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//
// GTMNSData+zlib.m
//
// Copyright 2007-2008 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy
// of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
//
#import "GTMNSData+zlib.h"
#import <zlib.h>
#import "GTMDefines.h"
#define kChunkSize 1024
@interface NSData (GTMZlibAdditionsPrivate)
+ (NSData *)gtm_dataByCompressingBytes:(const void *)bytes
length:(unsigned)length
compressionLevel:(int)level
useGzip:(BOOL)useGzip;
@end
@implementation NSData (GTMZlibAdditionsPrivate)
+ (NSData *)gtm_dataByCompressingBytes:(const void *)bytes
length:(unsigned)length
compressionLevel:(int)level
useGzip:(BOOL)useGzip {
if (!bytes || !length) {
return nil;
}
if (level == Z_DEFAULT_COMPRESSION) {
// the default value is actually outside the range, so we have to let it
// through specifically.
} else if (level < Z_BEST_SPEED) {
level = Z_BEST_SPEED;
} else if (level > Z_BEST_COMPRESSION) {
level = Z_BEST_COMPRESSION;
}
z_stream strm;
bzero(&strm, sizeof(z_stream));
int windowBits = 15; // the default
int memLevel = 8; // the default
if (useGzip) {
windowBits += 16; // enable gzip header instead of zlib header
}
int retCode;
if ((retCode = deflateInit2(&strm, level, Z_DEFLATED, windowBits,
memLevel, Z_DEFAULT_STRATEGY)) != Z_OK) {
// COV_NF_START - no real way to force this in a unittest (we guard all args)
_GTMDevLog(@"Failed to init for deflate w/ level %d, error %d",
level, retCode);
return nil;
// COV_NF_END
}
// hint the size at 1/4 the input size
NSMutableData *result = [NSMutableData dataWithCapacity:(length/4)];
unsigned char output[kChunkSize];
// setup the input
strm.avail_in = length;
strm.next_in = (unsigned char*)bytes;
// loop to collect the data
do {
// update what we're passing in
strm.avail_out = kChunkSize;
strm.next_out = output;
retCode = deflate(&strm, Z_FINISH);
if ((retCode != Z_OK) && (retCode != Z_STREAM_END)) {
// COV_NF_START - no real way to force this in a unittest
// (in inflate, we can feed bogus/truncated data to test, but an error
// here would be some internal issue w/in zlib, and there isn't any real
// way to test it)
_GTMDevLog(@"Error trying to deflate some of the payload, error %d",
retCode);
deflateEnd(&strm);
return nil;
// COV_NF_END
}
// collect what we got
unsigned gotBack = kChunkSize - strm.avail_out;
if (gotBack > 0) {
[result appendBytes:output length:gotBack];
}
} while (retCode == Z_OK);
// if the loop exits, we used all input and the stream ended
_GTMDevAssert(strm.avail_in == 0,
@"thought we finished deflate w/o using all input, %u bytes left",
strm.avail_in);
_GTMDevAssert(retCode == Z_STREAM_END,
@"thought we finished deflate w/o getting a result of stream end, code %d",
retCode);
// clean up
deflateEnd(&strm);
return result;
} // gtm_dataByCompressingBytes:length:compressionLevel:useGzip:
@end
@implementation NSData (GTMZLibAdditions)
+ (NSData *)gtm_dataByGzippingBytes:(const void *)bytes
length:(unsigned)length {
return [self gtm_dataByCompressingBytes:bytes
length:length
compressionLevel:Z_DEFAULT_COMPRESSION
useGzip:YES];
} // gtm_dataByGzippingBytes:length:
+ (NSData *)gtm_dataByGzippingData:(NSData *)data {
return [self gtm_dataByCompressingBytes:[data bytes]
length:[data length]
compressionLevel:Z_DEFAULT_COMPRESSION
useGzip:YES];
} // gtm_dataByGzippingData:
+ (NSData *)gtm_dataByGzippingBytes:(const void *)bytes
length:(unsigned)length
compressionLevel:(int)level {
return [self gtm_dataByCompressingBytes:bytes
length:length
compressionLevel:level
useGzip:YES];
} // gtm_dataByGzippingBytes:length:level:
+ (NSData *)gtm_dataByGzippingData:(NSData *)data
compressionLevel:(int)level {
return [self gtm_dataByCompressingBytes:[data bytes]
length:[data length]
compressionLevel:level
useGzip:YES];
} // gtm_dataByGzippingData:level:
+ (NSData *)gtm_dataByDeflatingBytes:(const void *)bytes
length:(unsigned)length {
return [self gtm_dataByCompressingBytes:bytes
length:length
compressionLevel:Z_DEFAULT_COMPRESSION
useGzip:NO];
} // gtm_dataByDeflatingBytes:length:
+ (NSData *)gtm_dataByDeflatingData:(NSData *)data {
return [self gtm_dataByCompressingBytes:[data bytes]
length:[data length]
compressionLevel:Z_DEFAULT_COMPRESSION
useGzip:NO];
} // gtm_dataByDeflatingData:
+ (NSData *)gtm_dataByDeflatingBytes:(const void *)bytes
length:(unsigned)length
compressionLevel:(int)level {
return [self gtm_dataByCompressingBytes:bytes
length:length
compressionLevel:level
useGzip:NO];
} // gtm_dataByDeflatingBytes:length:level:
+ (NSData *)gtm_dataByDeflatingData:(NSData *)data
compressionLevel:(int)level {
return [self gtm_dataByCompressingBytes:[data bytes]
length:[data length]
compressionLevel:level
useGzip:NO];
} // gtm_dataByDeflatingData:level:
+ (NSData *)gtm_dataByInflatingBytes:(const void *)bytes
length:(unsigned)length {
if (!bytes || !length) {
return nil;
}
z_stream strm;
bzero(&strm, sizeof(z_stream));
// setup the input
strm.avail_in = length;
strm.next_in = (unsigned char*)bytes;
int windowBits = 15; // 15 to enable any window size
windowBits += 32; // and +32 to enable zlib or gzip header detection.
int retCode;
if ((retCode = inflateInit2(&strm, windowBits)) != Z_OK) {
// COV_NF_START - no real way to force this in a unittest (we guard all args)
_GTMDevLog(@"Failed to init for inflate, error %d", retCode);
return nil;
// COV_NF_END
}
// hint the size at 4x the input size
NSMutableData *result = [NSMutableData dataWithCapacity:(length*4)];
unsigned char output[kChunkSize];
// loop to collect the data
do {
// update what we're passing in
strm.avail_out = kChunkSize;
strm.next_out = output;
retCode = inflate(&strm, Z_NO_FLUSH);
if ((retCode != Z_OK) && (retCode != Z_STREAM_END)) {
_GTMDevLog(@"Error trying to inflate some of the payload, error %d",
retCode);
inflateEnd(&strm);
return nil;
}
// collect what we got
unsigned gotBack = kChunkSize - strm.avail_out;
if (gotBack > 0) {
[result appendBytes:output length:gotBack];
}
} while (retCode == Z_OK);
// make sure there wasn't more data tacked onto the end of a valid compressed
// stream.
if (strm.avail_in != 0) {
_GTMDevLog(@"thought we finished inflate w/o using all input, %u bytes left",
strm.avail_in);
result = nil;
}
// the only way out of the loop was by hitting the end of the stream
_GTMDevAssert(retCode == Z_STREAM_END,
@"thought we finished inflate w/o getting a result of stream end, code %d",
retCode);
// clean up
inflateEnd(&strm);
return result;
} // gtm_dataByInflatingBytes:length:
+ (NSData *)gtm_dataByInflatingData:(NSData *)data {
return [self gtm_dataByInflatingBytes:[data bytes]
length:[data length]];
} // gtm_dataByInflatingData:
@end
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