mirror of
https://github.com/genuinetools/reg.git
synced 2024-08-21 14:20:23 -04:00
277 lines
5.8 KiB
Go
277 lines
5.8 KiB
Go
package fs
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import (
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"bytes"
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"context"
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"io"
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"os"
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"path/filepath"
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"strings"
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"github.com/pkg/errors"
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)
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var (
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errTooManyLinks = errors.New("too many links")
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)
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type currentPath struct {
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path string
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f os.FileInfo
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fullPath string
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}
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func pathChange(lower, upper *currentPath) (ChangeKind, string) {
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if lower == nil {
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if upper == nil {
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panic("cannot compare nil paths")
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}
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return ChangeKindAdd, upper.path
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}
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if upper == nil {
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return ChangeKindDelete, lower.path
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}
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// TODO: compare by directory
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switch i := strings.Compare(lower.path, upper.path); {
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case i < 0:
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// File in lower that is not in upper
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return ChangeKindDelete, lower.path
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case i > 0:
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// File in upper that is not in lower
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return ChangeKindAdd, upper.path
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default:
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return ChangeKindModify, upper.path
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}
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}
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func sameFile(f1, f2 *currentPath) (bool, error) {
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if os.SameFile(f1.f, f2.f) {
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return true, nil
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}
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equalStat, err := compareSysStat(f1.f.Sys(), f2.f.Sys())
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if err != nil || !equalStat {
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return equalStat, err
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}
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if eq, err := compareCapabilities(f1.fullPath, f2.fullPath); err != nil || !eq {
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return eq, err
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}
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// If not a directory also check size, modtime, and content
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if !f1.f.IsDir() {
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if f1.f.Size() != f2.f.Size() {
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return false, nil
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}
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t1 := f1.f.ModTime()
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t2 := f2.f.ModTime()
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if t1.Unix() != t2.Unix() {
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return false, nil
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}
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// If the timestamp may have been truncated in both of the
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// files, check content of file to determine difference
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if t1.Nanosecond() == 0 && t2.Nanosecond() == 0 {
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var eq bool
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if (f1.f.Mode() & os.ModeSymlink) == os.ModeSymlink {
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eq, err = compareSymlinkTarget(f1.fullPath, f2.fullPath)
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} else if f1.f.Size() > 0 {
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eq, err = compareFileContent(f1.fullPath, f2.fullPath)
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}
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if err != nil || !eq {
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return eq, err
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}
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} else if t1.Nanosecond() != t2.Nanosecond() {
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return false, nil
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}
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}
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return true, nil
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}
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func compareSymlinkTarget(p1, p2 string) (bool, error) {
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t1, err := os.Readlink(p1)
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if err != nil {
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return false, err
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}
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t2, err := os.Readlink(p2)
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if err != nil {
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return false, err
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}
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return t1 == t2, nil
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}
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const compareChuckSize = 32 * 1024
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// compareFileContent compares the content of 2 same sized files
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// by comparing each byte.
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func compareFileContent(p1, p2 string) (bool, error) {
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f1, err := os.Open(p1)
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if err != nil {
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return false, err
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}
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defer f1.Close()
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f2, err := os.Open(p2)
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if err != nil {
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return false, err
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}
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defer f2.Close()
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b1 := make([]byte, compareChuckSize)
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b2 := make([]byte, compareChuckSize)
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for {
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n1, err1 := f1.Read(b1)
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if err1 != nil && err1 != io.EOF {
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return false, err1
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}
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n2, err2 := f2.Read(b2)
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if err2 != nil && err2 != io.EOF {
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return false, err2
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}
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if n1 != n2 || !bytes.Equal(b1[:n1], b2[:n2]) {
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return false, nil
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}
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if err1 == io.EOF && err2 == io.EOF {
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return true, nil
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}
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}
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}
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func pathWalk(ctx context.Context, root string, pathC chan<- *currentPath) error {
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return filepath.Walk(root, func(path string, f os.FileInfo, err error) error {
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if err != nil {
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return err
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}
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// Rebase path
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path, err = filepath.Rel(root, path)
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if err != nil {
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return err
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}
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path = filepath.Join(string(os.PathSeparator), path)
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// Skip root
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if path == string(os.PathSeparator) {
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return nil
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}
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p := ¤tPath{
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path: path,
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f: f,
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fullPath: filepath.Join(root, path),
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}
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select {
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case <-ctx.Done():
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return ctx.Err()
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case pathC <- p:
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return nil
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}
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})
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}
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func nextPath(ctx context.Context, pathC <-chan *currentPath) (*currentPath, error) {
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select {
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case <-ctx.Done():
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return nil, ctx.Err()
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case p := <-pathC:
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return p, nil
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}
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}
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// RootPath joins a path with a root, evaluating and bounding any
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// symlink to the root directory.
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func RootPath(root, path string) (string, error) {
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if path == "" {
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return root, nil
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}
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var linksWalked int // to protect against cycles
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for {
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i := linksWalked
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newpath, err := walkLinks(root, path, &linksWalked)
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if err != nil {
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return "", err
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}
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path = newpath
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if i == linksWalked {
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newpath = filepath.Join("/", newpath)
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if path == newpath {
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return filepath.Join(root, newpath), nil
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}
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path = newpath
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}
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}
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}
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func walkLink(root, path string, linksWalked *int) (newpath string, islink bool, err error) {
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if *linksWalked > 255 {
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return "", false, errTooManyLinks
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}
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path = filepath.Join("/", path)
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if path == "/" {
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return path, false, nil
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}
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realPath := filepath.Join(root, path)
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fi, err := os.Lstat(realPath)
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if err != nil {
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// If path does not yet exist, treat as non-symlink
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if os.IsNotExist(err) {
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return path, false, nil
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}
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return "", false, err
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}
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if fi.Mode()&os.ModeSymlink == 0 {
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return path, false, nil
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}
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newpath, err = os.Readlink(realPath)
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if err != nil {
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return "", false, err
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}
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if filepath.IsAbs(newpath) && strings.HasPrefix(newpath, root) {
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newpath = newpath[:len(root)]
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if !strings.HasPrefix(newpath, "/") {
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newpath = "/" + newpath
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}
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}
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*linksWalked++
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return newpath, true, nil
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}
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func walkLinks(root, path string, linksWalked *int) (string, error) {
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switch dir, file := filepath.Split(path); {
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case dir == "":
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newpath, _, err := walkLink(root, file, linksWalked)
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return newpath, err
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case file == "":
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if os.IsPathSeparator(dir[len(dir)-1]) {
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if dir == "/" {
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return dir, nil
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}
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return walkLinks(root, dir[:len(dir)-1], linksWalked)
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}
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newpath, _, err := walkLink(root, dir, linksWalked)
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return newpath, err
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default:
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newdir, err := walkLinks(root, dir, linksWalked)
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if err != nil {
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return "", err
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}
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newpath, islink, err := walkLink(root, filepath.Join(newdir, file), linksWalked)
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if err != nil {
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return "", err
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}
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if !islink {
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return newpath, nil
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}
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if filepath.IsAbs(newpath) {
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return newpath, nil
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}
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return filepath.Join(newdir, newpath), nil
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}
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}
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