wip

crc.c

@@ -10,7 +10,7 @@
 #include "CRCLib.h"
 #include "crc.h"
 
-#define CHUNK 8
+#define CHUNK 1024
 const long idat_signature = 1229209940;
 const long iend_signature = 1229278788;
 
@@ -71,10 +71,63 @@ FILE *zlib_decompress_data(unsigned char *data_chunk, size_t file_length) {
 
 	(void)inflateEnd(&strm);
 
-
 	return of;
 }
 
+FILE *zlib_compress_data(unsigned char *data_chunk, size_t file_length) {
+	int ret, flush;
+	unsigned int have;
+	z_stream strm;
+	unsigned char in[CHUNK];
+	unsigned char out[CHUNK];
+	int level = 9;
+	int method = Z_DEFLATED;
+	int windowBits = 10;
+	int memLevel = 9;
+	//int strategy = Z_DEFAULT_STRATEGY;
+	int strategy = Z_FILTERED;
+
+	FILE *data_stream = fmemopen(data_chunk, file_length, "r");
+	FILE *out_data_stream = open_memstream(NULL, NULL);
+
+	strm.zalloc = Z_NULL;
+	strm.zfree = Z_NULL;
+	strm.opaque = Z_NULL;
+	ret = deflateInit2(&strm, level, method, windowBits, memLevel, strategy);
+	if (ret != Z_OK) {
+		return NULL;
+	}
+
+	do {
+		strm.avail_in = fread(in, 1, CHUNK, data_stream);
+		if (ferror(data_stream)) {
+			(void)deflateEnd(&strm);
+			return NULL;
+		}
+		flush = feof(data_stream) ? Z_FINISH : Z_NO_FLUSH;
+		strm.next_in = in;
+
+		do {
+			strm.avail_out = CHUNK;
+			strm.next_out = out;
+
+			ret = deflate(&strm, flush);
+			assert(ret != Z_STREAM_ERROR);
+			have = CHUNK - strm.avail_out;
+			if(fwrite(out, 1, have, out_data_stream) != have || ferror(out_data_stream)) {
+				(void)deflateEnd(&strm);
+				return NULL;
+			}
+		} while(strm.avail_out == 0);
+		assert(strm.avail_in == 0);
+
+	} while(flush != Z_FINISH);
+	assert(ret == Z_STREAM_END);
+
+	(void)deflateEnd(&strm);
+	return out_data_stream;
+}
+
 unsigned long first_idat(unsigned char *addr) {
 	int idat_found = 0;
 	unsigned long offset = 8;
@@ -124,6 +177,7 @@ int update_file_crc(unsigned char *addr, unsigned long offset , unsigned int crc
 
 void random_data_change(unsigned char *color_data, int width, int length) {
 	int searching = 1;
+	size_t rounds = 0;
 	width = 16;
 	int color_range = 3;	
 	unsigned char temp_color_data[length];
@@ -131,6 +185,7 @@ void random_data_change(unsigned char *color_data, int width, int length) {
 	memcpy(temp_color_data, color_data, length);
 
 	do {
+		rounds++;
 		// Creating temporary data set
 		memcpy(temp_color_data, color_data, length);
 		// Generating random byte to change
@@ -138,10 +193,28 @@ void random_data_change(unsigned char *color_data, int width, int length) {
 		// Checking for index break
 		if(random_num % ((width * color_range) + 1)) {
 			if(color_data[random_num] == 255) {
-				//temp_color_data[random_num]--;
+				temp_color_data[random_num]--;
 			} else {
-				//temp_color_data[random_num]++;
+				temp_color_data[random_num]++;
 			}
+			FILE *check_data = zlib_compress_data(temp_color_data, length);
+			size_t check_data_length = 0;
+
+			unsigned char *check_data_array = file_to_char_array(check_data, &check_data_length);
+			unsigned char full_data[check_data_length+4];
+			full_data[0] = 0x49;
+			full_data[1] = 0x44;
+			full_data[2] = 0x41;
+			full_data[3] = 0x54;
+			for(int i = 0; i < check_data_length; i++) {
+				full_data[i+4] = check_data_array[i];
+			}
+			unsigned int temp_crc = crc(full_data, check_data_length);
+			if ((temp_crc >> (8*3)) == 61 ) {
+				printf("Found in %zu rounds!\n", rounds);
+				searching = 0;
+			}
+
 		}
 	
 	} while(searching == 1);