jens@13: //
jens@13: //  GTMNSData+zlib.m
jens@13: //
jens@13: //  Copyright 2007-2008 Google Inc.
jens@13: //
jens@13: //  Licensed under the Apache License, Version 2.0 (the "License"); you may not
jens@13: //  use this file except in compliance with the License.  You may obtain a copy
jens@13: //  of the License at
jens@13: // 
jens@13: //  http://www.apache.org/licenses/LICENSE-2.0
jens@13: // 
jens@13: //  Unless required by applicable law or agreed to in writing, software
jens@13: //  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
jens@13: //  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
jens@13: //  License for the specific language governing permissions and limitations under
jens@13: //  the License.
jens@13: //
jens@13: 
jens@13: #import "GTMNSData+zlib.h"
jens@13: #import <zlib.h>
jens@13: #import "GTMDefines.h"
jens@13: 
jens@13: #define kChunkSize 1024
jens@13: 
jens@13: @interface NSData (GTMZlibAdditionsPrivate)
jens@13: + (NSData *)gtm_dataByCompressingBytes:(const void *)bytes
jens@13:                                 length:(NSUInteger)length
jens@13:                       compressionLevel:(int)level
jens@13:                                useGzip:(BOOL)useGzip;
jens@13: @end
jens@13: 
jens@13: @implementation NSData (GTMZlibAdditionsPrivate)
jens@13: + (NSData *)gtm_dataByCompressingBytes:(const void *)bytes
jens@13:                                 length:(NSUInteger)length
jens@13:                       compressionLevel:(int)level
jens@13:                                useGzip:(BOOL)useGzip {
jens@13:   if (!bytes || !length) {
jens@13:     return nil;
jens@13:   }
jens@13:   
jens@13:   // TODO: support 64bit inputs
jens@13:   // avail_in is a uInt, so if length > UINT_MAX we actually need to loop
jens@13:   // feeding the data until we've gotten it all in.  not supporting this
jens@13:   // at the moment.
jens@13:   _GTMDevAssert(length <= UINT_MAX, @"Currently don't support >32bit lengths");
jens@13: 
jens@13:   if (level == Z_DEFAULT_COMPRESSION) {
jens@13:     // the default value is actually outside the range, so we have to let it
jens@13:     // through specifically.
jens@13:   } else if (level < Z_BEST_SPEED) {
jens@13:     level = Z_BEST_SPEED;
jens@13:   } else if (level > Z_BEST_COMPRESSION) {
jens@13:     level = Z_BEST_COMPRESSION;
jens@13:   }
jens@13: 
jens@13:   z_stream strm;
jens@13:   bzero(&strm, sizeof(z_stream));
jens@13: 
jens@13:   int windowBits = 15; // the default
jens@13:   int memLevel = 8; // the default
jens@13:   if (useGzip) {
jens@13:     windowBits += 16; // enable gzip header instead of zlib header
jens@13:   }
jens@13:   int retCode;
jens@13:   if ((retCode = deflateInit2(&strm, level, Z_DEFLATED, windowBits,
jens@13:                               memLevel, Z_DEFAULT_STRATEGY)) != Z_OK) {
jens@13:     // COV_NF_START - no real way to force this in a unittest (we guard all args)
jens@13:     _GTMDevLog(@"Failed to init for deflate w/ level %d, error %d",
jens@13:                level, retCode);
jens@13:     return nil;
jens@13:     // COV_NF_END
jens@13:   }
jens@13: 
jens@13:   // hint the size at 1/4 the input size
jens@13:   NSMutableData *result = [NSMutableData dataWithCapacity:(length/4)];
jens@13:   unsigned char output[kChunkSize];
jens@13: 
jens@13:   // setup the input
jens@13:   strm.avail_in = (unsigned int)length;
jens@13:   strm.next_in = (unsigned char*)bytes;
jens@13: 
jens@13:   // loop to collect the data
jens@13:   do {
jens@13:     // update what we're passing in
jens@13:     strm.avail_out = kChunkSize;
jens@13:     strm.next_out = output;
jens@13:     retCode = deflate(&strm, Z_FINISH);
jens@13:     if ((retCode != Z_OK) && (retCode != Z_STREAM_END)) {
jens@13:       // COV_NF_START - no real way to force this in a unittest
jens@13:       // (in inflate, we can feed bogus/truncated data to test, but an error
jens@13:       // here would be some internal issue w/in zlib, and there isn't any real
jens@13:       // way to test it)
jens@13:       _GTMDevLog(@"Error trying to deflate some of the payload, error %d",
jens@13:                  retCode);
jens@13:       deflateEnd(&strm);
jens@13:       return nil;
jens@13:       // COV_NF_END
jens@13:     }
jens@13:     // collect what we got
jens@13:     unsigned gotBack = kChunkSize - strm.avail_out;
jens@13:     if (gotBack > 0) {
jens@13:       [result appendBytes:output length:gotBack];
jens@13:     }
jens@13: 
jens@13:   } while (retCode == Z_OK);
jens@13: 
jens@13:   // if the loop exits, we used all input and the stream ended
jens@13:   _GTMDevAssert(strm.avail_in == 0,
jens@13:                 @"thought we finished deflate w/o using all input, %u bytes left",
jens@13:                 strm.avail_in);
jens@13:   _GTMDevAssert(retCode == Z_STREAM_END,
jens@13:                 @"thought we finished deflate w/o getting a result of stream end, code %d",
jens@13:                 retCode);
jens@13: 
jens@13:   // clean up
jens@13:   deflateEnd(&strm);
jens@13: 
jens@13:   return result;
jens@13: } // gtm_dataByCompressingBytes:length:compressionLevel:useGzip:
jens@13:   
jens@13: 
jens@13: @end
jens@13: 
jens@13: 
jens@13: @implementation NSData (GTMZLibAdditions)
jens@13: 
jens@13: + (NSData *)gtm_dataByGzippingBytes:(const void *)bytes
jens@13:                              length:(NSUInteger)length {
jens@13:   return [self gtm_dataByCompressingBytes:bytes
jens@13:                                    length:length
jens@13:                          compressionLevel:Z_DEFAULT_COMPRESSION
jens@13:                                   useGzip:YES];
jens@13: } // gtm_dataByGzippingBytes:length:
jens@13: 
jens@13: + (NSData *)gtm_dataByGzippingData:(NSData *)data {
jens@13:   return [self gtm_dataByCompressingBytes:[data bytes]
jens@13:                                    length:[data length]
jens@13:                          compressionLevel:Z_DEFAULT_COMPRESSION
jens@13:                                   useGzip:YES];
jens@13: } // gtm_dataByGzippingData:
jens@13: 
jens@13: + (NSData *)gtm_dataByGzippingBytes:(const void *)bytes
jens@13:                              length:(NSUInteger)length
jens@13:                    compressionLevel:(int)level {
jens@13:   return [self gtm_dataByCompressingBytes:bytes
jens@13:                                    length:length
jens@13:                          compressionLevel:level
jens@13:                                   useGzip:YES];
jens@13: } // gtm_dataByGzippingBytes:length:level:
jens@13: 
jens@13: + (NSData *)gtm_dataByGzippingData:(NSData *)data
jens@13:                   compressionLevel:(int)level {
jens@13:   return [self gtm_dataByCompressingBytes:[data bytes]
jens@13:                                    length:[data length]
jens@13:                          compressionLevel:level
jens@13:                                   useGzip:YES];
jens@13: } // gtm_dataByGzippingData:level:
jens@13: 
jens@13: + (NSData *)gtm_dataByDeflatingBytes:(const void *)bytes
jens@13:                               length:(NSUInteger)length {
jens@13:   return [self gtm_dataByCompressingBytes:bytes
jens@13:                                    length:length
jens@13:                          compressionLevel:Z_DEFAULT_COMPRESSION
jens@13:                                   useGzip:NO];
jens@13: } // gtm_dataByDeflatingBytes:length:
jens@13: 
jens@13: + (NSData *)gtm_dataByDeflatingData:(NSData *)data {
jens@13:   return [self gtm_dataByCompressingBytes:[data bytes]
jens@13:                                    length:[data length]
jens@13:                          compressionLevel:Z_DEFAULT_COMPRESSION
jens@13:                                   useGzip:NO];
jens@13: } // gtm_dataByDeflatingData:
jens@13: 
jens@13: + (NSData *)gtm_dataByDeflatingBytes:(const void *)bytes
jens@13:                               length:(NSUInteger)length
jens@13:                     compressionLevel:(int)level {
jens@13:   return [self gtm_dataByCompressingBytes:bytes
jens@13:                                    length:length
jens@13:                          compressionLevel:level
jens@13:                                   useGzip:NO];
jens@13: } // gtm_dataByDeflatingBytes:length:level:
jens@13: 
jens@13: + (NSData *)gtm_dataByDeflatingData:(NSData *)data
jens@13:                    compressionLevel:(int)level {
jens@13:   return [self gtm_dataByCompressingBytes:[data bytes]
jens@13:                                    length:[data length]
jens@13:                          compressionLevel:level
jens@13:                                   useGzip:NO];
jens@13: } // gtm_dataByDeflatingData:level:
jens@13: 
jens@13: + (NSData *)gtm_dataByInflatingBytes:(const void *)bytes
jens@13:                               length:(NSUInteger)length {
jens@13:   if (!bytes || !length) {
jens@13:     return nil;
jens@13:   }
jens@13:   
jens@13:   // TODO: support 64bit inputs
jens@13:   // avail_in is a uInt, so if length > UINT_MAX we actually need to loop
jens@13:   // feeding the data until we've gotten it all in.  not supporting this
jens@13:   // at the moment.
jens@13:   _GTMDevAssert(length <= UINT_MAX, @"Currently don't support >32bit lengths");
jens@13: 
jens@13:   z_stream strm;
jens@13:   bzero(&strm, sizeof(z_stream));
jens@13: 
jens@13:   // setup the input
jens@13:   strm.avail_in = (unsigned int)length;
jens@13:   strm.next_in = (unsigned char*)bytes;
jens@13: 
jens@13:   int windowBits = 15; // 15 to enable any window size
jens@13:   windowBits += 32; // and +32 to enable zlib or gzip header detection.
jens@13:   int retCode;
jens@13:   if ((retCode = inflateInit2(&strm, windowBits)) != Z_OK) {
jens@13:     // COV_NF_START - no real way to force this in a unittest (we guard all args)
jens@13:     _GTMDevLog(@"Failed to init for inflate, error %d", retCode);
jens@13:     return nil;
jens@13:     // COV_NF_END
jens@13:   }
jens@13: 
jens@13:   // hint the size at 4x the input size
jens@13:   NSMutableData *result = [NSMutableData dataWithCapacity:(length*4)];
jens@13:   unsigned char output[kChunkSize];
jens@13: 
jens@13:   // loop to collect the data
jens@13:   do {
jens@13:     // update what we're passing in
jens@13:     strm.avail_out = kChunkSize;
jens@13:     strm.next_out = output;
jens@13:     retCode = inflate(&strm, Z_NO_FLUSH);
jens@13:     if ((retCode != Z_OK) && (retCode != Z_STREAM_END)) {
jens@13:       _GTMDevLog(@"Error trying to inflate some of the payload, error %d",
jens@13:                  retCode);
jens@13:       inflateEnd(&strm);
jens@13:       return nil;
jens@13:     }
jens@13:     // collect what we got
jens@13:     unsigned gotBack = kChunkSize - strm.avail_out;
jens@13:     if (gotBack > 0) {
jens@13:       [result appendBytes:output length:gotBack];
jens@13:     }
jens@13: 
jens@13:   } while (retCode == Z_OK);
jens@13: 
jens@13:   // make sure there wasn't more data tacked onto the end of a valid compressed
jens@13:   // stream.
jens@13:   if (strm.avail_in != 0) {
jens@13:     _GTMDevLog(@"thought we finished inflate w/o using all input, %u bytes left",
jens@13:                strm.avail_in);
jens@13:     result = nil;
jens@13:   }
jens@13:   // the only way out of the loop was by hitting the end of the stream
jens@13:   _GTMDevAssert(retCode == Z_STREAM_END,
jens@13:                 @"thought we finished inflate w/o getting a result of stream end, code %d",
jens@13:                 retCode);
jens@13: 
jens@13:   // clean up
jens@13:   inflateEnd(&strm);
jens@13: 
jens@13:   return result;
jens@13: } // gtm_dataByInflatingBytes:length:
jens@13: 
jens@13: + (NSData *)gtm_dataByInflatingData:(NSData *)data {
jens@13:   return [self gtm_dataByInflatingBytes:[data bytes]
jens@13:                                  length:[data length]];
jens@13: } // gtm_dataByInflatingData:
jens@13: 
jens@13: @end