recover.c

// Recovers JPEGS from memory card

#include <cs50.h>
#include <stdio.h>

int main(int argc, char *argv[])
{
    // ensure proper usage
    if (argc ==! 2)
    {
        fprintf(stderr, "Usage: recovery file\n");
        return 1;
    }

    // remember memory file name
    char *memfile = argv[1];

    // open memory card
    FILE* memcard = fopen(memfile, "r");
    if (memcard == NULL)
    {
        fprintf(stderr, "Could not open %s.\n", memfile);
        return 2;
    }

    // temporary storage
    int buffer[512 * sizeof(int)];
    int bytes_read;
    int img_count = 0;
    char filename[8];
    FILE* img = NULL;

    // until the end of the memory file
    do
    {
        // read from memory file
        bytes_read = fread(buffer, 1, 512, memcard);
        int x = buffer[0];
        int c = img_count;

        // determine if start of a new jpeg
        if (buffer[0] == 0xff && buffer[1] == 0xd8 && buffer[2] == 0xff && (buffer[3] & 0xf0) == 0xe0)
        {
            // determine if already found a jpeg
            if (img)
            {
                // close previous jpeg
                fclose(img);

                // increment jpeg counter
                img_count++;

                // start writing a new jpeg
                sprintf(filename, "%03i.jpg", img_count);
                img = fopen(filename, "w");
                fwrite(buffer, 1, 512, img);
            }

            else
            {
                // increment jpeg counter
                img_count++;

                // start writing a new jpeg
                sprintf(filename, "%03i.jpg", img_count);
                img = fopen(filename, "w");
                fwrite(buffer, 1, 512, img);
            }
        }

        else
        {
            // if already found jpeg, write those bytes to current jpeg
            if (img)
            {
                fwrite(buffer, 1, 512, img);
            }
        }

    }
    while (bytes_read == 512);

    // close memory file
    fclose(memcard);

    return 0;

}