CSE-381: Systems 2 Homework #2: Part B Solved

Objective
The objective of this part of the homework is to develop 1 C++ program to:

•      Understand the use of uid and gid in Linux (input data files are in the same format as /etc/passwd and /etc/group)

•      Gain familiarity with development and testing of C++ programs

•      Understand concepts of stream and file processing.

•      Review basics of problem solving

•      Understand the use of std::unordered_map 
 

Submission Instructions

 

This part of the homework assignment must be turned-in electronically via Canvas using the

without any warnings or style violations
CODE plugin. See video for using the plug-in at: https://youtu.be/P2bWUt5KqbU. Ensure your program compiles . Ensure you have tested operations of your program as indicated. Once you have tested your implementation, upload the following onto Canvas:

• Just the one C++ source file with the naming convention MUID_hw2.cpp, where MUID is your Miami University unique ID.

 

General Note: Upload each file associated with homework (or lab exercises) individually to Canvas. Do not upload archive file formats such as zip/tar/gz/7zip/rar etc.

 
 

Grading Rubric:

The programs submitted for this homework must pass necessary base case test(s) in order to qualify for earning any score at all. Programs that do not meet base case requirements will be assigned zero score!

Program that do not compile, have a method longer than 25 lines, or

                               just some skeleton code will be assigned zero score.
 

•      Base case points: 15 points • Additional tests: 10 points

•
Overall code quality, design, code reuse, docum
 
are typically the hardest to earn in more advanced courses.
entation etc.: 5 points. These points

 

•      -1 Points: for each warning generated by the compiler (warnings are most likely sources of errors in C++ programs)

•      -1 Points: for each style violation in the programs reported by CSE department's C++ style checker. Ensure you use correct Miami University C++ Project setting in NetBeans.

 

Develop program to print group membership
Objective
The objective of this program is to print login-IDs of the users belonging to a given set of gids specified as command-line arguments. The necessary data is read from 2 given text files.

Background
In Linux, users are internally represented using a unique number called user ID of uid. Moreover, a set of users can be logically organized into a group. Such groups are represented by a group ID or gid. Typically, these numbers are seldom used and instead a name is associated with these numbers and the names are often used. This program will serve as an excellent tool to quickly identify membership in a given group.

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 used are nearly in the same format as they are in a real Linux OS as described below. Needless to add, you will need to copy these files to your NetBeans project in order to read/use them.

 

•      User data (passwd): The supplied passwd file contains user information in the following colon (:) delimited format:

loginID:passkey:uid:…

For example the following line from passwd  "raodm:xyz:1000:…" contains the login ID raodm as the first entry, xyz is some passkey (not used) followed by the uid (int). Rest of the information in the line is not used. 

 

•      Group information (groups): The supplied groups file contains group information in the following colon (:) delimited format:

groupID:passkey:gid:members…

For example the following line from groups "staff:x123:3:1002,1000" contains the group ID staff as the first entry, x123 is some passkey (not used)

followed by the gid (int), followed by a comma separated list of uids. This results in

group corresponding to output "3 = staff:  lewisjp3(1002) raodm(1000)", where the uid for each member is shown in parentheses.

             

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 group IDs are 

 

Base case #1:

$ ./raodm_hw2 0

0 = root: root(0)

 

Base case #2:

$ ./raodm_hw2 1 1 = bin:

 

 

Test case #3 [Must pass to earn full points]:

$ ./raodm_hw2 100

100 = Group not found.

 

 

Test case #4 [Must pass to earn full points]:

$ ./raodm_hw2 0 1 2 6 100 6 2 0 = root: root(0) 1 = bin:

2 = faculty: raodm(1000) campbest(1001) kiperjd(1003) raychov(1004) bachmaer(2000) inclezd(1500) davisk4(2001) femianjc(2002) crossv(2010) castroa(2011) ahmede(2012)

6 = theory: davisk4(2001) inclezd(1500) raychov(1004) femianjc(2002)

100 = Group not found.

6 = theory: davisk4(2001) inclezd(1500) raychov(1004) femianjc(2002) 2 = faculty: raodm(1000) campbest(1001) kiperjd(1003) raychov(1004) bachmaer(2000) inclezd(1500) davisk4(2001) femianjc(2002) crossv(2010) castroa(2011) ahmede(2012) 
 

Notes/Tips:

•      Use std::istringstream to process each line. See example in slides on processing Comma Separated Values (in this example, instead of comma you are using colons)

•      Use a unordered_map to store uid⇔loginID information to ease look-up from processing group membership.

•      It would be easier to compute and store the line of output to print for each gid in another unordered_map.

 

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. Once you have tested your implementation, upload just one C++ source file via the CODE plugin.