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@beakr beakr/Decompress.cpp
Created Sep 24, 2014

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#include <cstdio>
#include <string>
#include <cstring>
#include <cstdlib>
#include "zlib.h"
#include "zconf.h"
using namespace std;
bool gzipInflate( const std::string& compressedBytes, std::string& uncompressedBytes ) {
if ( compressedBytes.size() == 0 ) {
uncompressedBytes = compressedBytes ;
return true ;
}
uncompressedBytes.clear() ;
unsigned full_length = compressedBytes.size() ;
unsigned half_length = compressedBytes.size() / 2;
unsigned uncompLength = full_length ;
char* uncomp = (char*) calloc( sizeof(char), uncompLength );
z_stream strm;
strm.next_in = (Bytef *) compressedBytes.c_str();
strm.avail_in = compressedBytes.size() ;
strm.total_out = 0;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
bool done = false ;
if (inflateInit2(&strm, (16+MAX_WBITS)) != Z_OK) {
free( uncomp );
return false;
}
while (!done) {
// If our output buffer is too small
if (strm.total_out >= uncompLength ) {
// Increase size of output buffer
char* uncomp2 = (char*) calloc( sizeof(char), uncompLength + half_length );
memcpy( uncomp2, uncomp, uncompLength );
uncompLength += half_length ;
free( uncomp );
uncomp = uncomp2 ;
}
strm.next_out = (Bytef *) (uncomp + strm.total_out);
strm.avail_out = uncompLength - strm.total_out;
// Inflate another chunk.
int err = inflate (&strm, Z_SYNC_FLUSH);
if (err == Z_STREAM_END) done = true;
else if (err != Z_OK) {
break;
}
}
if (inflateEnd (&strm) != Z_OK) {
free( uncomp );
return false;
}
for ( size_t i=0; i<strm.total_out; ++i ) {
uncompressedBytes += uncomp[ i ];
}
free( uncomp );
return true ;
}
/* Reads a file into memory. */
bool loadBinaryFile( const std::string& filename, std::string& contents ) {
// Open the gzip file in binary mode
FILE* f = fopen( filename.c_str(), "rb" );
if ( f == NULL )
return false ;
// Clear existing bytes in output vector
contents.clear();
// Read all the bytes in the file
int c = fgetc( f );
while ( c != EOF ) {
contents += (char) c ;
c = fgetc( f );
}
fclose (f);
return true ;
}
int main() {
// Read the gzip file data into memory
std::string fileData ;
if ( !loadBinaryFile( "archive.gz", fileData ) ) {
printf( "Error loading input file." );
return 0 ;
}
// Uncompress the file data
std::string data ;
if ( !gzipInflate( fileData, data ) ) {
printf( "Error decompressing file." );
return 0 ;
}
// Print the data
printf( "Data: \"" );
for ( size_t i=0; i<data.size(); ++i ) {
printf( "%c", data[i] );
}
printf ( "\"\n" );
return 0;
}
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