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0x00-ls

README.md

(308) 0x00. C - ls

Specializations > System programming & Algorithm > Linux Programming

Project author

Wilfried Hennuyer

Assignment dates

11-30-2020 to 12-04-2020

Description

Building a clone of the Linux function ls.

Requirements

  • Allowed Functions and System Calls
         
opendir(3) readdir(3) closedir(3) exit(3) free(3)
lstat(2) malloc(3) perror(3) write(2) printf(3)
sprintf(3) fprintf(3) readlink(2) ctime(3) getpwuid(3)
getgrgid(3) errno(3)
  • Compiled: gcc -Wall -Werror -Wextra -pedantic *.c -o hls
  • Your program should give the same result as the real ls:
$ ls test
abc  BCD  file  file2  file3  folder1  folder2  folder3
$ ./hls test
abc  BCD  file  file2  file3  folder1  folder2  folder3
$ ls -1
abc
BCD
file
file2
file3
folder1
folder2
folder3
hls
$ ./hls -1
abc
BCD
file
file2
file3
folder1
folder2
folder3
hls
$
  • For all tasks of this project, unless explicitly said otherwise:
    • You don’t have to worry about the spacing
    • You don’t have to worry about the sorting

Mandatory Tasks

⬜ 0. Let's start with something simple!

Create a program that lists the content of the current directory.

  • Usage: hls

⬜ 1. Maybe some parameters?

Your program should now take one or more file or directory names as parameters.

  • Usage: hls [FILE]...
  • Errors must be printed the same way than ls does:
    • In stderr
    • Starting by <program>: (<program> being argv[0])
    • No such file or directory, Permission denied, etc…
    • Don’t forget the exit value
$ ls
abc  file  File2  file3  folder1  Folder2  folder3  hls
$ ./hls
abc  file  File2  file3  folder1  Folder2  folder3  hls
$

⬜ 2. What about options?

Implement the -1 option.

  • Usage: hls [-1] [FILE]...
  • For the rest of the project, an option will be identified by a command-line argument starting with the character - (like ls).
  • Pay attention to “edge cases”: you should be able to handle multiple options, in any order.
$ ls test
abc  file  File2  file3  folder1  Folder2  folder3
$ ./hls test
abc  file  File2  file3  folder1  Folder2  folder3
$ ./hls test/folder1/ test
test:
abc  file  File2  file3  folder1  Folder2  folder3

test/folder1/:
folder1-1  folder1-2  folder1-3
/simple_ls$ ./hls test/random
./hls: cannot access test/random: No such file or directory
$

✅ 3. Hidden files

Implement the -a option.

  • Usage: hls [-a1] [FILE]...
$ ls test -1
abc
file
File2
file3
folder1
Folder2
folder3
$ ./hls test -1
abc
file
File2
file3
folder1
Folder2
folder3
$

✅ 4. Almost all

Implement the -A option.

  • Usage: hls [-A] [FILE]...
$ ls -a test
.  ..  abc  file  File2  file3  folder1  Folder2  folder3  .hidden1  .hidden2  ..hidden3
$ ./hls -a test
.  ..  abc  file  File2  file3  folder1  Folder2  folder3  .hidden1  .hidden2  ..hidden3
$ ./hls -a test/folder1
.  ..  folder1-1  folder1-2  folder1-3
$

✅ 5. More details

Implement the -l option.

  • Usage: hls [-l] [FILE]...
  • You might notice the total XX in the first line of ls -l. You can ignore this value for this exercise.
  • Pay attention to “edge cases”: Usernames and group names are not always defined.
$ ls -l test
total 12
-rw-rw-r-- 1 vagrant vagrant    0 May  8 00:19 abc
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 File2
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file3
drwxrwxr-x 5 vagrant vagrant 4096 Apr 30 15:22 folder1
drwxrwxr-x 2 vagrant vagrant 4096 May  7 15:36 Folder2
drwxrwxr-x 3 vagrant vagrant 4096 May  7 15:37 folder3
$ ./hls -l test
-rw-rw-r-- 1 vagrant vagrant    0 May  8 00:19 abc
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 File2
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file3
drwxrwxr-x 5 vagrant vagrant 4096 Apr 30 15:22 folder1
drwxrwxr-x 2 vagrant vagrant 4096 May  7 15:36 Folder2
drwxrwxr-x 3 vagrant vagrant 4096 May  7 15:37 folder3
$

Advanced Tasks

✅ 6. Mixing options

All options together.

  • Usage: hls [-1aAl] [FILE]...
$ ./hls -lA test
-rw-rw-r-- 1 vagrant vagrant    0 May  8 00:19 abc
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 File2
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file3
drwxrwxr-x 5 vagrant vagrant 4096 Apr 30 15:22 folder1
drwxrwxr-x 2 vagrant vagrant 4096 May  7 15:36 Folder2
drwxrwxr-x 3 vagrant vagrant 4096 May  7 15:37 folder3
-rw-rw-r-- 1 vagrant vagrant    0 Apr 30 16:30 .hidden1
-rw-rw-r-- 1 vagrant vagrant    0 Apr 30 16:30 .hidden2
-rw-rw-r-- 1 vagrant vagrant    0 Apr 30 17:08 ..hidden3
$ ./hls -lA -a test
drwxrwxr-x 5 vagrant vagrant 4096 May  8 01:12 .
drwxrwxr-x 4 vagrant vagrant 4096 May 15 11:51 ..
-rw-rw-r-- 1 vagrant vagrant    0 May  8 00:19 abc
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 File2
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file3
drwxrwxr-x 5 vagrant vagrant 4096 Apr 30 15:22 folder1
drwxrwxr-x 2 vagrant vagrant 4096 May  7 15:36 Folder2
drwxrwxr-x 3 vagrant vagrant 4096 May  7 15:37 folder3
-rw-rw-r-- 1 vagrant vagrant    0 Apr 30 16:30 .hidden1
-rw-rw-r-- 1 vagrant vagrant    0 Apr 30 16:30 .hidden2
-rw-rw-r-- 1 vagrant vagrant    0 Apr 30 17:08 ..hidden3
$ ./hls -1A test
abc
file
File2
file3
folder1
Folder2
folder3
.hidden1
.hidden2
..hidden3
$

✅ 7. Esrever

Implement the -r option.

  • Usage: hls [-1aAlr] [FILE]...
$ ./hls test
abc file File2 file3 folder1 Folder2 folder3
$ ./hls test -r
folder3  Folder2  folder1  file3  File2  file  abc
$ ./hls test/folder1/ test/folder3/ -r
test/folder3/:
symlink  folder3-1  file2  file1

test/folder1/:
folder1-3  folder1-2  folder1-1
$

✅ 8. More sorting?

Implement the -S option. Usage: hls [-1aAlrS] [FILE]...

$ ./hls -l test
-rw-rw-r-- 1 vagrant vagrant    0 May 16 12:36 abc
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 File2
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file3
drwxrwxr-x 5 vagrant vagrant 4096 Apr 30 15:22 folder1
drwxrwxr-x 2 vagrant vagrant 4096 May  7 15:36 Folder2
drwxrwxr-x 3 vagrant vagrant 4096 May  7 15:37 folder3
$ ./hls -lS test
drwxrwxr-x 5 vagrant vagrant 4096 Apr 30 15:22 folder1
drwxrwxr-x 2 vagrant vagrant 4096 May  7 15:36 Folder2
drwxrwxr-x 3 vagrant vagrant 4096 May  7 15:37 folder3
-rw-rw-r-- 1 vagrant vagrant    0 May 16 12:36 abc
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 File2
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file3
$ ./hls -lSr test
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file3
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 File2
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file
-rw-rw-r-- 1 vagrant vagrant    0 May 16 12:36 abc
drwxrwxr-x 3 vagrant vagrant 4096 May  7 15:37 folder3
drwxrwxr-x 2 vagrant vagrant 4096 May  7 15:36 Folder2
drwxrwxr-x 5 vagrant vagrant 4096 Apr 30 15:22 folder1
$

✅ 9. I know you like sorting things.

Implement the -t option.

  • Usage: hls [-1aAlrSt] [FILE]...
$ ./hls -l test
-rw-rw-r-- 1 vagrant vagrant    0 May 16 12:36 abc
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 File2
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file3
drwxrwxr-x 5 vagrant vagrant 4096 Apr 30 15:22 folder1
drwxrwxr-x 2 vagrant vagrant 4096 May  7 15:36 Folder2
drwxrwxr-x 3 vagrant vagrant 4096 May  7 15:37 folder3
$ ./hls -lt test
-rw-rw-r-- 1 vagrant vagrant    0 May 16 12:36 abc
drwxrwxr-x 3 vagrant vagrant 4096 May  7 15:37 folder3
drwxrwxr-x 2 vagrant vagrant 4096 May  7 15:36 Folder2
drwxrwxr-x 5 vagrant vagrant 4096 Apr 30 15:22 folder1
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file3
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 File2
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file
$ ./hls -ltr test
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 File2
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file3
drwxrwxr-x 5 vagrant vagrant 4096 Apr 30 15:22 folder1
drwxrwxr-x 2 vagrant vagrant 4096 May  7 15:36 Folder2
drwxrwxr-x 3 vagrant vagrant 4096 May  7 15:37 folder3
-rw-rw-r-- 1 vagrant vagrant    0 May 16 12:36 abc
$

✅ 10. The Juggernaut

Implement the -R option.

  • Usage: hls [-1aAlrStR] [FILE]...
$ ./hls -R test
test:
abc  ABC  file  File2  file3  folder1  Folder2  folder3

test/folder1:
folder1-1  folder1-2  folder1-3

test/folder1/folder1-1:
file1  file2  file3

test/folder1/folder1-2:
file1

test/folder1/folder1-3:
file1  file2

test/Folder2:
file1  file2

test/folder3:
file1  file2  folder3-1  symlink

test/folder3/folder3-1:
file1  folder3-1-1

test/folder3/folder3-1/folder3-1-1:
file1  file2
$ ./hls -Rl test
test:
-rw-rw-r-- 1 vagrant vagrant    0 May 16 12:36 abc
-rw-rw-r-- 1 vagrant vagrant    0 May  8 00:19 ABC
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 File2
-rw-rw-r-- 1 vagrant vagrant    0 Apr 18 14:04 file3
drwxrwxr-x 5 vagrant vagrant 4096 Apr 30 15:22 folder1
drwxrwxr-x 2 vagrant vagrant 4096 May  7 15:36 Folder2
drwxrwxr-x 3 vagrant vagrant 4096 May  7 15:37 folder3

test/folder1:
drwxrwxr-x 2 vagrant vagrant 4096 Apr 30 14:59 folder1-1
drwxrwxr-x 2 vagrant vagrant 4096 Apr 30 14:59 folder1-2
drwxrwxr-x 2 vagrant vagrant 4096 Apr 30 14:59 folder1-3

test/folder1/folder1-1:
-rw-rw-r-- 1 vagrant vagrant 0 Apr 30 14:59 file1
-rw-rw-r-- 1 vagrant vagrant 0 Apr 30 14:59 file2
-rw-rw-r-- 1 vagrant vagrant 0 Apr 30 14:59 file3

test/folder1/folder1-2:
-rw-rw-r-- 1 vagrant vagrant 0 Apr 30 14:59 file1

test/folder1/folder1-3:
-rw-rw-r-- 1 vagrant vagrant 0 Apr 30 14:59 file1
-rw-rw-r-- 1 vagrant vagrant 0 Apr 30 14:59 file2

test/Folder2:
-rw-rw-r-- 1 vagrant vagrant 0 Apr 30 14:59 file1
-rw-rw-r-- 1 vagrant vagrant 0 May  7 15:36 file2

test/folder3:
-rw-rw-r-- 1 vagrant vagrant    0 Apr 30 15:03 file1
-rw-rw-r-- 1 vagrant vagrant    0 Apr 30 15:03 file2
drwxrwxr-x 3 vagrant vagrant 4096 Apr 30 15:22 folder3-1
lrwxrwxrwx 1 vagrant vagrant    5 May  8 00:01 symlink -> file2

test/folder3/folder3-1:
-rw-rw-r-- 1 vagrant vagrant    0 Apr 30 15:03 file1
drwxrwxr-x 2 vagrant vagrant 4096 Apr 30 15:03 folder3-1-1

test/folder3/folder3-1/folder3-1-1:
-rw-rw-r-- 1 vagrant vagrant 0 Apr 30 15:03 file1
-rw-rw-r-- 1 vagrant vagrant 0 Apr 30 15:03 file2
$

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