lib-mail: message_snippet_generate() - Ignore NULs without shrinking …

…snippet size

Previously the NULs also weren't in the snippet content, but they were
included in the snippet size.

src/lib-mail/message-snippet.c

@@ -60,6 +60,10 @@ static bool snippet_generate(struct snippet_context *ctx,
 				count += 2; /* because we skip +1 next */
 				break;
 			}
+			if (data[i] == '\0') {
+				/* skip NULs without increasing snippet size */
+				break;
+			}
 			if (data[i] == '\r' || data[i] == '\n' ||
 			    data[i] == '\t' || data[i] == ' ') {
 				/* skip any leading whitespace */

src/lib-mail/test-message-snippet.c

@@ -84,10 +84,26 @@ static void test_message_snippet(void)
 	test_end();
 }
 
+static void test_message_snippet_nuls(void)
+{
+	const char input_text[] = "\nfoo\0bar";
+	string_t *str = t_str_new(128);
+	struct istream *input;
+
+	test_begin("message snippet with NULs");
+
+	input = i_stream_create_from_data(input_text, sizeof(input_text)-1);
+	test_assert(message_snippet_generate(input, 5, str) == 0);
+	test_assert(strcmp(str_c(str), "fooba") == 0);
+	i_stream_destroy(&input);
+	test_end();
+}
+
 int main(void)
 {
 	static void (*const test_functions[])(void) = {
 		test_message_snippet,
+		test_message_snippet_nuls,
 		NULL
 	};
 	return test_run(test_functions);