binary_size: Check debug data format before starting.

tools/binary_size/run_binary_size_analysis.py

 #!/usr/bin/env python
 # Copyright 2014 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.
 
 """Generate a spatial analysis against an arbitrary library.
 
 To use, build the 'binary_size_tool' target. Then run this tool, passing
 in the location of the library to be analyzed along with any other options
 you desire.
@@ skipping 526 matching lines @@
 def _find_in_system_path(binary):
   """Locate the full path to binary in the system path or return None
   if not found."""
   system_path = os.environ["PATH"].split(os.pathsep)
   for path in system_path:
     binary_path = os.path.join(path, binary)
     if os.path.isfile(binary_path):
       return binary_path
   return None
 
+def CheckDebugFormatSupport(library, addr2line_binary, nm_binary):
+  """There are two common versions of the DWARF debug formats and

[Primiano Tucci (use gerrit), 2014/05/27 09:40:10]

Nit: docstring format (1 line + blank line + description)

[Daniel Bratell, 2014/06/04 13:31:02]

Done.

+  since we are right now transitioning from DWARF2 to newer formats,
+  it's possible to have a mix of tools that are not compatible. Detect
+  that and abort rather than produce meaningless output."""
+  tool_output = subprocess.check_output([addr2line_binary, "--version"])
+  version_re = re.compile(r"^GNU [^ ]+ .* (\d+).(\d+).*?$", re.M)

[Primiano Tucci (use gerrit), 2014/05/27 09:40:10]

Please be consistent with quotes (double vs single)

[Daniel Bratell, 2014/06/04 13:31:02]

Done.

+  parsed_output = version_re.match(tool_output)
+  major = int(parsed_output.group(1))
+  minor = int(parsed_output.group(2))
+  supports_dwarf4 = major > 2 or major == 2 and minor > 22
+
+  if supports_dwarf4:
+    return
+
+  print("Checking version of debug information in %s." % library)
+  debug_info = subprocess.check_output(["readelf", "--debug-dump=info",
+                                       "--dwarf-depth=1", library])
+  dwarf_version_re = re.compile(r"^\s+Version:\s+(\d+)$", re.M)
+  parsed_dwarf_format_output = dwarf_version_re.search(debug_info)
+  version = int(parsed_dwarf_format_output.group(1))
+  if version > 2:
+    print("""\

[Primiano Tucci (use gerrit), 2014/05/27 09:40:10]

From code style:

Yes:
  print ("This is much nicer.\n"
         "Do it this way.\n")
  No:
    print """This is pretty ugly.
Don't do this.
"""

[Daniel Bratell, 2014/06/04 13:31:02]

Will fix, but the suggested format is really bad if the indentation plus the
string length would exceed ~70 characters. In another program I've tried both
and I found that for larger blocks of output, the """ format worked better.
Especially if the first line is """\ so that all lines are indented equally.

+The supplied tools only support DWARF2 debug data but the binary
+uses DWARF%d. Update the tools or compile the binary with -gdwarf-2.""" %
+          version)
+    sys.exit(1)
+
 
 def main():
   usage = """%prog [options]
 
   Runs a spatial analysis on a given library, looking up the source locations
   of its symbols and calculating how much space each directory, source file,
   and so on is taking. The result is a report that can be used to pinpoint
   sources of large portions of the binary, etceteras.
 
   Under normal circumstances, you only need to pass two arguments, thusly:
@@ skipping 74 matching lines @@
         'Use --addr2line-binary to specify location.'
 
   if opts.nm_binary:
     assert os.path.isfile(opts.nm_binary)
     nm_binary = opts.nm_binary
   else:
     nm_binary = _find_in_system_path('nm')
     assert nm_binary, 'Unable to find nm in the path. Use --nm-binary '\
         'to specify location.'
 
+  print('addr2line: %s' % addr2line_binary)
   print('nm: %s' % nm_binary)
-  print('addr2line: %s' % addr2line_binary)
+
+  CheckDebugFormatSupport(opts.library, addr2line_binary, nm_binary)
 
   symbols = GetNmSymbols(opts.nm_in, opts.nm_out, opts.library,
                          opts.jobs, opts.verbose is True,
                          addr2line_binary, nm_binary)
   if not os.path.exists(opts.destdir):
     os.makedirs(opts.destdir, 0755)
 
 
   if opts.legacy: # legacy report
     DumpTreemap(symbols, os.path.join(opts.destdir, 'treemap-dump.js'))
@@ skipping 28 matching lines @@
     print('Copying index.html')
     shutil.copy(os.path.join(template_src, 'index.html'), opts.destdir)
     shutil.copy(os.path.join(template_src, 'D3SymbolTreeMap.js'), opts.destdir)
 
   if opts.verbose:
     print 'Report saved to ' + opts.destdir + '/index.html'
 
 
 if __name__ == '__main__':
   sys.exit(main())