Refactor symlink handling to improve errors/performance

Signed-off-by: Stephen Levine <[email protected]>

Author: sclevine

node.go

@@ -22,15 +22,18 @@ func (f *File) sum() ([]byte, error) {
 	return f.Hash.File(f.Path)
 }
 
-func (f *File) stat() (os.FileInfo, error) {
+func (f *File) stat(subdir bool) (os.FileInfo, error) {
 	if f.Stdin {
 		return os.Stdin.Stat()
 	}
-	return os.Lstat(f.Path)
+	if !f.follow(subdir) {
+		return os.Lstat(f.Path)
+	}
+	return os.Stat(f.Path)
 }
 
-func (f *File) xattr() (*Xattr, error) {
-	hashes, err := getXattr(f.Path, f.Hash)
+func (f *File) xattr(subdir bool) (*Xattr, error) {
+	hashes, err := getXattr(f.Path, f.Hash, f.follow(subdir))
 	if err != nil {
 		return nil, err
 	}
@@ -40,6 +43,11 @@ func (f *File) xattr() (*Xattr, error) {
 	}, nil
 }
 
+func (f *File) follow(subdir bool) bool {
+	inclusive := f.Mask.Attr&AttrInclusive != 0
+	return f.Mask.Attr&AttrFollow != 0 || (!inclusive && !subdir)
+}
+
 type Node struct {
 	File
 	Sum   []byte

sum.go

@@ -144,8 +144,10 @@ func (s *Sum) walkFile(file File, subdir bool, sched func()) *Node {
 	if file.Stdin {
 		file.Mask.Attr &= ^AttrX
 	}
+	inclusive := file.Mask.Attr&AttrInclusive != 0
+	noData := file.Mask.Attr&AttrNoData != 0 && (inclusive || subdir)
 
-	fi, err := file.stat()
+	fi, err := file.stat(subdir)
 	if os.IsNotExist(err) {
 		return newFileErrorNode("", file, subdir, err)
 	}
@@ -161,17 +163,12 @@ func (s *Sum) walkFile(file File, subdir bool, sched func()) *Node {
 	}
 	var xattr *Xattr
 	if file.Mask.Attr&AttrX != 0 {
-		xattr, err = file.xattr()
+		xattr, err = file.xattr(subdir)
 		if err != nil {
 			return newFileErrorNode("get xattr", file, subdir, err)
 		}
 	}
 
-	portable := file.Mask.Attr&AttrNoName != 0
-	inclusive := file.Mask.Attr&AttrInclusive != 0
-	follow := file.Mask.Attr&AttrFollow != 0 || (!inclusive && !subdir)
-	noData := file.Mask.Attr&AttrNoData != 0 && (inclusive || subdir)
-
 	var sum []byte
 	switch {
 	case fi.IsDir():
@@ -201,7 +198,7 @@ func (s *Sum) walkFile(file File, subdir bool, sched func()) *Node {
 				return newFileErrorNode("", file, subdir, n.Err)
 			}
 			var name string
-			if !portable {
+			if file.Mask.Attr&AttrNoName == 0 {
 				// safe because subdir nodes have generated bases
 				name = filepath.Base(n.Path)
 			}
@@ -223,24 +220,6 @@ func (s *Sum) walkFile(file File, subdir bool, sched func()) *Node {
 			return newFileErrorNode("hash", file, subdir, err)
 		}
 
-	case fi.Mode()&os.ModeSymlink != 0 && follow:
-		link, err := filepath.EvalSymlinks(file.Path)
-		if err != nil {
-			return newFileErrorNode("", file, subdir, err) // closer to, e.g., shasum w/o action
-		}
-
-		rOnce.Do(s.releaseCPU) // will be re-acquired at dest
-		sOnce.Do(nil)          // prevent defer, will be called at dest
-
-		path := file.Path
-		file.Path = link
-		n := s.walkFile(file, subdir, sched) // FIXME: pass link here instead?
-		n.Path = path
-		fErr := &FileError{}
-		if errors.As(err, &fErr) && !subdir {
-			fErr.Path = path // FIXME: account for symlink to directory, track real vs. fake path?
-		}
-		return n
 	case fi.Mode()&os.ModeSymlink != 0:
 		sOnce.Do(sched)
 		file.Mask.Attr &= ^AttrNoName // not directory

sys_posix.go

@@ -8,14 +8,18 @@ import (
 	"github.com/sclevine/xsum/encoding"
 )
 
-func getXattr(path string, hash Hash) ([]encoding.NamedHash, error) {
-	attrs, err := xattr.LList(path)
+func getXattr(path string, hash Hash, follow bool) ([]encoding.NamedHash, error) {
+	xlist, xget := xattr.List, xattr.Get
+	if !follow {
+		xlist, xget = xattr.LList, xattr.LGet
+	}
+	attrs, err := xlist(path)
 	if err != nil {
 		return nil, err
 	}
 	var hashes []encoding.NamedHash
 	for _, attr := range attrs {
-		val, err := xattr.LGet(path, attr)
+		val, err := xget(path, attr)
 		if err != nil {
 			return nil, err
 		}

sys_windows.go

@@ -19,7 +19,7 @@ func getSys(fi os.FileInfo) (*Sys, error) {
 	return nil, ErrNoStat
 }
 
-func getXattr(_ string, _ Hash) ([]encoding.NamedHash, error) {
+func getXattr(_ string, _ Hash, _ bool) ([]encoding.NamedHash, error) {
 	return nil, ErrNoXattr
 }