recover.c

/**
 * recover.c
 */
#include <stdio.h>

#define BLOCK_SIZE 512

int main(int argc, char *argv[])
{
    if (argc != 2)
    {
        fprintf(stderr, "Please enter the correct number of arguments\n");
        return 1;
    }

    // open input file
    FILE *file = fopen(argv[1], "r");
    if (file == NULL)
    {
        fprintf(stderr, "Could not open %s.\n", argv[1]);
        return 2;
    }

    //create block
    unsigned char block[BLOCK_SIZE];

    //create outfile file
    int jpgcount = 0;
    FILE* pic = NULL;

    int jpg_found = 0;

    //read through the file til the end
    while(fread(block,BLOCK_SIZE,1, file)==1)
    {
        //Check for jpg signiture
        if (block[0] == 0xff && block[1] == 0xd8 && block[2] == 0xff &&
          (block[3] == 0xe0 || block[3] == 0xe1 || block[3] == 0xe2 || block[3] == 0xe3
        || block[3] == 0xe4 || block[3] == 0xe5 || block[3] == 0xe6 || block[3] == 0xe7
        || block[3] == 0xe8 || block[3] == 0xe9 || block[3] == 0xea || block[3] == 0xeb
        || block[3] == 0xec || block[3] == 0xed || block[3] == 0xee || block[3] == 0xef))
        {
            //check to see if a picture has already been found, if so close it
            if(jpg_found ==1)
            {
                fclose(pic);
            }
            else
            {
                jpg_found = 1;
            }

            //construct filename
            char filename[8];
            sprintf(filename,"%03d.jpg",jpgcount);
            pic = fopen(filename, "a");
            jpgcount++;
        }

        //write the file
        if(jpg_found == 1)
        {
            fwrite(&block, BLOCK_SIZE, 1, pic);
        }
    }

    //close files
    fclose(file);
    fclose(pic);

    //success
    return 0;
}