fix(inputs.filecount): Respect symlink files with FollowSymLinks (#14669)

plugins/inputs/filecount/filecount.go

@@ -130,7 +130,7 @@ func (fc *FileCount) count(acc telegraf.Accumulator, basedir string, glob globpa
 		if err == nil && rel == "." {
 			return nil
 		}
-		file, err := fc.Fs.Stat(path)
+		file, err := fc.resolveLink(path)
 		if err != nil {
 			if os.IsNotExist(err) {
 				return nil
@@ -244,6 +244,21 @@ func (fc *FileCount) Gather(acc telegraf.Accumulator) error {
 	return nil
 }
 
+func (fc *FileCount) resolveLink(path string) (os.FileInfo, error) {
+	if fc.FollowSymlinks {
+		return fc.Fs.Stat(path)
+	}
+	fi, err := fc.Fs.Lstat(path)
+	if err != nil {
+		return fi, err
+	}
+	if fi.Mode()&os.ModeSymlink != 0 {
+		// if this file is a symlink, skip it
+		return nil, godirwalk.SkipThis
+	}
+	return fi, nil
+}
+
 func (fc *FileCount) onlyDirectories(directories []string) []string {
 	out := make([]string, 0)
 	for _, path := range directories {

plugins/inputs/filecount/filesystem_helpers.go

@@ -14,6 +14,7 @@ import (
 type fileSystem interface {
 	Open(name string) (file, error)
 	Stat(name string) (os.FileInfo, error)
+	Lstat(name string) (os.FileInfo, error)
 }
 
 type file interface {
@@ -27,5 +28,6 @@ type file interface {
 // osFS implements fileSystem using the local disk
 type osFS struct{}
 
-func (osFS) Open(name string) (file, error)        { return os.Open(name) }
+func (osFS) Open(name string) (file, error)         { return os.Open(name) }
-func (osFS) Stat(name string) (os.FileInfo, error) { return os.Stat(name) }
+func (osFS) Stat(name string) (os.FileInfo, error)  { return os.Stat(name) }
+func (osFS) Lstat(name string) (os.FileInfo, error) { return os.Lstat(name) }

plugins/inputs/filecount/filesystem_helpers_notwindows.go

@@ -50,3 +50,8 @@ func (f fakeFileSystem) Stat(name string) (os.FileInfo, error) {
 	}
 	return nil, &os.PathError{Op: "Stat", Path: name, Err: errors.New("no such file or directory")}
 }
+
+func (f fakeFileSystem) Lstat(name string) (os.FileInfo, error) {
+	// not able to test with symlinks currently
+	return f.Stat(name)
+}