From: Andre Noll <maan@tuebingen.mpg.de>
Date: Tue, 18 Apr 2017 18:23:30 +0000 (+0200)
Subject: Remove COMPAT_TABLE_VERSION.
X-Git-Tag: v0.2.0~4^2~7
X-Git-Url: http://git.tuebingen.mpg.de/?p=osl.git;a=commitdiff_plain;h=d032b723ee4b7d25ec9be9387e2cc1fa04ec3190;hp=c283f067d330a9288aec5510836cd4a898dd07df

Remove COMPAT_TABLE_VERSION.

The compatibility version concept was introduced eight years ago in
commit (62d228ec), and was never needed. In fact, COMPAT_TABLE_VERSION
has always been zero so far. This commit gets rid of it.

Given a library version and the on-disk table version, we can still
tell whether the table can be opened by comparing the MIN_TABLE_VERSION
and the CURRENT_TABLE_VERSION numbers of the library against the
value stored in the table (i.e., the CURRENT_TABLE_VERSION value of
the library that created the table).
---

diff --git a/osl.c b/osl.c
index e31811b..c5f70ff 100644
--- a/osl.c
+++ b/osl.c
@@ -349,7 +349,7 @@ err:
 int read_table_desc(struct osl_object *map, struct osl_table_description *desc)
 {
 	char *buf = map->data;
-	uint8_t version, compat_version, create_version;
+	uint8_t table_version;
 	uint16_t header_size;
 	int ret, i;
 	unsigned offset;
@@ -359,20 +359,11 @@ int read_table_desc(struct osl_object *map, struct osl_table_description *desc)
 		return -E_OSL_SHORT_TABLE;
 	if (strncmp(buf + IDX_OSL_MAGIC, OSL_MAGIC, strlen(OSL_MAGIC)))
 		return -E_OSL_NO_MAGIC;
-	version = read_u8(buf + IDX_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 */
+	table_version = read_u8(buf + IDX_VERSION);
+	INFO_LOG("osl versions (table/min/current): %u/%u/%u\n",
+		table_version, MIN_TABLE_VERSION, CURRENT_TABLE_VERSION);
+	if (table_version < MIN_TABLE_VERSION /* table too old */
+		|| table_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);
@@ -507,8 +498,7 @@ 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
-		+ (COMPAT_TABLE_VERSION << 4));
+	write_u8(buf + IDX_VERSION, CURRENT_TABLE_VERSION);
 	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;
diff --git a/osl_core.h b/osl_core.h
index 6046d8c..9f31181 100644
--- a/osl_core.h
+++ b/osl_core.h
@@ -196,13 +196,6 @@ _static_inline_ size_t index_column_description_size(const char *name)
  */
 #define CURRENT_TABLE_VERSION 1
 
-/*
- * The lowest library version that is able to use tables of version
- * CURRENT_TABLE_VERSION. Also written to the index of new tables. If
- * compat_version(table) > current_version(lib) the table can not be opened.
- */
-#define COMPAT_TABLE_VERSION 0
-
 /*
  * The lowest table version this library understands. On open, if
  * current_version(table) < min_version(lib) the osl_open_table() call