feat: Introduce .kraftignore

[MdSahil-oss]

Prerequisite checklist

• Read the contribution guidelines regarding submitting new changes to the project;
• Tested your changes against relevant architectures and platforms;
• Ran make fmt on your commit series before opening this PR;
• Updated relevant documentation.

Description of changes

This PR fixes #135

Specifying contents (file or directory paths) in .kraftignore file in the working directory forces Kraftkit to ignore matching children files or directories sharing from the sharing directory as rootfs.

For now, .kraftignore only work when rootfs is specified for a directory path.

Rules for .kraftignore:

• Line starts with a # will be ignored by Kraftkit.

• Every blank line will be ignored by Kraftkit.

• Directory or File path that contains glob-patterns (characters like *, !, [ and ?) will be ignored by Kraftkit and return a warning message.

• File or Directory name can be enclosed by single or double quotes ('filename', "dir_name").

• File or Directory names which contain white spaces must be enclosed by single or double quotes. e.g.

  "sample file"
  'sample new file'

• One needs to specify the entire relative path (relative path to the sharing directory e.g. if rootfs=share/ and share directory contains sample.txtand sample/, So relative path in .kraftignore file can be defined as /sample.txt, sample.txt and ./sample.txt for share/sample.txt to ignore) of the file or directory that have to be ignored.

• Various directory and file paths can be specified in a .kraftignore file using space separator or new line e.g.

  random1/random01/random01.txt /random.txt
  
  random1/random01

• All the specified paths in .kraftignore will be relative to the root of sharing directory, means if share/ directory contains sample.txt and sample/, and set as rootfs to kraftkit then to ignore /share/sample.txt only sample.txt needs to be defined in kraftignore.
  Note: All the paths can start with ./ or / (Since prefix / and ./ with paths simply ignored by Kraftkit).

[craciunoiuc]

Some initial comments from my side, did not try out the code yet

[craciunoiuc]

I think we also need to document this somewhere otherwise it will be lost

@nderjung do you have a use case in mind? maybe an app which would currently benefit from .kraftignore?

[craciunoiuc]

Hey @MdSahil-oss found 1 small bug but otherwise it seems to work:

test.txt <-- works (ignored)

# test1.txt <-- works (not ignored)

nginx/test3.txt    #       test2.txt  <-- works (both ignored, basically # was ignored)

test.txt <-- works (nothing changed)

# test.txt <-- works (nothing changed)

./nginx <-- works (ignored)

./nginx/* <-- works (prints warning)

.///////////////////nginx <-- fails (multiple slashes are usually ignored)
./nginx/../test1.txt <-- fails (I think .. is not understood)
././././././././././././test1.txt <-- fails (I think . is not understood)

[craciunoiuc]

One more thing: does it support using "" or '' characters? I was thinking about the case of "./nginx/strange test.txt"

[craciunoiuc]

The code looks okay, waiting on your response for the comments above

[MdSahil-oss]

Hey @MdSahil-oss found 1 small bug but otherwise it seems to work:

test.txt <-- works (ignored)

# test1.txt <-- works (not ignored)

nginx/test3.txt    #       test2.txt  <-- works (both ignored, basically # was ignored)

test.txt <-- works (nothing changed)

# test.txt <-- works (nothing changed)

./nginx <-- works (ignored)

./nginx/* <-- works (prints warning)

.///////////////////nginx <-- fails (multiple slashes are usually ignored)
./nginx/../test1.txt <-- fails (I think .. is not understood)
././././././././././././test1.txt <-- fails (I think . is not understood)

Nice catch @craciunoiuc, I will work on your suggestions

[MdSahil-oss]

One more thing: does it support using "" or '' characters? I was thinking about the case of "./nginx/strange test.txt"

Don't think so, I will update this PR for these characters.

[craciunoiuc]

Hey @MdSahil-oss, some more comments from my side

[craciunoiuc]

Same here, I don't think we should trim this, but rather what I would do would be:

1. Find the full path of the initrd directory
2. Append the file path to the initrd directory
3. Check if it evaluates to a valid file, if yes, trim 1. from it and use that given path, if not, ignore

This goes for the whole file parsing logic

[MdSahil-oss]

Updated the logic to work in your recommended way, Please review again.

But still removing ../ if item (a path mentioned in .kraftignore) contains ../ as prefix because path inside rootfs which starts ../xyz refer to the file/dir outside of rootfs dir.

I hope this make sense to you otherwise ping me again ;)

[nderjung]

Hi @MdSahil-oss! Thanks so much for this contribution, I think it's a valuable addition to the usability of kraft! I've left you some feedback as in-line comments below. Overall, the implementation looks good.

[nderjung]

Same here, we can declare these as errors:

var (
  ErrFileExists    = fmt.Errorf("file exists")
  ErrFileNotExists = fmt.Errorf("filt does not exist")
  ErrIgnoreDir     = fmt.Errorf("ignored directory")
)

[nderjung]

You can then do comparisons via:

if errors.Is(err, ErrFileExists)

[MdSahil-oss]

Surely, It can be done. But kraftiignore.go not uses these vars as errors, These vars are being used as notifiers for filepath.WalkDir() function in directory.go.

Please have an eye on filepath.WalkDir() function then lemme know if you really want me to change const vars as error vars :)