fix: index file itself when file scan path has symlink (#2359)

Previously, building the index of the filesystem when source was file
would fail if part of the path syft was passed to the file included a
symlinked directory, resulting in cataloging misses.

---------

Signed-off-by: Will Murphy <will.murphy@anchore.com>

syft/source/file_source.go

@@ -159,11 +159,10 @@ func (s FileSource) FileResolver(_ Scope) (file.Resolver, error) {
 	}
 	isArchiveAnalysis := fi.IsDir()
 
-	absAnalysisPath, err := filepath.Abs(s.analysisPath)
+	absParentDir, err := absoluteSymlinkFreePathToParent(s.analysisPath)
 	if err != nil {
-		return nil, fmt.Errorf("unable to get absolute path for analysis path=%q: %w", s.analysisPath, err)
+		return nil, err
 	}
-	absParentDir := filepath.Dir(absAnalysisPath)
 
 	var res *fileresolver.Directory
 	if isArchiveAnalysis {
@@ -210,6 +209,18 @@ func (s FileSource) FileResolver(_ Scope) (file.Resolver, error) {
 	return s.resolver, nil
 }
 
+func absoluteSymlinkFreePathToParent(path string) (string, error) {
+	absAnalysisPath, err := filepath.Abs(path)
+	if err != nil {
+		return "", fmt.Errorf("unable to get absolute path for analysis path=%q: %w", path, err)
+	}
+	dereferencedAbsAnalysisPath, err := filepath.EvalSymlinks(absAnalysisPath)
+	if err != nil {
+		return "", fmt.Errorf("unable to get absolute path for analysis path=%q: %w", path, err)
+	}
+	return filepath.Dir(dereferencedAbsAnalysisPath), nil
+}
+
 func (s *FileSource) Close() error {
 	if s.closer == nil {
 		return nil

syft/source/file_source_test.go

@@ -48,6 +48,22 @@ func TestNewFromFile(t *testing.T) {
 			},
 			expRefs: 1,
 		},
+		{
+			desc:  "normal path",
+			input: "test-fixtures/actual-path/empty",
+			testPathFn: func(resolver file.Resolver) ([]file.Location, error) {
+				return resolver.FilesByPath("empty")
+			},
+			expRefs: 1,
+		},
+		{
+			desc:  "path containing symlink",
+			input: "test-fixtures/symlink/empty",
+			testPathFn: func(resolver file.Resolver) ([]file.Location, error) {
+				return resolver.FilesByPath("empty")
+			},
+			expRefs: 1,
+		},
 	}
 	for _, test := range testCases {
 		t.Run(test.desc, func(t *testing.T) {

syft/source/test-fixtures/symlink

@@ -0,0 +1 @@
+actual-path