Rebased PNaCl localmods in LLVM to 223109

lib/Bitcode/NaCl/Reader/NaClBitcodeHeader.cpp

+//===- NaClBitcodeHeader.cpp ----------------------------------------------===//
+//     PNaCl bitcode header reader.
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Bitcode/NaCl/NaClBitcodeHeader.h"
+#include "llvm/Bitcode/NaCl/NaClReaderWriter.h"
+#include "llvm/Bitcode/ReaderWriter.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/Format.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/StreamingMemoryObject.h"
+
+#include <limits>
+#include <cstring>
+#include <iomanip>
+
+using namespace llvm;
+
+NaClBitcodeHeaderField::NaClBitcodeHeaderField()
+    : ID(kInvalid), FType(kBufferType), Len(0), Data(0) {}
+
+NaClBitcodeHeaderField::NaClBitcodeHeaderField(Tag MyID, uint32_t MyValue)
+    : ID(MyID), FType(kUInt32Type), Len(4), Data(new uint8_t[4]) {
+  Data[0] = static_cast<uint8_t>(MyValue & 0xFF);
+  Data[1] = static_cast<uint8_t>((MyValue >> 8) & 0xFF);
+  Data[2] = static_cast<uint8_t>((MyValue >> 16) & 0xFF);
+  Data[3] = static_cast<uint8_t>((MyValue >> 24) & 0xFF);
+}
+
+uint32_t NaClBitcodeHeaderField::GetUInt32Value() const {
+  assert(FType == kUInt32Type && "Header field must be uint32");
+  return static_cast<uint32_t>(Data[0]) |
+         (static_cast<uint32_t>(Data[1]) << 8) |
+         (static_cast<uint32_t>(Data[2]) << 16) |
+         (static_cast<uint32_t>(Data[2]) << 24);
+}
+
+NaClBitcodeHeaderField::NaClBitcodeHeaderField(Tag MyID, size_t MyLen,
+                                               uint8_t *MyData)
+    : ID(MyID), FType(kBufferType), Len(MyLen), Data(new uint8_t[MyLen]) {
+  for (size_t i = 0; i < MyLen; ++i) {
+    Data[i] = MyData[i];
+  }
+}
+
+bool NaClBitcodeHeaderField::Write(uint8_t *Buf, size_t BufLen) const {
+  size_t FieldsLen = kTagLenSize + Len;
+  size_t PadLen = (WordSize - (FieldsLen & (WordSize-1))) & (WordSize-1);
+  // Ensure buffer is large enough and that length can be represented
+  // in 32 bits
+  if (BufLen < FieldsLen + PadLen ||
+      Len > std::numeric_limits<FixedSubfield>::max())
+    return false;
+
+  WriteFixedSubfield(EncodeTypedID(), Buf);
+  WriteFixedSubfield(static_cast<FixedSubfield>(Len),
+                     Buf + sizeof(FixedSubfield));
+  memcpy(Buf + kTagLenSize, Data, Len);
+  // Pad out to word alignment
+  if (PadLen) {
+    memset(Buf + FieldsLen, 0, PadLen);
+  }
+  return true;
+}
+
+bool NaClBitcodeHeaderField::Read(const uint8_t *Buf, size_t BufLen) {
+  if (BufLen < kTagLenSize)
+    return false;
+  FixedSubfield IdField;
+  ReadFixedSubfield(&IdField, Buf);
+  FixedSubfield LengthField;
+  ReadFixedSubfield(&LengthField, Buf + sizeof(FixedSubfield));
+  size_t Length = static_cast<size_t>(LengthField);
+  if (BufLen < kTagLenSize + Length)
+    return false;
+  if (Len != Length) {
+    // Need to reallocate data buffer.
+    if (Data)
+      delete[] Data;
+    Data = new uint8_t[Length];
+  }
+  Len = Length;
+  DecodeTypedID(IdField, ID, FType);
+  memcpy(Data, Buf + kTagLenSize, Len);
+  return true;
+}
+
+std::string NaClBitcodeHeaderField::Contents() const {
+  std::string buffer;
+  raw_string_ostream ss(buffer);
+  switch (ID) {
+  case kPNaClVersion:
+    ss << "PNaCl Version";
+    break;
+  case kInvalid:
+    ss << "Invalid";
+    break;
+  }
+  ss << ": ";
+  switch (FType) {
+  case kUInt32Type:
+    ss << GetUInt32Value();
+    break;
+  case kBufferType:
+    ss << "[";
+    for (size_t i = 0; i < Len; ++i) {
+      if (i)
+        ss << " ";
+      ss << format("%02x", Data[i]);
+    }
+    ss << "]";
+    break;
+  }
+  return ss.str();
+}
+
+NaClBitcodeHeader::NaClBitcodeHeader()
+    : HeaderSize(0), UnsupportedMessage(), IsSupportedFlag(false),
+      IsReadableFlag(false), PNaClVersion(0) {}
+
+NaClBitcodeHeader::~NaClBitcodeHeader() {
+  for (std::vector<NaClBitcodeHeaderField *>::const_iterator
+           Iter = Fields.begin(),
+           IterEnd = Fields.end();
+       Iter != IterEnd; ++Iter) {
+    delete *Iter;
+  }
+}
+
+bool NaClBitcodeHeader::ReadPrefix(const unsigned char *BufPtr,
+                                   const unsigned char *BufEnd,
+                                   unsigned &NumFields, unsigned &NumBytes) {
+  // Must contain PEXE.
+  if (!isNaClBitcode(BufPtr, BufEnd)) {
+    UnsupportedMessage = "Invalid PNaCl bitcode header";
+    if (isBitcode(BufPtr, BufEnd)) {
+      UnsupportedMessage += " (to run in Chrome, bitcode files must be "
+          "finalized using pnacl-finalize)";
+    }
+    return true;
+  }
+  BufPtr += WordSize;
+
+  // Read #Fields and number of bytes needed for the header.
+  if (BufPtr + WordSize > BufEnd)
+    return UnsupportedError("Bitcode read failure");
+  NumFields = static_cast<unsigned>(BufPtr[0]) |
+      (static_cast<unsigned>(BufPtr[1]) << 8);
+  NumBytes = static_cast<unsigned>(BufPtr[2]) |
+      (static_cast<unsigned>(BufPtr[3]) << 8);
+  BufPtr += WordSize;
+  return false;
+}
+
+bool NaClBitcodeHeader::ReadFields(const unsigned char *BufPtr,
+                                   const unsigned char *BufEnd,
+                                   unsigned NumFields, unsigned NumBytes) {
+  HeaderSize = NumBytes + (2 * WordSize);
+
+  // Read in each field.
+  for (size_t i = 0; i < NumFields; ++i) {
+    NaClBitcodeHeaderField *Field = new NaClBitcodeHeaderField();
+    Fields.push_back(Field);
+    if (!Field->Read(BufPtr, BufEnd - BufPtr))
+      return UnsupportedError("Bitcode read failure");
+    size_t FieldSize = Field->GetTotalSize();
+    BufPtr += FieldSize;
+  }
+  return false;
+}
+
+bool NaClBitcodeHeader::Read(const unsigned char *&BufPtr,
+                             const unsigned char *&BufEnd) {
+  unsigned NumFields;
+  unsigned NumBytes;
+  if (ReadPrefix(BufPtr, BufEnd, NumFields, NumBytes))
+    return true; // ReadPrefix sets UnsupportedMessage
+  BufPtr += 2 * WordSize;
+
+  if (ReadFields(BufPtr, BufEnd, NumFields, NumBytes))
+    return true; // ReadFields sets UnsupportedMessage
+  BufPtr += NumBytes;
+  InstallFields();
+  return false;
+}
+
+bool NaClBitcodeHeader::Read(MemoryObject *Bytes) {
+  unsigned NumFields;
+  unsigned NumBytes;
+  // First, read the prefix, which is 2 * WordSize, to determine the
+  // NumBytes and NumFields.
+  {
+    unsigned char Buffer[2 * WordSize];
+    if (Bytes->readBytes(Buffer, sizeof(Buffer), 0) != sizeof(Buffer))
+      return UnsupportedError("Bitcode read failure");
+    if (ReadPrefix(Buffer, Buffer + sizeof(Buffer), NumFields, NumBytes))
+      return true; // ReadPrefix sets UnsupportedMessage
+  }
+  // Then read the rest, starting after the 2 * WordSize of the prefix.
+  uint8_t *Header = new uint8_t[NumBytes];
+  bool failed =
+      Bytes->readBytes(Header, NumBytes, 2 * WordSize) != NumBytes ||
+      ReadFields(Header, Header + NumBytes, NumFields, NumBytes);
+  delete[] Header;
+  if (failed)
+    return UnsupportedError("Bitcode read failure");
+  InstallFields();
+  return false;
+}
+
+NaClBitcodeHeaderField *
+NaClBitcodeHeader::GetTaggedField(NaClBitcodeHeaderField::Tag ID) const {
+  for (std::vector<NaClBitcodeHeaderField *>::const_iterator
+           Iter = Fields.begin(),
+           IterEnd = Fields.end();
+       Iter != IterEnd; ++Iter) {
+    if ((*Iter)->GetID() == ID) {
+      return *Iter;
+    }
+  }
+  return 0;
+}
+
+NaClBitcodeHeaderField *NaClBitcodeHeader::GetField(size_t index) const {
+  if (index >= Fields.size())
+    return 0;
+  return Fields[index];
+}
+
+NaClBitcodeHeaderField *GetPNaClVersionPtr(NaClBitcodeHeader *Header) {
+  if (NaClBitcodeHeaderField *Version =
+          Header->GetTaggedField(NaClBitcodeHeaderField::kPNaClVersion)) {
+    if (Version->GetType() == NaClBitcodeHeaderField::kUInt32Type) {
+      return Version;
+    }
+  }
+  return 0;
+}
+
+void NaClBitcodeHeader::InstallFields() {
+  // Assume supported until contradicted.
+  bool UpdatedUnsupportedMessage = false;
+  IsSupportedFlag = true;
+  IsReadableFlag = true;
+  UnsupportedMessage = "Supported";
+  PNaClVersion = 0;
+  if (NaClBitcodeHeaderField *Version = GetPNaClVersionPtr(this)) {
+    PNaClVersion = Version->GetUInt32Value();
+  }
+  if (PNaClVersion != 2) {
+    IsSupportedFlag = false;
+    IsReadableFlag = false;
+    UpdatedUnsupportedMessage = true;
+    UnsupportedMessage.clear();
+    raw_string_ostream UnsupportedStream(UnsupportedMessage);
+    UnsupportedStream << "Unsupported PNaCl bitcode version: "
+                      << PNaClVersion << "\n";
+    UnsupportedStream.flush();
+  }
+  if (Fields.size() != 1) {
+    IsSupportedFlag = false;
+    IsReadableFlag = false;
+    if (!UpdatedUnsupportedMessage)
+      UnsupportedMessage = "Unknown header field(s) found";
+  }
+}