Re: Is there any compression library for Cocoa?

FROM : Trygve Inda
DATE : Wed Apr 30 11:24:16 2008

> There's a handy NSData-Compression class in Dustin Mierau's NetSocket
> 0.9 sample code available here:
>
> http://blackholemedia.com/code/
>
> Here's a snippet from the header file.
>
> @interface NSData (Compression)
> - (NSData*)compressedData;
> - (NSData*)compressedDataWithLevel:(int)inLevel;
> - (NSData*)uncompressedData;
> @end
>
> @interface NSMutableData (Compression)
> - (BOOL)compress;
> - (BOOL)uncompress;
> @end


This code (from above) appears to leak:

- (NSData*)compressedDataWithLevel:(int)inLevel
{
    Bytef*    data = (Bytef*)[self bytes];
    uLongf    originalLength = [self length];
    uLongf    bufferLength = ( [self length] * 1.1 ) + 16;
    Bytef*    buffer;
    int        err;
   
    if( inLevel > NSDataCompressionBest )
        inLevel = NSDataCompressionBest;
   
    if( inLevel < Z_DEFAULT_COMPRESSION )
        inLevel = NSDataCompressionNone;
   
    buffer = (Bytef*)malloc( (uInt)bufferLength );
    err = compress2( buffer, &bufferLength, (const Bytef*)data, [self
length], inLevel );
    if( err != Z_OK )
    {
        free( buffer );
        return nil;
    }
   
    bcopy( buffer, buffer + sizeof( uLongf ), bufferLength );
    bcopy( (void*)&originalLength, buffer, sizeof( uLongf ) );
   
    return [NSData dataWithBytesNoCopy:buffer length:bufferLength + sizeof(
uLongf )];
}


If the compression is successful, and I later release the (compressed)
NSData, buffer is still around, right?

Is there an update to this code?

How could I add buffer to a pool of sorts to be released when the object is
released as it is just malloc'd.

Thanks,

Trygve