From bd6749a2e16d1bfe35a594af4cd9d9519a251115 Mon Sep 17 00:00:00 2001
From: Rex P <rexpan@google.com>
Date: Thu, 7 Nov 2024 16:24:20 +1100
Subject: [PATCH] A quick fix to handle symbolic links

---
 internal/image/image.go      | 21 ++++++++++++++-------
 internal/image/layer.go      | 30 ++++++++++++++++++++++++------
 pkg/osvscanner/osvscanner.go |  7 +++++++
 3 files changed, 45 insertions(+), 13 deletions(-)

diff --git a/internal/image/image.go b/internal/image/image.go
index 0be6f53bf2..212845ebfd 100644
--- a/internal/image/image.go
+++ b/internal/image/image.go
@@ -180,6 +180,7 @@ func LoadImage(imagePath string) (*Image, error) {
 			// filepath.Clean first to convert to OS specific file path
 			// TODO: Escape invalid characters on windows that's valid on linux
 			absoluteDiskPath := filepath.Join(dirPath, filepath.Clean(cleanedFilePath))
+			symlinkTarget := ""
 
 			var fileType fileType
 			// write out the file/dir to disk
@@ -191,8 +192,7 @@ func LoadImage(imagePath string) (*Image, error) {
 					}
 				}
 				fileType = Dir
-
-			default: // Assume if it's not a directory, it's a normal file
+			case tar.TypeReg:
 				// Write all files as read/writable by the current user, inaccessible by anyone else
 				// Actual permission bits are stored in FileNode
 				f, err := os.OpenFile(absoluteDiskPath, os.O_CREATE|os.O_RDWR, filePermission)
@@ -210,6 +210,11 @@ func LoadImage(imagePath string) (*Image, error) {
 				}
 				fileType = RegularFile
 				f.Close()
+			case tar.TypeSymlink:
+				fileType = Symlink
+				symlinkTarget = header.Linkname
+			default: // Assume if it's not a directory or normal file
+				// TODO: Handle these cases
 			}
 
 			// Each outer loop, we add a layer to each relevant output flattenedLayers slice
@@ -238,11 +243,13 @@ func LoadImage(imagePath string) (*Image, error) {
 				err := currentMap.fileNodeTrie.Insert(virtualPath, &FileNode{
 					rootImage: &outputImage,
 					// Select the original layer of the file
-					originLayer: &outputImage.layers[i],
-					virtualPath: virtualPath,
-					fileType:    fileType,
-					isWhiteout:  tombstone,
-					permission:  fs.FileMode(header.Mode), //nolint:gosec
+					originLayer:    &outputImage.layers[i],
+					virtualPath:    virtualPath,
+					fileType:       fileType,
+					linkTargetPath: symlinkTarget,
+					isWhiteout:     tombstone,
+					// TODO: Fix file mode bits to contain the high bits
+					permission: fs.FileMode(header.Mode), //nolint:gosec
 				})
 
 				if err != nil {
diff --git a/internal/image/layer.go b/internal/image/layer.go
index eb66a37752..c25a089f93 100644
--- a/internal/image/layer.go
+++ b/internal/image/layer.go
@@ -18,17 +18,20 @@ type fileType int
 const (
 	RegularFile fileType = iota
 	Dir
+	Symlink
 )
 
 // FileNode represents a file on a specific layer, mapping the contents to an extracted file on disk
 type FileNode struct {
 	// TODO: Determine the performance implications of having a pointer to base image in every fileNode
-	rootImage   *Image
-	fileType    fileType
-	isWhiteout  bool
-	originLayer *Layer
-	virtualPath string
-	permission  fs.FileMode
+	rootImage *Image
+	// TODO: Filetype is redundant if permission is set correctly
+	fileType       fileType
+	isWhiteout     bool
+	originLayer    *Layer
+	virtualPath    string
+	linkTargetPath string
+	permission     fs.FileMode
 }
 
 var _ fs.DirEntry = FileNode{}
@@ -82,6 +85,13 @@ func (f FileNodeFileInfo) Sys() any {
 
 // Stat returns the FileInfo structure describing file.
 func (f *FileNode) Stat() (fs.FileInfo, error) {
+	// TODO: Implement this properly
+	if f.fileType == Symlink {
+		return FileNodeFileInfo{
+			fileNode: f,
+		}, nil
+	}
+
 	baseFileInfo, err := os.Stat(f.absoluteDiskPath())
 	if err != nil {
 		return nil, err
@@ -121,6 +131,10 @@ func (filemap Layer) Open(path string) (fs.File, error) {
 		return nil, err
 	}
 
+	if node.fileType == Symlink {
+		return filemap.Open(node.linkTargetPath)
+	}
+
 	return node.Open()
 }
 
@@ -130,6 +144,10 @@ func (filemap Layer) Stat(path string) (fs.FileInfo, error) {
 		return nil, err
 	}
 
+	if node.fileType == Symlink {
+		return filemap.Stat(node.linkTargetPath)
+	}
+
 	return node.Stat()
 }
 
diff --git a/pkg/osvscanner/osvscanner.go b/pkg/osvscanner/osvscanner.go
index e04b01b8d9..074f00613e 100644
--- a/pkg/osvscanner/osvscanner.go
+++ b/pkg/osvscanner/osvscanner.go
@@ -1118,6 +1118,13 @@ func patchPackageForRequest(pkg scannedPackage) scannedPackage {
 		}
 	}
 
+	// TODO: This should be done on the osv.dev side
+	// This is needed because Ubuntu ecosystem appends LTS
+	// but the scanner does not have this information.
+	if pkg.Ecosystem == "Ubuntu:20.04" {
+		pkg.Ecosystem = "Ubuntu:20.04:LTS"
+	}
+
 	return pkg
 }