recover.c

/**
 * recover.c
 *
 * Computer Science 50
 * Problem Set 4
 *
 * Recovers JPEGs from a forensic image.
 */
#include <stdio.h>
#include <stdlib.h>
#include <cs50.h>
#include <math.h>
#include <stdint.h>

FILE* inptr;

void make_jpg (FILE* new_jpg)
{
    uint8_t buffer[512];
    fread(&buffer, 512, 1, inptr);
    if((buffer[0]==0xff && buffer[1]==0xd8 && buffer[2]==0xff && buffer[3]==0xe1) || (buffer[0]==0xff && buffer[1]==0xd8 && buffer[2]==0xff && buffer[3]==0xe0))
    {
        fseek(inptr, -512, SEEK_CUR);
    }else if(feof(inptr)){

    }else{
        fwrite(&buffer, 512, 1, new_jpg);
        make_jpg(new_jpg);
    }
};

int main(void)
{
    char* infile = "card.raw";
    inptr = fopen(infile, "r");
    if (inptr == NULL)
    {
        printf("Could not open %s.\n", infile);
        return 2;
    }

    // Move inptr to first jpg filled block
    uint8_t check[4];
    fread(&check, 4, 1, inptr);
    bool look = true;
    while (look)
    {
        if((check[0]==0xff && check[1]==0xd8 && check[2]==0xff && check[3]==0xe1) || (check[0]==0xff && check[1]==0xd8 && check[2]==0xff && check[3]==0xe0))
        {
            look = false;
        }else{
            fseek(inptr, 508, SEEK_CUR);
            fread(&check, 4, 1, inptr);
        }
    }
    fseek(inptr, -4, SEEK_CUR);

    // set counter for jpg files
    int i = 0;

    // keep creating jpg files until eof
    while (!feof(inptr))
    {
        char str[7];
        sprintf(str, "%03d.jpg", i);
        FILE* outptr;
        char* outfile = str;
        outptr = fopen(outfile, "w");

        //write the first block
        uint8_t buffer[512];
        fread(&buffer, 512, 1, inptr);
        fwrite(&buffer, 512, 1, outptr);

        //finish remaining jpg if any
        make_jpg(outptr);

        //close
        fclose(outptr);
        i++;
    }
    fclose(inptr);
}