1 files changed, 37 insertions, 61 deletions

diff --git a/modules/git/tree_entry.go b/modules/git/tree_entry.go
index 9513121487..5099d8ee79 100644
--- a/modules/git/tree_entry.go
+++ b/modules/git/tree_entry.go
@@ -5,9 +5,11 @@
 package git
 
 import (
-	"io"
+	"path"
 	"sort"
 	"strings"
+
+	"code.gitea.io/gitea/modules/util"
 )
 
 // Type returns the type of the entry (commit, tree, blob)
@@ -22,83 +24,57 @@ func (te *TreeEntry) Type() string {
 	}
 }
 
-// FollowLink returns the entry pointed to by a symlink
-func (te *TreeEntry) FollowLink() (*TreeEntry, error) {
+type EntryFollowResult struct {
+	SymlinkContent string
+	TargetFullPath string
+	TargetEntry    *TreeEntry
+}
+
+func EntryFollowLink(commit *Commit, fullPath string, te *TreeEntry) (*EntryFollowResult, error) {
 	if !te.IsLink() {
-		return nil, ErrBadLink{te.Name(), "not a symlink"}
+		return nil, util.ErrorWrap(util.ErrUnprocessableContent, "%q is not a symlink", fullPath)
 	}
 
-	// read the link
-	r, err := te.Blob().DataAsync()
-	if err != nil {
-		return nil, err
+	// git's filename max length is 4096, hopefully a link won't be longer than multiple of that
+	const maxSymlinkSize = 20 * 4096
+	if te.Blob().Size() > maxSymlinkSize {
+		return nil, util.ErrorWrap(util.ErrUnprocessableContent, "%q content exceeds symlink limit", fullPath)
 	}
-	closed := false
-	defer func() {
-		if !closed {
-			_ = r.Close()
-		}
-	}()
-	buf := make([]byte, te.Size())
-	_, err = io.ReadFull(r, buf)
+
+	link, err := te.Blob().GetBlobContent(maxSymlinkSize)
 	if err != nil {
 		return nil, err
 	}
-	_ = r.Close()
-	closed = true
-
-	lnk := string(buf)
-	t := te.ptree
-
-	// traverse up directories
-	for ; t != nil && strings.HasPrefix(lnk, "../"); lnk = lnk[3:] {
-		t = t.ptree
+	if strings.HasPrefix(link, "/") {
+		// It's said that absolute path will be stored as is in Git
+		return &EntryFollowResult{SymlinkContent: link}, util.ErrorWrap(util.ErrUnprocessableContent, "%q is an absolute symlink", fullPath)
 	}
 
-	if t == nil {
-		return nil, ErrBadLink{te.Name(), "points outside of repo"}
-	}
-
-	target, err := t.GetTreeEntryByPath(lnk)
+	targetFullPath := path.Join(path.Dir(fullPath), link)
+	targetEntry, err := commit.GetTreeEntryByPath(targetFullPath)
 	if err != nil {
-		if IsErrNotExist(err) {
-			return nil, ErrBadLink{te.Name(), "broken link"}
-		}
-		return nil, err
+		return &EntryFollowResult{SymlinkContent: link}, err
 	}
-	return target, nil
+	return &EntryFollowResult{SymlinkContent: link, TargetFullPath: targetFullPath, TargetEntry: targetEntry}, nil
 }
 
-// FollowLinks returns the entry ultimately pointed to by a symlink
-func (te *TreeEntry) FollowLinks() (*TreeEntry, error) {
-	if !te.IsLink() {
-		return nil, ErrBadLink{te.Name(), "not a symlink"}
-	}
-	entry := te
-	for i := 0; i < 999; i++ {
-		if entry.IsLink() {
-			next, err := entry.FollowLink()
-			if err != nil {
-				return nil, err
-			}
-			if next.ID == entry.ID {
-				return nil, ErrBadLink{
-					entry.Name(),
-					"recursive link",
-				}
-			}
-			entry = next
-		} else {
+func EntryFollowLinks(commit *Commit, firstFullPath string, firstTreeEntry *TreeEntry, optLimit ...int) (res *EntryFollowResult, err error) {
+	limit := util.OptionalArg(optLimit, 10)
+	treeEntry, fullPath := firstTreeEntry, firstFullPath
+	for range limit {
+		res, err = EntryFollowLink(commit, fullPath, treeEntry)
+		if err != nil {
+			return res, err
+		}
+		treeEntry, fullPath = res.TargetEntry, res.TargetFullPath
+		if !treeEntry.IsLink() {
 			break
 		}
 	}
-	if entry.IsLink() {
-		return nil, ErrBadLink{
-			te.Name(),
-			"too many levels of symbolic links",
-		}
+	if treeEntry.IsLink() {
+		return res, util.ErrorWrap(util.ErrUnprocessableContent, "%q has too many links", firstFullPath)
 	}
-	return entry, nil
+	return res, nil
 }
 
 // returns the Tree pointed to by this TreeEntry, or nil if this is not a tree