config: fix path matching when path prefix is used

When someone invokes golangci-lint in a sub-directory, they can set the path
prefix to make the output look like the invocation had been done in the
root. But this prefix was ignored when checking path patterns of exclude,
severity, and skip files/dirs entries, so those with matching for directories
only worked when golangci-lint was always invoked in the same directory.

The underlying problem is that the rules from the configuration get checked
before updating the path associated with the issues in the path fixer. To make
the prefix work, it now gets passed down into processors and added there to the
issue path before checking against the path pattern.

For exclude and severity rules, this could have been done through a separate
parameter, but bundling it in a new fsutils helper struct made the change a bit
smaller.

.golangci.reference.yml

@@ -27,7 +27,8 @@ run:
     - mytag
 
   # Which dirs to skip: issues from them won't be reported.
-  # Can use regexp here: `generated.*`, regexp is applied on full path.
+  # Can use regexp here: `generated.*`, regexp is applied on full path,
+  # including the path prefix if one is set.
   # Default value is empty list,
   # but default dirs are skipped independently of this option's value (see skip-dirs-use-default).
   # "/" will be replaced by current OS file path separator to properly work on Windows.

docs/src/docs/usage/false-positives.mdx

@@ -66,6 +66,10 @@ issues:
 
 Exclude issues in path by `run.skip-dirs`, `run.skip-files` or `issues.exclude-rules` config options.
 
+Beware that the paths that get matched here are relative to the current working directory.
+When the configuration contains path patterns that check for specific directories,
+the `--path-prefix` parameter can be used to extend the paths before matching.
+
 In the following example, all the reports from the linters (`linters`) that concerns the path (`path`) are excluded:
 
 ```yml

pkg/fsutils/files.go

@@ -0,0 +1,33 @@
+package fsutils
+
+import "path/filepath"
+
+// Files combines different operations related to handling file paths and content.
+type Files struct {
+	*LineCache
+	pathPrefix string
+}
+
+func NewFiles(lc *LineCache, pathPrefix string) *Files {
+	return &Files{
+		LineCache:  lc,
+		pathPrefix: pathPrefix,
+	}
+}
+
+// WithPathPrefix takes a path that is relative to the current directory (as used in issues)
+// and adds the configured path prefix, if there is one.
+// The resulting path then can be shown to the user or compared against paths specified in the configuration.
+func (f *Files) WithPathPrefix(relativePath string) string {
+	return WithPathPrefix(f.pathPrefix, relativePath)
+}
+
+// WithPathPrefix takes a path that is relative to the current directory (as used in issues)
+// and adds the configured path prefix, if there is one.
+// The resulting path then can be shown to the user or compared against paths specified in the configuration.
+func WithPathPrefix(pathPrefix, relativePath string) string {
+	if pathPrefix == "" {
+		return relativePath
+	}
+	return filepath.Join(pathPrefix, relativePath)
+}

pkg/lint/runner.go

@@ -29,7 +29,12 @@ type Runner struct {
 
 func NewRunner(cfg *config.Config, log logutils.Log, goenv *goutil.Env, es *lintersdb.EnabledSet,
 	lineCache *fsutils.LineCache, dbManager *lintersdb.Manager, pkgs []*gopackages.Package) (*Runner, error) {
-	skipFilesProcessor, err := processors.NewSkipFiles(cfg.Run.SkipFiles)
+	// Beware that some processors need to add the path prefix when working with paths
+	// because they get invoked before the path prefixer (exclude and severity rules)
+	// or process other paths (skip files).
+	files := fsutils.NewFiles(lineCache, cfg.Output.PathPrefix)
+
+	skipFilesProcessor, err := processors.NewSkipFiles(cfg.Run.SkipFiles, cfg.Output.PathPrefix)
 	if err != nil {
 		return nil, err
 	}
@@ -38,7 +43,7 @@ func NewRunner(cfg *config.Config, log logutils.Log, goenv *goutil.Env, es *lint
 	if cfg.Run.UseDefaultSkipDirs {
 		skipDirs = append(skipDirs, packages.StdExcludeDirRegexps...)
 	}
-	skipDirsProcessor, err := processors.NewSkipDirs(skipDirs, log.Child(logutils.DebugKeySkipDirs), cfg.Run.Args)
+	skipDirsProcessor, err := processors.NewSkipDirs(skipDirs, log.Child(logutils.DebugKeySkipDirs), cfg.Run.Args, cfg.Output.PathPrefix)
 	if err != nil {
 		return nil, err
 	}
@@ -82,7 +87,7 @@ func NewRunner(cfg *config.Config, log logutils.Log, goenv *goutil.Env, es *lint
 			processors.NewIdentifierMarker(),
 
 			getExcludeProcessor(&cfg.Issues),
-			getExcludeRulesProcessor(&cfg.Issues, log, lineCache),
+			getExcludeRulesProcessor(&cfg.Issues, log, files),
 			processors.NewNolint(log.Child(logutils.DebugKeyNolint), dbManager, enabledLinters),
 
 			processors.NewUniqByLine(cfg),
@@ -92,7 +97,7 @@ func NewRunner(cfg *config.Config, log logutils.Log, goenv *goutil.Env, es *lint
 			processors.NewMaxFromLinter(cfg.Issues.MaxIssuesPerLinter, log.Child(logutils.DebugKeyMaxFromLinter), cfg),
 			processors.NewSourceCode(lineCache, log.Child(logutils.DebugKeySourceCode)),
 			processors.NewPathShortener(),
-			getSeverityRulesProcessor(&cfg.Severity, log, lineCache),
+			getSeverityRulesProcessor(&cfg.Severity, log, files),
 			processors.NewPathPrefixer(cfg.Output.PathPrefix),
 			processors.NewSortResults(cfg),
 		},
@@ -259,7 +264,7 @@ func getExcludeProcessor(cfg *config.Issues) processors.Processor {
 	return excludeProcessor
 }
 
-func getExcludeRulesProcessor(cfg *config.Issues, log logutils.Log, lineCache *fsutils.LineCache) processors.Processor {
+func getExcludeRulesProcessor(cfg *config.Issues, log logutils.Log, files *fsutils.Files) processors.Processor {
 	var excludeRules []processors.ExcludeRule
 	for _, r := range cfg.ExcludeRules {
 		excludeRules = append(excludeRules, processors.ExcludeRule{
@@ -287,21 +292,21 @@ func getExcludeRulesProcessor(cfg *config.Issues, log logutils.Log, lineCache *f
 	if cfg.ExcludeCaseSensitive {
 		excludeRulesProcessor = processors.NewExcludeRulesCaseSensitive(
 			excludeRules,
-			lineCache,
+			files,
 			log.Child(logutils.DebugKeyExcludeRules),
 		)
 	} else {
 		excludeRulesProcessor = processors.NewExcludeRules(
 			excludeRules,
-			lineCache,
+			files,
 			log.Child(logutils.DebugKeyExcludeRules),
 		)
 	}
 
 	return excludeRulesProcessor
 }
 
-func getSeverityRulesProcessor(cfg *config.Severity, log logutils.Log, lineCache *fsutils.LineCache) processors.Processor {
+func getSeverityRulesProcessor(cfg *config.Severity, log logutils.Log, files *fsutils.Files) processors.Processor {
 	var severityRules []processors.SeverityRule
 	for _, r := range cfg.Rules {
 		severityRules = append(severityRules, processors.SeverityRule{
@@ -320,14 +325,14 @@ func getSeverityRulesProcessor(cfg *config.Severity, log logutils.Log, lineCache
 		severityRulesProcessor = processors.NewSeverityRulesCaseSensitive(
 			cfg.Default,
 			severityRules,
-			lineCache,
+			files,
 			log.Child(logutils.DebugKeySeverityRules),
 		)
 	} else {
 		severityRulesProcessor = processors.NewSeverityRules(
 			cfg.Default,
 			severityRules,
-			lineCache,
+			files,
 			log.Child(logutils.DebugKeySeverityRules),
 		)
 	}

pkg/result/processors/base_rule.go

@@ -26,22 +26,22 @@ func (r *baseRule) isEmpty() bool {
 	return r.text == nil && r.source == nil && r.path == nil && len(r.linters) == 0
 }
 
-func (r *baseRule) match(issue *result.Issue, lineCache *fsutils.LineCache, log logutils.Log) bool {
+func (r *baseRule) match(issue *result.Issue, files *fsutils.Files, log logutils.Log) bool {
 	if r.isEmpty() {
 		return false
 	}
 	if r.text != nil && !r.text.MatchString(issue.Text) {
 		return false
 	}
-	if r.path != nil && !r.path.MatchString(issue.FilePath()) {
+	if r.path != nil && !r.path.MatchString(files.WithPathPrefix(issue.FilePath())) {
 		return false
 	}
 	if len(r.linters) != 0 && !r.matchLinter(issue) {
 		return false
 	}
 
 	// the most heavyweight checking last
-	if r.source != nil && !r.matchSource(issue, lineCache, log) {
+	if r.source != nil && !r.matchSource(issue, files.LineCache, log) {
 		return false
 	}
 

pkg/result/processors/exclude_rules.go

@@ -17,15 +17,15 @@ type ExcludeRule struct {
 }
 
 type ExcludeRules struct {
-	rules     []excludeRule
-	lineCache *fsutils.LineCache
-	log       logutils.Log
+	rules []excludeRule
+	files *fsutils.Files
+	log   logutils.Log
 }
 
-func NewExcludeRules(rules []ExcludeRule, lineCache *fsutils.LineCache, log logutils.Log) *ExcludeRules {
+func NewExcludeRules(rules []ExcludeRule, files *fsutils.Files, log logutils.Log) *ExcludeRules {
 	r := &ExcludeRules{
-		lineCache: lineCache,
-		log:       log,
+		files: files,
+		log:   log,
 	}
 	r.rules = createRules(rules, "(?i)")
 
@@ -59,7 +59,7 @@ func (p ExcludeRules) Process(issues []result.Issue) ([]result.Issue, error) {
 	return filterIssues(issues, func(i *result.Issue) bool {
 		for _, rule := range p.rules {
 			rule := rule
-			if rule.match(i, p.lineCache, p.log) {
+			if rule.match(i, p.files, p.log) {
 				return false
 			}
 		}
@@ -76,10 +76,10 @@ type ExcludeRulesCaseSensitive struct {
 	*ExcludeRules
 }
 
-func NewExcludeRulesCaseSensitive(rules []ExcludeRule, lineCache *fsutils.LineCache, log logutils.Log) *ExcludeRulesCaseSensitive {
+func NewExcludeRulesCaseSensitive(rules []ExcludeRule, files *fsutils.Files, log logutils.Log) *ExcludeRulesCaseSensitive {
 	r := &ExcludeRules{
-		lineCache: lineCache,
-		log:       log,
+		files: files,
+		log:   log,
 	}
 	r.rules = createRules(rules, "")
 

pkg/result/processors/exclude_rules_test.go

@@ -1,6 +1,7 @@
 package processors
 
 import (
+	"path"
 	"path/filepath"
 	"testing"
 
@@ -12,6 +13,8 @@ import (
 
 func TestExcludeRulesMultiple(t *testing.T) {
 	lineCache := fsutils.NewLineCache(fsutils.NewFileCache())
+	files := fsutils.NewFiles(lineCache, "")
+
 	p := NewExcludeRules([]ExcludeRule{
 		{
 			BaseRule: BaseRule{
@@ -37,7 +40,7 @@ func TestExcludeRulesMultiple(t *testing.T) {
 				Linters: []string{"lll"},
 			},
 		},
-	}, lineCache, nil)
+	}, files, nil)
 
 	cases := []issueTestCase{
 		{Path: "e.go", Text: "exclude", Linter: "linter"},
@@ -70,6 +73,43 @@ func TestExcludeRulesMultiple(t *testing.T) {
 	assert.Equal(t, expectedCases, resultingCases)
 }
 
+func TestExcludeRulesPathPrefix(t *testing.T) {
+	lineCache := fsutils.NewLineCache(fsutils.NewFileCache())
+	pathPrefix := path.Join("some", "dir")
+	files := fsutils.NewFiles(lineCache, pathPrefix)
+
+	p := NewExcludeRules([]ExcludeRule{
+		{
+			BaseRule: BaseRule{
+				Path: `some/dir/e\.go`,
+			},
+		},
+	}, files, nil)
+
+	cases := []issueTestCase{
+		{Path: "e.go"},
+		{Path: "other.go"},
+	}
+	var issues []result.Issue
+	for _, c := range cases {
+		issues = append(issues, newIssueFromIssueTestCase(c))
+	}
+	processedIssues := process(t, p, issues...)
+	var resultingCases []issueTestCase
+	for _, i := range processedIssues {
+		resultingCases = append(resultingCases, issueTestCase{
+			Path:   i.FilePath(),
+			Linter: i.FromLinter,
+			Text:   i.Text,
+			Line:   i.Line(),
+		})
+	}
+	expectedCases := []issueTestCase{
+		{Path: "other.go"},
+	}
+	assert.Equal(t, expectedCases, resultingCases)
+}
+
 func TestExcludeRulesText(t *testing.T) {
 	p := NewExcludeRules([]ExcludeRule{
 		{
@@ -104,6 +144,7 @@ func TestExcludeRulesEmpty(t *testing.T) {
 
 func TestExcludeRulesCaseSensitiveMultiple(t *testing.T) {
 	lineCache := fsutils.NewLineCache(fsutils.NewFileCache())
+	files := fsutils.NewFiles(lineCache, "")
 	p := NewExcludeRulesCaseSensitive([]ExcludeRule{
 		{
 			BaseRule: BaseRule{
@@ -129,7 +170,7 @@ func TestExcludeRulesCaseSensitiveMultiple(t *testing.T) {
 				Linters: []string{"lll"},
 			},
 		},
-	}, lineCache, nil)
+	}, files, nil)
 
 	cases := []issueTestCase{
 		{Path: "e.go", Text: "exclude", Linter: "linter"},

pkg/result/processors/path_prefixer.go

@@ -1,8 +1,7 @@
 package processors
 
 import (
-	"path/filepath"
-
+	"github.com/golangci/golangci-lint/pkg/fsutils"
 	"github.com/golangci/golangci-lint/pkg/result"
 )
 
@@ -27,7 +26,7 @@ func (*PathPrefixer) Name() string {
 func (p *PathPrefixer) Process(issues []result.Issue) ([]result.Issue, error) {
 	if p.prefix != "" {
 		for i := range issues {
-			issues[i].Pos.Filename = filepath.Join(p.prefix, issues[i].Pos.Filename)
+			issues[i].Pos.Filename = fsutils.WithPathPrefix(p.prefix, issues[i].Pos.Filename)
 		}
 	}
 	return issues, nil

pkg/result/processors/severity_rules.go

@@ -21,13 +21,13 @@ type SeverityRule struct {
 type SeverityRules struct {
 	defaultSeverity string
 	rules           []severityRule
-	lineCache       *fsutils.LineCache
+	files           *fsutils.Files
 	log             logutils.Log
 }
 
-func NewSeverityRules(defaultSeverity string, rules []SeverityRule, lineCache *fsutils.LineCache, log logutils.Log) *SeverityRules {
+func NewSeverityRules(defaultSeverity string, rules []SeverityRule, files *fsutils.Files, log logutils.Log) *SeverityRules {
 	r := &SeverityRules{
-		lineCache:       lineCache,
+		files:           files,
 		log:             log,
 		defaultSeverity: defaultSeverity,
 	}
@@ -70,7 +70,7 @@ func (p SeverityRules) Process(issues []result.Issue) ([]result.Issue, error) {
 				ruleSeverity = rule.severity
 			}
 
-			if rule.match(i, p.lineCache, p.log) {
+			if rule.match(i, p.files, p.log) {
 				i.Severity = ruleSeverity
 				return i
 			}
@@ -90,9 +90,9 @@ type SeverityRulesCaseSensitive struct {
 }
 
 func NewSeverityRulesCaseSensitive(defaultSeverity string, rules []SeverityRule,
-	lineCache *fsutils.LineCache, log logutils.Log) *SeverityRulesCaseSensitive {
+	files *fsutils.Files, log logutils.Log) *SeverityRulesCaseSensitive {
 	r := &SeverityRules{
-		lineCache:       lineCache,
+		files:           files,
 		log:             log,
 		defaultSeverity: defaultSeverity,
 	}