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
load_database(cron_db * old_db)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
link_user(cron_db * db,user * u)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
unlink_user(cron_db * db,user * u)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 *
find_user(cron_db * db,char * name)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
process_crontab(char * uname,char * fname,char * tabname,struct stat * statbuf,cron_db * new_db,cron_db * old_db)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 }
247