From 4d3c4606fba914dfa20c490660c913052de3e01c Mon Sep 17 00:00:00 2001
From: wntrmute <wntrmute@258c5a1a-4f63-435d-9564-e8f6d34ab52c>
Date: Tue, 9 Jun 2009 19:42:35 +0000
Subject: [PATCH] prevent caching off end of partition

git-svn-id: https://devkitpro.svn.sourceforge.net/svnroot/devkitpro/trunk/libfat@3592 258c5a1a-4f63-435d-9564-e8f6d34ab52c
---
 source/cache.c     | 14 +++++++++-----
 source/cache.h     |  3 ++-
 source/partition.c |  2 +-
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/source/cache.c b/source/cache.c
index 97ec2f5..a91656c 100644
--- a/source/cache.c
+++ b/source/cache.c
@@ -46,7 +46,7 @@
 
 #define CACHE_FREE UINT_MAX
 
-CACHE* _FAT_cache_constructor (unsigned int numberOfPages, unsigned int sectorsPerPage, const DISC_INTERFACE* discInterface) {
+CACHE* _FAT_cache_constructor (unsigned int numberOfPages, unsigned int sectorsPerPage, const DISC_INTERFACE* discInterface, sec_t endOfPartition) {
 	CACHE* cache;
 	unsigned int i;
 	CACHE_ENTRY* cacheEntries;
@@ -65,6 +65,7 @@ CACHE* _FAT_cache_constructor (unsigned int numberOfPages, unsigned int sectorsP
 	}
 
 	cache->disc = discInterface;
+	cache->endOfPartition = endOfPartition;
 	cache->numberOfPages = numberOfPages;
 	cache->sectorsPerPage = sectorsPerPage;
 
@@ -126,7 +127,7 @@ static CACHE_ENTRY* _FAT_cache_getPage(CACHE *cache,sec_t sector)
 			cacheEntries[i].last_access = accessTime();
 			return &(cacheEntries[i]);
 		}
-
+		
 		if(foundFree==false && (cacheEntries[i].sector==CACHE_FREE || cacheEntries[i].last_access<oldAccess)) {
 			if(cacheEntries[i].sector==CACHE_FREE) foundFree = true;
 			oldUsed = i;
@@ -139,11 +140,14 @@ static CACHE_ENTRY* _FAT_cache_getPage(CACHE *cache,sec_t sector)
 		cacheEntries[oldUsed].dirty = false;
 	}
 
-	sector = (sector/sectorsPerPage)*sectorsPerPage;
-	if(!_FAT_disc_readSectors(cache->disc,sector,sectorsPerPage,cacheEntries[oldUsed].cache)) return NULL;
+	sector = (sector/sectorsPerPage)*sectorsPerPage; // align base sector to page size
+	sec_t next_page = sector + sectorsPerPage;
+	if(next_page > cache->endOfPartition)	next_page = cache->endOfPartition;
+
+	if(!_FAT_disc_readSectors(cache->disc,sector,next_page-sector,cacheEntries[oldUsed].cache)) return NULL;
 
 	cacheEntries[oldUsed].sector = sector;
-	cacheEntries[oldUsed].count = sectorsPerPage;
+	cacheEntries[oldUsed].count = next_page-sector;
 	cacheEntries[oldUsed].last_access = accessTime();
 
 	return &(cacheEntries[oldUsed]);
diff --git a/source/cache.h b/source/cache.h
index 3e30550..c6e48d0 100644
--- a/source/cache.h
+++ b/source/cache.h
@@ -52,6 +52,7 @@ typedef struct {
 
 typedef struct {
 	const DISC_INTERFACE* disc;
+	sec_t		          endOfPartition;
 	unsigned int          numberOfPages;
 	unsigned int          sectorsPerPage;
 	CACHE_ENTRY*          cacheEntries;
@@ -121,7 +122,7 @@ Clear out the contents of the cache without writing any dirty sectors first
 */
 void _FAT_cache_invalidate (CACHE* cache);
 
-CACHE* _FAT_cache_constructor (unsigned int numberOfPages, unsigned int sectorsPerPage, const DISC_INTERFACE* discInterface);
+CACHE* _FAT_cache_constructor (unsigned int numberOfPages, unsigned int sectorsPerPage, const DISC_INTERFACE* discInterface, sec_t endOfPartition);
 
 void _FAT_cache_destructor (CACHE* cache);
 
diff --git a/source/partition.c b/source/partition.c
index 5f0fcc1..6be067c 100644
--- a/source/partition.c
+++ b/source/partition.c
@@ -220,7 +220,7 @@ PARTITION* _FAT_partition_constructor (const DISC_INTERFACE* disc, uint32_t cach
 	}
 
 	// Create a cache to use
-	partition->cache = _FAT_cache_constructor (cacheSize, sectorsPerPage, partition->disc);
+	partition->cache = _FAT_cache_constructor (cacheSize, sectorsPerPage, partition->disc, startSector+partition->numberOfSectors);
 
 	// Set current directory to the root
 	partition->cwdCluster = partition->rootDirCluster;
-- 
2.11.4.GIT