If we have a partial chunk whose length is < expected chunk length, and we've just extended the length of the file, we'll need to invalidate this partial chunk by removing it from _chunkDictionary. Thus, the next time someone needs an entry from this chunk, it will be properly recreated with its correct, updated entry count.

Author: Mallory Paine

FastImageCache/FICImageTable.m

@@ -453,6 +453,16 @@ - (void)_setEntryCount:(NSInteger)entryCount {
             _fileLength = fileLength;
             _entryCount = entryCount;
             _chunkCount = _entriesPerChunk > 0 ? ((_entryCount + _entriesPerChunk - 1) / _entriesPerChunk) : 0;
+            
+            NSDictionary *chunkDictionary = [_chunkDictionary copy];
+            for (FICImageTableChunk *chunk in [chunkDictionary allValues]) {
+                if ([chunk length] != _chunkLength) {
+                    // Issue 31: https://github.com/path/FastImageCache/issues/31
+                    // Somehow, we have a partial chunk whose length needs to be adjusted
+                    // since we changed our file length.
+                    [self _setChunk:nil index:[chunk index]];
+                }
+            }
         }
     }
 }

FastImageCache/FICImageTableChunk.h

@@ -36,6 +36,9 @@
  */
 @property (nonatomic, assign, readonly) off_t fileOffset;
 
+@property (nonatomic, assign, readonly) size_t length;
+
+
 ///----------------------------------------
 /// @name Initializing an Image Table Chunk
 ///----------------------------------------

FastImageCache/FICImageTableChunk.m

@@ -27,6 +27,7 @@ @implementation FICImageTableChunk
 
 @synthesize bytes = _bytes;
 @synthesize fileOffset = _fileOffset;
+@synthesize length = _length;
 
 #pragma mark - Object Lifecycle