Function newBasicFilesystem

lib/fs/basicfs.go:68–113

(root string, opts ...Option)

}

func newBasicFilesystem(root string, opts ...Option) *BasicFilesystem {
	if root == "" {
		root = "." // Otherwise "" becomes "/" below
	}

	// The reason it's done like this:
	// C:          ->  C:\            ->  C:\        (issue that this is trying to fix)
	// C:\somedir  ->  C:\somedir\    ->  C:\somedir
	// C:\somedir\ ->  C:\somedir\    ->  C:\somedir
	// This way in the tests, we get away without OS specific separators
	// in the test configs.
	sep := string(filepath.Separator)
	root = filepath.Clean(filepath.Dir(root + sep))

	// Attempt tilde expansion; leave unchanged in case of error
	if path, err := ExpandTilde(root); err == nil {
		root = path
	}

	// Attempt absolutification; leave unchanged in case of error
	if !filepath.IsAbs(root) {
		// Abs() looks like a fairly expensive syscall on Windows, while
		// IsAbs() is a whole bunch of string mangling. I think IsAbs() may be
		// somewhat faster in the general case, hence the outer if...
		if path, err := filepath.Abs(root); err == nil {
			root = path
		}
	}

	// Attempt to enable long filename support on Windows. We may still not
	// have an absolute path here if the previous steps failed.
	if build.IsWindows {
		root = longFilenameSupport(root)
	}

	fs := &BasicFilesystem{
		root:       root,
		options:    opts,
		userCache:  newValueCache(time.Hour, user.LookupId),
		groupCache: newValueCache(time.Hour, user.LookupGroupId),
	}
	for _, opt := range opts {
		opt.apply(fs)
	}
	return fs
}

// rooted expands the relative path to the full path that is then used with os
// package. If the relative path somehow causes the final path to escape the root