Breakpad DWARF parser: Add method to read DWARF "Initial length".

This patch moves the ReadInitialFunction from dwarf2reader.cc, where
it was a static function, to being a member function of
google_breakpad::ByteReader.

a=jimblandy, r=nealsid


git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@504 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/common/dwarf/bytereader.cc

@@ -1,4 +1,4 @@
-// Copyright 2006 Google Inc. All Rights Reserved.
+// Copyright 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
@@ -60,4 +60,21 @@ void ByteReader::SetAddressSize(uint8 size) {
   }
 }
 
+uint64 ByteReader::ReadInitialLength(const char* 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;
+}
+
 }  // namespace dwarf2reader

src/common/dwarf/bytereader.h

@@ -1,4 +1,6 @@
-// Copyright 2006 Google Inc. All Rights Reserved.
+// -*- mode: C++ -*-
+
+// Copyright 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
@@ -104,6 +106,12 @@ class ByteReader {
   // and will CHECK on anything else.
   uint64 ReadAddress(const char* buffer) const;
 
+  // Read a DWARF2/3 initial length field from START, and report the
+  // length of the length field in LEN. Return the value of the length
+  // field. Set this reader's offset size as indicated by the length
+  // field's encoding.
+  uint64 ReadInitialLength(const char* start, size_t* len);
+
  private:
 
   // Function pointer type for our address and offset readers.

src/common/dwarf/dwarf2reader.cc

@@ -40,27 +40,6 @@
 
 namespace dwarf2reader {
 
-// Read a DWARF2/3 initial length field from START, using READER, and
-// report the length in LEN.  Return the actual initial length.
-
-static uint64 ReadInitialLength(const char* start,
-                                ByteReader* reader, size_t* len) {
-  const uint64 initial_length = reader->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) {
-    reader->SetOffsetSize(8);
-    *len = 12;
-    return reader->ReadOffset(start);
-  } else {
-    reader->SetOffsetSize(4);
-    *len = 4;
-  }
-  return initial_length;
-}
-
 CompilationUnit::CompilationUnit(const SectionMap& sections, uint64 offset,
                                  ByteReader* reader, Dwarf2Handler* handler)
     : offset_from_section_start_(offset), reader_(reader),
@@ -243,8 +222,8 @@ void CompilationUnit::ReadHeader() {
   size_t initial_length_size;
 
   assert(headerptr + 4 < buffer_ + buffer_length_);
-  const uint64 initial_length = ReadInitialLength(headerptr, reader_,
-                                                  &initial_length_size);
+  const uint64 initial_length
+    = reader_->ReadInitialLength(headerptr, &initial_length_size);
   headerptr += initial_length_size;
   header_.length = initial_length;
 
@@ -563,8 +542,8 @@ void LineInfo::ReadHeader() {
   const char* lineptr = buffer_;
   size_t initial_length_size;
 
-  const uint64 initial_length = ReadInitialLength(lineptr, reader_,
-                                                  &initial_length_size);
+  const uint64 initial_length
+    = reader_->ReadInitialLength(lineptr, &initial_length_size);
 
   lineptr += initial_length_size;
   header_.total_length = initial_length;