From 60c07b259e398e044faa48742d034bfb96a0bc87 Mon Sep 17 00:00:00 2001
From: Jakob Borg <jakob@kastelo.net>
Date: Fri, 30 Aug 2019 10:36:31 +0100
Subject: [PATCH] lib/ignore: Don't crash in partial #include line (ref #5985)
 (#5986)

If the line is just "#include" with nothing following it we would crash
with an index out of bounds error. Now it's a little more careful.
---
 lib/ignore/ignore.go      | 13 ++++++++++++-
 lib/ignore/ignore_test.go | 19 +++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/lib/ignore/ignore.go b/lib/ignore/ignore.go
index 74d35c1e..81ee8f24 100644
--- a/lib/ignore/ignore.go
+++ b/lib/ignore/ignore.go
@@ -461,7 +461,18 @@ func parseIgnoreFile(fs fs.Filesystem, fd io.Reader, currentFile string, cd Chan
 		line = filepath.ToSlash(line)
 		switch {
 		case strings.HasPrefix(line, "#include"):
-			includeRel := strings.TrimSpace(line[len("#include "):])
+			fields := strings.SplitN(line, " ", 2)
+			if len(fields) != 2 {
+				err = fmt.Errorf("failed to parse #include line: no file?")
+				break
+			}
+
+			includeRel := strings.TrimSpace(fields[1])
+			if includeRel == "" {
+				err = fmt.Errorf("failed to parse #include line: no file?")
+				break
+			}
+
 			includeFile := filepath.Join(filepath.Dir(currentFile), includeRel)
 			var includePatterns []Pattern
 			if includePatterns, err = loadParseIncludeFile(fs, includeFile, cd, linesSeen); err == nil {
diff --git a/lib/ignore/ignore_test.go b/lib/ignore/ignore_test.go
index 18ff24e9..93a72c5d 100644
--- a/lib/ignore/ignore_test.go
+++ b/lib/ignore/ignore_test.go
@@ -1079,3 +1079,22 @@ func TestSpecialChars(t *testing.T) {
 		}
 	}
 }
+
+func TestPartialIncludeLine(t *testing.T) {
+	// Loading a partial #include line (no file mentioned) should error but not crash.
+
+	pats := New(fs.NewFilesystem(fs.FilesystemTypeBasic, "."), WithCache(true))
+	cases := []string{
+		"#include",
+		"#include\n",
+		"#include ",
+		"#include \n",
+		"#include   \n\n\n",
+	}
+
+	for _, tc := range cases {
+		if err := pats.Parse(bytes.NewBufferString(tc), ".stignore"); err == nil {
+			t.Fatal("should error out")
+		}
+	}
+}