Add FileSystem support

[amenzhinsky]

Hi there!

In some cases it would be really helpful to have possibility to use custom FS for opening files.
The best example is go-bindata integration when we need to embed file assets in go binary.

type BindataFS struct{}

// Open opens the named file
func (fs *BindataFS) Open(name string) (http.File, error) {
	b, err := bindata.Asset(name)
	if err != nil {
		return nil, err
	}

	return &file{
		Reader: bytes.NewReader(b),
		name:   name,
	}, nil
}

type file struct {
	*bytes.Reader
	name string
}

func (f *file) Close() error {
	return nil
}

func (f *file) Stat() (os.FileInfo, error) {
	return bindata.AssetInfo(f.name)
}

func (f *file) Readdir(count int) ([]os.FileInfo, error) {
	return nil, nil
}

Then we just change our filesystem and it works like a charm!

e := echo.New()
e.FS = &BindataFS{}

[coveralls]

Coverage increased (+0.007%) to 85.256% when pulling 04dc4b9 on amenzhinsky:fs into a8b6864 on labstack:master.

[amenzhinsky]

I'm not sure about the FS default value e.FS = http.Dir(".") because we won't be able to serve files outside of cwd, but at the same time this is a security enhancement.

func fileHandler(c echo.Context) error {
	return c.File("/etc/passwd") // won't work
}

If someone needs to make it work, FS has to be changed to Dir("/") or it can be default value.

[vishr]

@amenzhinsky Like you mentioned, people won't be able to serve files outside cwd, I think it is a breaking change. Even in our test cases we are using relative path, which actually failed.

[coveralls]

Coverage increased (+0.03%) to 84.701% when pulling e9eeddf on amenzhinsky:fs into 7a858a7 on labstack:master.

[amenzhinsky]

@vishr added generic FS implementation, which is basically wrapper of os.Open, please have a look.

[coveralls]

Coverage increased (+0.03%) to 84.701% when pulling 1ce8e18 on amenzhinsky:fs into 7a858a7 on labstack:master.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.