Fix matches_locale function

matches_locale was expecting input locale string to have at most one
underscore; as a result "zh_CN_#Hans" ignores "zh_CN" and matches into
"zh". Fix the match function and add unit tests.

Bug: 27837319
Change-Id: I4e8a66f91cae6ac2a46b6bf21f670d5ea564c7c8

minui/minui.h

@@ -84,6 +84,8 @@ int ev_get_epollfd();
 // Resources
 //
 
+bool matches_locale(const char* prefix, const char* locale);
+
 // res_create_*_surface() functions return 0 if no error, else
 // negative.
 //

minui/resources.cpp

@@ -370,21 +370,16 @@ int res_create_alpha_surface(const char* name, GRSurface** pSurface) {
     return result;
 }
 
-static int matches_locale(const char* loc, const char* locale) {
+// This function tests if a locale string stored in PNG (prefix) matches
-    if (locale == NULL) return 0;
+// the locale string provided by the system (locale).
+bool matches_locale(const char* prefix, const char* locale) {
+    if (locale == NULL) return false;
 
-    if (strcmp(loc, locale) == 0) return 1;
+    // Return true if the whole string of prefix matches the top part of
+    // locale. For instance, prefix == "en" matches locale == "en_US";
+    // and prefix == "zh_CN" matches locale == "zh_CN_#Hans".
 
-    // if loc does *not* have an underscore, and it matches the start
+    return (strncmp(prefix, locale, strlen(prefix)) == 0);
-    // of locale, and the next character in locale *is* an underscore,
-    // that's a match.  For instance, loc == "en" matches locale ==
-    // "en_US".
-
-    int i;
-    for (i = 0; loc[i] != 0 && loc[i] != '_'; ++i);
-    if (loc[i] == '_') return 0;
-
-    return (strncmp(locale, loc, i) == 0 && locale[i] == '_');
 }
 
 int res_create_localized_alpha_surface(const char* name,

tests/Android.mk

@@ -21,9 +21,13 @@ include $(CLEAR_VARS)
 LOCAL_CLANG := true
 LOCAL_MODULE := recovery_unit_test
 LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
-LOCAL_STATIC_LIBRARIES := libverifier
+LOCAL_STATIC_LIBRARIES := \
+    libverifier \
+    libminui
+
 LOCAL_SRC_FILES := unit/asn1_decoder_test.cpp
 LOCAL_SRC_FILES += unit/recovery_test.cpp
+LOCAL_SRC_FILES += unit/locale_test.cpp
 LOCAL_C_INCLUDES := bootable/recovery
 LOCAL_SHARED_LIBRARIES := liblog
 include $(BUILD_NATIVE_TEST)

tests/unit/locale_test.cpp

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gtest/gtest.h>
+
+#include "minui/minui.h"
+
+TEST(LocaleTest, Misc) {
+    EXPECT_TRUE(matches_locale("zh_CN", "zh_CN_#Hans"));
+    EXPECT_TRUE(matches_locale("zh", "zh_CN_#Hans"));
+    EXPECT_FALSE(matches_locale("zh_HK", "zh_CN_#Hans"));
+    EXPECT_TRUE(matches_locale("en_GB", "en_GB"));
+    EXPECT_TRUE(matches_locale("en", "en_GB"));
+    EXPECT_FALSE(matches_locale("en_GB", "en"));
+    EXPECT_FALSE(matches_locale("en_GB", "en_US"));
+}