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CS50 pset4 - "Recover"
/**
* recover.c
*
* Computer Science 50
* Problem Set 4
*
* Recovers JPEGs from a forensic image.
*/
#include <cs50.h>
#include <stdio.h>
#include <stdlib.h>
#define BUFFER_SIZE 512
int main(void)
{
// open memory card file
FILE* input = fopen("card.raw", "r");
if (input == NULL)
{
printf("Could not open card.raw.\n");
return 2;
}
// create buffer
unsigned char buffer[BUFFER_SIZE];
// filename counter
int filecount = 0;
FILE* picture = NULL;
// check if we've found a jpeg yet or not
int jpg_found = 0; //false
// go through cardfile until there aren't any blocks left
while (fread(buffer, BUFFER_SIZE, 1, input) == 1)
{
// read first 4 bytes of buffer and see if jpg signature using bitwise on last byte
if (buffer[0] == 0xff && buffer[1] == 0xd8 && buffer[2] == 0xff && (buffer[3] & 0xe0) == 0xe0)
{
if (jpg_found == 1)
{
// We found the start of a new pic so close out current picture
fclose(picture);
}
else
{
// jpg discovered and now we have the green light to write
jpg_found = 1;
}
char filename[8];
sprintf(filename, "%03d.jpg", filecount);
picture = fopen(filename, "a");
filecount++;
}
if (jpg_found == 1)
{
// write 512 bytes to file once we start finding jpgs
fwrite(&buffer, BUFFER_SIZE, 1, picture);
}
}
// close files
fclose(input);
fclose(picture);
return 0;
}
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