Fix infinity loop due to negative width

am: 0385197086

Change-Id: I912f123239be95d7a4b773d024c247066257c78d

4 files changed, 64 insertions, 3 deletions

diff --git a/include/minikin/AndroidLineBreakerHelper.h b/include/minikin/AndroidLineBreakerHelper.h
index a9b4914..462644d 100644
--- a/include/minikin/AndroidLineBreakerHelper.h
+++ b/include/minikin/AndroidLineBreakerHelper.h
@@ -17,6 +17,8 @@
 #ifndef MINIKIN_ANDROID_LINE_BREAKER_HELPERS_H
 #define MINIKIN_ANDROID_LINE_BREAKER_HELPERS_H
 
+#include <algorithm>
+
 #include "minikin/LineBreaker.h"
 
 namespace minikin {
@@ -37,7 +39,7 @@ public:
 
     float getAt(size_t lineNo) const override {
         const float width = ((ssize_t)lineNo < (ssize_t)mFirstLineCount) ? mFirstWidth : mRestWidth;
-        return width - get(mIndents, lineNo);
+        return std::max(0.0f, width - get(mIndents, lineNo));
     }
 
     float getMin() const override {
diff --git a/include/minikin/LineBreaker.h b/include/minikin/LineBreaker.h
index 7d59c63..2974c20 100644
--- a/include/minikin/LineBreaker.h
+++ b/include/minikin/LineBreaker.h
@@ -78,10 +78,10 @@ class LineWidth {
 public:
     virtual ~LineWidth() {}
 
-    // Called to find out the width for the line.
+    // Called to find out the width for the line. This must not return negative values.
     virtual float getAt(size_t lineNo) const = 0;
 
-    // Called to find out the minimum line width.
+    // Called to find out the minimum line width. This mut not return negative values.
     virtual float getMin() const = 0;
 
     // Called to find out the available left-side padding for the line.
diff --git a/tests/unittest/Android.bp b/tests/unittest/Android.bp
index ba593a5..fcaab69 100644
--- a/tests/unittest/Android.bp
+++ b/tests/unittest/Android.bp
@@ -39,6 +39,7 @@ cc_test {
     ],
 
     srcs: [
+        "AndroidLineBreakerHelperTest.cpp",
         "BidiUtilsTest.cpp",
         "CmapCoverageTest.cpp",
         "EmojiTest.cpp",
diff --git a/tests/unittest/AndroidLineBreakerHelperTest.cpp b/tests/unittest/AndroidLineBreakerHelperTest.cpp
new file mode 100644
index 0000000..ea977c0
--- /dev/null
+++ b/tests/unittest/AndroidLineBreakerHelperTest.cpp
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2018 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 "minikin/AndroidLineBreakerHelper.h"
+
+#include <gtest/gtest.h>
+
+namespace minikin {
+namespace android {
+
+TEST(AndroidLineWidth, negativeWidthTest) {
+    const int LINE_COUNT = 10;
+    const std::vector<float> EMPTY;
+    {
+        AndroidLineWidth lineWidth(-10 /* first width */, 1 /* first count */, 0 /* rest width */,
+                                   EMPTY, EMPTY, EMPTY, 0);
+
+        EXPECT_LE(0.0f, lineWidth.getMin());
+        for (int i = 0; i < LINE_COUNT; ++i) {
+            EXPECT_LE(0.0f, lineWidth.getAt(i));
+        }
+    }
+    {
+        AndroidLineWidth lineWidth(0 /* first width */, 0 /* first count */, -10 /* rest width */,
+                                   EMPTY, EMPTY, EMPTY, 0);
+
+        EXPECT_LE(0.0f, lineWidth.getMin());
+        for (int i = 0; i < LINE_COUNT; ++i) {
+            EXPECT_LE(0.0f, lineWidth.getAt(i));
+        }
+    }
+    {
+        std::vector<float> indents = {10};
+        AndroidLineWidth lineWidth(0 /* first width */, 0 /* first count */, 0 /* rest width */,
+                                   indents, EMPTY, EMPTY, 0);
+
+        EXPECT_LE(0.0f, lineWidth.getMin());
+        for (int i = 0; i < LINE_COUNT; ++i) {
+            EXPECT_LE(0.0f, lineWidth.getAt(i));
+        }
+    }
+}
+
+}  // namespace android
+}  // namespace minikin