cs50/recover.c

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

#define BLOCKSIZE 512
#define NAMESIZE 8

int main(int argc, char *argv[])
{
    if (argc != 2)
    {
        printf("Usage: ./recover FILE\n");
        return 1;
    }

    FILE *card = fopen(argv[1], "r");
    if (card == NULL)
    {
        printf("Could not open file.\n");
        return 1;
    }

    uint8_t buffer[BLOCKSIZE];
    int count = 0, first = 1;
    char *filename = malloc(NAMESIZE);
    FILE *jpg = NULL;

    while (fread(buffer, 1, BLOCKSIZE, card) == BLOCKSIZE)
    {
        // JPG header found
        if (buffer[0] == 0xff && buffer[1] == 0xd8 && buffer[2] == 0xff &&
            (buffer[3] & 0xf0) == 0xe0)
        {
            if (first == 1)
            {
                sprintf(filename, "%03i.jpg", count);
                jpg = fopen(filename, "w");
                if (jpg == NULL)
                {
                    printf("Could not open file.\n");
                    return 1;
                }
                first = 0;
            }
            else
            {
                fclose(jpg);
                sprintf(filename, "%03i.jpg", count);
                jpg = fopen(filename, "w");
                if (jpg == NULL)
                {
                    printf("Could not open file.\n");
                    return 1;
                }
            }
            count++;
        }
        if (first == 0) // Ignore data before first JPG header
        {
            fwrite(buffer, 1, BLOCKSIZE, jpg);
        }
    }
    fclose(jpg);
    fclose(card);
    free(filename);
}