myls Project
COP-3402

Overview
Input
Output
System call and library references
Submitting your project
Troubleshooting
Grading schema

Overview

In this project, you will develop a simple version of an ls-style command that lists the contents of a given directory.

Input

USAGE: ./myls [dir]

The program should be called myls. It only takes a single argument, which is optional. The argument is the path to a directory, either relative or absolute. If a directory is not provided, use the current working directory, i.e., ".", the dot directory.

Output

Error handling

If the input directory is not accessible (due to non-existence, permissions, etc.), then exit with error code EXIT_FAILURE (stdlib.h).
- How can you tell that the directory failed to open?

Output contents

For each entry in the directory (including hidden files, ., and ..), print the following information

The name of the file in the directory (not including its full path, just the from the directory entry)
The number of hard links to the file (from stat)
The type of file (from stat), which is one of the following, corresponding the S_IFMT names without the S_IF prefix:
- REG
- DIR
- SOCK
- LNK
- BLK
- CHR
- FIFO
The size of the file, which is either
- The number of directory entries if the file itself is a directory (S_IFDIR). Put "unknown" if the directory is inaccessible.
- The total size (from stat), in bytes, of the file for all other types
If the file is a regular file (S_IFREG), then a preview of the file, consisting of the first 16 characters of the file (or the whole file if it is less than 16 characters), with spaces replacing any non-printable or non-ASCII characters.

Output format

Column	Contents	Format string
1	name	"%16.16s\t"
2	# hard links	"%" PRIdMAX "\t"
3	type	String literals
4	size	"%" PRIdMAX "\t"
5	preview	"%s"

Notes:

PRIdMAX is a macro containing the format string for the maxmimum integer size and can be included with #include <inttypes.h>
For type, use the literal strings as given in Output contents, following by a "\t".

Example output

wget https://www.cs.ucf.edu/~gazzillo/teaching/cop3402fall24/files/myls_example.tar
tar -xvf myls_example.tar

We can inspect the contents of the directory:

ls -a myls_example/contents/

Output:

.  ..  lorem.txt  message.png  message.txt  subdir

We can run our myls program on the directory :

./myls myls_example/contents/

Output:

          .	3	DIR	6	
         ..	3	DIR	3	
message.txt	1	REG	6	hello 
  lorem.txt	1	REG	738	Lorem ipsum dolo
     subdir	2	DIR	3	
message.png	1	REG	865	 PNG        IHDR

Try also testing on /dev/ to see more file types:

./myls /dev

System call and library references

Do not use helper libraries or other simplified calls to achieve similar results as functions below. Just use the syscalls below for these aspects of the project.

Symbol	Reference	Reading
opendir()	`man 3 opendir`	LPI 18.8
readdir()	`man 3 readdir`
closedir()	`man 3 closedir`
stat()	`man 2 stat`	LPI 15.1
struct stat	`man 2 stat`
st_mode	`man 7 inode`
open()	`man 2 open`	LPI 4.1
read()	`man 2 read`
close()	`man 2 close`
perror()	`man 3 perror`	LPI 3.4
exit(EXIT_FAILURE)	`man 3 exit`

man is the command-line manual.
LPI is The Linux Program Interface book.
Knowledge of memory management and string processing is assumed.

Submitting your project

Setup the repo

ssh into eustis, replacing NID with your UCF NID.
```
ssh NID@eustis.eecs.ucf.edu
```

Create a new git repo

cd ~
mkdir myls
cd myls/
git init
echo "myls" > README
git add README
git commit -m "initial commit" README

Add the URL of your personal remote repository, replacing NID with your UCF NID.
```
git remote add submission gitolite3@eustis3.eecs.ucf.edu:cop3402/NID/myls
```
Synchronize your local repo with the remote eustis3 repo.
```
git push --set-upstream submission master
```

Keeping your repository up to date

Use git commit and git push regularly to keep the remote repo up to date.

Building and running the tool

Your project should be buildable with make and runnable with ./myls, both from the root of your repo, i.e.,

make
./myls

Create a Makefile that will build your project and give the resulting program the name myls.

Self-check

cd ~
git clone gitolite3@eustis3.eecs.ucf.edu:cop3402/NID/myls myls_new
cd myls_new
make
wget https://www.cs.ucf.edu/~gazzillo/teaching/cop3402fall24/files/myls_example.tar
tar -xvf myls_example.tar
./myls myls_example/contents/

Troubleshooting

If you make a mistake in typing the URL, you can remove the submission remote and try the add step again:

This will show what the current remote URL is:
```
git remote -v
```
This will remove the remote:
```
git remote rm submission
```
Then try re-adding the remote:
```
git remote add submission gitolite3@eustis3.eecs.ucf.edu:cop3402/NID/myls
```
And see if push will work now:
```
git push --set-upstream submission master
```
Do not try creating a new repo if you make a mistake. You will not be able to push the new repo to gitolite3, since there already is one there. You can always make new changes and commit them to fix mistakes.

Grading schema

Criterion	Points
The git repo exists	1
The program is written, builds, and runs as described here	1
Prorated lines correct for public test cases	2
Prorated lines correct for private test cases	2
TOTAL	6

myls Project COP-3402

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