Question

The parent process reads in an integer input through standard input

(terminal), passes the input to the child (through a pipe), the child passes the input to the grandchild
through a pipe, the grandchild replies back to the child with the square of the input (also through a pipe),
the child multiplies the received square with the input to calculate the cube of the input before passing
the cube to the parent (also through a pipe), and the parent displays the cube through the standard
output (terminal) before prompting the user for the next input. This procedure repeats till the user
enters a negative (-ve) input. Given a -ve input, the grandchild still computes the square of the input,
and the child still computes the cube of the input based on the square of the input received from the
grandchild and replies to the parent about the cube to display on the terminal before the program exits.
The program should (1) create only one child process and for only once and (2) create
only one grandchild process and, also, for only once. That is, fork() is called only twice during the course
of your program – once for the child and once for the grandchild. Each of child process and the
grandchild process is reused for computing of all input values.
Below attached is what I have so far for the program. Also, this is a program in C. In my program, it is printing "Error: Could not create a child process. Error code: 87". It is having trouble with creating the child process. My question is, can you help fix and debug my code to help it create the parent, child and grandchild process so that it can calculate the cube of the input?

Answer 1

The error indicates an issue with the fork system call in the C program or with the operating system environment. Ensure fork is used correctly, pipes are set up properly, and file descriptors are managed accurately within the parent, child, and grandchild processes.

Step-by-step explanation:

To assist with your C programming task of creating a parent, child, and grandchild process to calculate the cube of an input, we must ensure that the fork system call creates processes successfully and that the interprocess communication is correctly implemented using pipes.

Since you are getting the error message 'Error: Could not create a child process. Error code: 87', this indicates that there might be an issue either with the way fork() is called or handled in your code, or with your operating system environment that produces this error code.

Ensure that you are checking the return value of fork() properly. Fork will return a negative value if the child process cannot be created, zero to the newly created child process, and the process ID of the child to the parent process. Additionally, make certain that pipes are correctly set up before forking processes and that file descriptors are managed accurately for reading and writing operations in parent, child, and grandchild processes.

Use different sets of file descriptors for each pipe, close unnecessary file descriptors after forking to ensure that pipes behave correctly, and read/write only the necessary information. Organize the parent, child, and grandchild code into separate blocks, typically using if-else conditions to differentiate their behavior based on the fork return value.

If the error code is not related to the fork functionality but the operating system environment, ensure you are compiling the C code in an environment that supports the fork function, typically UNIX-like systems such as Linux or macOS. Remember, proper error handling and cleanup are essential for avoiding resource leaks and ensuring the correctness of your program.

The first step after fixing issues with fork is to implement the logic for the square and cube calculations in the corresponding processes, making sure the input is correctly passed through pipes between these processes. The program should terminate when a negative number is entered, after following the proper sequence of squaring the number and computing the cube.