Truncate slice when reading yaml file to unmarshal it

I am faced with the following issue:

I am using go-git to checkout a repo in memory.

I am then opening a file using the billy package and reading it in a byte slice (since it implements the io.Reader interface)

file, err := fs.Open("releases/redash.yaml")

	if err != nil {

	data := make([]byte, 10000)
	_, err = file.Read(data)
	if err != nil {
		log.Fatalf("ERROR reading file")
	err = yaml.Unmarshal(data, &v)
	if err != nil {
		log.Fatalf("ERROR Unmarshaling yaml\n", err)

The above fails:

2020/02/06 12:58:45 ERROR Unmarshaling yaml
yaml: control characters are not allowed
exit status 1

From what I understand, this is due to the data buffer having extra / zero-valued characters which yaml tries to incorporate and throws error.

Given that billy.File will not allow me to use ioutil.ReadFile against it, is there a way to address this problem? (say by trimming data to the appropriate length? - I am unable to know in advance the EXACT file length so as to instantiate an appropriately sized buffer)

How do you know that? Which characters are they?

If i fmt.Println(data) I get numerous 0 at the end.

I was also hinted towards this direction by this SO post.

file.Read will return the number of bytes read which you ignore. This information should help you to pass the appropriate slice of data to yaml.Unmarshal.

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Can you provide an example how to use fileRead. The link you posted to io.Reader does not include such a method (unless I am missed it)

Nevermind, got it

	data := make([]byte, 10000)
	n, err := file.Read(data)
	data = data[:n]
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You might enjoy ioutil.ReadFile or ioutil.ReadAll.

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