Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit b99e5092 authored by Donald Chai's avatar Donald Chai
Browse files

Fix computation of 'entry_length' in AAPT2 container format 

When the protobuf header (or data payload) size are a multiple of 4,
"entry_length" (called "aligned size" in the code) would have counted bytes that
are never actually written.

Bug: 139418052
Change-Id: Ia688a82a67f3807f7feb0be03670bf2827b1d6a1
parent 7780ab30

tools/aapt2/format/Container.cpp

+15 −8
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ namespace aapt { 


constexpr const static uint32_t kContainerFormatMagic = 0x54504141u;

constexpr const static uint32_t kContainerFormatVersion = 1u;

constexpr const static size_t kPaddingAlignment = 4u;



ContainerWriter::ContainerWriter(ZeroCopyOutputStream* out, size_t entry_count)

    : out_(out), total_entry_count_(entry_count), current_entry_count_(0u) {
@@ -49,12 +50,18 @@ ContainerWriter::ContainerWriter(ZeroCopyOutputStream* out, size_t entry_count) 
  }

}



inline static void WritePadding(int padding, CodedOutputStream* out) {

  if (padding < 4) {

inline static size_t CalculatePaddingForAlignment(size_t size) {

  size_t overage = size % kPaddingAlignment;

  return overage == 0 ? 0 : kPaddingAlignment - overage;

}



inline static void WritePadding(size_t padding, CodedOutputStream* out) {

  CHECK(padding < kPaddingAlignment);

  const uint32_t zero = 0u;

  static_assert(sizeof(zero) >= kPaddingAlignment, "Not enough source bytes for padding");



  out->WriteRaw(&zero, padding);

}

}



bool ContainerWriter::AddResTableEntry(const pb::ResourceTable& table) {

  if (current_entry_count_ >= total_entry_count_) {
@@ -70,7 +77,7 @@ bool ContainerWriter::AddResTableEntry(const pb::ResourceTable& table) { 


  // Write the aligned size.

  const ::google::protobuf::uint64 size = table.ByteSize();

  const int padding = 4 - (size % 4);

  const int padding = CalculatePaddingForAlignment(size);

  coded_out.WriteLittleEndian64(size);



  // Write the table.
@@ -103,9 +110,9 @@ bool ContainerWriter::AddResFileEntry(const pb::internal::CompiledFile& file, 


  // Write the aligned size.

  const ::google::protobuf::uint32 header_size = file.ByteSize();

  const int header_padding = 4 - (header_size % 4);

  const int header_padding = CalculatePaddingForAlignment(header_size);

  const ::google::protobuf::uint64 data_size = in->TotalSize();

  const int data_padding = 4 - (data_size % 4);

  const int data_padding = CalculatePaddingForAlignment(data_size);

  coded_out.WriteLittleEndian64(kResFileEntryHeaderSize + header_size + header_padding + data_size +

                                data_padding);

tools/aapt2/formats.md

+9 −8
Original line number Diff line number Diff line
@@ -23,7 +23,7 @@ boundary, so if a previous entry ends unaligned, padding must be inserted. 
| Size (in bytes) | Field          | Description                                                                                               |

|:----------------|:---------------|:----------------------------------------------------------------------------------------------------------|

| `4`             | `entry_type`   | The type of the entry. This can be one of two types: `RES_TABLE (0x00000000)` or `RES_FILE (0x00000001)`. |

| `8`             | `entry_length` | The length of the data that follows.                                                                      |

| `8`             | `entry_length` | The length of the data that follows.  Do not use if `entry_type` is `RES_FILE`; this value may be wrong.  |

| `entry_length`  | `data`         | The payload. The contents of this varies based on the `entry_type`.                                       |



If the `entry_type` is equal to `RES_TABLE (0x00000000)`, the `data` field contains a serialized
@@ -33,12 +33,13 @@ If the `entry_type` is equal to `RES_FILE (0x00000001)`, the `data` field contai 




| Size (in bytes) | Field            | Description                                                                                               |

|:----------------|:---------------|:----------------------------------------------------------------------------------------------------------|

|:----------------|:-----------------|:----------------------------------------------------------------------------------------------------------|

| `4`             | `header_size`    | The size of the `header` field.                                                                           |

| `8`             | `data_size`      | The size of the `data` field.                                                                             |

| `header_size`   | `header`         | The serialized Protobuf message [aapt.pb.internal.CompiledFile](ResourcesInternal.proto).                 |

| `x`             | `padding`      | Up to 4 bytes of zeros, if padding is necessary to align the `data` field on a 32-bit boundary. |

| `x`             | `header_padding` | Up to 3 bytes of zeros, if padding is necessary to align the `data` field on a 32-bit boundary.           |

| `data_size`     | `data`           | The payload, which is determined by the `type` field in the `aapt.pb.internal.CompiledFile`. This can be a PNG file, binary XML, or [aapt.pb.XmlNode](Resources.proto). |

| `y`             | `data_padding`   | Up to 3 bytes of zeros, if `data_size` is not a multiple of 4.                                            |



## AAPT2 Static Library Format (extension `.sapk`)