## Wednesday, 1 March 2017

### GATE Computer Science Solved Paper 2017 Session I - Part 2

11.       Consider the C struct defined below:
struct data {
int marks [100];
int cnumber;
};
struct data student;
The base address of student is available in register R1. The field student.grade can be
accessed efficiently using
(C) Register direct addressing mode, R1
(D) Index addressing mode, X(R1), where X is an offset represented in 2’s complement 16-bit representation.
12.       Consider the following intermediate program in three address code
p=a-b
q=p*c
p=u*v
q=p+q
Which one of the following corresponds to a static single assignment form of the above code?
(A) p1 = a-b
q1 = p1*c
p1 = u*v
q1 = p1+q1
(B) p3 = a-b
q4 = p3*c
p4 = u*v
q5 = p4+q4
(C) p1 = a-b
q1 = p2*c
p3 = u*v
q2 = p4+q3
(D) p1 = a-b
q1 = p*c
p2 = u*v
q2 = p+q
13.       Consider the following C code:
#include <stdio.h>
int *assignval(int *x, int val) {
*x = val;
return x;
}

void main () {
int *x = malloc(sizeof(int));
if (NULL == x) return;
x = assignval(x,0);
if(x) {
x = (int *)malloc(sizeof(int));
if (NULL == x) return;
x = assignval(x,10);
}
printf(“%d\n”, *x);
free (x);
}
The code suffers from which one of the following problems:
(A) compiler error as the return of malloc is not typecast appropriately
(B) compiler error because the comparison should be made as x == NULL and not as shown
(C) compiles successfully but execution may result in dangling pointer
(D) compiles successfully but execution may result in memory leak
14.       Consider a TCP client and a TCP server running on two different machines. After completing data transfer, the TCP client calls close to terminate the connection and a FIN segment is sent to the TCP server. Server-side TCP responds by sending an ACK, which is received by the client-side TCP. As per the TCP connection state diagram (RFC 793), in which state does the client-side TCP connection wait for the FIN from the server-side TCP?
(A) LAST-ACK
(B) TIME-WAIT
(C) FIN-WAIT-1
(D) FIN-WAIT-2
15.       A sender S sends a message m to receiver R. which is digitally signed by S with its private key. In this scenario, one or more of the following security violations can take place.
(I) S can launch a birthday attack to replace m with a fraudulent message.
(II) A third party attacker can launch a birthday attack to replace m with a fraudulent message.
(III) R can launch a birthday attack to replace m with a fraudulent message.
Which of the following are possible security violations?
(A) (I) and (II) only
(B) (I) only
(C) (II) only
(D) (II) and (III) only

16.       The following functional dependencies hold true for the relational schema R{V,W,X,Y,Z}:
V→W
VW→X
Y→VX
Y→Z
Which of the following is irreducible equivalent for this set of functional dependencies?
(A) V→W
V→X
Y→V
Y→Z
(B) V→W
W→X
Y→V
Y→Z
(C) V→W
V→X
Y→V
Y→X
Y→Z
(D) V→W
W→X
Y→V
Y→X
Y→Z
17.       Consider the following grammar:
P→xQRS
Q→yz | z
R→w | ε
S→y
What is FOLLOW(Q)?
(A) {R}
(B) {w}
(C) {w, y}
(D) {w, \$)
18.       Threads of a process share
(A) global variables but not heap.
(B) heap but not global variables.
(C) neither global variables nor heap.
(D) both heap and global variables.