/*      $NetBSD: database.c,v 1.9 2017/06/09 17:36:30 christos Exp $    */

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

/*
* Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
* Copyright (c) 1997,2000 by Internet Software Consortium, Inc.
*
* 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 ISC DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC 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.
*/
#include <sys/cdefs.h>
#if !defined(lint) && !defined(LINT)
#if 0
static char rcsid[] = "Id: database.c,v 1.7 2004/01/23 18:56:42 vixie Exp";
#else
__RCSID("$NetBSD: database.c,v 1.9 2017/06/09 17:36:30 christos Exp $");
#endif
#endif

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

#include "cron.h"

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

struct spooldir {
       const char *path;
       const char *uname;
       const char *fname;
       struct stat st;
};

static struct spooldir spools[] = {
       { .path = SPOOL_DIR, },
       { .path = CROND_DIR, .uname = "root", .fname = "*system*", },
       { .path = NULL, }
};

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

static void
process_dir(struct spooldir *sp, cron_db *new_db, cron_db *old_db)
{
       DIR *dir;
       DIR_T *dp;
       const char *dname = sp->path;
       struct stat *st = &sp->st;

       if (st->st_mtime == 0)
               return;

       /* 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(dname))) {
               log_it("CRON", getpid(), "OPENDIR FAILED", dname);
               (void) exit(ERROR_EXIT);
       }

       while (NULL != (dp = readdir(dir))) {
               char    fname[MAXNAMLEN+1], tabname[MAXNAMLEN+1];
               size_t i, len;
               /*
                * Homage to...
                */
               static const char *junk[] = {
                       "rpmsave", "rpmorig", "rpmnew",
               };

               /* avoid file names beginning with ".".  this is good
                * because we would otherwise waste two guaranteed calls
                * to getpwnam() for . and .., and there shouldn't be
                * hidden files in here anyway (in the non system case).
                */
               if (dp->d_name[0] == '.')
                       continue;

               /* ignore files starting with # ... */
               if (dp->d_name[0] == '#')
                       continue;

               len = strlen(dp->d_name);

               /* ... or too big or to small ... */
               if (len == 0 || len >= sizeof(fname)) {
                       log_it(dp->d_name, getpid(), "ORPHAN",
                           "name too short or long");
                       continue;
               }

               /* ... or ending with ~ ... */
               if (dp->d_name[len - 1] == '~')
                       continue;

               (void)strlcpy(fname, dp->d_name, sizeof(fname));

               /* ... or look for blacklisted extensions */
               for (i = 0; i < __arraycount(junk); i++) {
                       char *p;
                       if ((p = strrchr(fname, '.')) != NULL &&
                           strcmp(p + 1, junk[i]) == 0)
                               break;
               }
               if (i != __arraycount(junk))
                       continue;

               if (!glue_strings(tabname, sizeof tabname, dname, fname, '/')) {
                       log_it(fname, getpid(), "ORPHAN",
                           "could not glue strings");
                       continue;
               }

               process_crontab(sp->uname ? sp->uname : fname,
                               sp->fname ? sp->fname : fname,
                               tabname, st, new_db, old_db);
       }
       (void)closedir(dir);
}

void
load_database(cron_db *old_db) {
       struct stat syscron_stat;
       cron_db new_db;
       user *u, *nu;
       time_t maxtime;

       Debug(DLOAD, ("[%ld] load_database()\n", (long)getpid()));

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

       maxtime = syscron_stat.st_mtime;
       for (struct spooldir *p = spools; p->path; p++) {
               if (stat(p->path, &p->st) < OK) {
                       if (errno == ENOENT) {
                               p->st.st_mtime = 0;
                               continue;
                       }
                       log_it("CRON", getpid(), "STAT FAILED", p->path);
                       (void) exit(ERROR_EXIT);
               }
               if (p->st.st_mtime > maxtime)
                       maxtime = p->st.st_mtime;
       }

       /* 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 == maxtime) {
               Debug(DLOAD, ("[%ld] spool dir mtime unch, no load needed.\n",
                             (long)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 = maxtime;
       new_db.head = new_db.tail = NULL;

       if (syscron_stat.st_mtime)
               process_crontab("root", "*system*", SYSCRONTAB,
                   &syscron_stat, &new_db, old_db);

       for (struct spooldir *p = spools; p->path; p++)
               process_dir(p, &new_db, old_db);

       /* 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;
       mode_t eqmode = 0400, badmode = 0;
       user *u;

       if (strcmp(fname, "*system*") == 0) {
               /*
                * SYSCRONTAB:
                * Allow it to become readable by group and others, but
                * not writable.
                */
               eqmode = 0;
               badmode = 022;
       } else if ((pw = getpwnam(uname)) == NULL) {
               /* 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|O_NONBLOCK|O_NOFOLLOW, 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;
       }
       if (!S_ISREG(statbuf->st_mode)) {
               log_it(fname, getpid(), "NOT REGULAR", tabname);
               goto next_crontab;
       }
       if ((eqmode && (statbuf->st_mode & 07577) != eqmode) ||
           (badmode && (statbuf->st_mode & badmode) != 0)) {
               log_it(fname, getpid(), "BAD FILE MODE", tabname);
               goto next_crontab;
       }
       if (statbuf->st_uid != ROOT_UID && (pw == NULL ||
           statbuf->st_uid != pw->pw_uid || strcmp(uname, pw->pw_name) != 0)) {
               log_it(fname, getpid(), "WRONG FILE OWNER", tabname);
               goto next_crontab;
       }
       if (statbuf->st_nlink != 1) {
               log_it(fname, getpid(), "BAD LINK COUNT", 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;
               link_user(new_db, u);
       }

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

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