Homework #2 Print login-IDs

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

Maximum Points for This Part: 30
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
CODE plugin. See video for using the plug-in at: https://youtu.be/P2bWUt5KqbU. Ensure your
program compiles without any warnings or style violations. 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, documentation etc.: 5 points. These points
are typically the hardest to earn in more advanced courses.
• -1 Points: for each warning generated by the compiler (warnings are most likely sources
of errors in C++ programs)
DUE DATE: Tue, September 18 2018 Before 11:59 PM (EST)
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• -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.
DUE DATE: Tue, September 18 2018 Before 11:59 PM (EST)
Page 3 of 3
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.