diff options
| author | Michael Adam <obnox@samba.org> | 2012-04-11 15:48:02 +0200 |
|---|---|---|
| committer | Andreas Schneider <asn@samba.org> | 2012-04-25 14:31:11 +0200 |
| commit | 7ea8bd3605adb3a53ca44ebdabfdcdb9c1aeaa18 (patch) | |
| tree | f2391dbe4b5a8f19a42d9c8635a59f3cb25a4f95 | |
| parent | ab83005b30c621230db674faa1d123f44c9122e7 (diff) | |
| download | samba-7ea8bd3605adb3a53ca44ebdabfdcdb9c1aeaa18.tar.gz samba-7ea8bd3605adb3a53ca44ebdabfdcdb9c1aeaa18.tar.bz2 samba-7ea8bd3605adb3a53ca44ebdabfdcdb9c1aeaa18.zip | |
s3:registry: fix seqnum race in fetch_values_internal
This prevents race between fetching seqnum and key content.
Because there is currently no way to atomically fetch the
record along with the seqnum, I use a loop.
This is far from optimal and should should ideally be done
differently. But for now it fixes the race.
Signed-off-by: Andreas Schneider <asn@samba.org>
| -rw-r--r-- | source3/registry/reg_backend_db.c | 24 |
1 files changed, 21 insertions, 3 deletions
diff --git a/source3/registry/reg_backend_db.c b/source3/registry/reg_backend_db.c index 65355aec23..abe9f7bdca 100644 --- a/source3/registry/reg_backend_db.c +++ b/source3/registry/reg_backend_db.c @@ -1862,6 +1862,7 @@ static int regdb_fetch_values_internal(struct db_context *db, const char* key, int ret = 0; TDB_DATA value; WERROR werr; + int seqnum[2], count; DEBUG(10,("regdb_fetch_values: Looking for values of key [%s]\n", key)); @@ -1874,10 +1875,27 @@ static int regdb_fetch_values_internal(struct db_context *db, const char* key, goto done; } - werr = regval_ctr_set_seqnum(values, dbwrap_get_seqnum(db)); - W_ERROR_NOT_OK_GOTO_DONE(werr); + ZERO_STRUCT(value); + count = 0; + seqnum[0] = dbwrap_get_seqnum(db); + + do { + count++; + TALLOC_FREE(value.dptr); + value = regdb_fetch_key_internal(db, ctx, keystr); + seqnum[count % 2] = dbwrap_get_seqnum(db); + } while (seqnum[0] != seqnum[1]); + + if (count > 1) { + DEBUG(5, ("regdb_fetch_values_internal: it took %d attempts " + "to fetch key '%s' with constant seqnum\n", + count, key)); + } - value = regdb_fetch_key_internal(db, ctx, keystr); + werr = regval_ctr_set_seqnum(values, seqnum[0]); + if (!W_ERROR_IS_OK(werr)) { + goto done; + } if (!value.dptr) { /* all keys have zero values by default */ |