Answered: // TODO: put numbers in input.txt to…

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Question

Find the input needed to get the "pass" result

#include <stdio.h>
#include <stdlib.h>
void end_now();
char *next_input();

int hash = 8765309;
int INPUTS[4];

void phase03(){
// TODO: put numbers in input.txt to pass the code below
int a = atoi(next_input());
int b = atoi(next_input());
int c = atoi(next_input());
int d = atoi(next_input());

int targ = 0;
targ |= 1 << (hash % 13);
targ = targ << (hash % 3);
targ |= 1 << (hash % 19);
targ = targ << (hash % 5);
targ |= 1 << (hash % 31);
targ = targ << (hash % 7);

int shot = 0;
shot |= 1 << a;
shot |= 1 << b;
shot |= 1 << c;
shot |= 1 << d;

int hit = shot ^ targ;
hit = !hit;

if(hit){
printf("Right on target: nice shootin' bitslinger!\n");
return;
}

printf("Shifty bits hit? Xor not it seems...\n");
end_now();
}

////////////////////////////////////////////////////////////////////////////////
// additional code to get inputs/start up the program/run main()

#define BUFSIZE 128
char inputs[BUFSIZE][BUFSIZE] = {}; // array of inputs read from input file
int input_idx = -1; // index of most recently read input
FILE *input_fh = NULL; // file handle for inputs

// Open the provided input file
void setup_input(char *fname){
input_fh = fopen(fname,"r");
if(input_fh == NULL){
perror("Couldn't open input file");
exit(1);
}
}

// Close the input file
void close_input(){
if(input_fh == NULL){
fprintf(stderr,"Input file not open\n");
exit(1);
}
fclose(input_fh);
}

// Retrieve the next input from the file. Empty strings are placed in
// the inputs array if the file is out of input.
char *next_input(){
input_idx++;
int ret = fscanf(input_fh, "%s", inputs[input_idx]);
if(ret != 1){
fprintf(stderr, "!! No more input: assuming \"\" for input %d\n", input_idx);
inputs[input_idx][0] = '\0';
}
return inputs[input_idx];
}

// Ending sequence for program
void end_now(){
close_input();
exit(0);
}

int main(int argc, char *argv[]){
if(argc < 2){
printf("usage: %s <infile>\n",argv[0]);
return 1;
}
char *infile = argv[1];
setup_input(infile);
printf("Running mock Phase03\n");
phase03();
printf("Phase complete\n");
end_now();
return 0;
}

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