MYZip.m

//
//  MYZip.m
//  MYUtilities
//
//  Created by Jens Alfke on 2/26/15.
//  Copyright (c) 2015 Jens Alfke. All rights reserved.
//

#import "MYZip.h"
#import "Logging.h"
#import <zlib.h>

#define kBufferSize (8*1024)


@implementation MYZip
{
    z_stream _strm;
    BOOL _open;
    BOOL _compressing;
    uint8_t _buffer[kBufferSize];
}

@synthesize status=_status;


- (instancetype) initForCompressing: (BOOL)compressing {
    self = [super init];
    if (self) {
        _strm.next_out  = _buffer;
        _strm.avail_out = (uInt)kBufferSize;
        _strm.total_out = 0;
        _compressing = compressing;
        int rval;
        if (compressing)
            rval = deflateInit2(&_strm,
                                Z_DEFAULT_COMPRESSION,
                                Z_DEFLATED, // Only legal value
                                15 + 16,    // Default window size, plus write gzip header
                                8,          // Default mem level
                                Z_DEFAULT_STRATEGY);
        else
            rval = inflateInit2(&_strm,
                                15 + 32);   // Default window size, plus accept gzip headers
        if (rval != Z_OK)
            return nil;
        _open = YES;
        _status = Z_OK;
    }
    return self;
}

- (void) dealloc {
    [self close];
}

- (BOOL) close {
    if (_open) {
        int status;
        if (_compressing)
            status = deflateEnd(&_strm);
        else
            status = inflateEnd(&_strm);
        if (_status < Z_OK && _status >= Z_OK)
            _status = status;
        _open = NO;
    }
    return (_status >= Z_OK);
}

- (BOOL) addBytes: (const void*)bytes length: (size_t)length
         onOutput: (void(^)(const void*,size_t))onOutput
{
    if (!_open) {
        if (length == 0)
            return YES;
        if (_status >= 0)
            _status = MYZipStatusReadPastEOF;
        return NO;
    }
    _strm.next_in  = (Bytef*) bytes;
    _strm.avail_in = (uInt)length;
    do {
        int rval;
        if (_compressing)
            rval = deflate(&_strm, (length > 0 ? Z_NO_FLUSH : Z_FINISH));
        else
            rval = inflate(&_strm, Z_SYNC_FLUSH);
        if (rval == Z_BUF_ERROR || rval == Z_STREAM_END || length == 0) {
            // Output is full, or at EOF, so deliver it:
            onOutput(_buffer, kBufferSize - _strm.avail_out);
            _strm.next_out  = _buffer;
            _strm.avail_out = (uInt)kBufferSize;
            if (rval == Z_BUF_ERROR)
                rval = Z_OK;
        }
        if (rval != Z_OK) {
            _status = rval;
            [self close];
            return rval == Z_STREAM_END;
        }
    } while (_strm.avail_in > 0 || length == 0);
    return YES;
}

+ (NSData*) processData: (NSData*)input compress: (BOOL)compress {
    NSUInteger capacity = input.length;
    capacity = compress ? (capacity / 2) : (capacity * 2);
    NSMutableData* output = [NSMutableData dataWithCapacity: capacity];
    MYZip* gzip = [[self alloc] initForCompressing: compress];
    [gzip addBytes: input.bytes length: input.length onOutput: ^(const void *bytes, size_t len) {
        [output appendBytes: bytes length: len];
    }];
    [gzip addBytes: NULL length: 0 onOutput: ^(const void *bytes, size_t len) {
        [output appendBytes: bytes length: len];
    }];
    if (gzip.status < MYZipStatusOK) {
        Warn(@"GZip error %d %scompressing data", gzip.status, (compress ?"" :"de"));
        return nil;
    }
    return output;
}

+ (NSData*) dataByCompressingData: (NSData*)src {
    return [self processData: src compress: YES];
}

+ (NSData*) dataByDecompressingData: (NSData*)src {
    return [self processData: src compress: NO];
}


@end



/*
 Copyright (c) 2008-2013, Jens Alfke <jens@mooseyard.com>. All rights reserved.

 Redistribution and use in source and binary forms, with or without modification, are permitted
 provided that the following conditions are met:

 * Redistributions of source code must retain the above copyright notice, this list of conditions
 and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice, this list of conditions
 and the following disclaimer in the documentation and/or other materials provided with the
 distribution.

 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRI-
 BUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */