blat1

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <dirent.h>

#define FALSE (0)
#define TRUE !FALSE
#define NAME_LEN (64)
#define LOG_NAME "AntiVirusLog.txt"

int getFileSize(FILE *file);
char *getText(FILE *file, size_t size);
void checkAllocation(void *p);
char isInBin(void *data, size_t len, void *subdata, size_t sublen);

int main(int argc, const char *argv[]) {
	FILE *virusSign = NULL, *scanFile = NULL,
		*logFile = NULL;
	int signSize = 0, scanFileSize = 0, chunkSize = 0,
		isNormalFind = 0, isFTwentFound = 0, isLTwentFound = 0;
	size_t curFileSize = 0, virusSignSize = 0;
	char curFileName[NAME_LEN] = { 0 }, logFileName[NAME_LEN] = { 0 }, choice = 0;
	struct dirent *ep;
	DIR *dp = opendir(argv[1]);

	/* LOG AND PRINT STUFF */

	// PRINT
	printf("Welcome to my Virus Scan!\n\n"
		"Folder to scan: %s\n"
		"Virus sinature: %s\n\n"
		"Press 0 for a normal scan or any key for a quick scan: ",
		argv[1], argv[2]);
	scanf("%d", &choice);
	puts("Scanning began...\nThis process may take several minutes...\n\nScanning:");

	// LOG
	sprintf(logFileName, "%s/%s", argv[1], LOG_NAME);
	logFile = fopen(logFileName, "w");

	fprintf(logFile, "Anti-virus began! Welcome!\n\n"
		"Folder to scan:\n%s\nVirus signature:\n%s\n\n"
		"Scanning option:\n%s Scan\n\nResults:\n",
		argv[1], argv[2], !choice ? "Normal" : "Quick");

	/* END OF LOG AND PRINT */

	// Getting the virus sign
	virusSign = fopen(argv[2], "rb");
	virusSignSize = getFileSize(virusSign);
	char *sign = getText(virusSign, (int)virusSignSize);

	if (dp) {
		// Move over every file in the folder
		while (ep = readdir(dp)) {
			// Checking if it's a file
			if (ep->d_type == DT_DIR || !strcmp(ep->d_name, LOG_NAME)) {
				continue;
			}

			sprintf(curFileName, "%s/%s", argv[1], ep->d_name);

			scanFile = fopen(curFileName, "rb");
			curFileSize = getFileSize(scanFile);

			// Saving some CPU cycles ;)
			if (curFileSize < virusSignSize) {
				fprintf(logFile, "%s  Not Infected\n", curFileName);
				continue;
			}

			char *curFileText = getText(scanFile, curFileSize);

			if (choice) {
				chunkSize = curFileSize / 5; // Getting the size of the %20

				// Saving some CPU cycles
				if (chunkSize > virusSignSize) {
					isFTwentFound = isInBin(curFileText, chunkSize, sign, virusSignSize);
					isLTwentFound = isInBin(curFileText + (chunkSize * 4), curFileSize - (chunkSize * 4), sign,
						virusSignSize);
				}
				else {
					isFTwentFound = FALSE;
					isLTwentFound = FALSE;
				}
			}

			if (isLTwentFound) {
				fprintf(logFile, "%s  %s\n", curFileName, "Infected! (last 20%)");
			}
			else if (isFTwentFound) {
				fprintf(logFile, "%s  %s\n", curFileName, "Infected! (first 20%)");
			}
			else if (isInBin(curFileText, curFileSize, sign, virusSignSize)) {
				fprintf(logFile, "%s  Infected!\n", curFileName);
			}
			else {
				fprintf(logFile, "%s  Not Infected\n", curFileName);
			}

			free(curFileText);
			puts(curFileName);
		}

		free(sign);
		(void)closedir(dp);

	}
	else {
		perror("Couldn't open the directory");
	}

	printf("Scan Completed.\nSee log path for results: %s\nGoodbye", logFileName);

	return 0;
}

/*
* Function which get data and subdata and check if the string contains the substring,
* the punch is that it is working with binary char-chunck
*
* For the protocol, GNU also has function which do the same (memmem)
*
* @param  the data, it's len, the subdata and it's len
* @return 1 - it contains, 0 - else
*/
char isInBin(void *data, size_t len, void *subdata, size_t sublen) {
	// Running from the end of the file through the start minus the size of the subdata, so by the end - everything got checked
	for (len -= sublen; len >= 1; --len)
		if (!memcmp(data + len, subdata,
			sublen)) // Checking if the each chuck, one by one (chunk size = virus sign size)
			return TRUE;

	// For the worst case, when it's at the end (or start from another perspective)
	return !memcmp(data, subdata, sublen);
}

/*
* returns given file size
* @param file
* @return files size
*/
int getFileSize(FILE *file) {
	int size = 0;

	fseek(file, 0, SEEK_END);
	size = (int)ftell(file);
	rewind(file);

	return size;
}

/*
* gets text from given file
* @param file and it is size
* @return the file s text
*/
char *getText(FILE *file, size_t size) {
	char *tmpBuff = NULL;
	size_t res = 0;

	tmpBuff = (char *)malloc(sizeof(char) * size);
	checkAllocation(tmpBuff);

	res = fread(tmpBuff, 1, size, file);

	if (res != size) {
		perror("Can't read file!");
		exit(2);
	}

	return tmpBuff;
}

/*
* checks for wrong allocation
* @param pointer to allocated addr
* @return none
*/
void checkAllocation(void *p) {
	if (!p) {
		perror("Allocation error!");
		exit(1);
	}
}