maildir,notmuch: avoid leaking open files

Previously, Message.NewReader returned the wrapped buffered reader
without a reference to the opened file, so the files descriptors
were left unclosed after reading.  Now, the file reader is returned
directly and closed on the call site.  Buffering is not needed here
because it is an implementation detail of go-message.

Fixes: https://todo.sr.ht/~rjarry/aerc/9

worker/lib/parse.go

@@ -211,7 +211,7 @@ func parseAddressList(h *mail.Header, key string) ([]*mail.Address, error) {
 
 // RawMessage is an interface that describes a raw message
 type RawMessage interface {
-	NewReader() (io.Reader, error)
+	NewReader() (io.ReadCloser, error)
 	ModelFlags() ([]models.Flag, error)
 	Labels() ([]string, error)
 	UID() uint32
@@ -225,6 +225,7 @@ func MessageInfo(raw RawMessage) (*models.MessageInfo, error) {
 	if err != nil {
 		return nil, err
 	}
+	defer r.Close()
 	msg, err := message.Read(r)
 	if err != nil {
 		return nil, fmt.Errorf("could not read message: %v", err)

worker/lib/parse_test.go

@@ -1,9 +1,9 @@
 package lib
 
 import (
-	"bytes"
 	"io"
 	"io/ioutil"
+	"os"
 	"path/filepath"
 	"testing"
 
@@ -36,23 +36,17 @@ func TestMessageInfoHandledError(t *testing.T) {
 }
 
 type mockRawMessage struct {
-	body []byte
-}
-
-func newMockRawMessage(body []byte) *mockRawMessage {
-	return &mockRawMessage{
-		body: body,
-	}
+	path string
 }
 
 func newMockRawMessageFromPath(p string) *mockRawMessage {
-	b, err := ioutil.ReadFile(p)
-	die(err)
-	return newMockRawMessage(b)
+	return &mockRawMessage{
+		path: p,
+	}
 }
 
-func (m *mockRawMessage) NewReader() (io.Reader, error) {
-	return bytes.NewReader(m.body), nil
+func (m *mockRawMessage) NewReader() (io.ReadCloser, error) {
+	return os.Open(m.path)
 }
 func (m *mockRawMessage) ModelFlags() ([]models.Flag, error) { return nil, nil }
 func (m *mockRawMessage) Labels() ([]string, error)          { return nil, nil }

worker/maildir/message.go

@@ -1,7 +1,6 @@
 package maildir
 
 import (
-	"bufio"
 	"fmt"
 	"io"
 
@@ -20,12 +19,8 @@ type Message struct {
 }
 
 // NewReader reads a message into memory and returns an io.Reader for it.
-func (m Message) NewReader() (io.Reader, error) {
-	f, err := m.dir.Open(m.key)
-	if err != nil {
-		return nil, err
-	}
-	return bufio.NewReader(f), nil
+func (m Message) NewReader() (io.ReadCloser, error) {
+	return m.dir.Open(m.key)
 }
 
 // Flags fetches the set of flags currently applied to the message.

worker/maildir/search.go

@@ -159,6 +159,7 @@ func (w *Worker) searchKey(key uint32, criteria *searchCriteria,
 		if err != nil {
 			return false, err
 		}
+		defer reader.Close()
 		bytes, err := ioutil.ReadAll(reader)
 		if err != nil {
 			return false, err

worker/maildir/worker.go

@@ -432,6 +432,7 @@ func (w *Worker) handleFetchFullMessages(msg *types.FetchFullMessages) error {
 			w.worker.Logger.Printf("could not get message reader: %v", err)
 			return err
 		}
+		defer r.Close()
 		w.worker.PostMessage(&types.FullMessage{
 			Message: types.RespondTo(msg),
 			Content: &models.FullMessage{

worker/notmuch/message.go

@@ -4,7 +4,6 @@
 package notmuch
 
 import (
-	"bufio"
 	"fmt"
 	"io"
 	"os"
@@ -23,16 +22,12 @@ type Message struct {
 }
 
 // NewReader returns a reader for a message
-func (m *Message) NewReader() (io.Reader, error) {
+func (m *Message) NewReader() (io.ReadCloser, error) {
 	name, err := m.Filename()
 	if err != nil {
 		return nil, err
 	}
-	f, err := os.Open(name)
-	if err != nil {
-		return nil, err
-	}
-	return bufio.NewReader(f), nil
+	return os.Open(name)
 }
 
 // MessageInfo populates a models.MessageInfo struct for the message.

worker/notmuch/worker.go

@@ -367,6 +367,7 @@ func (w *worker) handleFetchFullMessages(msg *types.FetchFullMessages) error {
 			w.w.Logger.Printf("could not get message reader: %v", err)
 			return err
 		}
+		defer r.Close()
 		w.w.PostMessage(&types.FullMessage{
 			Message: types.RespondTo(msg),
 			Content: &models.FullMessage{