recover.c - shared from CS50 IDE

recover.c

 *
 * Recovers JPEGs from a forensic image.
 */
#include <stdio.h>
#include <stdint.h>

// prevent magic numbers
#define BLOCKSIZE 512

typedef uint8_t BYTE;

int main(void)
{
    // open memory card
    FILE* fp = fopen("card.raw", "r");
    
    // check file permission
    if (fp == NULL)
    {
        fclose(fp);
        printf("Unable to retrieve file from card.raw\n");
        return 1;
    }
    
    // create a char to name new image files
    char iname[8];
    
    // set a counter
    int counter = 0;
    
    // set a buffer of 512 bytes
    BYTE buff[BLOCKSIZE];
    
    // open output file
    FILE* outfile = NULL;
    
    // repeat until the end
    while (!feof(fp))
    {
        // find the start of the jpg
        if (buff[0] == 0xff && buff[1] == 0xd8 && buff[2] == 0xff && (buff[3] == 0xe0 || && buff[3] == 0xe1))
        {
            // if an outfile is open, close it
            if (outfile != NULL)
            {
                fclose(outfile);
            }
            
            // label files with three digits
            sprintf(iname, "%03d.jpg", counter);
            
            // open new file with name given by sprinft
            outfile = fopen(iname, "w");
            
            counter++;
            
            if (NULL == outfile)
            {
                printf("Couldn't open %s.\n", iname);
                return 1;
            }
            
            fwrite(buff, sizeof(buff), 1, outfile);
            
        }
        else if (counter > 0)
        {
            fwrite(buff, sizeof(buff), 1, outfile);
        }
        
        fwrite(buff, sizeof(buff), 1, fp);
    }
    
    // close file
    fclose(fp);
    
    // that's all folks
    return 0;
}