Description
Develop a C++ program to print full process hierarchy
Objective
The objective of this program (developed as a C++ class) is to print the full hierarchy of
processes for a given PID (process ID, specified as the 2nd command-line argument). The data
about processes is read from a given text file (as 1st command-line argument).
¤ Essentially this program automates the manual process of tracing the Linux
process hierarchy that was done as part of an earlier lab exercise. Refer to the
earlier lab exercise of using the output of ps -fe to trace processes to recollect
the manual process of tracing the process hierarchy.
Background
In Linux, processes are organized as a tree, rooted at /sbin/init or
/lib/systemd/system which is the first process that the Linux
kernel starts running. Each process is identified by a unique ID called PID
(short for process ID). Furthermore, each process has a PPID (short for
parent process ID). The process hierarchy can be determined manually,
by recursively tracing the PPID in the output of ps -fe command.
However, this program is designed to automate this task of tracing the
process hierarchy.
Data file formats
Prior to solving any problem is important to study the supplied data. So, ensure you view the
data files (yes, of course you can do this in NetBeans). The supplied data files are pretty much
the output of ps -fe command, also reviewed in lab exercise(s).
Program requirements:
• This program should be developed as a C++ class with the following 2 files (other than the
main function, all methods and instance variables should be part of the class):
o MUID_hw3.h: This header file should contain the class declaration. You must have
2 public methods – u a method that loads process data from a given file into 2
unordered_maps (discussed below) v a method that prints the process tree for a
given PID. You may add any private helper methods as you see fit. It is up to you to
decide meaningful names for methods and their parameters. Each method and
instance variable must be documented using Javadoc/doxygen style comments.
o MUID_hw3.cpp: This source file should contain the implementation for the
methods you have defined in the header file (ensure you #include
“MUID_hw3.h” in this source file). This file should document implementation
details as comments. This file will also contain the implementation for the main
method. Your main method should create an MUID_hw3 object and calls methods
on the object with suitable parameters.
DUE DATE: Wed, September 9 2020 Before 11:59 PM (EST)
Page 3 of 4
Tips and Notes:
• In your source file (.cpp), remember to prefix each method with your class name, as in:
void MUID_hw3::doSomething() to let the compiler know that this implementation
is for the doSomething method in MUID_hw3 class.
• To ease printing the process hierarchy, in your class use 2 unordered_maps as instance
variables in your class to store the following:
1. pid Û ppid information to ease look-up of parent process ID.
2. pid Û cmd information to ease look-up the command associated with a PID.
• Note that each input text file has the 1st line as a header line, which should be ignored.
• Use std::istringstream to process each line. Even if you don’t use a specific column
of data, it is still easier to read it and simply not use it. After that, to read the full command
(which has spaces in it) use std::getline method after reading specific columns. Refer
to your C++ reference sheet and keep I/O simple and straightforward. Excluding variable
definitions, processing the input file is just 7-to-8 lines of code.
• Note the order in which processes are printed in the sample output. It is top-down (and not
bottom-up). Each column is separated by 1-tab (i.e., ”\t”)
• For printing the process hierarchy in a top-down manner, you may use an iterative or a
recursive solution as you see fit. However, the recursive solution will most likely be shorter
than an iterative solution and is preferred. The reference solution uses recursion and prints
the process tree is 7-to-8 lines of simple code without any additional containers. Hence, the
full 12-points will be assigned only for a simple recursive solution.
Sample outputs
One you have completed your program you can test its operation using the command shows
below and compare your output to the output shown below. Note that for the 3-column output,
each column is separated by 1-tab (i.e., “PID\tPPID\tCMD”) character
Base case #1 [Must pass to earn any points]:
$ ./raodm_hw3 proc_info1.txt 1
Process tree for PID: 1
PID PPID CMD
1 0 /sbin/init
Base case #2 [Must pass to earn any points]:
$ ./raodm_hw3 proc_info2.txt 1
Process tree for PID: 1
PID PPID CMD
1 0 /lib/systemd/systemd –system –deserialize 19
Test case #3 [Must pass to earn full points]:
$ ./raodm_hw3 proc_info1.txt 27426
Process tree for PID: 27426
PID PPID CMD
1 0 /sbin/init
949 1 /usr/sbin/sshd -D -d
DUE DATE: Wed, September 9 2020 Before 11:59 PM (EST)
Page 4 of 4
27282 949 sshd: salvucwa [ priv]
27323 27282 sshd: salvucwa@pts/31
27324 27323 -bash
27425 27324 script
27426 27425 bash -i
Test case #4 [Must pass to earn full points]:
$ ./raodm_hw3 proc_info1.txt 27535
Process tree for PID: 27535
PID PPID CMD
1 0 /sbin/init
949 1 /usr/sbin/sshd -D -d
25640 949 sshd: raodm [priv]
25681 25640 sshd: raodm@pts/22
25697 25681 -bash –posix –norc
27535 25697 ps -fe
Test case #5 [Must pass to earn full points]:
$ ./raodm_hw3 proc_info2.txt 25474
Process tree for PID: 25474
PID PPID CMD
1 0 /lib/systemd/systemd –system –deserialize 19
917 1 /usr/sbin/sshd -D
25150 917 sshd: raodm [priv]
25175 25150 sshd: raodm@pts/0
25176 25175 -bash
25474 25176 ps -fea
Test case #6 [Must pass to earn full points]:
$ ./raodm_hw3 proc_info2.txt 25464
Process tree for PID: 25464
PID PPID CMD
1 0 /lib/systemd/systemd –system –deserialize 19
917 1 /usr/sbin/sshd -D
25150 917 sshd: raodm [priv]
25175 25150 sshd: raodm@pts/0
25176 25175 -bash
25454 25176 ./a.out
25455 25454 ./a.out -10 –wait 20
25456 25455 ./a.out
25457 25456 ./a.out
25458 25457 ./a.out
25459 25458 ./a.out
25460 25459 ./a.out –one –two -3
25461 25460 ./a.out
25462 25461 ./a.out
25463 25462 ./a.out –2
25464 25463 ./a.out
Submit to Canvas
This homework assignment must be turned-in electronically via Canvas via the CODE Plugin.
Ensure your program compiles without any warnings or style violations and operates correctly, at
least for the base case. Ensure you have Javadoc/doxygen style comments in the header file.
Once you have tested your implementation, upload just one C++ source file via the CODE
plugin.
