fix: follows symbolic links with formatter exclusion paths

pkg/goformat/runner.go

@@ -223,8 +223,13 @@ func NewRunnerOptions(cfg *config.Config, diff, diffColored, stdin bool) (Runner
 		return RunnerOptions{}, fmt.Errorf("get base path: %w", err)
 	}
 
+	evaluatedBasePath, err := fsutils.EvalSymlinks(basePath)
+	if err != nil {
+		return RunnerOptions{}, fmt.Errorf("evaluate base path: %w", err)
+	}
+
 	opts := RunnerOptions{
-		basePath:            basePath,
+		basePath:            evaluatedBasePath,
 		generated:           cfg.Formatters.Exclusions.Generated,
 		diff:                diff || diffColored,
 		colors:              diffColored,
@@ -251,7 +256,12 @@ func (o RunnerOptions) MatchAnyPattern(path string) (bool, error) {
 		return false, nil
 	}
 
-	rel, err := filepath.Rel(o.basePath, path)
+	evaluatedPath, err := fsutils.EvalSymlinks(path)
+	if err != nil {
+		return false, err
+	}
+
+	rel, err := filepath.Rel(o.basePath, evaluatedPath)
 	if err != nil {
 		return false, err
 	}

pkg/goformat/runner_test.go

@@ -0,0 +1,135 @@
+package goformat
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/golangci/golangci-lint/v2/pkg/config"
+)
+
+func TestRunnerOptions_MatchAnyPattern(t *testing.T) {
+	testCases := []struct {
+		desc     string
+		cfg      *config.Config
+		filename string
+
+		assertMatch   assert.BoolAssertionFunc
+		expectedCount int
+	}{
+		{
+			desc: "match",
+			cfg: &config.Config{
+				Formatters: config.Formatters{
+					Exclusions: config.FormatterExclusions{
+						Paths: []string{`generated\.go`},
+					},
+				},
+			},
+			filename:      "generated.go",
+			assertMatch:   assert.True,
+			expectedCount: 1,
+		},
+		{
+			desc: "no match",
+			cfg: &config.Config{
+				Formatters: config.Formatters{
+					Exclusions: config.FormatterExclusions{
+						Paths: []string{`excluded\.go`},
+					},
+				},
+			},
+			filename:      "test.go",
+			assertMatch:   assert.False,
+			expectedCount: 0,
+		},
+		{
+			desc:        "no patterns",
+			cfg:         &config.Config{},
+			filename:    "test.go",
+			assertMatch: assert.False,
+		},
+	}
+
+	for _, test := range testCases {
+		t.Run(test.desc, func(t *testing.T) {
+			t.Parallel()
+
+			tmpDir := t.TempDir()
+
+			testFile := filepath.Join(tmpDir, test.filename)
+
+			err := os.WriteFile(testFile, []byte("package main"), 0o600)
+			require.NoError(t, err)
+
+			test.cfg.SetConfigDir(tmpDir)
+
+			opts, err := NewRunnerOptions(test.cfg, false, false, false)
+			require.NoError(t, err)
+
+			match, err := opts.MatchAnyPattern(testFile)
+			require.NoError(t, err)
+
+			test.assertMatch(t, match)
+
+			require.Len(t, opts.patterns, len(test.cfg.Formatters.Exclusions.Paths))
+
+			if len(opts.patterns) == 0 {
+				assert.Empty(t, opts.excludedPathCounter)
+			} else {
+				assert.Equal(t, test.expectedCount, opts.excludedPathCounter[opts.patterns[0]])
+			}
+		})
+	}
+}
+
+func TestRunnerOptions_MatchAnyPattern_withSymlinks(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	testFile := filepath.Join(tmpDir, "project", "test.go")
+
+	realDir := filepath.Dir(testFile)
+
+	err := os.MkdirAll(realDir, 0o755)
+	require.NoError(t, err)
+
+	err = os.WriteFile(testFile, []byte("package main"), 0o600)
+	require.NoError(t, err)
+
+	// Create a symlink in a completely different part of the tree.
+	symlink := filepath.Join(tmpDir, "somewhere", "symlink")
+
+	err = os.MkdirAll(filepath.Dir(symlink), 0o755)
+	require.NoError(t, err)
+
+	err = os.Symlink(realDir, symlink)
+	require.NoError(t, err)
+
+	cfg := &config.Config{
+		Formatters: config.Formatters{
+			Exclusions: config.FormatterExclusions{
+				// Creates a pattern that matches files in the root directory only.
+				// This pattern will match `test.go" but not `../../../test.go` or similar broken paths.
+				Paths: []string{`^[^/\\]+\.go$`},
+			},
+		},
+	}
+
+	cfg.SetConfigDir(realDir)
+
+	opts, err := NewRunnerOptions(cfg, false, false, false)
+	require.NoError(t, err)
+
+	match, err := opts.MatchAnyPattern(filepath.Join(symlink, "test.go"))
+	require.NoError(t, err)
+
+	assert.True(t, match)
+
+	require.NotEmpty(t, opts.patterns)
+	require.Len(t, opts.patterns, len(cfg.Formatters.Exclusions.Paths))
+
+	assert.Equal(t, 1, opts.excludedPathCounter[opts.patterns[0]])
+}