The test result with only 42 lines of code:

$ ./Path 
TEST1: /a/b/c/d/e.ext
TOT DIR: 4
a/b/c/d
ARCH:e.ext
PATH:/a/b/c/d/e.ext

TEST2: /a/b//c/e.ext
TOT DIR: 3
a/b/c
ARCH:e.ext
PATH:/a/b/c/e.ext

TEST3: /a/b///c/e.ext
TOT DIR: 3
a/b/c
ARCH:e.ext
PATH:/a/b/c/e.ext

TEST4: /a/b/./c/d/e/../../f/g/e.ext
TOT DIR: 5
a/b/c/f/g
ARCH:e.ext
PATH:/a/b/c/f/g/e.ext

TEST5: /a/b/c////d/e/f/g/../../../../../../../../../../../h/e.ext
TOT DIR: 1
h
ARCH:e.ext
PATH:/h/e.ext

SETBASE: x/y/z

TEST6: /a/b/c////d/e/f/g/../../../../../../../../../../../h/e.ext
TOT DIR: 1
h
ARCH:e.ext
PATH:/x/y/z/h/e.ext

• Work with root directory or relative directory.

• Trace link without leaving the root directory.

• Open the file according to arranged mode.

I have solved it in a simple way, and much shorter than the previous time.

I have designed it not to leave the root directory in each workspace. That way I can make each user have different work areas at the same time.