Operating System代写:COMP420 Fork



Project Deliverables

Your project deliverables are to be posted to CUNY Blackboard using the Project 1 link.

  • 1) Only one source code file as follows with filename format showing your last name and student id: MYLASTNAME_MYSTUDENTID.c
    • a) At top of the file: your full name and student id in comments, for example: // MYFIRSTNAME MYLASTNAME MYSTUDENTID
    • b) In-line code comments no fewer than every 5 lines of code which describe your algorithmic steps in plain English language.
      That is, I do not want to see literal syntax transcriptions of the code.
  • 2) An MS Word or PDF document with a write-up of your software design and an explanation of the issues encountered and resolved. (1 page)
    The write-up is essay style with no bullet points nor itemized lists nor source code nor pseudo-code listings.

Filename format is MYLASTNAME_MYSTUDENTID.doc (or pdf). You are to use Times New Roman Font with font size = 11 and 1.5 line spacing.

  • 3) Text file of program output (text files only, that is, no graphics files from copying screen output) according to output format in
    Project Instructions further below for your program execution. I will provide sample input files and sample program execution commands on CUNY Blackboard for which program output is to be submitted.
  • 4) Please please ensure that your program will compile and link using the GNU C compiler. I will compile and link your source code to generate an executable file using the following command:

Project Specification

In your first project you will design and implement a program that, when executed, has both a parent process and a child process. You use the fork() system call to create a child process. The exec() system call is NOT to be used in this project. The parent and child utilize only two IPC resources between them: one POSIX message queue and one ordinary pipe.
Your program execution and command line arguments follows this syntax to provide counts for each input given on the command line:


The OPTIONS are the following. If none are specified on the command line then -ncb is used by default.

  • -n prints the newline count for each input
  • -c prints the word counts for each input
  • -b prints the character counts for each input
  • -m prints the maximum line length for each input

BUFFER_SIZE is a number between 32 and 256 inclusively and must be specified.

[INPUT FILE] contains a list of input files. If no input file is specified, then myinpfile.txt is used.

Project Instructions

  1. Your program source code must be provided in the C programming language.
  2. Your program must use the POSIX system file I/O and process management system calls which were discussed in lectures and reading assignments as well as those for POSIX message queues and ordinary pipes.
  3. You are NOT permitted to use any C standard I/O library functions nor string library functions.
  4. Only the child process will read the input as given by [INPUT FILE]. The child will write the input file contents in chunks as indicated by BUFFER_SIZE to the pipe. The parent will read this content from the pipe in chunks as indicated by BUFFER_SIZE.
  5. The parent process will compute the counts as indicated by [OPTION] for each input file separately from any other input file.
  6. The parent process will send each count (as indicated by [OPTION]) for each input file as its own POSIX message into the POSIX message queue. Therefore, as an example, if -ncbm is indicated with three input files on the command line, the parent process will send at least 4 * 3 = 12 messages into the POSIX message queue.
  7. The child process will receive the messages from (6) above in the POSIX message queue and will write the following to standard output in the following format according to each [OPTION] requested for each input file [INPUT FILE] where NEWLINE_COUNT indicates the newline count, WORD_COUNT is the word count, CHAR_COUNT is the character count, and MAX_LINE is the maximum line length.
  8. After all input files have been processed and the standard output in (7) has been generated, the parent and child processes will terminate. The parent will print its last output to standard output as follows:
Parent: Terminating.\n

Similarly, The child will print its last output to standard output as follows:

Child: Terminating.\n