recover.c

recover.c

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

int main(int argc, char *argv[])
{

    // take in one command-line argument only
    if (argc != 2)
    {
        fprintf(stderr, "Wrong!\n");
        return 1;
    }

    // remember filenames
    char *raw_file = argv[1];

    // open input file
    FILE *rawptr = fopen(raw_file, "r");
    if (rawptr == NULL)
    {
        fprintf(stderr, "Could not open %s.\n", raw_file);
        return 2;
    }

    //title number
    int t = 0;

    // create a charcter holder for title of file
    char jpegFile[9];

    // create place holder for 512 bytes, one jpeg block
    char jpegBlock[512];// = (char *)malloc(512 * sizeof(char));

    do
    {
        fread(&jpegBlock, sizeof(jpegBlock), 1, rawptr);
    }
    while (jpegBlock[0] != (char)0xff && jpegBlock[1] != (char)0xd8 && jpegBlock[2]
           != (char)0xff && (jpegBlock[3] & (char)0xf0) != (char)0xe0);

    // scan for the total number of jpegs
    for (int i = 0; i < 3; i++)
    {
        t++;

        // create jpeg file with titled name
        sprintf(jpegFile, "%03i.jpeg", t);

        // open jpeg file to write on
        FILE *jpegptr = fopen(jpegFile, "w");

        // check if jpeg file exists
        if (jpegptr == NULL)
        {
            fclose(rawptr);
            fprintf(stderr, "Could not create %s.\n", jpegFile);
            return 3;
        }

        do
        {
            fwrite(&jpegBlock, sizeof(jpegBlock), 1, jpegptr);

            fread(&jpegBlock, sizeof(jpegBlock), 1, rawptr);
        }
        while (jpegBlock[0] != (char)0xff && jpegBlock[1] != (char)0xd8 && jpegBlock[2]
               != (char)0xff && (jpegBlock[3] & (char)0xf0) != (char)0xe0);

        // close current jpeg file
        fclose(jpegptr);
    }

    // close infile
    fclose(rawptr);

    // success
    return 0;
}