Inter-process communication (pipes, shared memory) in Operating Systems - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a pipe for communication between processes.

Operating Systems

int pipefd[2];
if (pipe([1]) == -1) {
    perror("pipe");
    exit(EXIT_FAILURE);
}

Drag options to blanks, or click blank then click option'

Apipefd_array

Bfd

Cfd_pipe

Dpipefd

Attempts:

3 left

💡 Hint

Common Mistakes

Using a single integer instead of an array.

Passing an uninitialized pointer instead of an array.

The pipe system call requires an array of two integers to hold the file descriptors for the read and write ends of the pipe. Here, pipefd is the correct array name.

2fill in blank

medium

Complete the code to write data to the write end of the pipe.

Operating Systems

char buf[] = "Hello";
write([1], buf, sizeof(buf));

Drag options to blanks, or click blank then click option'

Afd[0]

Bpipefd[0]

Cpipefd[1]

Dfd[1]

Attempts:

3 left

💡 Hint

Common Mistakes

Writing to the read end of the pipe.

Confusing the indices of the pipe file descriptors.

In a pipe, pipefd[1] is the write end. To send data, you write to this descriptor.

3fill in blank

hard

Fix the error in the shared memory segment creation code.

Operating Systems

int shmid = shmget(key, [1], IPC_CREAT | 0666);
if (shmid < 0) {
    perror("shmget");
    exit(1);
}

Drag options to blanks, or click blank then click option'

A0

B1024

Csizeof(int)

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using zero as the size, which causes failure.

Using negative values or invalid sizes.

The size argument to shmget must be a positive integer specifying the number of bytes to allocate. 1024 bytes is a common size for a shared memory segment.

4fill in blank

hard

Fill both blanks to attach to a shared memory segment and write a value.

Operating Systems

char *shm_ptr = (char *) shmat(shmid, [1], [2]);
if (shm_ptr == (char *) -1) {
    perror("shmat");
    exit(1);
}
*shm_ptr = 'A';

Drag options to blanks, or click blank then click option'

ANULL

B0

CSHM_RDONLY

DIPC_CREAT

Attempts:

3 left

💡 Hint

Common Mistakes

Using SHM_RDONLY when intending to write.

Passing IPC_CREAT to shmat, which is invalid.

To attach to shared memory with default address and read-write access, pass NULL as the address and 0 as the flags.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps process IDs to their shared memory keys if the key is positive.

Operating Systems

shm_dict = { [1]: [2] for pid, key in processes.items() if key [3] 0 }

Drag options to blanks, or click blank then click option'

Apid

Bkey

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping keys and values in the dictionary.

Using the wrong comparison operator in the condition.

This comprehension creates a dictionary where each process ID (pid) maps to its shared memory key (key) only if the key is greater than zero.