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package filesystem
import (
"io"
"os"
"path"
"github.com/go-git/go-git/v5/plumbing"
"github.com/go-git/go-git/v5/plumbing/filemode"
"github.com/go-git/go-git/v5/utils/merkletrie/noder"
"github.com/go-git/go-billy/v5"
)
var ignore = map[string]bool{
".git": true,
}
// The node represents a file or a directory in a billy.Filesystem. It
// implements the interface noder.Noder of merkletrie package.
//
// This implementation implements a "standard" hash method being able to be
// compared with any other noder.Noder implementation inside of go-git.
type node struct {
fs billy.Filesystem
submodules map[string]plumbing.Hash
path string
hash []byte
children []noder.Noder
isDir bool
mode os.FileMode
size int64
}
// NewRootNode returns the root node based on a given billy.Filesystem.
//
// In order to provide the submodule hash status, a map[string]plumbing.Hash
// should be provided where the key is the path of the submodule and the commit
// of the submodule HEAD
func NewRootNode(
fs billy.Filesystem,
submodules map[string]plumbing.Hash,
) noder.Noder {
return &node{fs: fs, submodules: submodules, isDir: true}
}
// Hash the hash of a filesystem is the result of concatenating the computed
// plumbing.Hash of the file as a Blob and its plumbing.FileMode; that way the
// difftree algorithm will detect changes in the contents of files and also in
// their mode.
//
// Please note that the hash is calculated on first invocation of Hash(),
// meaning that it will not update when the underlying file changes
// between invocations.
//
// The hash of a directory is always a 24-bytes slice of zero values
func (n *node) Hash() []byte {
if n.hash == nil {
n.calculateHash()
}
return n.hash
}
func (n *node) Name() string {
return path.Base(n.path)
}
func (n *node) IsDir() bool {
return n.isDir
}
func (n *node) Skip() bool {
return false
}
func (n *node) Children() ([]noder.Noder, error) {
if err := n.calculateChildren(); err != nil {
return nil, err
}
return n.children, nil
}
func (n *node) NumChildren() (int, error) {
if err := n.calculateChildren(); err != nil {
return -1, err
}
return len(n.children), nil
}
func (n *node) calculateChildren() error {
if !n.IsDir() {
return nil
}
if len(n.children) != 0 {
return nil
}
files, err := n.fs.ReadDir(n.path)
if err != nil {
if os.IsNotExist(err) {
return nil
}
return err
}
for _, file := range files {
if _, ok := ignore[file.Name()]; ok {
continue
}
if file.Mode()&os.ModeSocket != 0 {
continue
}
c, err := n.newChildNode(file)
if err != nil {
return err
}
n.children = append(n.children, c)
}
return nil
}
func (n *node) newChildNode(file os.FileInfo) (*node, error) {
path := path.Join(n.path, file.Name())
node := &node{
fs: n.fs,
submodules: n.submodules,
path: path,
isDir: file.IsDir(),
size: file.Size(),
mode: file.Mode(),
}
if _, isSubmodule := n.submodules[path]; isSubmodule {
node.isDir = false
}
return node, nil
}
func (n *node) calculateHash() {
if n.isDir {
n.hash = make([]byte, 24)
return
}
mode, err := filemode.NewFromOSFileMode(n.mode)
if err != nil {
n.hash = plumbing.ZeroHash[:]
return
}
if submoduleHash, isSubmodule := n.submodules[n.path]; isSubmodule {
n.hash = append(submoduleHash[:], filemode.Submodule.Bytes()...)
return
}
var hash plumbing.Hash
if n.mode&os.ModeSymlink != 0 {
hash = n.doCalculateHashForSymlink()
} else {
hash = n.doCalculateHashForRegular()
}
n.hash = append(hash[:], mode.Bytes()...)
}
func (n *node) doCalculateHashForRegular() plumbing.Hash {
f, err := n.fs.Open(n.path)
if err != nil {
return plumbing.ZeroHash
}
defer f.Close()
h := plumbing.NewHasher(plumbing.BlobObject, n.size)
if _, err := io.Copy(h, f); err != nil {
return plumbing.ZeroHash
}
return h.Sum()
}
func (n *node) doCalculateHashForSymlink() plumbing.Hash {
target, err := n.fs.Readlink(n.path)
if err != nil {
return plumbing.ZeroHash
}
h := plumbing.NewHasher(plumbing.BlobObject, n.size)
if _, err := h.Write([]byte(target)); err != nil {
return plumbing.ZeroHash
}
return h.Sum()
}
func (n *node) String() string {
return n.path
}
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