compression.c
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#include "compression.h"
ssize_t inflateGzip(void* compData, size_t compDataLen, void** unCompData, int headerless) {
unsigned int increase = compDataLen/2;
unsigned int uncompLength = compDataLen; // Later to be increased
char* uncomp = (char*)calloc(uncompLength, sizeof(char));
z_stream strm;
strm.next_in = (Bytef*) compData;
strm.avail_in = compDataLen;
strm.total_out = 0;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
int err = Z_OK;
if(headerless) {
err = inflateInit(&strm);
} else {
err = inflateInit2(&strm, 16+MAX_WBITS);
}
if(err != Z_OK) {
fprintf(stderr, "Unable to initialize zlib zstream for decompression\n");
free(uncomp);
return -1;
}
do {
// If our output buffer is too small
if(strm.total_out >= uncompLength ) {
// Increase size of output buffer
void* newptr = realloc(uncomp,uncompLength + increase);
if(newptr == NULL) {
fprintf(stderr,"Unable to request memory realloc\n");
inflateEnd(&strm);
free(uncomp);
return -2;
}
uncomp = newptr;
uncompLength += increase;
}
strm.next_out = (Bytef *) (uncomp + strm.total_out);
strm.avail_out = uncompLength - strm.total_out;
// Inflate another chunk.
err = inflate(&strm, Z_SYNC_FLUSH);
if(err != Z_OK && err != Z_STREAM_END) {
fprintf(stderr, "Error while inflating buffer: %d - %s.\n", err,strm.msg);
inflateEnd(&strm);
free(uncomp);
return -3;
}
} while(err != Z_STREAM_END);
uncompLength = strm.total_out;
if(inflateEnd(&strm) != Z_OK) {
fprintf(stderr,"Error while deallocating libz zstream\n");
free(uncomp);
return -4;
}
*unCompData = uncomp;
return uncompLength;
}
ssize_t deflateGzip(void* unCompData, size_t unCompDataLen, void** compData, int headerless) {
unsigned int compLength = unCompDataLen;
unsigned int increase = compLength/4;
char* comp = (char*)calloc(compLength, sizeof(char));
z_stream strm;
strm.next_in = (Bytef*) unCompData;
strm.avail_in = unCompDataLen;
strm.total_out = 0;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
int err = Z_OK;
if(headerless) {
err = deflateInit(&strm, Z_DEFAULT_COMPRESSION);
} else {
err = deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED, 16+MAX_WBITS, 8, Z_DEFAULT_STRATEGY);
}
if(err != Z_OK) {
fprintf(stderr, "Unable to initialize zlib zstream for compression\n");
free(comp);
return -1;
}
do {
// If our output buffer is too small
if (strm.total_out >= compLength) {
// Increase size of output buffer
void* newptr = realloc(comp, compLength + increase);
if(newptr == NULL) {
fprintf(stderr,"Unable to request memory realloc\n");
deflateEnd(&strm);
free(comp);
return -2;
}
comp = newptr;
compLength += increase;
}
strm.next_out = (Bytef*) (comp + strm.total_out);
strm.avail_out = compLength - strm.total_out;
// deflate another chunk
err = deflate(&strm, Z_FINISH);
if(err != Z_OK && err != Z_STREAM_END) {
fprintf(stderr, "Error while deflating buffer: %d - %s\n",err,strm.msg);
deflateEnd(&strm);
free(comp);
return -3;
}
} while(err != Z_STREAM_END);
compLength = strm.total_out;
if(deflateEnd(&strm) != Z_OK) {
fprintf(stderr,"Error while deallocating libz zstream\n");
free(comp);
return -4;
}
if(!headerless) {
// Set OS Flag to 0x00: "FAT filesystem (MS-DOS, OS/2, NT/Win32)"
comp[OS_FLAG_OFFSET] = 0x00;
}
*compData = comp;
return compLength;
}