Sanizize mailbox name for exporting

Changelog.md

@@ -8,6 +8,7 @@ Changelog [format](http://keepachangelog.com/en/1.0.0/)
 * GODT-749 Don't force PGP/Inline when sending plaintext messages.
 * GODT-764 Fix deadlock in integration tests for Import-Export.
 * GODT-662 Do not resume paused transfer progress after dismissing cancel popup.
+* GODT-772 Sanitize mailbox names for exporting to follow OS restrictions.
 
 ### Changed
 * Bump crypto version to v0.0.0-20200818122824-ed5d25e28db8

internal/transfer/provider_eml_target.go

@@ -61,7 +61,7 @@ func (p *EMLProvider) TransferFrom(rules transferRules, progress *Progress, ch <
 func (p *EMLProvider) createFolders(rules transferRules) error {
 	for rule := range rules.iterateActiveRules() {
 		for _, mailbox := range rule.TargetMailboxes {
-			path := filepath.Join(p.root, mailbox.Name)
+			path := filepath.Join(p.root, sanitizeFileName(mailbox.Name))
 			if err := os.MkdirAll(path, os.ModePerm); err != nil {
 				return err
 			}
@@ -71,7 +71,7 @@ func (p *EMLProvider) createFolders(rules transferRules) error {
 }
 
 func (p *EMLProvider) writeFile(msg Message) error {
-	fileName := filepath.Base(msg.ID)
+	fileName := sanitizeFileName(filepath.Base(msg.ID))
 	if filepath.Ext(fileName) != ".eml" {
 		fileName += ".eml"
 	}

internal/transfer/provider_mbox_target.go

@@ -57,7 +57,7 @@ func (p *MBOXProvider) TransferFrom(rules transferRules, progress *Progress, ch
 func (p *MBOXProvider) writeMessage(msg Message) error {
 	var multiErr error
 	for _, mailbox := range msg.Targets {
-		mboxName := filepath.Base(mailbox.Name)
+		mboxName := sanitizeFileName(mailbox.Name)
 		if !strings.HasSuffix(mboxName, ".mbox") {
 			mboxName += ".mbox"
 		}

internal/transfer/utils.go

@@ -24,6 +24,7 @@ import (
 	"net/mail"
 	"net/textproto"
 	"path/filepath"
+	"runtime"
 	"sort"
 	"strings"
 
@@ -139,3 +140,24 @@ func getMessageHeader(body []byte) (mail.Header, error) {
 	}
 	return mail.Header(header), nil
 }
+
+// sanitizeFileName replaces problematic special characters with underscore.
+func sanitizeFileName(fileName string) string {
+	if len(fileName) == 0 {
+		return fileName
+	}
+	if runtime.GOOS != "windows" && (fileName[0] == '-' || fileName[0] == '.') { //nolint[goconst]
+		fileName = "_" + fileName[1:]
+	}
+	return strings.Map(func(r rune) rune {
+		switch r {
+		case '\\', '/', ':', '*', '?', '"', '<', '>', '|':
+			return '_'
+		case '[', ']', '(', ')', '{', '}', '^', '#', '%', '&', '!', '@', '+', '=', '\'', '~':
+			if runtime.GOOS != "windows" {
+				return '_'
+			}
+		}
+		return r
+	}, fileName)
+}

internal/transfer/utils_test.go

@@ -21,6 +21,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"runtime"
 	"testing"
 
 	r "github.com/stretchr/testify/require"
@@ -188,3 +189,26 @@ Body
 	r.Equal(t, header.Get("subject"), "Hello")
 	r.Equal(t, header.Get("from"), "user@example.com")
 }
+
+func TestSanitizeFileName(t *testing.T) {
+	tests := map[string]string{
+		"hello":            "hello",
+		"a\\b/c:*?d\"<>|e": "a_b_c___d____e",
+	}
+	if runtime.GOOS == "darwin" || runtime.GOOS == "linux" {
+		tests[".hello"] = "_hello"
+		tests["-hello"] = "_hello"
+	}
+	if runtime.GOOS == "windows" {
+		tests["[hello]&@=~~"] = "_hello______"
+	}
+
+	for path, wantPath := range tests {
+		path := path
+		wantPath := wantPath
+		t.Run(path, func(t *testing.T) {
+			gotPath := sanitizeFileName(path)
+			r.Equal(t, wantPath, gotPath)
+		})
+	}
+}