/* Copyright 1988,1990,1993,1994 by Paul Vixie
 * All rights reserved
 */

/*
 * Copyright (c) 1997 by Internet Software Consortium
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */

#if !defined(lint) && !defined(LINT)
static const char rcsid[] =
    "$Id: database.c,v 1.3 1998/08/14 00:32:38 vixie Exp $";
#endif

/* vix 26jan87 [RCS has the log]
 */

#include "cron.h"

#define TMAX(a,b) ((a)>(b)?(a):(b))

static  void            process_crontab(const char *, const char *,
                                        const char *, struct stat *,
                                        cron_db *, cron_db *);

void
load_database(cron_db *old_db)
{
        struct stat statbuf, syscron_stat, st;
        cron_db new_db;
        DIR_T *dp;
        DIR *dir;
        user *u, *nu;
        time_t maxmtime;
        struct {
                const char *name;
                struct stat st;
        } syscrontabs [] = {
                { SYSCRONTABS },
                { LOCALSYSCRONTABS }
        };
        int i, ret;

        Debug(DLOAD, ("[%d] load_database()\n", getpid()))

        /* before we start loading any data, do a stat on SPOOL_DIR
         * so that if anything changes as of this moment (i.e., before we've
         * cached any of the database), we'll see the changes next time.
         */
        if (stat(SPOOL_DIR, &statbuf) < OK) {
                log_it("CRON", getpid(), "STAT FAILED", SPOOL_DIR);
                (void) exit(ERROR_EXIT);
        }

        /* track system crontab file
         */
        if (stat(SYSCRONTAB, &syscron_stat) < OK)
                syscron_stat.st_mtime = 0;

        maxmtime = TMAX(statbuf.st_mtime, syscron_stat.st_mtime);

        for (i = 0; i < nitems(syscrontabs); i++) {
                if (stat(syscrontabs[i].name, &syscrontabs[i].st) != -1) {
                        maxmtime = TMAX(syscrontabs[i].st.st_mtime, maxmtime);
                        /* Traverse into directory */
                        if (!(dir = opendir(syscrontabs[i].name)))
                                continue;
                        while (NULL != (dp = readdir(dir))) {
                                if (dp->d_name[0] == '.')
                                        continue;
                                ret = fstatat(dirfd(dir), dp->d_name, &st, 0);
                                if (ret != 0 || !S_ISREG(st.st_mode))
                                        continue;
                                maxmtime = TMAX(st.st_mtime, maxmtime);
                        }
                        closedir(dir);
                } else {
                        syscrontabs[i].st.st_mtime = 0;
                }
        }

        /* if spooldir's mtime has not changed, we don't need to fiddle with
         * the database.
         *
         * Note that old_db->mtime is initialized to 0 in main(), and
         * so is guaranteed to be different than the stat() mtime the first
         * time this function is called.
         */
        if (old_db->mtime == maxmtime) {
                Debug(DLOAD, ("[%d] spool dir mtime unch, no load needed.\n",
                              getpid()))
                return;
        }

        /* something's different.  make a new database, moving unchanged
         * elements from the old database, reloading elements that have
         * actually changed.  Whatever is left in the old database when
         * we're done is chaff -- crontabs that disappeared.
         */
        new_db.mtime = maxmtime;
        new_db.head = new_db.tail = NULL;

        if (syscron_stat.st_mtime) {
                process_crontab("root", SYS_NAME,
                                SYSCRONTAB, &syscron_stat,
                                &new_db, old_db);
        }

        for (i = 0; i < nitems(syscrontabs); i++) {
                char tabname[MAXPATHLEN];
                if (syscrontabs[i].st.st_mtime == 0)
                        continue;
                if (!(dir = opendir(syscrontabs[i].name))) {
                        log_it("CRON", getpid(), "OPENDIR FAILED",
                            syscrontabs[i].name);
                        (void) exit(ERROR_EXIT);
                }

                while (NULL != (dp = readdir(dir))) {
                        if (dp->d_name[0] == '.')
                                continue;
                        if (fstatat(dirfd(dir), dp->d_name, &st, 0) == 0 &&
                            !S_ISREG(st.st_mode))
                                continue;
                        snprintf(tabname, sizeof(tabname), "%s/%s",
                            syscrontabs[i].name, dp->d_name);
                        process_crontab("root", SYS_NAME, tabname,
                            &syscrontabs[i].st, &new_db, old_db);
                }
                closedir(dir);
        }

        /* we used to keep this dir open all the time, for the sake of
         * efficiency.  however, we need to close it in every fork, and
         * we fork a lot more often than the mtime of the dir changes.
         */
        if (!(dir = opendir(SPOOL_DIR))) {
                log_it("CRON", getpid(), "OPENDIR FAILED", SPOOL_DIR);
                (void) exit(ERROR_EXIT);
        }

        while (NULL != (dp = readdir(dir))) {
                char fname[MAXNAMLEN+1], tabname[MAXNAMLEN+1];

                /* avoid file names beginning with ".".  this is good
                 * because we would otherwise waste two guaranteed calls
                 * to getpwnam() for . and .., and also because user names
                 * starting with a period are just too nasty to consider.
                 */
                if (dp->d_name[0] == '.')
                        continue;

                (void) strncpy(fname, dp->d_name, sizeof(fname));
                fname[sizeof(fname)-1] = '\0';

                if (snprintf(tabname, sizeof tabname, CRON_TAB(fname))
                    >= sizeof(tabname))
                        continue;       /* XXX log? */

                process_crontab(fname, fname, tabname,
                                &statbuf, &new_db, old_db);
        }
        closedir(dir);

        /* if we don't do this, then when our children eventually call
         * getpwnam() in do_command.c's child_process to verify MAILTO=,
         * they will screw us up (and v-v).
         */
        endpwent();

        /* whatever's left in the old database is now junk.
         */
        Debug(DLOAD, ("unlinking old database:\n"))
        for (u = old_db->head;  u != NULL;  u = nu) {
                Debug(DLOAD, ("\t%s\n", u->name))
                nu = u->next;
                unlink_user(old_db, u);
                free_user(u);
        }

        /* overwrite the database control block with the new one.
         */
        *old_db = new_db;
        Debug(DLOAD, ("load_database is done\n"))
}

void
link_user(cron_db *db, user *u)
{
        if (db->head == NULL)
                db->head = u;
        if (db->tail)
                db->tail->next = u;
        u->prev = db->tail;
        u->next = NULL;
        db->tail = u;
}

void
unlink_user(cron_db *db, user *u)
{
        if (u->prev == NULL)
                db->head = u->next;
        else
                u->prev->next = u->next;

        if (u->next == NULL)
                db->tail = u->prev;
        else
                u->next->prev = u->prev;
}

user *
find_user(cron_db *db, const char *name)
{
        user *u;

        for (u = db->head;  u != NULL;  u = u->next)
                if (strcmp(u->name, name) == 0)
                        break;
        return (u);
}

static void
process_crontab(const char *uname, const char *fname, const char *tabname,
                struct stat *statbuf, cron_db *new_db, cron_db *old_db)
{
        struct passwd *pw = NULL;
        int crontab_fd = OK - 1;
        user *u;
        entry *e;
        time_t now;

        if (strcmp(fname, SYS_NAME) != 0 && !(pw = getpwnam(uname))) {
                /* file doesn't have a user in passwd file.
                 */
                log_it(fname, getpid(), "ORPHAN", "no passwd entry");
                goto next_crontab;
        }

        if ((crontab_fd = open(tabname, O_RDONLY, 0)) < OK) {
                /* crontab not accessible?
                 */
                log_it(fname, getpid(), "CAN'T OPEN", tabname);
                goto next_crontab;
        }

        if (fstat(crontab_fd, statbuf) < OK) {
                log_it(fname, getpid(), "FSTAT FAILED", tabname);
                goto next_crontab;
        }

        Debug(DLOAD, ("\t%s:", fname))
        u = find_user(old_db, fname);
        if (u != NULL) {
                /* if crontab has not changed since we last read it
                 * in, then we can just use our existing entry.
                 */
                if (u->mtime == statbuf->st_mtime) {
                        Debug(DLOAD, (" [no change, using old data]"))
                        unlink_user(old_db, u);
                        link_user(new_db, u);
                        goto next_crontab;
                }

                /* before we fall through to the code that will reload
                 * the user, let's deallocate and unlink the user in
                 * the old database.  This is more a point of memory
                 * efficiency than anything else, since all leftover
                 * users will be deleted from the old database when
                 * we finish with the crontab...
                 */
                Debug(DLOAD, (" [delete old data]"))
                unlink_user(old_db, u);
                free_user(u);
                log_it(fname, getpid(), "RELOAD", tabname);
        }
        u = load_user(crontab_fd, pw, fname);
        if (u != NULL) {
                u->mtime = statbuf->st_mtime;
                /*
                 * TargetTime == 0 when we're initially populating the database,
                 * and TargetTime > 0 any time after that (i.e. we're reloading
                 * cron.d/ files because they've been created/modified).  In the
                 * latter case, we should check for any interval jobs and run
                 * them 'n' seconds from the time the job was loaded/reloaded.
                 * Otherwise, they will not be run until cron is restarted.
                 */
                if (TargetTime != 0) {
                        now = time(NULL);
                        for (e = u->crontab; e != NULL; e = e->next) {
                                if ((e->flags & INTERVAL) != 0)
                                        e->lastexit = now;
                        }
                }
                link_user(new_db, u);
        }

 next_crontab:
        if (crontab_fd >= OK) {
                Debug(DLOAD, (" [done]\n"))
                close(crontab_fd);
        }
}