Added support for symbolic links that are pointing to directory

cmd/kosli/fingerprint.go

@@ -16,6 +16,10 @@ exclude ^zam/file.txt^ which is relative to the DIR-PATH.
 The supported glob pattern syntax is what is documented here: https://pkg.go.dev/path/filepath#Match , 
 plus the ability to use recursive globs "**"
 
+If the directory structure contains symbolic links to a file the content of the file it points to is included in the
+fingerprint calculation. If a symbolic link points to a directory the path it is pointing to is include in the
+fingerprint calculation.
+
 ` + kosliIgnoreDesc
 
 const fingerprintLongDesc = fingerprintShortDesc + `

cmd/kosli/fingerprint_test.go

@@ -44,6 +44,18 @@ func (suite *FingerprintTestSuite) TestFingerprintCmd() {
 			cmd:    "fingerprint --artifact-type dir testdata/folder1-with-ignore",
 			golden: "038897ea5334462098d65125380d58a493671fb3b8bdbbee1e75ec8bd4a65c23\n",
 		},
+		{
+			name:   "dir fingerprint with symbolic links 1",
+			cmd:    "fingerprint --artifact-type dir testdata/folder-with-symlinks-1",
+			golden: "1c0740265b38509fb9ce7babf00d7eb57e7e08b59dad8be66897c1ebb5b36409\n",
+		},
+		{
+			// The two folders contains the same files and folder, but a/b/c/point-to-dir points
+			// different directories
+			name:   "dir fingerprint with symbolic links 2",
+			cmd:    "fingerprint --artifact-type dir testdata/folder-with-symlinks-2",
+			golden: "2a5fe76bc616a97b2ff6f30f46380f1230b98a58df8aec6e96c1fb0e03b41fd9\n",
+		},
 		{
 			name:      "fails if type is directory but the argument is not a dir",
 			cmd:       "fingerprint --artifact-type dir testdata/file1",

cmd/kosli/testdata/folder-with-symlinks-1/a/b/bob.txt

@@ -0,0 +1 @@
+bob

cmd/kosli/testdata/folder-with-symlinks-1/a/b/c/d/dorris.txt

@@ -0,0 +1 @@
+dorris

cmd/kosli/testdata/folder-with-symlinks-1/a/b/c/point-to-dir

@@ -0,0 +1 @@
+../../../a

cmd/kosli/testdata/folder-with-symlinks-1/a/b/point-to-dorris

@@ -0,0 +1 @@
+c/d/dorris.txt

cmd/kosli/testdata/folder-with-symlinks-2/a/b/bob.txt

@@ -0,0 +1 @@
+bob

cmd/kosli/testdata/folder-with-symlinks-2/a/b/c/d/dorris.txt

@@ -0,0 +1 @@
+dorris

cmd/kosli/testdata/folder-with-symlinks-2/a/b/c/point-to-dir

@@ -0,0 +1 @@
+../../b

cmd/kosli/testdata/folder-with-symlinks-2/a/b/point-to-dorris

@@ -0,0 +1 @@
+c/d/dorris.txt

internal/digest/digest.go

@@ -131,14 +131,50 @@ func calculateDirContentSha256(digestsFile *os.File, dirPath, tmpDir string, exc
 			return nil
 		}
 
+		// If it's a symlink, resolve the target
+		var stat fs.FileInfo
+		if info.Type()&os.ModeSymlink != 0 {
+			resolved, err := os.Stat(path) // follows the symlink
+			if err != nil {
+				return err
+			}
+			stat = resolved
+		} else {
+			// Convert fs.DirEntry to fs.FileInfo for consistency
+			resolved, err := info.Info()
+			if err != nil {
+				return err
+			}
+			stat = resolved
+		}
+
 		nameSha256, err := addNameDigest(tmpDir, info.Name(), digestsFile)
 		if err != nil {
 			return err
 		}
 
-		if info.IsDir() {
-			logger.Debug("dir path: %s -- dirname digest: %v", path, nameSha256)
+		if stat.IsDir() {
+			if info.Type()&os.ModeSymlink != 0 {
+				// This is a symlink to a directory
+				logger.Debug("symlink path: %s -- linkname digest: %v", path, nameSha256)
+
+				targetPath, err := os.Readlink(path)
+				if err != nil {
+					return err
+				}
+
+				// Calculate fingerprint of what link points to (for this: a -> c/d calculate the fingerprint of c/d)
+				targetSha256, err := addNameDigest(tmpDir, targetPath, digestsFile)
+				if err != nil {
+					return err
+				}
+				logger.Debug("symlink: %s (points to %s) -- digest: %v", path, targetPath, targetSha256)
+			} else {
+				// Normal directory
+				logger.Debug("dir path: %s -- dirname digest: %v", path, nameSha256)
+			}
 		} else {
+			// File or symlink -> file
 			logger.Debug("file path: %s -- filename digest: %s", path, nameSha256)
 			fileContentSha256, err := FileSha256(path)
 			if err != nil {