Pwnable.kr - fd

fd.c

#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
char buf[32]; 
int main(int argc, char* argv[], char* envp[]){ 
 if(argc<2){ 
 printf("pass argv[1] a number\n"); 
 return 0; 
 } 
 int fd = atoi( argv[1] ) - 0x1234; 
 int len = 0; 
 len = read(fd, buf, 32); 
 if(!strcmp("LETMEWIN\n", buf)){ 
 printf("good job :)\n"); 
 system("/bin/cat flag"); 
 exit(0); 
 } 
 printf("learn about Linux file IO\n"); 
 return 0; 

}