Pset 4 Recover: Stuck, the program only recover 13 pics

Question

Here's my code:

int main(int argc, char* argv[])
{
    FILE* card = fopen("card.raw", "r");
    if (card == NULL)
    {
        printf ("File doesn't exist");
        return 1;
    }

    uint8_t cardMemo[512];

    if (cardMemo == 0)
    {
        printf ("Out of Memory");
        return 2;
    }
    int t = 0;
    FILE* image = NULL;
    while (fread(&cardMemo, 512, 1, card) == 1)
    {  
        if (cardMemo[0] == 0xff && cardMemo[1] == 0xd8 && cardMemo[2] == 0xff && (cardMemo[3] == 0xe0 || cardMemo[3] == 0xe0))
        {
            //close previous image, if any
            if (image != NULL)            
                fclose(image);

            //setting for title
            char title[8];

            if (t<10)
            sprintf (title, "00%i.jpg", t);

            else if (t>=10)
            sprintf (title, "0%i.jpg", t);
            //create JPG
            image = fopen(title, "a");
            fwrite(&cardMemo, 512, 1, image);

            t++;
        }

        else
        {
            if (image != NULL)
            fwrite(&cardMemo, 512, 1, image);
        }
    }
fclose(image);
}

Answer 1

• feof tests whether the EOF was already reached not whether the next thing to reach is the EOF. see What is the difference in behavior between fread and feof?

• you don't need to keep track of the location of the file position indicator. all you need to do is to read the data block by block, check whether the first 4 bytes of a block are a JPG signature, and behave accordingly.

• you are shadowing the variable called image inside your loop and this is probably the main cause of the segmentation fault.