I am trying to unzip data using ZLib on the iPhone, but always with the error "Invalid header Check" .
To compress the data, I use the following in Java
Implementation: The standard Java implementation for Zlib
Deflator: java.util.zip.Deflater
version 1.45, 04/07/06
Compression Level: BEST_COMPRESSION
On iPhone, the following code to unpack:
- (NSData *)zlibInflate { if ([self length] == 0) return self; unsigned full_length = [self length]; unsigned half_length = [self length] / 2; NSMutableData *decompressed = [NSMutableData dataWithLength: full_length + half_length]; BOOL done = NO; int status; z_stream strm; strm.next_in = (Bytef *)[self bytes]; strm.avail_in = [self length]; strm.total_out = 0; strm.zalloc = Z_NULL; strm.zfree = Z_NULL; if (inflateInit (&strm) != Z_OK) return nil; while (!done) { // Make sure we have enough room and reset the lengths. if (strm.total_out >= [decompressed length]) [decompressed increaseLengthBy: half_length]; strm.next_out = [decompressed mutableBytes] + strm.total_out; strm.avail_out = [decompressed length] - strm.total_out; // Inflate another chunk. status = inflate (&strm, Z_SYNC_FLUSH); if (status == Z_STREAM_END) done = YES; else if (status != Z_OK) { NSLog(@"%s", strm.msg); break; } } if (inflateEnd (&strm) != Z_OK) return nil; // Set real length. if (done) { [decompressed setLength: strm.total_out]; return [NSData dataWithData: decompressed]; } else return nil; }
The following is an example of a compressed line:
xÚÝUko²Jþ~?ó?¥¾?¤?©?´ÚjCMX,Òµ?ª?µßVX¹È?¿.øë_?¯¶ZÏ%íùxHH&Ã<ÏÌ3ÌÎ @2.ðE?ºqþpéEzÏ09IoÒ?ª? ?®?£àÌönì$brÛ#fl95?¿»a//Tçáò?¢?¿½ µ©ÊÃÉPÔ¼:8y¦ý.äÎ?µ?¥?¼y?©ã¯9ö?¥½?¢±ÝûwÛ?§ãga?©á8?¨?m\Õ?»6,'Îe?¬}(L}7ÆÅ6#gJ(¥7´s?¬d.ó,Ë°¦prßýÕÖ?
The following is the function for the compressor:
public static byte[] compress(String s) { Deflater comp = new Deflater(); //comp.setLevel(Deflater.BEST_COMPRESSION); comp.setInput(s.getBytes()); comp.finish(); ByteArrayOutputStream bos = new ByteArrayOutputStream(s.length()); // Compress the data byte[] buf = new byte[1024]; try { while (!comp.finished()) { int count = comp.deflate(buf); bos.write(buf, 0, count); } bos.close(); } catch (Exception e) { //Log.d(TAG, e.getMessage()); e.printStackTrace(); } // Get the compressed data byte[] compressedData = bos.toByteArray(); // put in this fix for Symbol scanners byte[] compressedDataForSymbol = mungeForSymbol(compressedData); /* * byte[] decompressedDataForSymbol = * decompressedDataAfterSymbol(compressedDataForSymbol); // check they * are the same for(int i=0;i<compressedData.length;i++) { if * (compressedData[i] != decompressedDataForSymbol[i]) { * //System.out.println("Error at " + i); } } */ return compressedDataForSymbol; // return s.getBytes(); }
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