Fix abspath references in md_browser.

tools/md_browser/md_browser.py

 #!/usr/bin/env 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.
 
 """Simple Markdown browser for a Git checkout."""
 from __future__ import print_function
 
 import SimpleHTTPServer
 import SocketServer
 import argparse
 import codecs
 import os
 import re
 import socket
 import sys
 import threading
 import time
 import webbrowser
 
 
-THIS_DIR = os.path.abspath(os.path.dirname(__file__))
+THIS_DIR = os.path.realpath(os.path.dirname(__file__))
 SRC_DIR = os.path.dirname(os.path.dirname(THIS_DIR))
 sys.path.append(os.path.join(SRC_DIR, 'third_party', 'Python-Markdown'))
 import markdown
 
 
 def main(argv):
   parser = argparse.ArgumentParser(prog='md_browser')
   parser.add_argument('-p', '--port', type=int, default=8080,
                       help='port to run on (default = %(default)s)')
   parser.add_argument('-d', '--directory', type=str, default=SRC_DIR)
   parser.add_argument('file', nargs='?',
                       help='open file in browser')
   args = parser.parse_args(argv)
 
-  top_level = os.path.abspath(args.directory)
+  top_level = os.path.realpath(args.directory)
 
   s = Server(args.port, top_level)
 
   print('Listening on http://localhost:%s/' % args.port)
   thread = None
   if args.file:
-    path = os.path.abspath(args.file)
+    path = os.path.realpath(args.file)
     if not path.startswith(top_level):
       print('%s is not under %s' % (args.file, args.directory))
       return 1
     rpath = os.path.relpath(path, top_level)
     url = 'http://localhost:%d/%s' % (args.port, rpath)
     print('Opening %s' % url)
     thread = threading.Thread(target=_open_url, args=(url,))
     thread.start()
 
   elif os.path.isfile(os.path.join(top_level, 'docs', 'README.md')):
@@ skipping 46 matching lines @@
   value = re.sub(r'[^- a-zA-Z0-9]', '_', value)  # Non-alphanumerics to '_'.
   value = value.replace(u' ', u'-')
   value = re.sub(r'([-_])[-_]+', r'\1', value)  # Fold hyphens and underscores.
   return value
 
 
 class Server(SocketServer.TCPServer):
   def __init__(self, port, top_level):
     SocketServer.TCPServer.__init__(self, ('0.0.0.0', port), Handler)
     self.port = port
-    self.top_level = os.path.abspath(top_level)
+    self.top_level = top_level
     self.retcode = None
 
   def server_bind(self):
     self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
     self.socket.bind(self.server_address)
 
 
 class Handler(SimpleHTTPServer.SimpleHTTPRequestHandler):
   def do_GET(self):
     path = self.path
 
     # strip off the repo and branch info, if present, for compatibility
     # with gitiles.
     if path.startswith('/chromium/src/+/master'):
       path = path[len('/chromium/src/+/master'):]
 
-    full_path = os.path.abspath(os.path.join(self.server.top_level, path[1:]))
+    full_path = os.path.realpath(os.path.join(self.server.top_level, path[1:]))
 
     if not full_path.startswith(self.server.top_level):
       self._DoUnknown()
     elif path == '/doc.css':
       self._DoCSS('doc.css')
     elif not os.path.exists(full_path):
       self._DoNotFound()
     elif path.lower().endswith('.md'):
       self._DoMD(path)
     elif os.path.exists(full_path + '/README.md'):
@@ skipping 55 matching lines @@
     self.end_headers()
 
   def _WriteTemplate(self, template):
     contents = self._Read(os.path.join('tools', 'md_browser', template),
                           relative_to=SRC_DIR)
     self.wfile.write(contents.encode('utf-8'))
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))