#include <stdio.h>
#include <stdint.h>

typedef uint8_t BYTE;

typedef struct
{
    BYTE a;
    BYTE b;
    BYTE c;
    BYTE d;
}JBLK;

int main(int argc, char* argv[])
{
    if(argc!=2)
    {
        fprintf(stderr, "Usage: ./recover image\n");
        return 1;
    }
    FILE* src=fopen(argv[1],"r");
    if(src==NULL)
    {
        fprintf(stderr, "File cannot be opened\n");
        return 2;
    }
    int c=0;
    fpos_t pos;
    while(fgetc(src)!=EOF)
    {
        JBLK tmp;
        fread(&tmp,sizeof(JBLK),1,src);
        if(tmp.a==255&&tmp.b==216&&tmp.c==255&&(tmp.d>=224&&tmp.d<=239))
        {
            char tg[50];
            sprintf(tg,"00%i.jpg",c);
            FILE* tgt=fopen(tg,"w");
            fwrite(&tmp,sizeof(JBLK),1,tgt);
            fread(&tmp,sizeof(JBLK),1,src);
            while(!(tmp.a==255&&tmp.b==216&&tmp.c==255&&(tmp.d>=224&&tmp.d<=239)))
            {
                fwrite(&tmp,sizeof(JBLK),1,tgt);
                fgetpos(src,&pos);
                fread(&tmp,sizeof(JBLK),1,src);
            }
            fclose(tgt);
            c++;
            fsetpos(src,&pos);
        }
        else continue;
    }
    fclose(src);
    return 0;
}