libexec/cron/database.c

   1 /* Copyright 1988,1990,1993 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
  18 #if !defined(lint) && !defined(LINT)
  19 static char rcsid[] = "$Id: database.c,v 1.1 1994/01/05 20:40:14 jtc Exp $";
  20 #endif
  21
  22 /* vix 26jan87 [RCS has the log]
  23  */
  24
  25
  26 #include "cron.h"
  27 #include "externs.h"
  28 #include <pwd.h>
  29 #include <fcntl.h>
  30 #include <sys/stat.h>
  31 #include <sys/file.h>
  32
  33
  34 #define TMAX(a,b) ((a)>(b)?(a):(b))
  35
  36
  37 static  void            process_crontab __P((char *, char *, char *,
  38                                              struct stat *,
  39                                              cron_db *, cron_db *));
  40
  41
  42 void
  43 load_database(old_db)
  44         cron_db         *old_db;
  45 {
  46         DIR             *dir;
  47         struct stat     statbuf;
  48         struct stat     syscron_stat;
  49         DIR_T           *dp;
  50         cron_db         new_db;
  51         user            *u, *nu;
  52
  53         Debug(DLOAD, ("[%d] load_database()\n", getpid()))
  54
  55         /* before we start loading any data, do a stat on SPOOL_DIR
  56          * so that if anything changes as of this moment (i.e., before we've
  57          * cached any of the database), we'll see the changes next time.
  58          */
  59         if (stat(SPOOL_DIR, &statbuf) < OK) {
  60                 log_it("CRON", getpid(), "STAT FAILED", SPOOL_DIR);
  61                 (void) exit(ERROR_EXIT);
  62         }
  63
  64         /* track system crontab file
  65          */
  66         if (stat(SYSCRONTAB, &syscron_stat) < OK)
  67                 syscron_stat.st_mtime = 0;
  68
  69         /* if spooldir's mtime has not changed, we don't need to fiddle with
  70          * the database.  Note that if /etc/passwd changes (like, someone's
  71          * UID/GID/HOME/SHELL, we won't see it.  Maybe we should
  72          * keep an mtime for the passwd file?  HINT
  73          *
  74          * Note that old_db->mtime is initialized to 0 in main(), and
  75          * so is guaranteed to be different than the stat() mtime the first
  76          * time this function is called.
  77          */
  78         if (old_db->mtime == TMAX(statbuf.st_mtime, syscron_stat.st_mtime)) {
  79                 Debug(DLOAD, ("[%d] spool dir mtime unch, no load needed.\n",
  80                               getpid()))
  81                 return;
  82         }
  83
  84         /* we used to keep this dir open all the time, for the sake of
  85          * efficiency.  however, we need to close it in every fork, and
  86          * we fork a lot more often than the mtime of the dir changes.
  87          */
  88         if (!(dir = opendir(SPOOL_DIR))) {
  89                 log_it("CRON", getpid(), "OPENDIR FAILED", SPOOL_DIR);
  90                 (void) exit(ERROR_EXIT);
  91         }
  92
  93         /* something's different.  make a new database, moving unchanged
  94          * elements from the old database, reloading elements that have
  95          * actually changed.  Whatever is left in the old database when
  96          * we're done is chaff -- crontabs that disappeared.
  97          */
  98         new_db.mtime = TMAX(statbuf.st_mtime, syscron_stat.st_mtime);
  99         new_db.head = new_db.tail = NULL;
 100
 101         if (syscron_stat.st_mtime) {
 102                 process_crontab("root", "*root*", SYSCRONTAB,
 103                                 &syscron_stat, &new_db, old_db);
 104         }
 105
 106         while (NULL != (dp = readdir(dir))) {
 107                 char    fname[MAXNAMLEN+1],
 108                         tabname[MAXNAMLEN+1];
 109
 110                 /* avoid file names beginning with ".".  this is good
 111                  * because we would otherwise waste two guaranteed calls
 112                  * to getpwnam() for . and .., and also because user names
 113                  * starting with a period are just too nasty to consider.
 114                  */
 115                 if (dp->d_name[0] == '.')
 116                         continue;
 117
 118                 (void) strcpy(fname, dp->d_name);
 119                 sprintf(tabname, CRON_TAB(fname));
 120
 121                 process_crontab(fname, fname, tabname,
 122                                 &statbuf, &new_db, old_db);
 123         }
 124         closedir(dir);
 125
 126         /* if we don't do this, then when our children eventually call
 127          * getpwnam() in do_command.c's child_process to verify MAILTO=,
 128          * they will screw us up (and v-v).
 129          */
 130         endpwent();
 131
 132         /* whatever's left in the old database is now junk.
 133          */
 134         Debug(DLOAD, ("unlinking old database:\n"))
 135         for (u = old_db->head;  u != NULL;  u = nu) {
 136                 Debug(DLOAD, ("\t%s\n", env_get("LOGNAME", u->envp)))
 137                 nu = u->next;
 138                 unlink_user(old_db, u);
 139                 free_user(u);
 140         }
 141
 142         /* overwrite the database control block with the new one.
 143          */
 144         Debug(DLOAD, ("installing new database\n"))
 145         *old_db = new_db;
 146         Debug(DLOAD, ("load_database is done\n"))
 147 }
 148
 149
 150 void
 151 link_user(db, u)
 152         cron_db *db;
 153         user    *u;
 154 {
 155         if (db->head == NULL)
 156                 db->head = u;
 157         if (db->tail)
 158                 db->tail->next = u;
 159         u->prev = db->tail;
 160         u->next = NULL;
 161         db->tail = u;
 162 }
 163
 164
 165 void
 166 unlink_user(db, u)
 167         cron_db *db;
 168         user    *u;
 169 {
 170         if (u->prev == NULL)
 171                 db->head = u->next;
 172         else
 173                 u->prev->next = u->next;
 174
 175         if (u->next == NULL)
 176                 db->tail = u->prev;
 177         else
 178                 u->next->prev = u->prev;
 179 }
 180
 181
 182 user *
 183 find_user(db, name)
 184         cron_db *db;
 185         char    *name;
 186 {
 187         char    *env_get();
 188         user    *u;
 189
 190         for (u = db->head;  u != NULL;  u = u->next)
 191                 if (!strcmp(env_get("LOGNAME", u->envp), name))
 192                         break;
 193         return u;
 194 }
 195
 196
 197 static void
 198 process_crontab(uname, fname, tabname, statbuf, new_db, old_db)
 199         char            *uname;         /* these are the same except for */
 200         char            *fname;         /* *root* processing /etc/crontab */
 201         char            *tabname;
 202         struct stat     *statbuf;
 203         cron_db         *new_db;
 204         cron_db         *old_db;
 205 {
 206         struct passwd           *pw;
 207         int                     crontab_fd = OK - 1;
 208         user                    *u;
 209
 210         if (NULL == (pw = getpwnam(uname))) {
 211                 /* file doesn't have a user in passwd file.
 212                  */
 213                 log_it(fname, getpid(), "ORPHAN", "no passwd entry");
 214                 goto next_crontab;
 215         }
 216
 217         if ((crontab_fd = open(tabname, O_RDONLY, 0)) < OK) {
 218                 /* crontab not accessible?
 219                  */
 220                 log_it(fname, getpid(), "CAN'T OPEN", tabname);
 221                 goto next_crontab;
 222         }
 223
 224         if (fstat(crontab_fd, statbuf) < OK) {
 225                 log_it(fname, getpid(), "FSTAT FAILED", tabname);
 226                 goto next_crontab;
 227         }
 228
 229         Debug(DLOAD, ("\t%s:", fname))
 230         u = find_user(old_db, fname);
 231         if (u != NULL) {
 232                 /* if crontab has not changed since we last read it
 233                  * in, then we can just use our existing entry.
 234                  * XXX - note that we do not check for changes in the
 235                  * passwd entry (uid, home dir, etc).
 236                  */
 237                 if (u->mtime == statbuf->st_mtime) {
 238                         Debug(DLOAD, (" [no change, using old data]"))
 239                         unlink_user(old_db, u);
 240                         link_user(new_db, u);
 241                         goto next_crontab;
 242                 }
 243
 244                 /* before we fall through to the code that will reload
 245                  * the user, let's deallocate and unlink the user in
 246                  * the old database.  This is more a point of memory
 247                  * efficiency than anything else, since all leftover
 248                  * users will be deleted from the old database when
 249                  * we finish with the crontab...
 250                  */
 251                 Debug(DLOAD, (" [delete old data]"))
 252                 unlink_user(old_db, u);
 253                 free_user(u);
 254         }
 255         u = load_user(crontab_fd, pw->pw_name, pw->pw_uid, pw->pw_gid,
 256                       pw->pw_dir, (!strcmp(fname, "*root*"))); /* XXX cookie */
 257         if (u != NULL) {
 258                 u->mtime = statbuf->st_mtime;
 259                 link_user(new_db, u);
 260         }
 261
 262 next_crontab:
 263         if (crontab_fd >= OK) {
 264                 Debug(DLOAD, (" [done]\n"))
 265                 close(crontab_fd);
 266         }
 267 }