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单军华

2018-07-31 21d3023a9b7b6aff68c1170e345951396b1c6cfd

 screendisplay/Pods/ASIHTTPRequest/Classes/ASIDataCompressor.m

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//
//  ASIDataCompressor.m
//  Part of ASIHTTPRequest -> http://allseeing-i.com/ASIHTTPRequest
//
//  Created by Ben Copsey on 17/08/2010.
//  Copyright 2010 All-Seeing Interactive. All rights reserved.
//

#import "ASIDataCompressor.h"
#import "ASIHTTPRequest.h"

#define DATA_CHUNK_SIZE 262144 // Deal with gzipped data in 256KB chunks
#define COMPRESSION_AMOUNT Z_DEFAULT_COMPRESSION

@interface ASIDataCompressor ()
+ (NSError *)deflateErrorWithCode:(int)code;
@end

@implementation ASIDataCompressor

+ (id)compressor
{
   ASIDataCompressor *compressor = [[[self alloc] init] autorelease];
   [compressor setupStream];
   return compressor;
}

- (void)dealloc
{
   if (streamReady) {
      [self closeStream];
   }
   [super dealloc];
}

- (NSError *)setupStream
{
   if (streamReady) {
      return nil;
   }
   // Setup the inflate stream
   zStream.zalloc = Z_NULL;
   zStream.zfree = Z_NULL;
   zStream.opaque = Z_NULL;
   zStream.avail_in = 0;
   zStream.next_in = 0;
   int status = deflateInit2(&zStream, COMPRESSION_AMOUNT, Z_DEFLATED, (15+16), 8, Z_DEFAULT_STRATEGY);
   if (status != Z_OK) {
      return [[self class] deflateErrorWithCode:status];
   }
   streamReady = YES;
   return nil;
}

- (NSError *)closeStream
{
   if (!streamReady) {
      return nil;
   }
   // Close the deflate stream
   streamReady = NO;
   int status = deflateEnd(&zStream);
   if (status != Z_OK) {
      return [[self class] deflateErrorWithCode:status];
   }
   return nil;
}

- (NSData *)compressBytes:(Bytef *)bytes length:(NSUInteger)length error:(NSError **)err shouldFinish:(BOOL)shouldFinish
{
   if (length == 0) return nil;
	
   NSUInteger halfLength = length/2;
	
   // We'll take a guess that the compressed data will fit in half the size of the original (ie the max to compress at once is half DATA_CHUNK_SIZE), if not, we'll increase it below
   NSMutableData *outputData = [NSMutableData dataWithLength:length/2]; 
	
   int status;
	
   zStream.next_in = bytes;
   zStream.avail_in = (unsigned int)length;
   zStream.avail_out = 0;

   NSInteger bytesProcessedAlready = zStream.total_out;
   while (zStream.avail_out == 0) {
		
      if (zStream.total_out-bytesProcessedAlready >= [outputData length]) {
         [outputData increaseLengthBy:halfLength];
      }
		
      zStream.next_out = (Bytef*)[outputData mutableBytes] + zStream.total_out-bytesProcessedAlready;
      zStream.avail_out = (unsigned int)([outputData length] - (zStream.total_out-bytesProcessedAlready));
      status = deflate(&zStream, shouldFinish ? Z_FINISH : Z_NO_FLUSH);
		
      if (status == Z_STREAM_END) {
         break;
      } else if (status != Z_OK) {
         if (err) {
            *err = [[self class] deflateErrorWithCode:status];
         }
         return NO;
      }
   }

   // Set real length
   [outputData setLength: zStream.total_out-bytesProcessedAlready];
   return outputData;
}


+ (NSData *)compressData:(NSData*)uncompressedData error:(NSError **)err
{
   NSError *theError = nil;
   NSData *outputData = [[ASIDataCompressor compressor] compressBytes:(Bytef *)[uncompressedData bytes] length:[uncompressedData length] error:&theError shouldFinish:YES];
   if (theError) {
      if (err) {
         *err = theError;
      }
      return nil;
   }
   return outputData;
}



+ (BOOL)compressDataFromFile:(NSString *)sourcePath toFile:(NSString *)destinationPath error:(NSError **)err
{
   NSFileManager *fileManager = [[[NSFileManager alloc] init] autorelease];

   // Create an empty file at the destination path
   if (![fileManager createFileAtPath:destinationPath contents:[NSData data] attributes:nil]) {
      if (err) {
         *err = [NSError errorWithDomain:NetworkRequestErrorDomain code:ASICompressionError userInfo:[NSDictionary dictionaryWithObjectsAndKeys:[NSString stringWithFormat:@"Compression of %@ failed because we were to create a file at %@",sourcePath,destinationPath],NSLocalizedDescriptionKey,nil]];
      }
      return NO;
   }
	
   // Ensure the source file exists
   if (![fileManager fileExistsAtPath:sourcePath]) {
      if (err) {
         *err = [NSError errorWithDomain:NetworkRequestErrorDomain code:ASICompressionError userInfo:[NSDictionary dictionaryWithObjectsAndKeys:[NSString stringWithFormat:@"Compression of %@ failed the file does not exist",sourcePath],NSLocalizedDescriptionKey,nil]];
      }
      return NO;
   }
	
   UInt8 inputData[DATA_CHUNK_SIZE];
   NSData *outputData;
   NSInteger readLength;
   NSError *theError = nil;
	
   ASIDataCompressor *compressor = [ASIDataCompressor compressor];
	
   NSInputStream *inputStream = [NSInputStream inputStreamWithFileAtPath:sourcePath];
   [inputStream open];
   NSOutputStream *outputStream = [NSOutputStream outputStreamToFileAtPath:destinationPath append:NO];
   [outputStream open];
	
    while ([compressor streamReady]) {
		
      // Read some data from the file
      readLength = [inputStream read:inputData maxLength:DATA_CHUNK_SIZE];

      // Make sure nothing went wrong
      if ([inputStream streamStatus] == NSStreamStatusError) {
         if (err) {
            *err = [NSError errorWithDomain:NetworkRequestErrorDomain code:ASICompressionError userInfo:[NSDictionary dictionaryWithObjectsAndKeys:[NSString stringWithFormat:@"Compression of %@ failed because we were unable to read from the source data file",sourcePath],NSLocalizedDescriptionKey,[inputStream streamError],NSUnderlyingErrorKey,nil]];
         }
         [compressor closeStream];
         return NO;
      }
      // Have we reached the end of the input data?
      if (!readLength) {
         break;
      }
		
      // Attempt to deflate the chunk of data
      outputData = [compressor compressBytes:inputData length:readLength error:&theError shouldFinish:readLength < DATA_CHUNK_SIZE ];
      if (theError) {
         if (err) {
            *err = theError;
         }
         [compressor closeStream];
         return NO;
      }
		
      // Write the deflated data out to the destination file
      [outputStream write:(const uint8_t *)[outputData bytes] maxLength:[outputData length]];
		
      // Make sure nothing went wrong
      if ([inputStream streamStatus] == NSStreamStatusError) {
         if (err) {
            *err = [NSError errorWithDomain:NetworkRequestErrorDomain code:ASICompressionError userInfo:[NSDictionary dictionaryWithObjectsAndKeys:[NSString stringWithFormat:@"Compression of %@ failed because we were unable to write to the destination data file at %@",sourcePath,destinationPath],NSLocalizedDescriptionKey,[outputStream streamError],NSUnderlyingErrorKey,nil]];
            }
         [compressor closeStream];
         return NO;
      }
		
    }
   [inputStream close];
   [outputStream close];

   NSError *error = [compressor closeStream];
   if (error) {
      if (err) {
         *err = error;
      }
      return NO;
   }

   return YES;
}

+ (NSError *)deflateErrorWithCode:(int)code
{
   return [NSError errorWithDomain:NetworkRequestErrorDomain code:ASICompressionError userInfo:[NSDictionary dictionaryWithObjectsAndKeys:[NSString stringWithFormat:@"Compression of data failed with code %d",code],NSLocalizedDescriptionKey,nil]];
}

@synthesize streamReady;
@end