1 files changed, 250 insertions, 0 deletions
diff --git a/toolkit/crashreporter/google-breakpad/src/common/dwarf/bytereader.cc b/toolkit/crashreporter/google-breakpad/src/common/dwarf/bytereader.cc
new file mode 100644
index 0000000000..14b43adb8f
--- /dev/null
+++ b/toolkit/crashreporter/google-breakpad/src/common/dwarf/bytereader.cc
@@ -0,0 +1,250 @@
+// Copyright (c) 2010 Google Inc. All Rights Reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <assert.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "common/dwarf/bytereader-inl.h"
+#include "common/dwarf/bytereader.h"
+
+namespace dwarf2reader {
+
+ByteReader::ByteReader(enum Endianness endian)
+    :offset_reader_(NULL), address_reader_(NULL), endian_(endian),
+     address_size_(0), offset_size_(0),
+     have_section_base_(), have_text_base_(), have_data_base_(),
+     have_function_base_() { }
+
+ByteReader::~ByteReader() { }
+
+void ByteReader::SetOffsetSize(uint8 size) {
+  offset_size_ = size;
+  assert(size == 4 || size == 8);
+  if (size == 4) {
+    this->offset_reader_ = &ByteReader::ReadFourBytes;
+  } else {
+    this->offset_reader_ = &ByteReader::ReadEightBytes;
+  }
+}
+
+void ByteReader::SetAddressSize(uint8 size) {
+  address_size_ = size;
+  assert(size == 4 || size == 8);
+  if (size == 4) {
+    this->address_reader_ = &ByteReader::ReadFourBytes;
+  } else {
+    this->address_reader_ = &ByteReader::ReadEightBytes;
+  }
+}
+
+uint64 ByteReader::ReadInitialLength(const uint8_t *start, size_t* len) {
+  const uint64 initial_length = ReadFourBytes(start);
+  start += 4;
+
+  // In DWARF2/3, if the initial length is all 1 bits, then the offset
+  // size is 8 and we need to read the next 8 bytes for the real length.
+  if (initial_length == 0xffffffff) {
+    SetOffsetSize(8);
+    *len = 12;
+    return ReadOffset(start);
+  } else {
+    SetOffsetSize(4);
+    *len = 4;
+  }
+  return initial_length;
+}
+
+bool ByteReader::ValidEncoding(DwarfPointerEncoding encoding) const {
+  if (encoding == DW_EH_PE_omit) return true;
+  if (encoding == DW_EH_PE_aligned) return true;
+  if ((encoding & 0x7) > DW_EH_PE_udata8)
+    return false;
+  if ((encoding & 0x70) > DW_EH_PE_funcrel)
+    return false;
+  return true;
+}
+
+bool ByteReader::UsableEncoding(DwarfPointerEncoding encoding) const {
+  switch (encoding & 0x70) {
+    case DW_EH_PE_absptr:  return true;
+    case DW_EH_PE_pcrel:   return have_section_base_;
+    case DW_EH_PE_textrel: return have_text_base_;
+    case DW_EH_PE_datarel: return have_data_base_;
+    case DW_EH_PE_funcrel: return have_function_base_;
+    default:               return false;
+  }
+}
+
+uint64 ByteReader::ReadEncodedPointer(const uint8_t *buffer,
+                                      DwarfPointerEncoding encoding,
+                                      size_t *len) const {
+  // UsableEncoding doesn't approve of DW_EH_PE_omit, so we shouldn't
+  // see it here.
+  assert(encoding != DW_EH_PE_omit);
+
+  // The Linux Standards Base 4.0 does not make this clear, but the
+  // GNU tools (gcc/unwind-pe.h; readelf/dwarf.c; gdb/dwarf2-frame.c)
+  // agree that aligned pointers are always absolute, machine-sized,
+  // machine-signed pointers.
+  if (encoding == DW_EH_PE_aligned) {
+    assert(have_section_base_);
+
+    // We don't need to align BUFFER in *our* address space. Rather, we
+    // need to find the next position in our buffer that would be aligned
+    // when the .eh_frame section the buffer contains is loaded into the
+    // program's memory. So align assuming that buffer_base_ gets loaded at
+    // address section_base_, where section_base_ itself may or may not be
+    // aligned.
+
+    // First, find the offset to START from the closest prior aligned
+    // address.
+    uint64 skew = section_base_ & (AddressSize() - 1);
+    // Now find the offset from that aligned address to buffer.
+    uint64 offset = skew + (buffer - buffer_base_);
+    // Round up to the next boundary.
+    uint64 aligned = (offset + AddressSize() - 1) & -AddressSize();
+    // Convert back to a pointer.
+    const uint8_t *aligned_buffer = buffer_base_ + (aligned - skew);
+    // Finally, store the length and actually fetch the pointer.
+    *len = aligned_buffer - buffer + AddressSize();
+    return ReadAddress(aligned_buffer);
+  }
+
+  // Extract the value first, ignoring whether it's a pointer or an
+  // offset relative to some base.
+  uint64 offset;
+  switch (encoding & 0x0f) {
+    case DW_EH_PE_absptr:
+      // DW_EH_PE_absptr is weird, as it is used as a meaningful value for
+      // both the high and low nybble of encoding bytes. When it appears in
+      // the high nybble, it means that the pointer is absolute, not an
+      // offset from some base address. When it appears in the low nybble,
+      // as here, it means that the pointer is stored as a normal
+      // machine-sized and machine-signed address. A low nybble of
+      // DW_EH_PE_absptr does not imply that the pointer is absolute; it is
+      // correct for us to treat the value as an offset from a base address
+      // if the upper nybble is not DW_EH_PE_absptr.
+      offset = ReadAddress(buffer);
+      *len = AddressSize();
+      break;
+
+    case DW_EH_PE_uleb128:
+      offset = ReadUnsignedLEB128(buffer, len);
+      break;
+
+    case DW_EH_PE_udata2:
+      offset = ReadTwoBytes(buffer);
+      *len = 2;
+      break;
+
+    case DW_EH_PE_udata4:
+      offset = ReadFourBytes(buffer);
+      *len = 4;
+      break;
+
+    case DW_EH_PE_udata8:
+      offset = ReadEightBytes(buffer);
+      *len = 8;
+      break;
+
+    case DW_EH_PE_sleb128:
+      offset = ReadSignedLEB128(buffer, len);
+      break;
+
+    case DW_EH_PE_sdata2:
+      offset = ReadTwoBytes(buffer);
+      // Sign-extend from 16 bits.
+      offset = (offset ^ 0x8000) - 0x8000;
+      *len = 2;
+      break;
+
+    case DW_EH_PE_sdata4:
+      offset = ReadFourBytes(buffer);
+      // Sign-extend from 32 bits.
+      offset = (offset ^ 0x80000000ULL) - 0x80000000ULL;
+      *len = 4;
+      break;
+
+    case DW_EH_PE_sdata8:
+      // No need to sign-extend; this is the full width of our type.
+      offset = ReadEightBytes(buffer);
+      *len = 8;
+      break;
+
+    default:
+      abort();
+  }
+
+  // Find the appropriate base address.
+  uint64 base;
+  switch (encoding & 0x70) {
+    case DW_EH_PE_absptr:
+      base = 0;
+      break;
+
+    case DW_EH_PE_pcrel:
+      assert(have_section_base_);
+      base = section_base_ + (buffer - buffer_base_);
+      break;
+
+    case DW_EH_PE_textrel:
+      assert(have_text_base_);
+      base = text_base_;
+      break;
+
+    case DW_EH_PE_datarel:
+      assert(have_data_base_);
+      base = data_base_;
+      break;
+
+    case DW_EH_PE_funcrel:
+      assert(have_function_base_);
+      base = function_base_;
+      break;
+
+    default:
+      abort();
+  }
+
+  uint64 pointer = base + offset;
+
+  // Remove inappropriate upper bits.
+  if (AddressSize() == 4)
+    pointer = pointer & 0xffffffff;
+  else
+    assert(AddressSize() == sizeof(uint64));
+
+  return pointer;
+}
+
+Endianness ByteReader::GetEndianness() const {
+  return endian_;
+}
+
+}  // namespace dwarf2reader