Add bound checks to utf16_to_utf8

Test: ran libaapt2_tests64
Bug: 29250543
Change-Id: I1ebc017af623b6514cf0c493e8cd8e1d59ea26c3
(cherry picked from commit 4781057e78)

tools/aapt/Android.mk

@@ -57,8 +57,8 @@ aaptTests := \
 aaptHostStaticLibs := \
     libandroidfw \
     libpng \
-    liblog \
     libutils \
+    liblog \
     libcutils \
     libexpat \
     libziparchive-host \

tools/aapt2/util/Util.cpp

@@ -441,8 +441,10 @@ std::string utf16ToUtf8(const StringPiece16& utf16) {
     }
 
     std::string utf8;
+    // Make room for '\0' explicitly.
+    utf8.resize(utf8Length + 1);
+    utf16_to_utf8(utf16.data(), utf16.length(), &*utf8.begin(), utf8Length + 1);
     utf8.resize(utf8Length);
-    utf16_to_utf8(utf16.data(), utf16.length(), &*utf8.begin());
     return utf8;
 }
 

tools/split-select/Android.mk

@@ -47,8 +47,8 @@ hostStaticLibs := \
     libaapt \
     libandroidfw \
     libpng \
-    liblog \
     libutils \
+    liblog \
     libcutils \
     libexpat \
     libziparchive-host \