From 53ef87d70bcddd1678edaeeeb5f4e0b0cb55c843 Mon Sep 17 00:00:00 2001
From: Andre Noll <maan@tuebingen.mpg.de>
Date: Wed, 19 Apr 2017 15:05:53 +0200
Subject: [PATCH 1/1] Store table version in struct osl_table.

This modifies read_table_desc() to return the table version read from
the index header. The returned version number is stored in the newly
added field of struct osl_table. This will allow us to choose a hash
function based on the version.
---
 fsck.c     |  6 ++++--
 osl.c      | 10 ++++++----
 osl_core.h |  7 +++++++
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/fsck.c b/fsck.c
index f96f77c..8a32aba 100644
--- a/fsck.c
+++ b/fsck.c
@@ -872,21 +872,23 @@ static void set_dummy_contents(struct osl_table_description *desc)
 static int fsck_init(struct osl_table_description *desc, struct osl_table **t)
 {
 	struct osl_object map;
-	int ret = map_index(desc, &map);
+	int version, ret = map_index(desc, &map);
 
 	if (ret < 0)
 		goto out;
-	ret = read_table_desc(&map, desc);
+	ret = read_table_desc(&map, desc); /* checks table version */
 	if (ret < 0) {
 		osl_munmap(map.data, map.size);
 		goto out;
 	}
+	version = ret;
 	set_dummy_contents(desc);
 	ret = init_table_structure(desc, t);
 	if (ret < 0) {
 		osl_munmap(map.data, map.size);
 		goto out;
 	}
+	(*t)->version = version;
 	DEBUG_LOG("unmapping index\n");
 	osl_munmap(map.data, map.size);
 	if (OPT_GIVEN(FORCE))
diff --git a/osl.c b/osl.c
index b9c2339..40b0a24 100644
--- a/osl.c
+++ b/osl.c
@@ -340,7 +340,7 @@ err:
  * Read the index header, check for the osl magic string and the table version
  * number.  Read all information stored in the index header into \a desc.
  *
- * \return Standard.
+ * \return The on-disk table version number on success, negative on errors.
  *
  * \sa struct osl_table_description, osl_create_table.
  */
@@ -406,7 +406,7 @@ int read_table_desc(struct osl_object *map, struct osl_table_description *desc)
 			offset, header_size);
 		goto err;
 	}
-	return 1;
+	return table_version;
 err:
 	FOR_EACH_COLUMN(i, desc, cd)
 		free(cd->name);
@@ -427,6 +427,7 @@ static int compare_table_descriptions(struct osl_table *t)
 	ret = read_table_desc(&t->index_map, &desc);
 	if (ret < 0)
 		return ret;
+	t->version = ret;
 	ret = -E_OSL_BAD_TABLE_FLAGS;
 	if (desc.flags != t->desc->flags)
 		goto out;
@@ -496,7 +497,7 @@ 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);
+	write_u8(buf + IDX_VERSION, t->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;
@@ -534,7 +535,8 @@ __export int osl_create_table(const struct osl_table_description *desc)
 
 	if (ret < 0)
 		return ret;
-	INFO_LOG("creating %s\n", desc->name);
+	t->version = CURRENT_TABLE_VERSION;
+	INFO_LOG("creating version %u table %s\n", t->version, desc->name);
 	FOR_EACH_COLUMN(i, t->desc, cd) {
 		if (cd->storage_type == OSL_NO_STORAGE)
 			continue;
diff --git a/osl_core.h b/osl_core.h
index 9f31181..9879b1e 100644
--- a/osl_core.h
+++ b/osl_core.h
@@ -38,6 +38,13 @@ struct osl_column {
 struct osl_table {
 	/** Pointer to the table description */
 	const struct osl_table_description *desc;
+	/**
+	 * The CURRENT_TABLE_VERSION value of the library which created the
+	 * table. This value is stored in the index header at table creation
+	 * time. When the table is opened, the field is initialized from the
+	 * on-disk value.
+	 */
+	uint8_t version;
 	/** The size of the index header of this table. */
 	uint16_t index_header_size;
 	/** Contains the mapping of the table's index file */
-- 
2.39.2