Add additional check on float precision after parsing, only compile the

value to a float when the difference between float and double parsed
from same raw string is smaller than 1.

Bug: b/69347762
Test: Verified affected atests pass and added new atest
Change-Id: I25da0baccba580484db39aa2d0a1bb765706635d

libs/androidfw/ResourceTypes.cpp

@@ -5436,37 +5436,66 @@ bool ResTable::stringToInt(const char16_t* s, size_t len, Res_value* outValue)
     return U16StringToInt(s, len, outValue);
 }
 
-bool ResTable::stringToFloat(const char16_t* s, size_t len, Res_value* outValue)
-{
-    while (len > 0 && isspace16(*s)) {
-        s++;
-        len--;
+template <typename T>
+bool parseFloatingPoint(const char16_t* inBuf, size_t inLen, char* tempBuf,
+                                  const char** outEnd, T& out){
+    while (inLen > 0 && isspace16(*inBuf)) {
+        inBuf++;
+        inLen--;
     }
 
-    if (len <= 0) {
+    if (inLen <= 0) {
         return false;
     }
 
-    char buf[128];
     int i=0;
-    while (len > 0 && *s != 0 && i < 126) {
-        if (*s > 255) {
+    while (inLen > 0 && *inBuf != 0 && i < 126) {
+        if (*inBuf > 255) {
             return false;
         }
-        buf[i++] = *s++;
-        len--;
+        tempBuf[i++] = *inBuf++;
+        inLen--;
     }
 
-    if (len > 0) {
+    if (inLen > 0) {
         return false;
     }
-    if ((buf[0] < '0' || buf[0] > '9') && buf[0] != '.' && buf[0] != '-' && buf[0] != '+') {
+    if ((tempBuf[0] < '0' || tempBuf[0] > '9') && tempBuf[0] != '.' && tempBuf[0] != '-' && tempBuf[0] != '+') {
         return false;
     }
 
-    buf[i] = 0;
-    const char* end;
-    float f = strtof(buf, (char**)&end);
+    tempBuf[i] = 0;
+    if constexpr(std::is_same_v<T, float>) {
+        out = strtof(tempBuf, (char**)outEnd);
+    } else {
+        out = strtod(tempBuf, (char**)outEnd);
+    }
+    return true;
+}
+
+bool ResTable::stringToDouble(const char16_t* s, size_t len, double& d){
+    char buf[128];
+    const char* end = nullptr;
+    if (!parseFloatingPoint(s, len, buf, &end, d)) {
+        return false;
+    }
+
+    while (*end != 0 && isspace((unsigned char)*end)) {
+        end++;
+    }
+
+    return *end == 0;
+}
+
+bool ResTable::stringToFloat(const char16_t* s, size_t len, Res_value* outValue)
+{
+    char buf[128];
+    const char* end = nullptr;
+    float f;
+
+    if (!parseFloatingPoint(s, len, buf, &end, f)) {
+        return false;
+    }
 
     if (*end != 0 && !isspace((unsigned char)*end)) {
         // Might be a unit...

libs/androidfw/include/androidfw/ResourceTypes.h

@@ -2162,6 +2162,7 @@ public:
 
     static bool stringToInt(const char16_t* s, size_t len, Res_value* outValue);
     static bool stringToFloat(const char16_t* s, size_t len, Res_value* outValue);
+    static bool stringToDouble(const char16_t* s, size_t len, double& outValue);
 
     // Used with stringToValue.
     class Accessor

tools/aapt2/ResourceUtils.cpp

@@ -670,8 +670,26 @@ std::unique_ptr<Item> TryParseItemForAttribute(
     // Try parsing this as a float.
     auto floating_point = TryParseFloat(value);
     if (floating_point) {
+      // Only check if the parsed result lost precision when the parsed item is
+      // android::Res_value::TYPE_FLOAT and there is other possible types saved in type_mask, like
+      // ResTable_map::TYPE_INTEGER.
       if (type_mask & AndroidTypeToAttributeTypeMask(floating_point->value.dataType)) {
-        return std::move(floating_point);
+        const bool mayOnlyBeFloat = (type_mask & ~float_mask) == 0;
+        const bool parsedAsFloat = floating_point->value.dataType == android::Res_value::TYPE_FLOAT;
+        if (!mayOnlyBeFloat && parsedAsFloat) {
+          float f = reinterpret_cast<float&>(floating_point->value.data);
+          std::u16string str16 = android::util::Utf8ToUtf16(util::TrimWhitespace(value));
+          double d;
+          if (android::ResTable::stringToDouble(str16.data(), str16.size(), d)) {
+            // Parse as a float only if the difference between float and double parsed from the
+            // same string is smaller than 1, otherwise return as raw string.
+            if (fabs(f - d) < 1) {
+              return std::move(floating_point);
+            }
+          }
+        } else {
+          return std::move(floating_point);
+        }
       }
     }
   }

tools/aapt2/ResourceUtils_test.cpp

@@ -228,6 +228,26 @@ TEST(ResourceUtilsTest, ItemsWithWhitespaceAreParsedCorrectly) {
               Pointee(ValueEq(BinaryPrimitive(Res_value::TYPE_FLOAT, expected_float_flattened))));
 }
 
+TEST(ResourceUtilsTest, FloatAndBigIntegerParsedCorrectly) {
+  const float expected_float = 0.125f;
+  const uint32_t expected_float_flattened = *(uint32_t*)&expected_float;
+  EXPECT_THAT(ResourceUtils::TryParseItemForAttribute("0.125", ResTable_map::TYPE_FLOAT),
+              Pointee(ValueEq(BinaryPrimitive(Res_value::TYPE_FLOAT, expected_float_flattened))));
+
+  const float special_float = 1.0f;
+  const uint32_t special_float_flattened = *(uint32_t*)&special_float;
+  EXPECT_THAT(ResourceUtils::TryParseItemForAttribute("1.0", ResTable_map::TYPE_FLOAT),
+              Pointee(ValueEq(BinaryPrimitive(Res_value::TYPE_FLOAT, special_float_flattened))));
+
+  EXPECT_EQ(ResourceUtils::TryParseItemForAttribute("1099511627776", ResTable_map::TYPE_INTEGER),
+            std::unique_ptr<Item>(nullptr));
+
+  const float big_float = 1099511627776.0f;
+  const uint32_t big_flattened = *(uint32_t*)&big_float;
+  EXPECT_THAT(ResourceUtils::TryParseItemForAttribute("1099511627776", ResTable_map::TYPE_FLOAT),
+              Pointee(ValueEq(BinaryPrimitive(Res_value::TYPE_FLOAT, big_flattened))));
+}
+
 TEST(ResourceUtilsTest, ParseSdkVersionWithCodename) {
   EXPECT_THAT(ResourceUtils::ParseSdkVersion("Q"), Eq(std::optional<int>(10000)));
   EXPECT_THAT(ResourceUtils::ParseSdkVersion("Q.fingerprint"), Eq(std::optional<int>(10000)));

tools/aapt2/ResourceValues.cpp

@@ -439,6 +439,21 @@ static std::string ComplexToString(uint32_t complex_value, bool fraction) {
   return str;
 }
 
+// This function is designed to using different specifier to print different floats,
+// which can print more accurate format rather than using %g only.
+const char* BinaryPrimitive::DecideFormat(float f) {
+  // if the float is either too big or too tiny, print it in scientific notation.
+  // eg: "10995116277760000000000" to 1.099512e+22, "0.00000000001" to 1.000000e-11
+  if (fabs(f) > std::numeric_limits<int64_t>::max() || fabs(f) < 1e-10) {
+    return "%e";
+    // Else if the number is an integer exactly, print it without trailing zeros.
+    // eg: "1099511627776" to 1099511627776
+  } else if (int64_t(f) == f) {
+    return "%.0f";
+  }
+  return "%g";
+}
+
 void BinaryPrimitive::PrettyPrint(Printer* printer) const {
   using ::android::Res_value;
   switch (value.dataType) {
@@ -470,7 +485,9 @@ void BinaryPrimitive::PrettyPrint(Printer* printer) const {
       break;
 
     case Res_value::TYPE_FLOAT:
-      printer->Print(StringPrintf("%g", *reinterpret_cast<const float*>(&value.data)));
+      float f;
+      f = *reinterpret_cast<const float*>(&value.data);
+      printer->Print(StringPrintf(DecideFormat(f), f));
       break;
 
     case Res_value::TYPE_DIMENSION:

tools/aapt2/ResourceValues.h

@@ -284,6 +284,7 @@ struct BinaryPrimitive : public TransformableItem<BinaryPrimitive, BaseItem<Bina
   bool Equals(const Value* value) const override;
   bool Flatten(android::Res_value* out_value) const override;
   void Print(std::ostream* out) const override;
+  static const char* DecideFormat(float f);
   void PrettyPrint(text::Printer* printer) const override;
 };