clang-tools-extra/clangd/RIFF.cpp

   1 //===--- RIFF.cpp - Binary container file format --------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "RIFF.h"
  10 #include "support/Logger.h"
  11 #include "llvm/Support/Endian.h"
  12
  13 namespace clang {
  14 namespace clangd {
  15 namespace riff {
  16
  17 llvm::Expected<Chunk> readChunk(llvm::StringRef &Stream) {
  18   if (Stream.size() < 8)
  19     return error("incomplete chunk header: {0} bytes available", Stream.size());
  20   Chunk C;
  21   std::copy(Stream.begin(), Stream.begin() + 4, C.ID.begin());
  22   Stream = Stream.drop_front(4);
  23   uint32_t Len = llvm::support::endian::read32le(Stream.take_front(4).begin());
  24   Stream = Stream.drop_front(4);
  25   if (Stream.size() < Len)
  26     return error("truncated chunk: want {0}, got {1}", Len, Stream.size());
  27   C.Data = Stream.take_front(Len);
  28   Stream = Stream.drop_front(Len);
  29   if ((Len % 2) && !Stream.empty()) { // Skip padding byte.
  30     if (Stream.front())
  31       return error("nonzero padding byte");
  32     Stream = Stream.drop_front();
  33   }
  34   return std::move(C);
  35 }
  36
  37 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const Chunk &C) {
  38   OS.write(C.ID.data(), C.ID.size());
  39   char Size[4];
  40   llvm::support::endian::write32le(Size, C.Data.size());
  41   OS.write(Size, sizeof(Size));
  42   OS << C.Data;
  43   if (C.Data.size() % 2)
  44     OS.write(0);
  45   return OS;
  46 }
  47
  48 llvm::Expected<File> readFile(llvm::StringRef Stream) {
  49   auto RIFF = readChunk(Stream);
  50   if (!RIFF)
  51     return RIFF.takeError();
  52   if (RIFF->ID != fourCC("RIFF"))
  53     return error("not a RIFF container: root is {0}", fourCCStr(RIFF->ID));
  54   if (RIFF->Data.size() < 4)
  55     return error("RIFF chunk too short");
  56   File F;
  57   std::copy(RIFF->Data.begin(), RIFF->Data.begin() + 4, F.Type.begin());
  58   for (llvm::StringRef Body = RIFF->Data.drop_front(4); !Body.empty();)
  59     if (auto Chunk = readChunk(Body)) {
  60       F.Chunks.push_back(*Chunk);
  61     } else
  62       return Chunk.takeError();
  63   return std::move(F);
  64 }
  65
  66 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const File &F) {
  67   // To avoid copies, we serialize the outer RIFF chunk "by hand".
  68   size_t DataLen = 4; // Predict length of RIFF chunk data.
  69   for (const auto &C : F.Chunks)
  70     DataLen += 4 + 4 + C.Data.size() + (C.Data.size() % 2);
  71   OS << "RIFF";
  72   char Size[4];
  73   llvm::support::endian::write32le(Size, DataLen);
  74   OS.write(Size, sizeof(Size));
  75   OS.write(F.Type.data(), F.Type.size());
  76   for (const auto &C : F.Chunks)
  77     OS << C;
  78   return OS;
  79 }
  80
  81 } // namespace riff
  82 } // namespace clangd
  83 } // namespace clang