X-Git-Url: http://git.tuebingen.mpg.de/?p=osl.git;a=blobdiff_plain;f=osl.c;h=90601dc287e3b8ec3de7baf7b9d1c6f2862e1c72;hp=430d120fb3a286f61e1eb2a8ab3c2912d6652206;hb=ff1143ae3ce5886309483fae6ac5237ee2802fb0;hpb=c9d2589c6764a308142afd17e92cef630c7fe940

diff --git a/osl.c b/osl.c
index 430d120..90601dc 100644
--- a/osl.c
+++ b/osl.c
@@ -341,7 +341,7 @@ err:
 int read_table_desc(struct osl_object *map, struct osl_table_description *desc)
 {
 	char *buf = map->data;
-	uint8_t version;
+	uint8_t version, compat_version, create_version;
 	uint16_t header_size;
 	int ret, i;
 	unsigned offset;
@@ -352,7 +352,19 @@ int read_table_desc(struct osl_object *map, struct osl_table_description *desc)
 	if (strncmp(buf + IDX_OSL_MAGIC, OSL_MAGIC, strlen(OSL_MAGIC)))
 		return -E_OSL_NO_MAGIC;
 	version = read_u8(buf + IDX_VERSION);
-	if (version < MIN_TABLE_VERSION || version > MAX_TABLE_VERSION)
+	/*
+	 * The on-disk version consists of two version numbers: the
+	 * create_version (low 4 bits) is the CURRENT_TABLE_VERSION version
+	 * number of the library that created the table, and compat_version
+	 * (high 4 bits) tells us the lowest version of the library that can
+	 * still read this table.
+	 */
+	create_version = version & 0xf;
+	compat_version = version >> 4;
+	INFO_LOG("create_version: %u, compat_version: %u\n", create_version,
+		compat_version);
+	if (create_version < MIN_TABLE_VERSION /* table too old */
+		|| compat_version > CURRENT_TABLE_VERSION) /* libosl too old */
 		return -E_OSL_VERSION_MISMATCH;
 	desc->flags = read_u8(buf + IDX_TABLE_FLAGS);
 	desc->num_columns = read_u16(buf + IDX_NUM_COLUMNS);
@@ -487,7 +499,8 @@ static int create_table_index(struct osl_table *t)
 	sprintf(buf + IDX_OSL_MAGIC, "%s", OSL_MAGIC);
 	write_u8(buf + IDX_TABLE_FLAGS, t->desc->flags);
 	write_u8(buf + IDX_DIRTY_FLAG, 0);
-	write_u8(buf + IDX_VERSION, CURRENT_TABLE_VERSION);
+	write_u8(buf + IDX_VERSION, CURRENT_TABLE_VERSION
+		+ (COMPAT_TABLE_VERSION << 4));
 	write_u16(buf + IDX_NUM_COLUMNS, t->num_mapped_columns + t->num_disk_storage_columns);
 	write_u16(buf + IDX_HEADER_SIZE, t->index_header_size);
 	offset = IDX_COLUMN_DESCRIPTIONS;