Lab Assignment--System Calls for I/0

Lab Code

   wget www.labs.cs.uregina.ca/330/SystemCall_IO/Lab7.zip
   unzip Lab7.zip
      

Exercise Description

The idea of this exercise is to communicate between a child and a parent using a shared file that the user will specify.

Your program will require the name of the file to be sent as a command line argument (argv[1])

A skeleton algorithm is provided below:

1. Check that the number of command line arguments is 2. If it isn't, produce an error message. Note: you cannot use perror here.
    
2. Before forking, declare all necessary variables for both parent and child, including a 8 byte character buffer for reads and writes.
   
   
3. Use fork to produce a child and parent
• Child will:
• open the file for writing (make sure to use the "create" flag and permissions for the user to read and write)
• check for errors on opening and use perror to describe the error.
• read from standard input (until end of file,ie., you type CTRL-D on a blank line)
• write to the file
• when done, close the file
• Parent will:
• wait for the child
• open the file for reading
• check for errors on opening and use perror to describe the error.
• Call fstat() and print the following information about the file the child created: the file size (in bytes), the owner and group IDs, and the time it was last modified. The output can be in the following format:

  This is the status of file.txt
  File Size      Owner         Group ID          Last Modified
  35             1005002087    1005000003        1722374520

  If you want to do more, you can output in the following format:

  This is the status of file.txt
  File Size      Owner         Group ID          Last Modified
  35             nova          csfac             Tue Jul 30 15:18:48 2024
                    

  To do this, you can make use of library calls: getgrgid, getpwuid, and ctime. Check out the man pages for these calls.
  
  You do not have to use the write system call for this last step. If you want, you can use printf to format your output nicely. For more on printf(), click here.
• write a message "hello from the parent" to stdout
• read from the file (until end of file)
• write to standard output
• when done, close the file

Don't forget to handle the error situation

Deliverables

Submit 2 files to URCourses

1. Your Code
2. Script containing the following commands (executable is called myIO):
   1. ls -l (Goal: show that no .txt files exist aside from your script file)
   2. ./myIO (Result: error message-not enough arguments)
   3. ./myIO file.txt (Result: no errors; gets input from the keyboard until you type CTRL-D; and creates file.txt with contents of what you typed)
   4. ls -l (Goal: show that file.txt has been created)
   5. cat file.txt (Goal: display the contents of the output file)
   6. ./myIO /file.txt (Result: two error messages - (1) permission denied on creating and (2) no such file when opening for reading- on file.txt in the root directory)

Notes

• Do not create a zip file
• Submission is on UR Courses
• Submit your own work
• Please properly indent your work. I will deduct marks for ziggy-zaggy code.
• Be mindful that your assignment is due two hours before the start of your next lab