tdb2: feature support.

As detailed in doc/design.lyx section 2.15 "Extending The Header Is
Difficult"; we add features_used and features_offered fields to the
header, so we can identify if we add new features, and then if someone
opens it who doesn't understand that feature.

diff --git a/ccan/tdb2/doc/design.lyx b/ccan/tdb2/doc/design.lyx
index 3487a7dae8b456d4f46fede2c26a6996ddbcf06c..af94f6b9c1b1a84ae49d4997bbd6affbea964a85 100644 (file)
--- a/ccan/tdb2/doc/design.lyx
+++ b/ccan/tdb2/doc/design.lyx
@@ -1398,7 +1398,13 @@ Status
 \end_layout
 
 \begin_layout Standard
+
+\change_deleted 0 1300360753
 Incomplete.
+\change_inserted 0 1300360754
+Complete.
+\change_unchanged
+
 \end_layout
 
 \begin_layout Subsection

diff --git a/ccan/tdb2/private.h b/ccan/tdb2/private.h
index e15d1ad835968bfe76a89ac97f64ead1e6db1b2a..8e7df501b716a139c77e8de2ff673fe1afa55266 100644 (file)
--- a/ccan/tdb2/private.h
+++ b/ccan/tdb2/private.h
@@ -116,6 +116,9 @@ typedef int tdb_bool_err;
 #define TDB_OFF_HASH_EXTRA_BIT 57
 #define TDB_OFF_UPPER_STEAL_SUBHASH_BIT 56
 
+/* Additional features we understand.  Currently: none. */
+#define TDB_FEATURE_MASK ((uint64_t)0)
+
 /* The bit number where we store the extra hash bits. */
 /* Convenience mask to get actual offset. */
 #define TDB_OFF_MASK \
@@ -240,7 +243,10 @@ struct tdb_header {
        tdb_off_t free_table; /* (First) free table. */
        tdb_off_t recovery; /* Transaction recovery area. */
 
-       tdb_off_t reserved[26];
+       uint64_t features_used; /* Features all writers understand */
+       uint64_t features_offered; /* Features offered */
+
+       tdb_off_t reserved[24];
 
        /* Top level hash table. */
        tdb_off_t hashtable[1ULL << TDB_TOPLEVEL_HASH_BITS];

diff --git a/ccan/tdb2/tdb.c b/ccan/tdb2/tdb.c
index ce431208bf4cb4fa28d09f9158c7fb02c93d7d37..4ffcebf56150bffe381018b4f401aa5503455196 100644 (file)
--- a/ccan/tdb2/tdb.c
+++ b/ccan/tdb2/tdb.c
@@ -112,6 +112,7 @@ static enum TDB_ERROR tdb_new_database(struct tdb_context *tdb,
                                         newdb.hdr.hash_seed,
                                         tdb->hash_priv);
        newdb.hdr.recovery = 0;
+       newdb.hdr.features_used = newdb.hdr.features_offered = TDB_FEATURE_MASK;
        memset(newdb.hdr.reserved, 0, sizeof(newdb.hdr.reserved));
        /* Initial hashes are empty. */
        memset(newdb.hdr.hashtable, 0, sizeof(newdb.hdr.hashtable));
@@ -361,6 +362,16 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
                goto fail;
        }
 
+       /* Clear any features we don't understand. */
+       if ((open_flags & O_ACCMODE) != O_RDONLY) {
+               hdr.features_used &= TDB_FEATURE_MASK;
+               if (tdb_write_convert(tdb, offsetof(struct tdb_header,
+                                                   features_used),
+                                     &hdr.features_used,
+                                     sizeof(hdr.features_used)) == -1)
+                       goto fail;
+       }
+
        tdb->device = st.st_dev;
        tdb->inode = st.st_ino;
        tdb_unlock_open(tdb);

diff --git a/ccan/tdb2/test/failtest_helper.h b/ccan/tdb2/test/failtest_helper.h
index 25bf21d04cb20e972614ee2f5553601ae35ca0f4..418c19686da4d9292289c272971c346115fc87d7 100644 (file)
--- a/ccan/tdb2/test/failtest_helper.h
+++ b/ccan/tdb2/test/failtest_helper.h
@@ -4,7 +4,7 @@
 #include <stdbool.h>
 
 /* FIXME: Check these! */
-#define INITIAL_TDB_MALLOC     "tdb.c", 190, FAILTEST_MALLOC
+#define INITIAL_TDB_MALLOC     "tdb.c", 191, FAILTEST_MALLOC
 #define URANDOM_OPEN           "tdb.c", 49, FAILTEST_OPEN
 #define URANDOM_READ           "tdb.c", 29, FAILTEST_READ
 

diff --git a/ccan/tdb2/test/run-features.c b/ccan/tdb2/test/run-features.c
new file mode 100644 (file)
index 0000000..a09ddb9
--- /dev/null
+++ b/ccan/tdb2/test/run-features.c
@@ -0,0 +1,71 @@
+#include <ccan/tdb2/tdb.c>
+#include <ccan/tdb2/free.c>
+#include <ccan/tdb2/lock.c>
+#include <ccan/tdb2/io.c>
+#include <ccan/tdb2/hash.c>
+#include <ccan/tdb2/check.c>
+#include <ccan/tdb2/summary.c>
+#include <ccan/tdb2/transaction.c>
+#include <ccan/tap/tap.h>
+#include "logging.h"
+
+int main(int argc, char *argv[])
+{
+       unsigned int i, j;
+       struct tdb_context *tdb;
+       int flags[] = { TDB_DEFAULT, TDB_NOMMAP,
+                       TDB_CONVERT, TDB_NOMMAP|TDB_CONVERT };
+       struct tdb_data key = { (unsigned char *)&j, sizeof(j) };
+       struct tdb_data data = { (unsigned char *)&j, sizeof(j) };
+
+       plan_tests(sizeof(flags) / sizeof(flags[0]) * 8 + 1);
+       for (i = 0; i < sizeof(flags) / sizeof(flags[0]); i++) {
+               uint64_t features;
+               tdb = tdb_open("run-features.tdb", flags[i],
+                              O_RDWR|O_CREAT|O_TRUNC, 0600, &tap_log_attr);
+               ok1(tdb);
+               if (!tdb)
+                       continue;
+
+               /* Put some stuff in there. */
+               for (j = 0; j < 100; j++) {
+                       if (tdb_store(tdb, key, data, TDB_REPLACE) != 0)
+                               fail("Storing in tdb");
+               }
+
+               /* Mess with features fields in hdr. */
+               features = (~TDB_FEATURE_MASK ^ 1);
+               ok1(tdb_write_convert(tdb, offsetof(struct tdb_header,
+                                                   features_used), 
+                                     &features, sizeof(features)) == 0);
+               ok1(tdb_write_convert(tdb, offsetof(struct tdb_header,
+                                                   features_offered), 
+                                     &features, sizeof(features)) == 0);
+               tdb_close(tdb);
+
+               tdb = tdb_open("run-features.tdb", flags[i], O_RDWR, 0,
+                              &tap_log_attr);
+               ok1(tdb);
+               if (!tdb)
+                       continue;
+
+               /* Should not have changed features offered. */
+               ok1(tdb_read_convert(tdb, offsetof(struct tdb_header,
+                                                  features_offered), 
+                                    &features, sizeof(features)) == 0);
+               ok1(features == (~TDB_FEATURE_MASK ^ 1));
+
+               /* Should have cleared unknown bits in features_used. */
+               ok1(tdb_read_convert(tdb, offsetof(struct tdb_header,
+                                                  features_used), 
+                                    &features, sizeof(features)) == 0);
+               ok1(features == (1 & TDB_FEATURE_MASK));
+
+               tdb_close(tdb);
+       }
+
+       ok1(tap_log_messages == 0);
+       return exit_status();
+}
+
+