source: vendor/3.5.11/source3/lib/tdb_validate.c

/*
 * Unix SMB/CIFS implementation.
 *
 * A general tdb content validation mechanism
 *
 * Copyright (C) Michael Adam      2007
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "tdb_validate.h"
#include "includes.h"

/*
 * internal validation function, executed by the child.
 */
static int tdb_validate_child(struct tdb_context *tdb,
                              tdb_validate_data_func validate_fn)
{
        int ret = 1;
        int num_entries = 0;
        struct tdb_validation_status v_status;

        v_status.tdb_error = False;
        v_status.bad_freelist = False;
        v_status.bad_entry = False;
        v_status.unknown_key = False;
        v_status.success = True;

        if (!tdb) {
                v_status.tdb_error = True;
                v_status.success = False;
                goto out;
        }

        /*
         * we can simplify this by passing a check function,
         * but I don't want to change all the callers...
         */
        ret = tdb_check(tdb, NULL, NULL);
        if (ret == -1) {
                v_status.tdb_error = True;
                v_status.success = False;
                goto out;
        }

        /* Check if the tdb's freelist is good. */
        if (tdb_validate_freelist(tdb, &num_entries) == -1) {
                v_status.bad_freelist = True;
                v_status.success = False;
                goto out;
        }

        DEBUG(10,("tdb_validate_child: tdb %s freelist has %d entries\n",
                  tdb_name(tdb), num_entries));

        /* Now traverse the tdb to validate it. */
        num_entries = tdb_traverse(tdb, validate_fn, (void *)&v_status);
        if (!v_status.success) {
                goto out;
        } else if (num_entries == -1) {
                v_status.tdb_error = True;
                v_status.success = False;
                goto out;
        }

        DEBUG(10,("tdb_validate_child: tdb %s is good with %d entries\n",
                  tdb_name(tdb), num_entries));
        ret = 0; /* Cache is good. */

out:
        DEBUG(10,   ("tdb_validate_child: summary of validation status:\n"));
        DEBUGADD(10,(" * tdb error: %s\n", v_status.tdb_error ? "yes" : "no"));
        DEBUGADD(10,(" * bad freelist: %s\n",v_status.bad_freelist?"yes":"no"));
        DEBUGADD(10,(" * bad entry: %s\n", v_status.bad_entry ? "yes" : "no"));
        DEBUGADD(10,(" * unknown key: %s\n", v_status.unknown_key?"yes":"no"));
        DEBUGADD(10,(" => overall success: %s\n", v_status.success?"yes":"no"));

        return ret;
}

/*
 * tdb validation function.
 * returns 0 if tdb is ok, != 0 if it isn't.
 * this function expects an opened tdb.
 */
int tdb_validate(struct tdb_context *tdb, tdb_validate_data_func validate_fn)
{
        pid_t child_pid = -1;
        int child_status = 0;
        int wait_pid = 0;
        int ret = 1;

        if (tdb == NULL) {
                DEBUG(1, ("Error: tdb_validate called with tdb == NULL\n"));
                return ret;
        }

        DEBUG(5, ("tdb_validate called for tdb '%s'\n", tdb_name(tdb)));

        /* fork and let the child do the validation.
         * benefit: no need to twist signal handlers and panic functions.
         * just let the child panic. we catch the signal. */

        DEBUG(10, ("tdb_validate: forking to let child do validation.\n"));
        child_pid = sys_fork();
        if (child_pid == 0) {
                /* child code */
                DEBUG(10, ("tdb_validate (validation child): created\n"));
                DEBUG(10, ("tdb_validate (validation child): "
                           "calling tdb_validate_child\n"));
                exit(tdb_validate_child(tdb, validate_fn));
        }
        else if (child_pid < 0) {
                DEBUG(1, ("tdb_validate: fork for validation failed.\n"));
                goto done;
        }

        /* parent */

        DEBUG(10, ("tdb_validate: fork succeeded, child PID = %u\n",
                (unsigned int)child_pid));

        DEBUG(10, ("tdb_validate: waiting for child to finish...\n"));
        while  ((wait_pid = sys_waitpid(child_pid, &child_status, 0)) < 0) {
                if (errno == EINTR) {
                        DEBUG(10, ("tdb_validate: got signal during waitpid, "
                                   "retrying\n"));
                        errno = 0;
                        continue;
                }
                DEBUG(1, ("tdb_validate: waitpid failed with error '%s'.\n",
                          strerror(errno)));
                goto done;
        }
        if (wait_pid != child_pid) {
                DEBUG(1, ("tdb_validate: waitpid returned pid %d, "
                          "but %u was expected\n", wait_pid, (unsigned int)child_pid));
                goto done;
        }

        DEBUG(10, ("tdb_validate: validating child returned.\n"));
        if (WIFEXITED(child_status)) {
                DEBUG(10, ("tdb_validate: child exited, code %d.\n",
                           WEXITSTATUS(child_status)));
                ret = WEXITSTATUS(child_status);
        }
        if (WIFSIGNALED(child_status)) {
                DEBUG(10, ("tdb_validate: child terminated by signal %d\n",
                           WTERMSIG(child_status)));
#ifdef WCOREDUMP
                if (WCOREDUMP(child_status)) {
                        DEBUGADD(10, ("core dumped\n"));
                }
#endif
                ret = WTERMSIG(child_status);
        }
        if (WIFSTOPPED(child_status)) {
                DEBUG(10, ("tdb_validate: child was stopped by signal %d\n",
                           WSTOPSIG(child_status)));
                ret = WSTOPSIG(child_status);
        }

done:
        DEBUG(5, ("tdb_validate returning code '%d' for tdb '%s'\n", ret,
                  tdb_name(tdb)));

        return ret;
}

/*
 * tdb validation function.
 * returns 0 if tdb is ok, != 0 if it isn't.
 * this is a wrapper around the actual validation function that opens and closes
 * the tdb.
 */
int tdb_validate_open(const char *tdb_path, tdb_validate_data_func validate_fn)
{
        TDB_CONTEXT *tdb = NULL;
        int ret = 1;

        DEBUG(5, ("tdb_validate_open called for tdb '%s'\n", tdb_path));

        tdb = tdb_open_log(tdb_path, 0, TDB_DEFAULT, O_RDWR, 0);
        if (!tdb) {
                DEBUG(1, ("Error opening tdb %s\n", tdb_path));
                return ret;
        }

        ret = tdb_validate(tdb, validate_fn);
        tdb_close(tdb);
        return ret;
}

/*
 * tdb backup function and helpers for tdb_validate wrapper with backup
 * handling.
 */

/* this structure eliminates the need for a global overall status for
 * the traverse-copy */
struct tdb_copy_data {
        struct tdb_context *dst;
        bool success;
};

static int traverse_copy_fn(struct tdb_context *tdb, TDB_DATA key,
                            TDB_DATA dbuf, void *private_data)
{
        struct tdb_copy_data *data = (struct tdb_copy_data *)private_data;

        if (tdb_store(data->dst, key, dbuf, TDB_INSERT) != 0) {
                DEBUG(4, ("Failed to insert into %s: %s\n", tdb_name(data->dst),
                          strerror(errno)));
                data->success = False;
                return 1;
        }
        return 0;
}

static int tdb_copy(struct tdb_context *src, struct tdb_context *dst)
{
        struct tdb_copy_data data;
        int count;

        data.dst = dst;
        data.success = True;

        count = tdb_traverse(src, traverse_copy_fn, (void *)(&data));
        if ((count < 0) || (data.success == False)) {
                return -1;
        }
        return count;
}

static int tdb_verify_basic(struct tdb_context *tdb)
{
        return tdb_traverse(tdb, NULL, NULL);
}

/* this backup function is essentially taken from lib/tdb/tools/tdbbackup.tdb
 */
static int tdb_backup(TALLOC_CTX *ctx, const char *src_path,
                      const char *dst_path, int hash_size)
{
        struct tdb_context *src_tdb = NULL;
        struct tdb_context *dst_tdb = NULL;
        char *tmp_path = NULL;
        struct stat st;
        int count1, count2;
        int saved_errno = 0;
        int ret = -1;

        if (stat(src_path, &st) != 0) {
                DEBUG(3, ("Could not stat '%s': %s\n", src_path,
                          strerror(errno)));
                goto done;
        }

        /* open old tdb RDWR - so we can lock it */
        src_tdb = tdb_open_log(src_path, 0, TDB_DEFAULT, O_RDWR, 0);
        if (src_tdb == NULL) {
                DEBUG(3, ("Failed to open tdb '%s'\n", src_path));
                goto done;
        }

        if (tdb_lockall(src_tdb) != 0) {
                DEBUG(3, ("Failed to lock tdb '%s'\n", src_path));
                goto done;
        }

        tmp_path = talloc_asprintf(ctx, "%s%s", dst_path, ".tmp");
        unlink(tmp_path);
        dst_tdb = tdb_open_log(tmp_path,
                               hash_size ? hash_size : tdb_hash_size(src_tdb),
                               TDB_DEFAULT, O_RDWR | O_CREAT | O_EXCL,
                               st.st_mode & 0777);
        if (dst_tdb == NULL) {
                DEBUG(3, ("Error creating tdb '%s': %s\n", tmp_path,
                          strerror(errno)));
                saved_errno = errno;
                unlink(tmp_path);
                goto done;
        }

        count1 = tdb_copy(src_tdb, dst_tdb);
        if (count1 < 0) {
                DEBUG(3, ("Failed to copy tdb '%s': %s\n", src_path,
                          strerror(errno)));
                tdb_close(dst_tdb);
                goto done;
        }

        /* reopen ro and do basic verification */
        tdb_close(dst_tdb);
        dst_tdb = tdb_open_log(tmp_path, 0, TDB_DEFAULT, O_RDONLY, 0);
        if (!dst_tdb) {
                DEBUG(3, ("Failed to reopen tdb '%s': %s\n", tmp_path,
                          strerror(errno)));
                goto done;
        }
        count2 = tdb_verify_basic(dst_tdb);
        if (count2 != count1) {
                DEBUG(3, ("Failed to verify result of copying tdb '%s'.\n",
                          src_path));
                tdb_close(dst_tdb);
                goto done;
        }

        DEBUG(10, ("tdb_backup: successfully copied %d entries\n", count1));

        /* make sure the new tdb has reached stable storage
         * then rename it to its destination */
        fsync(tdb_fd(dst_tdb));
        tdb_close(dst_tdb);
        unlink(dst_path);
        if (rename(tmp_path, dst_path) != 0) {
                DEBUG(3, ("Failed to rename '%s' to '%s': %s\n",
                          tmp_path, dst_path, strerror(errno)));
                goto done;
        }

        /* success */
        ret = 0;

done:
        if (src_tdb != NULL) {
                tdb_close(src_tdb);
        }
        if (tmp_path != NULL) {
                unlink(tmp_path);
                TALLOC_FREE(tmp_path);
        }
        if (saved_errno != 0) {
                errno = saved_errno;
        }
        return ret;
}

static int rename_file_with_suffix(TALLOC_CTX *ctx, const char *path,
                                   const char *suffix)
{
        int ret = -1;
        char *dst_path;

        dst_path = talloc_asprintf(ctx, "%s%s", path, suffix);

        ret = (rename(path, dst_path) != 0);

        if (ret == 0) {
                DEBUG(5, ("moved '%s' to '%s'\n", path, dst_path));
        } else if (errno == ENOENT) {
                DEBUG(3, ("file '%s' does not exist - so not moved\n", path));
                ret = 0;
        } else {
                DEBUG(3, ("error renaming %s to %s: %s\n", path, dst_path,
                          strerror(errno)));
        }

        TALLOC_FREE(dst_path);
        return ret;
}

/*
 * do a backup of a tdb, moving the destination out of the way first
 */
static int tdb_backup_with_rotate(TALLOC_CTX *ctx, const char *src_path,
                                  const char *dst_path, int hash_size,
                                  const char *rotate_suffix,
                                  bool retry_norotate_if_nospc,
                                  bool rename_as_last_resort_if_nospc)
{
        int ret;

        rename_file_with_suffix(ctx, dst_path, rotate_suffix);

        ret = tdb_backup(ctx, src_path, dst_path, hash_size);

        if (ret != 0) {
                DEBUG(10, ("backup of %s failed: %s\n", src_path, strerror(errno)));
        }
        if ((ret != 0) && (errno == ENOSPC) && retry_norotate_if_nospc)
        {
                char *rotate_path = talloc_asprintf(ctx, "%s%s", dst_path,
                                                    rotate_suffix);
                DEBUG(10, ("backup of %s failed due to lack of space\n",
                           src_path));
                DEBUGADD(10, ("trying to free some space by removing rotated "
                              "dst %s\n", rotate_path));
                if (unlink(rotate_path) == -1) {
                        DEBUG(10, ("unlink of %s failed: %s\n", rotate_path,
                                   strerror(errno)));
                } else {
                        ret = tdb_backup(ctx, src_path, dst_path, hash_size);
                }
                TALLOC_FREE(rotate_path);
        }

        if ((ret != 0) && (errno == ENOSPC) && rename_as_last_resort_if_nospc)
        {
                DEBUG(10, ("backup of %s failed due to lack of space\n", 
                           src_path));
                DEBUGADD(10, ("using 'rename' as a last resort\n"));
                ret = rename(src_path, dst_path);
        }

        return ret;
}

/*
 * validation function with backup handling:
 *
 *  - calls tdb_validate
 *  - if the tdb is ok, create a backup "name.bak", possibly moving
 *    existing backup to name.bak.old,
 *    return 0 (success) even if the backup fails
 *  - if the tdb is corrupt:
 *    - move the tdb to "name.corrupt"
 *    - check if there is valid backup.
 *      if so, restore the backup.
 *      if restore is successful, return 0 (success),
 *    - otherwise return -1 (failure)
 */
int tdb_validate_and_backup(const char *tdb_path,
                            tdb_validate_data_func validate_fn)
{
        int ret = -1;
        const char *backup_suffix = ".bak";
        const char *corrupt_suffix = ".corrupt";
        const char *rotate_suffix = ".old";
        char *tdb_path_backup;
        struct stat st;
        TALLOC_CTX *ctx = NULL;

        ctx = talloc_new(NULL);
        if (ctx == NULL) {
                DEBUG(0, ("tdb_validate_and_backup: out of memory\n"));
                goto done;
        }

        tdb_path_backup = talloc_asprintf(ctx, "%s%s", tdb_path, backup_suffix);

        ret = tdb_validate_open(tdb_path, validate_fn);

        if (ret == 0) {
                DEBUG(1, ("tdb '%s' is valid\n", tdb_path));
                ret = tdb_backup_with_rotate(ctx, tdb_path, tdb_path_backup, 0,
                                             rotate_suffix, True, False);
                if (ret != 0) {
                        DEBUG(1, ("Error creating backup of tdb '%s'\n",
                                  tdb_path));
                        /* the actual validation was successful: */
                        ret = 0;
                } else {
                        DEBUG(1, ("Created backup '%s' of tdb '%s'\n",
                                  tdb_path_backup, tdb_path));
                }
        } else {
                DEBUG(1, ("tdb '%s' is invalid\n", tdb_path));

                ret =stat(tdb_path_backup, &st);
                if (ret != 0) {
                        DEBUG(5, ("Could not stat '%s': %s\n", tdb_path_backup,
                                  strerror(errno)));
                        DEBUG(1, ("No backup found.\n"));
                } else {
                        DEBUG(1, ("backup '%s' found.\n", tdb_path_backup));
                        ret = tdb_validate_open(tdb_path_backup, validate_fn);
                        if (ret != 0) {
                                DEBUG(1, ("Backup '%s' is invalid.\n",
                                          tdb_path_backup));
                        }
                }

                if (ret != 0) {
                        int renamed = rename_file_with_suffix(ctx, tdb_path,
                                                              corrupt_suffix);
                        if (renamed != 0) {
                                DEBUG(1, ("Error moving tdb to '%s%s'\n",
                                          tdb_path, corrupt_suffix));
                        } else {
                                DEBUG(1, ("Corrupt tdb stored as '%s%s'\n",
                                          tdb_path, corrupt_suffix));
                        }
                        goto done;
                }

                DEBUG(1, ("valid backup '%s' found\n", tdb_path_backup));
                ret = tdb_backup_with_rotate(ctx, tdb_path_backup, tdb_path, 0,
                                             corrupt_suffix, True, True);
                if (ret != 0) {
                        DEBUG(1, ("Error restoring backup from '%s'\n",
                                  tdb_path_backup));
                } else {
                        DEBUG(1, ("Restored tdb backup from '%s'\n",
                                  tdb_path_backup));
                }
        }

done:
        TALLOC_FREE(ctx);
        return ret;
}