Fix collector_whitelist feature (#284)

* Fix collector_whitelist feature

* Fix collector_whitelist feature

The previous fix for #279 introduced an error,
because result.Path was not always set.

Instead of failing on non-existant files, still perform the PathMatch
but report them in result.DoesExist.

Broken symlinks are always reported as an error, because we cannot
resolve their actual path using EvalSymlinks.

Add some tests.

Fixes #279

common/helper.go

@@ -170,25 +170,32 @@ func Sprintf(format string, values ...interface{}) (string, error) {
 }
 
 type PathMatchResult struct {
-	Path   string
-	Match  bool
-	IsLink bool
+	Path      string
+	Match     bool
+	IsLink    bool
+	DoesExist bool
 }
 
 func PathMatch(path string, patternList []string) (PathMatchResult, error) {
-	result := PathMatchResult{}
-	if _, err := os.Stat(path); os.IsExist(err) {
+	result := PathMatchResult{Path: path, DoesExist: true}
+
+	if _, err := os.Lstat(path); err == nil {
 		resolvedPath, err := filepath.EvalSymlinks(path)
 		if err != nil {
+			// error out on broken symlinks, because we cannot resolve
+			// their path with EvalSymlinks
+			result.DoesExist = false
 			return result, err
 		} else {
-			result.Path = resolvedPath
+			if resolvedPath != path {
+				result.IsLink = true
+				result.Path = resolvedPath
+			}
 		}
+	} else {
+		result.DoesExist = false
 	}
 
-	if result.Path != path {
-		result.IsLink = true
-	}
 	for _, pattern := range patternList {
 		match, err := filepath.Match(pattern, result.Path)
 		if err != nil {

common/helper_test.go

@@ -20,6 +20,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"runtime"
 	"strings"
 	"testing"
 )
@@ -98,3 +99,74 @@ func TestEncloseWithoutData(t *testing.T) {
 		t.Fail()
 	}
 }
+
+func TestPathMatch(t *testing.T) {
+	dir, err := ioutil.TempDir("", "test-path-match")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+
+	execfile := filepath.Join(dir, "myexec")
+	patternList := []string{"/usr/bin/moo", "/sbin/bar"}
+	result, err := PathMatch(execfile, patternList)
+	if err != nil || result.Match {
+		t.Fatalf("'%s' should not match patternList %v err '%v' result '%v'", execfile, patternList, err, result)
+	}
+	if result.DoesExist {
+		t.Fatalf("DoesExist should not be set")
+	}
+
+	os.Create(execfile)
+	patternList = []string{"/usr/bin/moo", "/sbin/bar", execfile}
+	result, err = PathMatch(execfile, patternList)
+	if err != nil || !result.Match {
+		t.Fatalf("'%s' should match patternList %v err '%v' result '%v'", execfile, patternList, err, result)
+	}
+	if !result.DoesExist {
+		t.Fatalf("DoesExist should be set")
+	}
+
+	patternList = []string{"/usr/bin/moo", "/sbin/bar", dir + "/*"}
+	result, err = PathMatch(execfile, patternList)
+	if err != nil || !result.Match {
+		t.Fatalf("'%s' should match globbing patternList %v err '%v' result '%v'",
+			execfile, patternList, err, result)
+	}
+
+}
+
+func TestPathMatchSymlink(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip()
+	}
+
+	dir, err := ioutil.TempDir("", "test-path-match")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+
+	execfile := filepath.Join(dir, "myexec")
+	symlink := filepath.Join(dir, "symlink")
+	if err = os.Symlink(execfile, symlink); err != nil {
+		t.Fatal()
+	}
+	patternList := []string{"moo", "bar", execfile}
+	result, err := PathMatch(symlink, patternList)
+	if err == nil {
+		t.Fatalf("broken symlinks should report an error")
+	}
+
+	os.Create(execfile)
+	result, err = PathMatch(symlink, patternList)
+	if err != nil || !result.Match {
+		t.Fatalf("'%s' should match patternList %v err '%v' result '%v'", execfile, patternList, err, result)
+	}
+	if !result.IsLink {
+		t.Fatalf("result.IsLink is false")
+	}
+	if result.Path != execfile {
+		t.Fatalf("result.Path did not contain resolved symlink")
+	}
+}