if (db->head == NULL)
 147                 db->head = u;
 148         if (db->tail)
 149                 db->tail->next = u;
 150         u->prev = db->tail;
 151         u->next = NULL;
 152         db->tail = u;
 153 }
 154
 155
 156 void
 157 unlink_user(cron_db *db, user *u)
 158 {
 159         if (u->prev == NULL)
 160                 db->head = u->next;
 161         else
 162                 u->prev->next = u->next;
 163
 164         if (u->next == NULL)
 165                 db->tail = u->prev;
 166         else
 167                 u->next->prev = u->prev;
 168 }
 169
 170
 171 user *
 172 find_user(cron_db *db, char *name)
 173 {
 174         char    *env_get();
 175         user    *u;
 176
 177         for (u = db->head;  u != NULL;  u = u->next)
 178                 if (!strcmp(u->name, name))
 179                         break;
 180         return u;
 181 }
 182
 183
 184 static void
 185 process_crontab(char *uname, char *fname, char *tabname, struct stat *statbuf,
 186                 cron_db *new_db, cron_db *old_db)
 187 {
 188         struct passwd   *pw = NULL;
 189         int             crontab_fd = OK - 1;
 190         user            *u;
 191
 192         if (strcmp(fname, SYS_NAME) && !(pw = getpwnam(uname))) {
 193                 /* file doesn't have a user in passwd file.
 194                  */
 195                 log_it(fname, getpid(), "ORPHAN", "no passwd entry");
 196                 goto next_crontab;
 197         }
 198
 199         if ((crontab_fd = open(tabname, O_RDONLY, 0)) < OK) {
 200                 /* crontab not accessible?
 201                  */
 202                 log_it(fname, getpid(), "CAN'T OPEN", tabname);
 203                 goto next_crontab;
 204         }
 205
 206         if (fstat(crontab_fd, statbuf) < OK) {
 207                 log_it(fname, getpid(), "FSTAT FAILED", tabname);
 208                 goto next_crontab;
 209         }
 210
 211         Debug(DLOAD, ("\t%s:", fname))
 212         u = find_user(old_db, fname);
 213         if (u != NULL) {
 214                 /* if crontab has not changed since we last read it
 215                  * in, then we can just use our existing entry.
 216                  */
 217                 if (u->mtime == statbuf->st_mtime) {
 218                         Debug(DLOAD, (" [no change, using old data]"))
 219                         unlink_user(old_db, u);
 220                         link_user(new_db, u);
 221                         goto next_crontab;
 222                 }
 223
 224                 /* before we fall through to the code that will reload
 225                  * the user, let's deallocate and unlink the user in
 226                  * the old database.  This is more a point of memory
 227                  * efficiency than anything else, since all leftover
 228                  * users will be deleted from the old database when
 229                  * we finish with the crontab...
 230                  */
 231                 Debug(DLOAD, (" [delete old data]"))
 232                 unlink_user(old_db, u);
 233                 free_user(u);
 234                 log_it(fname, getpid(), "RELOAD", tabname);
 235         }
 236         u = load_user(crontab_fd, pw, fname);
 237         if (u != NULL) {
 238                 u->mtime = statbuf->st_mtime;
 239                 link_user(new_db, u);
 240         }
 241
 242 next_crontab:
 243         if (crontab_fd >= OK) {
 244                 Debug(DLOAD, (" [done]\n"))
 245                 close(crontab_fd);
 246         }
 247 }