usr.sbin/cron/database.c

   1 /*      $NetBSD: database.c,v 1.6 2002/11/16 04:34:13 itojun Exp $      */
   2
   3 /* Copyright 1988,1990,1993,1994 by Paul Vixie
   4  * All rights reserved
   5  *
   6  * Distribute freely, except: don't remove my name from the source or
   7  * documentation (don't take credit for my work), mark your changes (don't
   8  * get me blamed for your possible bugs), don't alter or remove this
   9  * notice.  May be sold if buildable source is provided to buyer.  No
  10  * warrantee of any kind, express or implied, is included with this
  11  * software; use at your own risk, responsibility for damages (if any) to
  12  * anyone resulting from the use of this software rests entirely with the
  13  * user.
  14  *
  15  * Send bug reports, bug fixes, enhancements, requests, flames, etc., and
  16  * I'll try to keep a version up to date.  I can be reached as follows:
  17  * Paul Vixie          <paul@vix.com>          uunet!decwrl!vixie!paul
  18  */
  19
  20 #include <sys/cdefs.h>
  21 #if !defined(lint) && !defined(LINT)
  22 #if 0
  23 static char rcsid[] = "Id: database.c,v 2.8 1994/01/15 20:43:43 vixie Exp";
  24 #else
  25 __RCSID("$NetBSD: database.c,v 1.6 2002/11/16 04:34:13 itojun Exp $");
  26 #endif
  27 #endif
  28
  29 /* vix 26jan87 [RCS has the log]
  30  */
  31
  32
  33 #include "cron.h"
  34 #include <fcntl.h>
  35 #include <sys/stat.h>
  36 #include <sys/file.h>
  37
  38
  39 #define TMAX(a,b) ((a)>(b)?(a):(b))
  40
  41
  42 static  void            process_crontab(const char *, const char *,
  43                                         const char *, struct stat *,
  44                                         cron_db *, cron_db *);
  45
  46
  47 void
  48 load_database(cron_db *old_db)
  49 {
  50         DIR             *dir;
  51         struct stat     statbuf;
  52         struct stat     syscron_stat;
  53         DIR_T           *dp;
  54         cron_db         new_db;
  55         user            *u, *nu;
  56
  57         Debug(DLOAD, ("[%d] load_database()\n", getpid()))
  58
  59         /* before we start loading any data, do a stat on SPOOL_DIR
  60          * so that if anything changes as of this moment (i.e., before we've
  61          * cached any of the database), we'll see the changes next time.
  62          */
  63         if (stat(SPOOL_DIR, &statbuf) < OK) {
  64                 log_it("CRON", getpid(), "STAT FAILED", SPOOL_DIR);
  65                 (void) exit(ERROR_EXIT);
  66         }
  67
  68         /* track system crontab file
  69          */
  70         if (stat(SYSCRONTAB, &syscron_stat) < OK)
  71                 syscron_stat.st_mtime = 0;
  72
  73         /* if spooldir's mtime has not changed, we don't need to fiddle with
  74          * the database.
  75          *
  76          * Note that old_db->mtime is initialized to 0 in main(), and
  77          * so is guaranteed to be different than the stat() mtime the first
  78          * time this function is called.
  79          */
  80         if (old_db->mtime == TMAX(statbuf.st_mtime, syscron_stat.st_mtime)) {
  81                 Debug(DLOAD, ("[%d] spool dir mtime unch, no load needed.\n",
  82                               getpid()))
  83                 return;
  84         }
  85
  86         /* something's different.  make a new database, moving unchanged
  87          * elements from the old database, reloading elements that have
  88          * actually changed.  Whatever is left in the old database when
  89          * we're done is chaff -- crontabs that disappeared.
  90          */
  91         new_db.mtime = TMAX(statbuf.st_mtime, syscron_stat.st_mtime);
  92         new_db.head = new_db.tail = NULL;
  93
  94         if (syscron_stat.st_mtime) {
  95                 process_crontab("root", NULL, SYSCRONTAB, &syscron_stat,
  96                     &new_db, old_db);
  97         }
  98
  99         /* we used to keep this dir open all the time, for the sake of
 100          * efficiency.  however, we need to close it in every fork, and
 101          * we fork a lot more often than the mtime of the dir changes.
 102          */
 103         if (!(dir = opendir(SPOOL_DIR))) {
 104                 log_it("CRON", getpid(), "OPENDIR FAILED", SPOOL_DIR);
 105                 (void) exit(ERROR_EXIT);
 106         }
 107
 108         while (NULL != (dp = readdir(dir))) {
 109                 char    fname[MAXNAMLEN+1],
 110                         tabname[MAXNAMLEN+1];
 111
 112                 /* avoid file names beginning with ".".  this is good
 113                  * because we would otherwise waste two guaranteed calls
 114                  * to getpwnam() for . and .., and also because user names
 115                  * starting with a period are just too nasty to consider.
 116                  */
 117                 if (dp->d_name[0] == '.')
 118                         continue;
 119
 120                 (void) strlcpy(fname, dp->d_name, sizeof(fname));
 121                 snprintf(tabname, sizeof(tabname), CRON_TAB(fname));
 122
 123                 process_crontab(fname, fname, tabname,
 124                                 &statbuf, &new_db, old_db);
 125         }
 126         closedir(dir);
 127
 128         /* if we don't do this, then when our children eventually call
 129          * getpwnam() in do_command.c's child_process to verify MAILTO=,
 130          * they will screw us up (and v-v).
 131          */
 132         endpwent();
 133
 134         /* whatever's left in the old database is now junk.
 135          */
 136         Debug(DLOAD, ("unlinking old database:\n"))
 137         for (u = old_db->head;  u != NULL;  u = nu) {
 138                 Debug(DLOAD, ("\t%s\n", u->name))
 139                 nu = u->next;
 140                 unlink_user(old_db, u);
 141                 free_user(u);
 142         }
 143
 144         /* overwrite the database control block with the new one.
 145          */
 146         *old_db = new_db;
 147         Debug(DLOAD, ("load_database is done\n"))
 148 }
 149
 150
 151 void
 152 link_user(cron_db *db, user *u)
 153 {
 154         if (db->head == NULL)
 155                 db->head = u;
 156         if (db->tail)
 157                 db->tail->next = u;
 158         u->prev = db->tail;
 159         u->next = NULL;
 160         db->tail = u;
 161 }
 162
 163
 164 void
 165 unlink_user(cron_db *db, user *u)
 166 {
 167         if (u->prev == NULL)
 168                 db->head = u->next;
 169         else
 170                 u->prev->next = u->next;
 171
 172         if (u->next == NULL)
 173                 db->tail = u->prev;
 174         else
 175                 u->next->prev = u->prev;
 176 }
 177
 178
 179 user *
 180 find_user(cron_db *db, const char *name)
 181 {
 182         user    *u;
 183
 184         for (u = db->head;  u != NULL;  u = u->next)
 185                 if (!strcmp(u->name, name))
 186                         break;
 187         return u;
 188 }
 189
 190
 191 static void
 192 process_crontab(const char *uname, const char *fname, const char *tabname,
 193                 struct stat *statbuf, cron_db *new_db, cron_db *old_db)
 194 {
 195         struct passwd   *pw = NULL;
 196         int             crontab_fd = OK - 1;
 197         user            *u;
 198
 199         if (fname == NULL) {
 200                 /* must be set to something.
 201                  */
 202                 fname = "*system*";
 203         } else if ((pw = getpwnam(uname)) == NULL) {
 204                 /* file doesn't have a user in passwd file.
 205                  */
 206                 log_it(fname, getpid(), "ORPHAN", "no passwd entry");
 207                 goto next_crontab;
 208         }
 209
 210         if ((crontab_fd = open(tabname, O_RDONLY, 0)) < OK) {
 211                 /* crontab not accessible?
 212                  */
 213                 log_it(fname, getpid(), "CAN'T OPEN", tabname);
 214                 goto next_crontab;
 215         }
 216
 217         if (fstat(crontab_fd, statbuf) < OK) {
 218                 log_it(fname, getpid(), "FSTAT FAILED", tabname);
 219                 goto next_crontab;
 220         }
 221
 222         Debug(DLOAD, ("\t%s:", fname))
 223         u = find_user(old_db, fname);
 224         if (u != NULL) {
 225                 /* if crontab has not changed since we last read it
 226                  * in, then we can just use our existing entry.
 227                  */
 228                 if (u->mtime == statbuf->st_mtime) {
 229                         Debug(DLOAD, (" [no change, using old data]"))
 230                         unlink_user(old_db, u);
 231                         link_user(new_db, u);
 232                         goto next_crontab;
 233                 }
 234
 235                 /* before we fall through to the code that will reload
 236                  * the user, let's deallocate and unlink the user in
 237                  * the old database.  This is more a point of memory
 238                  * efficiency than anything else, since all leftover
 239                  * users will be deleted from the old database when
 240                  * we finish with the crontab...
 241                  */
 242                 Debug(DLOAD, (" [delete old data]"))
 243                 unlink_user(old_db, u);
 244                 free_user(u);
 245                 log_it(fname, getpid(), "RELOAD", tabname);
 246         }
 247         u = load_user(crontab_fd, pw, fname);
 248         if (u != NULL) {
 249                 u->mtime = statbuf->st_mtime;
 250                 link_user(new_db, u);
 251         }
 252
 253 next_crontab:
 254         if (crontab_fd >= OK) {
 255                 Debug(DLOAD, (" [done]\n"))
 256                 close(crontab_fd);
 257         }
 258 }