tdb: adding readonly locks mode to tdbbackup tool

The netcmd 'domain backup offline' command will use the tdbbackup tool but
require readonly locking of tdb databases, otherwise all database access would
be blocked during a backup.  This patch adds the option.  A backup script
should use this tool with the readonly locks option after taking a transaction
lock on the target database.

Signed-off-by: Aaron Haslett <aaronhaslett@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>

diff --git a/lib/tdb/tools/tdbbackup.c b/lib/tdb/tools/tdbbackup.c
index eb33e257b4c4dbf8348c27cbbf6d41bf2274f77f..1125987c950b42b9c06d5c0e6a2c45d4a6f954f4 100644 (file)
--- a/lib/tdb/tools/tdbbackup.c
+++ b/lib/tdb/tools/tdbbackup.c
@@ -105,7 +105,7 @@ static int test_fn(TDB_CONTEXT *tdb, TDB_DATA key, TDB_DATA dbuf, void *state)
   this function is also used for restore
 */
 static int backup_tdb(const char *old_name, const char *new_name,
-                     int hash_size, int nolock)
+                     int hash_size, int nolock, bool readonly)
 {
        TDB_CONTEXT *tdb;
        TDB_CONTEXT *tdb_new;
@@ -145,8 +145,17 @@ static int backup_tdb(const char *old_name, const char *new_name,
                return 1;
        }
 
-       if (tdb_transaction_start(tdb) != 0) {
-               printf("Failed to start transaction on old tdb\n");
+       if (readonly) {
+               if (tdb_lockall_read(tdb) != 0) {
+                       printf("Failed to obtain read only lock on old tdb\n");
+                       tdb_close(tdb);
+                       tdb_close(tdb_new);
+                       unlink(tmp_name);
+                       free(tmp_name);
+                       return 1;
+               }
+       } else if (tdb_transaction_start(tdb) != 0) {
+               printf("Failed to start transaction on db\n");
                tdb_close(tdb);
                tdb_close(tdb_new);
                unlink(tmp_name);
@@ -167,7 +176,15 @@ static int backup_tdb(const char *old_name, const char *new_name,
        failed = 0;
 
        /* traverse and copy */
-       count1 = tdb_traverse(tdb, copy_fn, (void *)tdb_new);
+       if (readonly) {
+               count1 = tdb_traverse_read(tdb,
+                                          copy_fn,
+                                          (void *)tdb_new);
+       } else {
+               count1 = tdb_traverse(tdb,
+                                     copy_fn,
+                                     (void *)tdb_new);
+       }
        if (count1 < 0 || failed) {
                fprintf(stderr,"failed to copy %s\n", old_name);
                tdb_close(tdb);
@@ -251,7 +268,7 @@ static int verify_tdb(const char *fname, const char *bak_name)
        /* count is < 0 means an error */
        if (count < 0) {
                printf("restoring %s\n", fname);
-               return backup_tdb(bak_name, fname, 0, 0);
+               return backup_tdb(bak_name, fname, 0, 0, 0);
        }
 
        printf("%s : %d records\n", fname, count);
@@ -282,6 +299,7 @@ static void usage(void)
        printf("   -v            verify mode (restore if corrupt)\n");
        printf("   -n hashsize   set the new hash size for the backup\n");
        printf("   -l            open without locking to back up mutex dbs\n");
+       printf("   -r            open with read only locking\n");
 }
 
  int main(int argc, char *argv[])
@@ -292,11 +310,12 @@ static void usage(void)
        int verify = 0;
        int hashsize = 0;
        int nolock = 0;
+       bool readonly = false;
        const char *suffix = ".bak";
 
        log_ctx.log_fn = tdb_log;
 
-       while ((c = getopt(argc, argv, "vhs:n:l")) != -1) {
+       while ((c = getopt(argc, argv, "vhs:n:lr")) != -1) {
                switch (c) {
                case 'h':
                        usage();
@@ -313,6 +332,8 @@ static void usage(void)
                case 'l':
                        nolock = 1;
                        break;
+               case 'r':
+                       readonly = true;
                }
        }
 
@@ -337,7 +358,7 @@ static void usage(void)
                } else {
                        if (file_newer(fname, bak_name) &&
                            backup_tdb(fname, bak_name, hashsize,
-                                      nolock) != 0) {
+                                      nolock, readonly) != 0) {
                                ret = 1;
                        }
                }