1 files changed, 355 insertions, 0 deletions
diff --git a/lib/Wrap/bitcode_wrapperer.cpp b/lib/Wrap/bitcode_wrapperer.cpp
new file mode 100644
index 0000000000..eeb2825793
--- /dev/null
+++ b/lib/Wrap/bitcode_wrapperer.cpp
@@ -0,0 +1,355 @@
+/* Copyright 2012 The Native Client Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can
+ * be found in the LICENSE file.
+ */
+
+#include "llvm/Wrap/bitcode_wrapperer.h"
+
+#include <stdio.h>
+#include <sys/stat.h>
+
+using std::vector;
+
+// The number of bytes in a 32 bit integer.
+static const uint32_t kWordSize = 4;
+
+// Number of LLVM-defined fixed fields in the header.
+static const uint32_t kLLVMFields = 4;
+
+// Total number of fixed fields in the header.
+static const uint32_t kFixedFields = 7;
+
+// The magic number that must exist for bitcode wrappers.
+static const uint32_t kWrapperMagicNumber = 0x0B17C0DE;
+
+// The version number associated with a wrapper file.
+// Note: llvm currently only allows the value 0. When this changes,
+// we should consider making this a command line option.
+static const uint32_t kLLVMVersionNumber = 0;
+
+// Fields defined by Android bitcode header.
+static const uint32_t kAndroidHeaderVersion = 0;
+static const uint32_t kAndroidTargetAPI = 0;
+static const uint32_t kAndroidDefaultCompilerVersion = 0;
+static const uint32_t kAndroidDefaultOptimizationLevel = 3;
+
+// PNaCl bitcode version number.
+static const uint32_t kPnaclBitcodeVersion = 0;
+
+// Max size for variable fields. Currently only used for writing them
+// out to files (the parsing works for arbitrary sizes).
+static const size_t kMaxVariableFieldSize = 256;
+
+BitcodeWrapperer::BitcodeWrapperer(WrapperInput* infile, WrapperOutput* outfile)
+    : infile_(infile),
+      outfile_(outfile),
+      buffer_size_(0),
+      cursor_(0),
+      infile_at_eof_(false),
+      infile_bc_offset_(0),
+      wrapper_bc_offset_(0),
+      wrapper_bc_size_(0),
+      android_header_version_(kAndroidHeaderVersion),
+      android_target_api_(kAndroidTargetAPI),
+      pnacl_bc_version_(0),
+      error_(false) {
+  buffer_.resize(kBitcodeWrappererBufferSize);
+  if (IsInputBitcodeWrapper()) {
+    ParseWrapperHeader();
+  } else if (IsInputBitcodeFile()) {
+    wrapper_bc_offset_ = kWordSize * kFixedFields;
+    wrapper_bc_size_ = GetInFileSize();
+  } else {
+    fprintf(stderr, "Error: input file is not a bitcode file.\n");
+    error_ = true;
+  }
+}
+
+BitcodeWrapperer::~BitcodeWrapperer() {
+  for(size_t i = 0; i < variable_field_data_.size(); i++) {
+    delete [] variable_field_data_[i];
+  }
+}
+
+
+void BitcodeWrapperer::ClearBuffer() {
+  buffer_size_ = 0;
+  cursor_ = 0;
+  infile_at_eof_ = false;
+}
+
+bool BitcodeWrapperer::Seek(uint32_t pos) {
+  if (infile_ != NULL && infile_->Seek(pos)) {
+    ClearBuffer();
+    return true;
+  }
+  return false;
+}
+
+bool BitcodeWrapperer::CanReadWord() {
+  if (GetBufferUnreadBytes() < kWordSize) {
+    FillBuffer();
+    return GetBufferUnreadBytes() >= kWordSize;
+  } else {
+    return true;
+  }
+}
+
+void BitcodeWrapperer::FillBuffer() {
+  if (cursor_ > 0) {
+    // Before filling, move any remaining bytes to the
+    // front of the buffer. This allows us to assume
+    // that after the call to FillBuffer, readable
+    // text is contiguous.
+    if (cursor_ < buffer_size_) {
+      size_t i = 0;
+      while (cursor_ < buffer_size_) {
+        buffer_[i++] = buffer_[cursor_++];
+      }
+      cursor_ = 0;
+      buffer_size_ = i;
+    }
+  } else {
+    // Assume the buffer contents have been used,
+    // and we want to completely refill it.
+    buffer_size_ = 0;
+  }
+
+  // If we don't have an input, we can't refill the buffer at all.
+  if (infile_ == NULL) {
+    return;
+  }
+
+  // Now fill in remaining space.
+  size_t needed = buffer_.size() - buffer_size_;
+
+  while (buffer_.size() > buffer_size_) {
+    int actually_read = infile_->Read(&buffer_[buffer_size_], needed);
+    if (infile_->AtEof()) {
+      infile_at_eof_ = true;
+    }
+    if (actually_read) {
+      buffer_size_ += actually_read;
+      needed -= actually_read;
+    } else if (infile_at_eof_) {
+      break;
+    }
+  }
+}
+
+bool BitcodeWrapperer::ReadWord(uint32_t& word) {
+  if (!CanReadWord()) return false;
+  word = (((uint32_t) BufferLookahead(0)) << 0)
+      | (((uint32_t) BufferLookahead(1)) << 8)
+      | (((uint32_t) BufferLookahead(2)) << 16)
+      | (((uint32_t) BufferLookahead(3)) << 24);
+  cursor_ += kWordSize;
+  return true;
+}
+
+bool BitcodeWrapperer::WriteWord(uint32_t value) {
+  uint8_t buffer[kWordSize];
+  buffer[3] = (value >> 24) & 0xFF;
+  buffer[2] = (value >> 16) & 0xFF;
+  buffer[1] = (value >> 8)  & 0xFF;
+  buffer[0] = (value >> 0)  & 0xFF;
+  return outfile_->Write(buffer, kWordSize);
+}
+
+bool BitcodeWrapperer::WriteVariableFields() {
+  // This buffer may have to be bigger if we start using the fields
+  // for larger things.
+  uint8_t buffer[kMaxVariableFieldSize];
+  for (vector<BCHeaderField>::iterator it = header_fields_.begin();
+       it != header_fields_.end(); ++it) {
+    if (!it->Write(buffer, kMaxVariableFieldSize) ||
+        !outfile_->Write(buffer, it->GetTotalSize())) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool BitcodeWrapperer::ParseWrapperHeader() {
+  // Make sure LLVM-defined fields have been parsed
+  if (!IsInputBitcodeWrapper()) return false;
+  // Check the android/pnacl fields
+  if (!ReadWord(android_header_version_) ||
+      !ReadWord(android_target_api_) || !ReadWord(pnacl_bc_version_)) {
+    fprintf(stderr, "Error: file not long enough to contain header\n");
+    return false;
+  }
+  if (pnacl_bc_version_ != kPnaclBitcodeVersion) {
+    fprintf(stderr, "Error: bad PNaCl Bitcode version\n");
+    return false;
+  }
+  int field_data_total = wrapper_bc_offset_ - kWordSize * kFixedFields;
+  if (field_data_total > 0) {
+    // Read in the variable fields. We need to allocate space for the data.
+    int field_data_read = 0;
+
+    while (field_data_read < field_data_total) {
+      FillBuffer();
+      size_t buffer_needed = BCHeaderField::GetDataSizeFromSerialized(
+          &buffer_[cursor_]);
+      if (buffer_needed > buffer_.size()) {
+        buffer_.resize(buffer_needed +
+                       sizeof(BCHeaderField::FixedSubfield) * 2);
+        FillBuffer();
+      }
+      variable_field_data_.push_back(new uint8_t[buffer_needed]);
+
+      BCHeaderField field(BCHeaderField::kInvalid, 0,
+                          variable_field_data_.back());
+      field.Read(&buffer_[cursor_], buffer_size_);
+      header_fields_.push_back(field);
+      size_t field_size = field.GetTotalSize();
+      cursor_ += field_size;
+      field_data_read += field_size;
+      if (field_data_read > field_data_total) {
+        // We read too much data, the header is corrupted
+        fprintf(stderr, "Error: raw bitcode offset inconsistent with "
+                "variable field data\n");
+        return false;
+      }
+    }
+    Seek(0);
+  }
+  return true;
+}
+
+bool BitcodeWrapperer::IsInputBitcodeWrapper() {
+  ResetCursor();
+  // First make sure that there are enough words (LLVM header)
+  // to peek at.
+  if (GetBufferUnreadBytes() < kLLVMFields * kWordSize) {
+    FillBuffer();
+    if (GetBufferUnreadBytes() < kLLVMFields * kWordSize) return false;
+  }
+
+  // Now make sure the magic number is right.
+  uint32_t first_word;
+  if ((!ReadWord(first_word)) ||
+      (kWrapperMagicNumber != first_word)) return false;
+
+  // Make sure the version is right.
+  uint32_t second_word;
+  if ((!ReadWord(second_word)) ||
+      (kLLVMVersionNumber != second_word)) return false;
+
+  // Make sure that the offset and size (for llvm) is defined.
+  uint32_t bc_offset;
+  uint32_t bc_size;
+  if (ReadWord(bc_offset) &&
+      ReadWord(bc_size)) {
+    // Before returning, save the extracted values.
+    wrapper_bc_offset_ = bc_offset;
+    infile_bc_offset_ = bc_offset;
+    wrapper_bc_size_ = bc_size;
+    return true;
+  }
+  // If reached, unable to read wrapped header.
+  return false;
+}
+
+bool BitcodeWrapperer::IsInputBitcodeFile() {
+  ResetCursor();
+  // First make sure that there are four bytes to peek at.
+  if (GetBufferUnreadBytes() < kWordSize) {
+    FillBuffer();
+    if (GetBufferUnreadBytes() < kWordSize) return false;
+  }
+  // If reached, Check if first 4 bytes match bitcode
+  // file magic number.
+  return (BufferLookahead(0) == 'B') &&
+      (BufferLookahead(1) == 'C') &&
+      (BufferLookahead(2) == 0xc0) &&
+      (BufferLookahead(3) == 0xde);
+}
+
+bool BitcodeWrapperer::BufferCopyInToOut(uint32_t size) {
+  while (size > 0) {
+    // Be sure buffer is non-empty before writing.
+    if (0 == buffer_size_) {
+      FillBuffer();
+      if (0 == buffer_size_) {
+        return false;
+      }
+    }
+    // copy the buffer to the output file.
+    size_t block = (buffer_size_ < size) ? buffer_size_ : size;
+    if (!outfile_->Write(&buffer_[cursor_], block)) return false;
+    size -= block;
+    buffer_size_ = 0;
+  }
+  // Be sure that there isn't more bytes on the input stream.
+  FillBuffer();
+  return buffer_size_ == 0;
+}
+
+void BitcodeWrapperer::AddHeaderField(BCHeaderField* field) {
+  vector<BCHeaderField>::iterator it = header_fields_.begin();
+  for (; it != header_fields_.end(); ++it) {
+    // If this field is the same as an existing one, overwrite it.
+    if (it->getID() == field->getID()) {
+      wrapper_bc_offset_ += (field->GetTotalSize() - it->GetTotalSize());
+      *it = *field;
+      break;
+    }
+  }
+  if (it == header_fields_.end()) { // there was no match, add a new field
+    header_fields_.push_back(*field);
+    wrapper_bc_offset_ += field->GetTotalSize();
+  }
+}
+
+bool BitcodeWrapperer::WriteBitcodeWrapperHeader() {
+  return
+      // Note: This writes out the 4 word header required by llvm wrapped
+      // bitcode.
+      WriteWord(kWrapperMagicNumber) &&
+      WriteWord(kLLVMVersionNumber) &&
+      WriteWord(wrapper_bc_offset_) &&
+      WriteWord(wrapper_bc_size_) &&
+      // 2 fixed fields defined by Android
+      WriteWord(android_header_version_) &&
+      WriteWord(android_target_api_) &&
+      // PNaClBitcode version
+      WriteWord(kPnaclBitcodeVersion) &&
+      // Common variable-length fields
+      WriteVariableFields();
+}
+
+void BitcodeWrapperer::PrintWrapperHeader() {
+  if (error_) {
+    fprintf(stderr, "Error condition exists: the following"
+            "data may not be reliable\n");
+  }
+  fprintf(stderr, "Wrapper magic:\t\t%x\n", kWrapperMagicNumber);
+  fprintf(stderr, "LLVM Bitcode version:\t%d\n", kLLVMVersionNumber);
+  fprintf(stderr, "Raw bitcode offset:\t%d\n", wrapper_bc_offset_);
+  fprintf(stderr, "Raw bitcode size:\t%d\n", wrapper_bc_size_);
+  fprintf(stderr, "Android header version:\t%d\n", android_header_version_);
+  fprintf(stderr, "Android target API:\t%d\n", android_target_api_);
+  fprintf(stderr, "PNaCl bitcode version:\t%d\n", kPnaclBitcodeVersion);
+  for (size_t i = 0; i < header_fields_.size(); i++) header_fields_[i].Print();
+}
+
+bool BitcodeWrapperer::GenerateWrappedBitcodeFile() {
+  if (!error_ &&
+      WriteBitcodeWrapperHeader() &&
+      Seek(infile_bc_offset_) &&
+      BufferCopyInToOut(wrapper_bc_size_)) {
+    off_t dangling = wrapper_bc_size_ & 3;
+    if (dangling) {
+      return outfile_->Write((const uint8_t*) "\0\0\0\0", 4 - dangling);
+    }
+    return true;
+  }
+  return false;
+}
+
+bool BitcodeWrapperer::GenerateRawBitcodeFile() {
+  return !error_ && Seek(infile_bc_offset_) &&
+      BufferCopyInToOut(wrapper_bc_size_);
+}