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