MYUtilities: GoogleToolboxSubset/GTMNSData+zlib.m@256370e8935a

     1 //

     2 //  GTMNSData+zlib.m

     3 //

     4 //  Copyright 2007-2008 Google Inc.

     5 //

     6 //  Licensed under the Apache License, Version 2.0 (the "License"); you may not

     7 //  use this file except in compliance with the License.  You may obtain a copy

     8 //  of the License at

     9 //

    10 //  http://www.apache.org/licenses/LICENSE-2.0

    11 //

    12 //  Unless required by applicable law or agreed to in writing, software

    13 //  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT

    14 //  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the

    15 //  License for the specific language governing permissions and limitations under

    16 //  the License.

    17 //

    19 #import "GTMNSData+zlib.h"

    20 #import <zlib.h>

    21 #import "GTMDefines.h"

    23 #define kChunkSize 1024

    25 @interface NSData (GTMZlibAdditionsPrivate)

    26 + (NSData *)gtm_dataByCompressingBytes:(const void *)bytes

    27                                 length:(NSUInteger)length

    28                       compressionLevel:(int)level

    29                                useGzip:(BOOL)useGzip;

    30 @end

    32 @implementation NSData (GTMZlibAdditionsPrivate)

    33 + (NSData *)gtm_dataByCompressingBytes:(const void *)bytes

    34                                 length:(NSUInteger)length

    35                       compressionLevel:(int)level

    36                                useGzip:(BOOL)useGzip {

    37   if (!bytes || !length) {

    38     return nil;

    39   }

    41   // TODO: support 64bit inputs

    42   // avail_in is a uInt, so if length > UINT_MAX we actually need to loop

    43   // feeding the data until we've gotten it all in.  not supporting this

    44   // at the moment.

    45   _GTMDevAssert(length <= UINT_MAX, @"Currently don't support >32bit lengths");

    47   if (level == Z_DEFAULT_COMPRESSION) {

    48     // the default value is actually outside the range, so we have to let it

    49     // through specifically.

    50   } else if (level < Z_BEST_SPEED) {

    51     level = Z_BEST_SPEED;

    52   } else if (level > Z_BEST_COMPRESSION) {

    53     level = Z_BEST_COMPRESSION;

    54   }

    56   z_stream strm;

    57   bzero(&strm, sizeof(z_stream));

    59   int windowBits = 15; // the default

    60   int memLevel = 8; // the default

    61   if (useGzip) {

    62     windowBits += 16; // enable gzip header instead of zlib header

    63   }

    64   int retCode;

    65   if ((retCode = deflateInit2(&strm, level, Z_DEFLATED, windowBits,

    66                               memLevel, Z_DEFAULT_STRATEGY)) != Z_OK) {

    67     // COV_NF_START - no real way to force this in a unittest (we guard all args)

    68     _GTMDevLog(@"Failed to init for deflate w/ level %d, error %d",

    69                level, retCode);

    70     return nil;

    71     // COV_NF_END

    72   }

    74   // hint the size at 1/4 the input size

    75   NSMutableData *result = [NSMutableData dataWithCapacity:(length/4)];

    76   unsigned char output[kChunkSize];

    78   // setup the input

    79   strm.avail_in = (unsigned int)length;

    80   strm.next_in = (unsigned char*)bytes;

    82   // loop to collect the data

    83   do {

    84     // update what we're passing in

    85     strm.avail_out = kChunkSize;

    86     strm.next_out = output;

    87     retCode = deflate(&strm, Z_FINISH);

    88     if ((retCode != Z_OK) && (retCode != Z_STREAM_END)) {

    89       // COV_NF_START - no real way to force this in a unittest

    90       // (in inflate, we can feed bogus/truncated data to test, but an error

    91       // here would be some internal issue w/in zlib, and there isn't any real

    92       // way to test it)

    93       _GTMDevLog(@"Error trying to deflate some of the payload, error %d",

    94                  retCode);

    95       deflateEnd(&strm);

    96       return nil;

    97       // COV_NF_END

    98     }

    99     // collect what we got

   100     unsigned gotBack = kChunkSize - strm.avail_out;

   101     if (gotBack > 0) {

   102       [result appendBytes:output length:gotBack];

   103     }

   105   } while (retCode == Z_OK);

   107   // if the loop exits, we used all input and the stream ended

   108   _GTMDevAssert(strm.avail_in == 0,

   109                 @"thought we finished deflate w/o using all input, %u bytes left",

   110                 strm.avail_in);

   111   _GTMDevAssert(retCode == Z_STREAM_END,

   112                 @"thought we finished deflate w/o getting a result of stream end, code %d",

   113                 retCode);

   115   // clean up

   116   deflateEnd(&strm);

   118   return result;

   119 } // gtm_dataByCompressingBytes:length:compressionLevel:useGzip:

   122 @end

   125 @implementation NSData (GTMZLibAdditions)

   127 + (NSData *)gtm_dataByGzippingBytes:(const void *)bytes

   128                              length:(NSUInteger)length {

   129   return [self gtm_dataByCompressingBytes:bytes

   130                                    length:length

   131                          compressionLevel:Z_DEFAULT_COMPRESSION

   132                                   useGzip:YES];

   133 } // gtm_dataByGzippingBytes:length:

   135 + (NSData *)gtm_dataByGzippingData:(NSData *)data {

   136   return [self gtm_dataByCompressingBytes:[data bytes]

   137                                    length:[data length]

   138                          compressionLevel:Z_DEFAULT_COMPRESSION

   139                                   useGzip:YES];

   140 } // gtm_dataByGzippingData:

   142 + (NSData *)gtm_dataByGzippingBytes:(const void *)bytes

   143                              length:(NSUInteger)length

   144                    compressionLevel:(int)level {

   145   return [self gtm_dataByCompressingBytes:bytes

   146                                    length:length

   147                          compressionLevel:level

   148                                   useGzip:YES];

   149 } // gtm_dataByGzippingBytes:length:level:

   151 + (NSData *)gtm_dataByGzippingData:(NSData *)data

   152                   compressionLevel:(int)level {

   153   return [self gtm_dataByCompressingBytes:[data bytes]

   154                                    length:[data length]

   155                          compressionLevel:level

   156                                   useGzip:YES];

   157 } // gtm_dataByGzippingData:level:

   159 + (NSData *)gtm_dataByDeflatingBytes:(const void *)bytes

   160                               length:(NSUInteger)length {

   161   return [self gtm_dataByCompressingBytes:bytes

   162                                    length:length

   163                          compressionLevel:Z_DEFAULT_COMPRESSION

   164                                   useGzip:NO];

   165 } // gtm_dataByDeflatingBytes:length:

   167 + (NSData *)gtm_dataByDeflatingData:(NSData *)data {

   168   return [self gtm_dataByCompressingBytes:[data bytes]

   169                                    length:[data length]

   170                          compressionLevel:Z_DEFAULT_COMPRESSION

   171                                   useGzip:NO];

   172 } // gtm_dataByDeflatingData:

   174 + (NSData *)gtm_dataByDeflatingBytes:(const void *)bytes

   175                               length:(NSUInteger)length

   176                     compressionLevel:(int)level {

   177   return [self gtm_dataByCompressingBytes:bytes

   178                                    length:length

   179                          compressionLevel:level

   180                                   useGzip:NO];

   181 } // gtm_dataByDeflatingBytes:length:level:

   183 + (NSData *)gtm_dataByDeflatingData:(NSData *)data

   184                    compressionLevel:(int)level {

   185   return [self gtm_dataByCompressingBytes:[data bytes]

   186                                    length:[data length]

   187                          compressionLevel:level

   188                                   useGzip:NO];

   189 } // gtm_dataByDeflatingData:level:

   191 + (NSData *)gtm_dataByInflatingBytes:(const void *)bytes

   192                               length:(NSUInteger)length {

   193   if (!bytes || !length) {

   194     return nil;

   195   }

   197   // TODO: support 64bit inputs

   198   // avail_in is a uInt, so if length > UINT_MAX we actually need to loop

   199   // feeding the data until we've gotten it all in.  not supporting this

   200   // at the moment.

   201   _GTMDevAssert(length <= UINT_MAX, @"Currently don't support >32bit lengths");

   203   z_stream strm;

   204   bzero(&strm, sizeof(z_stream));

   206   // setup the input

   207   strm.avail_in = (unsigned int)length;

   208   strm.next_in = (unsigned char*)bytes;

   210   int windowBits = 15; // 15 to enable any window size

   211   windowBits += 32; // and +32 to enable zlib or gzip header detection.

   212   int retCode;

   213   if ((retCode = inflateInit2(&strm, windowBits)) != Z_OK) {

   214     // COV_NF_START - no real way to force this in a unittest (we guard all args)

   215     _GTMDevLog(@"Failed to init for inflate, error %d", retCode);

   216     return nil;

   217     // COV_NF_END

   218   }

   220   // hint the size at 4x the input size

   221   NSMutableData *result = [NSMutableData dataWithCapacity:(length*4)];

   222   unsigned char output[kChunkSize];

   224   // loop to collect the data

   225   do {

   226     // update what we're passing in

   227     strm.avail_out = kChunkSize;

   228     strm.next_out = output;

   229     retCode = inflate(&strm, Z_NO_FLUSH);

   230     if ((retCode != Z_OK) && (retCode != Z_STREAM_END)) {

   231       _GTMDevLog(@"Error trying to inflate some of the payload, error %d",

   232                  retCode);

   233       inflateEnd(&strm);

   234       return nil;

   235     }

   236     // collect what we got

   237     unsigned gotBack = kChunkSize - strm.avail_out;

   238     if (gotBack > 0) {

   239       [result appendBytes:output length:gotBack];

   240     }

   242   } while (retCode == Z_OK);

   244   // make sure there wasn't more data tacked onto the end of a valid compressed

   245   // stream.

   246   if (strm.avail_in != 0) {

   247     _GTMDevLog(@"thought we finished inflate w/o using all input, %u bytes left",

   248                strm.avail_in);

   249     result = nil;

   250   }

   251   // the only way out of the loop was by hitting the end of the stream

   252   _GTMDevAssert(retCode == Z_STREAM_END,

   253                 @"thought we finished inflate w/o getting a result of stream end, code %d",

   254                 retCode);

   256   // clean up

   257   inflateEnd(&strm);

   259   return result;

   260 } // gtm_dataByInflatingBytes:length:

   262 + (NSData *)gtm_dataByInflatingData:(NSData *)data {

   263   return [self gtm_dataByInflatingBytes:[data bytes]

   264                                  length:[data length]];

   265 } // gtm_dataByInflatingData:

   267 @end

author	Jens Alfke <jens@mooseyard.com>
	Sun May 03 10:13:31 2009 -0700 (2009-05-03)
changeset 27	256370e8935a
permissions	-rw-r--r--