Pset4 Recover: Code generates blurry, discoloured images

Question

My code below compiles and generates 50 images, but all appear blurry or are a coloured mess.

I've tried debugging but without success. I must be missing a logical step. May anyone advise?

#include <stdlib.h>

// Initialize variables.
char fileName[8];
int numberOfJpegsFound = 0;
FILE *img = NULL;

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

    // Open the memory card - exit program if error
    FILE *file = fopen(argv[1], "r");
    if (file == NULL)
    {
        printf("Failed to read image.\n");
        return 1;
    }

    // Initialize buffer for storage.
    unsigned char buffer[512];

    // Read 512 bytes until memory card finishes.
    while (fread(buffer, 512, 1, file) > 0)
    {
        // Assess if first 512 bytes is a JPEG header

        if (buffer[0] == 0xff && buffer[1] == 0xd8 && buffer[2] == 0xff && (buffer[3] & 0xf0) == 0xe0)
        {
            // If first JPEG is found, write the first file
            if (img == NULL)
            {
                sprintf(fileName, "%03i.jpg", numberOfJpegsFound);
                img = fopen(fileName, "w");
                fwrite(buffer, 512, 1, img);
            }
            //  Close current image, increment counter, and write an additional new file
            else
            {
                fclose(img);
                numberOfJpegsFound++;
                sprintf(fileName, "%03i.jpg", numberOfJpegsFound);
                img = fopen(fileName, "w");
                fwrite(buffer, 512, 1, img);
            }
        }
        // Continue writing to current JPEG file.
        else if (img != NULL)
        {
            img = fopen(fileName, "a");
            fwrite(buffer, 512, 1, img);
        }
    }
    return 0;
}

Answer 1

Solution was to remove the following line in the block - upon doing so the tests in check50 passed.

img = fopen(fileName, "a");