Refactor the symbol parsing, and move to NDK's nm.

tools/cygprofile/symbol_extractor.py

Index: tools/cygprofile/symbol_extractor.py
diff --git a/tools/cygprofile/symbol_extractor.py b/tools/cygprofile/symbol_extractor.py
new file mode 100755
index 0000000000000000000000000000000000000000..d3a2ee06fc2b100a5735075c0791b43f96edf205
--- /dev/null
+++ b/tools/cygprofile/symbol_extractor.py
@@ -0,0 +1,120 @@
+#!/usr/bin/python
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Utilities to get and manipulate symbols from a binary."""
+
+import collections
+import os
+import re
+import subprocess
+import sys
+
+sys.path.insert(
+    0, os.path.join(sys.path[0], '..', '..', 'third_party', 'android_platform',
+                    'development', 'scripts'))
+import symbol
+
+
+# TODO(lizeb): Change symbol.ARCH to the proper value when "arm" is no longer
+# the only possible value.
+_NM_BINARY = symbol.ToolPath('nm')
+
+
+SymbolInfo = collections.namedtuple('SymbolInfo', ('name', 'offset', 'size'))
+
+
+def FromNmLine(line):
+  """Create a SymbolInfo by parsing a properly formatted nm output line.
+
+  Args:
+    line: line from nm
+
+  Returns:
+    An instance of SymbolInfo if the line represents a symbol, None otherwise.
+  """
+  # We are interested in two types of lines:
+  # This:
+  # 00210d59 00000002 t _ZN34BrowserPluginHostMsg_Attach_ParamsD2Ev
+  # offset size <symbol_type> symbol_name
+  # And that:
+  # 0070ee8c T WebRtcSpl_ComplexBitReverse
+  # In the second case we don't have a size, so use -1 as a sentinel
+  if not re.search(' (t|W|T) ', line):
+    return None
+  parts = line.split()
+  if len(parts) == 4:
+    return SymbolInfo(
+        offset=int(parts[0], 16), size=int(parts[1], 16), name=parts[3])
+  elif len(parts) == 3:
+    return SymbolInfo(
+        offset=int(parts[0], 16), size=-1, name=parts[2])
+  else:
+    return None
+
+
+def SymbolInfosFromStream(nm_lines):
+  """Parses the output of nm, and get all the symbols from a binary.
+
+  Args:
+    nm_lines: An iterable of lines
+
+  Returns:
+    A list of SymbolInfo.
+  """
+  # TODO(lizeb): Consider switching to objdump to simplify parsing.
+  symbol_infos = []
+  for line in nm_lines:
+    symbol_info = FromNmLine(line)
+    if symbol_info is not None:
+      symbol_infos.append(symbol_info)
+  return symbol_infos
+
+
+def SymbolInfosFromBinary(binary_filename):
+  """Runs nm to get all the symbols from a binary.
+
+  Args:
+    binary_filename: path to the binary.
+
+  Returns:
+    A list of SymbolInfo from the binary.
+  """
+  command = (_NM_BINARY, '-S', '-n', binary_filename)
+  p = subprocess.Popen(command, shell=False, stdout=subprocess.PIPE)
+  try:
+    result = SymbolInfosFromStream(p.stdout)
+    return result
+  finally:
+    p.wait()
+
+
+def GroupSymbolInfosByOffset(symbol_infos):
+  """Create a dict {offset: [symbol_info1, ...], ...}.
+
+  As several symbols can be at the same offset, this is a 1-to-many
+  relationship.
+
+  Args:
+    symbol_infos: iterable of SymbolInfo instances
+
+  Returns:
+    a dict {offset: [symbol_info1, ...], ...}
+  """
+  offset_to_symbol_infos = collections.defaultdict(list)
+  for symbol_info in symbol_infos:
+    offset_to_symbol_infos[symbol_info.offset].append(symbol_info)
+  return dict(offset_to_symbol_infos)
+
+
+def CreateNameToSymbolInfo(symbol_infos):
+  """Create a dict {name: symbol_info, ...}.
+
+  Args:
+    symbol_infos: iterable of SymbolInfo instances
+
+  Returns:
+    a dict {name: symbol_info, ...}
+  """
+  return {symbol_info.name: symbol_info for symbol_info in symbol_infos}