Group SCM-specific functions in classes to simplify generalization of the interface.

scm.py

Index: scm.py
diff --git a/scm.py b/scm.py
index 12848152abcde2efa2de76c51085450f98d30ebc..c47afaa3fa8b7e08375a274ce45974f20f4676bd 100644
--- a/scm.py
+++ b/scm.py
@@ -2,335 +2,414 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-"""SCM-specific functions."""
+"""SCM-specific utility classes."""
 
 import os
 import re
 import subprocess
 import sys
+import tempfile
 import xml.dom.minidom
 
 import gclient_utils
 
 
-SVN_COMMAND = "svn"
-GIT_COMMAND = "git"
-
-# -----------------------------------------------------------------------------
-# Git utils:
-
-
-def CaptureGit(args, in_directory=None, print_error=True):
-  """Runs git, capturing output sent to stdout as a string.
-
-  Args:
-    args: A sequence of command line parameters to be passed to git.
-    in_directory: The directory where git is to be run.
-
-  Returns:
-    The output sent to stdout as a string.
-  """
-  c = [GIT_COMMAND]
-  c.extend(args)
-
-  # *Sigh*:  Windows needs shell=True, or else it won't search %PATH% for
-  # the git.exe executable, but shell=True makes subprocess on Linux fail
-  # when it's called with a list because it only tries to execute the
-  # first string ("git").
-  stderr = None
-  if not print_error:
-    stderr = subprocess.PIPE
-  return subprocess.Popen(c,
-                          cwd=in_directory,
-                          shell=sys.platform.startswith('win'),
-                          stdout=subprocess.PIPE,
-                          stderr=stderr).communicate()[0]
-
-
-def CaptureGitStatus(files, upstream_branch='origin'):
-  """Returns git status.
-
-  @files can be a string (one file) or a list of files.
-
-  Returns an array of (status, file) tuples."""
-  command = ["diff", "--name-status", "-r", "%s.." % upstream_branch]
-  if not files:
-    pass
-  elif isinstance(files, basestring):
-    command.append(files)
-  else:
-    command.extend(files)
-
-  status = CaptureGit(command).rstrip()
-  results = []
-  if status:
-    for statusline in status.split('\n'):
-      m = re.match('^(\w)\t(.+)$', statusline)
-      if not m:
-        raise Exception("status currently unsupported: %s" % statusline)
-      results.append(('%s      ' % m.group(1), m.group(2)))
-  return results
-
-
-# -----------------------------------------------------------------------------
-# SVN utils:
-
-
-def RunSVN(args, in_directory):
-  """Runs svn, sending output to stdout.
-
-  Args:
-    args: A sequence of command line parameters to be passed to svn.
-    in_directory: The directory where svn is to be run.
-
-  Raises:
-    Error: An error occurred while running the svn command.
-  """
-  c = [SVN_COMMAND]
-  c.extend(args)
-
-  gclient_utils.SubprocessCall(c, in_directory)
-
-
-def CaptureSVN(args, in_directory=None, print_error=True):
-  """Runs svn, capturing output sent to stdout as a string.
-
-  Args:
-    args: A sequence of command line parameters to be passed to svn.
-    in_directory: The directory where svn is to be run.
-
-  Returns:
-    The output sent to stdout as a string.
-  """
-  c = [SVN_COMMAND]
-  c.extend(args)
-
-  # *Sigh*:  Windows needs shell=True, or else it won't search %PATH% for
-  # the svn.exe executable, but shell=True makes subprocess on Linux fail
-  # when it's called with a list because it only tries to execute the
-  # first string ("svn").
-  stderr = None
-  if not print_error:
-    stderr = subprocess.PIPE
-  return subprocess.Popen(c,
-                          cwd=in_directory,
-                          shell=(sys.platform == 'win32'),
-                          stdout=subprocess.PIPE,
-                          stderr=stderr).communicate()[0]
-
-
-def RunSVNAndGetFileList(options, args, in_directory, file_list):
-  """Runs svn checkout, update, or status, output to stdout.
-
-  The first item in args must be either "checkout", "update", or "status".
-
-  svn's stdout is parsed to collect a list of files checked out or updated.
-  These files are appended to file_list.  svn's stdout is also printed to
-  sys.stdout as in RunSVN.
-
-  Args:
-    options: command line options to gclient
-    args: A sequence of command line parameters to be passed to svn.
-    in_directory: The directory where svn is to be run.
-
-  Raises:
-    Error: An error occurred while running the svn command.
-  """
-  command = [SVN_COMMAND]
-  command.extend(args)
-
-  # svn update and svn checkout use the same pattern: the first three columns
-  # are for file status, property status, and lock status.  This is followed
-  # by two spaces, and then the path to the file.
-  update_pattern = '^...  (.*)$'
-
-  # The first three columns of svn status are the same as for svn update and
-  # svn checkout.  The next three columns indicate addition-with-history,
-  # switch, and remote lock status.  This is followed by one space, and then
-  # the path to the file.
-  status_pattern = '^...... (.*)$'
-
-  # args[0] must be a supported command.  This will blow up if it's something
-  # else, which is good.  Note that the patterns are only effective when
-  # these commands are used in their ordinary forms, the patterns are invalid
-  # for "svn status --show-updates", for example.
-  pattern = {
-        'checkout': update_pattern,
-        'status':   status_pattern,
-        'update':   update_pattern,
-      }[args[0]]
-
-  compiled_pattern = re.compile(pattern)
-
-  def CaptureMatchingLines(line):
-    match = compiled_pattern.search(line)
-    if match:
-      file_list.append(match.group(1))
-
-  RunSVNAndFilterOutput(args,
-                        in_directory,
-                        options.verbose,
-                        True,
-                        CaptureMatchingLines)
-
-def RunSVNAndFilterOutput(args,
-                          in_directory,
-                          print_messages,
-                          print_stdout,
-                          filter):
-  """Runs svn checkout, update, status, or diff, optionally outputting
-  to stdout.
-
-  The first item in args must be either "checkout", "update",
-  "status", or "diff".
-
-  svn's stdout is passed line-by-line to the given filter function. If
-  print_stdout is true, it is also printed to sys.stdout as in RunSVN.
-
-  Args:
-    args: A sequence of command line parameters to be passed to svn.
-    in_directory: The directory where svn is to be run.
-    print_messages: Whether to print status messages to stdout about
-      which Subversion commands are being run.
-    print_stdout: Whether to forward Subversion's output to stdout.
-    filter: A function taking one argument (a string) which will be
-      passed each line (with the ending newline character removed) of
-      Subversion's output for filtering.
-
-  Raises:
-    Error: An error occurred while running the svn command.
-  """
-  command = [SVN_COMMAND]
-  command.extend(args)
-
-  gclient_utils.SubprocessCallAndFilter(command,
-                                        in_directory,
-                                        print_messages,
-                                        print_stdout,
-                                        filter=filter)
-
-def CaptureSVNInfo(relpath, in_directory=None, print_error=True):
-  """Returns a dictionary from the svn info output for the given file.
-
-  Args:
-    relpath: The directory where the working copy resides relative to
-      the directory given by in_directory.
-    in_directory: The directory where svn is to be run.
-  """
-  output = CaptureSVN(["info", "--xml", relpath], in_directory, print_error)
-  dom = gclient_utils.ParseXML(output)
-  result = {}
-  if dom:
-    GetNamedNodeText = gclient_utils.GetNamedNodeText
-    GetNodeNamedAttributeText = gclient_utils.GetNodeNamedAttributeText
-    def C(item, f):
-      if item is not None: return f(item)
-    # /info/entry/
-    #   url
-    #   reposityory/(root|uuid)
-    #   wc-info/(schedule|depth)
-    #   commit/(author|date)
-    # str() the results because they may be returned as Unicode, which
-    # interferes with the higher layers matching up things in the deps
-    # dictionary.
-    # TODO(maruel): Fix at higher level instead (!)
-    result['Repository Root'] = C(GetNamedNodeText(dom, 'root'), str)
-    result['URL'] = C(GetNamedNodeText(dom, 'url'), str)
-    result['UUID'] = C(GetNamedNodeText(dom, 'uuid'), str)
-    result['Revision'] = C(GetNodeNamedAttributeText(dom, 'entry', 'revision'),
-                           int)
-    result['Node Kind'] = C(GetNodeNamedAttributeText(dom, 'entry', 'kind'),
-                            str)
-    result['Schedule'] = C(GetNamedNodeText(dom, 'schedule'), str)
-    result['Path'] = C(GetNodeNamedAttributeText(dom, 'entry', 'path'), str)
-    result['Copied From URL'] = C(GetNamedNodeText(dom, 'copy-from-url'), str)
-    result['Copied From Rev'] = C(GetNamedNodeText(dom, 'copy-from-rev'), str)
-  return result
-
-
-def CaptureSVNHeadRevision(url):
-  """Get the head revision of a SVN repository.
-
-  Returns:
-    Int head revision
-  """
-  info = CaptureSVN(["info", "--xml", url], os.getcwd())
-  dom = xml.dom.minidom.parseString(info)
-  return dom.getElementsByTagName('entry')[0].getAttribute('revision')
-
-
-def CaptureSVNStatus(files):
-  """Returns the svn 1.5 svn status emulated output.
-
-  @files can be a string (one file) or a list of files.
-
-  Returns an array of (status, file) tuples."""
-  command = ["status", "--xml"]
-  if not files:
-    pass
-  elif isinstance(files, basestring):
-    command.append(files)
-  else:
-    command.extend(files)
-
-  status_letter = {
-    None: ' ',
-    '': ' ',
-    'added': 'A',
-    'conflicted': 'C',
-    'deleted': 'D',
-    'external': 'X',
-    'ignored': 'I',
-    'incomplete': '!',
-    'merged': 'G',
-    'missing': '!',
-    'modified': 'M',
-    'none': ' ',
-    'normal': ' ',
-    'obstructed': '~',
-    'replaced': 'R',
-    'unversioned': '?',
-  }
-  dom = gclient_utils.ParseXML(CaptureSVN(command))
-  results = []
-  if dom:
-    # /status/target/entry/(wc-status|commit|author|date)
-    for target in dom.getElementsByTagName('target'):
-      for entry in target.getElementsByTagName('entry'):
-        file_path = entry.getAttribute('path')
-        wc_status = entry.getElementsByTagName('wc-status')
-        assert len(wc_status) == 1
-        # Emulate svn 1.5 status ouput...
-        statuses = [' '] * 7
-        # Col 0
-        xml_item_status = wc_status[0].getAttribute('item')
-        if xml_item_status in status_letter:
-          statuses[0] = status_letter[xml_item_status]
-        else:
-          raise Exception('Unknown item status "%s"; please implement me!' %
-                          xml_item_status)
-        # Col 1
-        xml_props_status = wc_status[0].getAttribute('props')
-        if xml_props_status == 'modified':
-          statuses[1] = 'M'
-        elif xml_props_status == 'conflicted':
-          statuses[1] = 'C'
-        elif (not xml_props_status or xml_props_status == 'none' or
-              xml_props_status == 'normal'):
-          pass
-        else:
-          raise Exception('Unknown props status "%s"; please implement me!' %
-                          xml_props_status)
-        # Col 2
-        if wc_status[0].getAttribute('wc-locked') == 'true':
-          statuses[2] = 'L'
-        # Col 3
-        if wc_status[0].getAttribute('copied') == 'true':
-          statuses[3] = '+'
-        # Col 4
-        if wc_status[0].getAttribute('switched') == 'true':
-          statuses[4] = 'S'
-        # TODO(maruel): Col 5 and 6
-        item = (''.join(statuses), file_path)
-        results.append(item)
-  return results
+class GIT(object):
+  COMMAND = "git"
+
+  @staticmethod
+  def Capture(args, in_directory=None, print_error=True):
+    """Runs git, capturing output sent to stdout as a string.
+
+    Args:
+      args: A sequence of command line parameters to be passed to git.
+      in_directory: The directory where git is to be run.
+
+    Returns:
+      The output sent to stdout as a string.
+    """
+    c = [GIT.COMMAND]
+    c.extend(args)
+
+    # *Sigh*:  Windows needs shell=True, or else it won't search %PATH% for
+    # the git.exe executable, but shell=True makes subprocess on Linux fail
+    # when it's called with a list because it only tries to execute the
+    # first string ("git").
+    stderr = None
+    if not print_error:
+      stderr = subprocess.PIPE
+    return subprocess.Popen(c,
+                            cwd=in_directory,
+                            shell=sys.platform.startswith('win'),
+                            stdout=subprocess.PIPE,
+                            stderr=stderr).communicate()[0]
+
+
+  @staticmethod
+  def CaptureStatus(files, upstream_branch='origin'):
+    """Returns git status.
+
+    @files can be a string (one file) or a list of files.
+
+    Returns an array of (status, file) tuples."""
+    command = ["diff", "--name-status", "-r", "%s.." % upstream_branch]
+    if not files:
+      pass
+    elif isinstance(files, basestring):
+      command.append(files)
+    else:
+      command.extend(files)
+
+    status = GIT.Capture(command).rstrip()
+    results = []
+    if status:
+      for statusline in status.split('\n'):
+        m = re.match('^(\w)\t(.+)$', statusline)
+        if not m:
+          raise Exception("status currently unsupported: %s" % statusline)
+        results.append(('%s      ' % m.group(1), m.group(2)))
+    return results
+
+
+class SVN(object):
+  COMMAND = "svn"
+
+  @staticmethod
+  def Run(args, in_directory):
+    """Runs svn, sending output to stdout.
+
+    Args:
+      args: A sequence of command line parameters to be passed to svn.
+      in_directory: The directory where svn is to be run.
+
+    Raises:
+      Error: An error occurred while running the svn command.
+    """
+    c = [SVN.COMMAND]
+    c.extend(args)
+
+    gclient_utils.SubprocessCall(c, in_directory)
+
+  @staticmethod
+  def Capture(args, in_directory=None, print_error=True):
+    """Runs svn, capturing output sent to stdout as a string.
+
+    Args:
+      args: A sequence of command line parameters to be passed to svn.
+      in_directory: The directory where svn is to be run.
+
+    Returns:
+      The output sent to stdout as a string.
+    """
+    c = [SVN.COMMAND]
+    c.extend(args)
+
+    # *Sigh*:  Windows needs shell=True, or else it won't search %PATH% for
+    # the svn.exe executable, but shell=True makes subprocess on Linux fail
+    # when it's called with a list because it only tries to execute the
+    # first string ("svn").
+    stderr = None
+    if not print_error:
+      stderr = subprocess.PIPE
+    return subprocess.Popen(c,
+                            cwd=in_directory,
+                            shell=(sys.platform == 'win32'),
+                            stdout=subprocess.PIPE,
+                            stderr=stderr).communicate()[0]
+
+  @staticmethod
+  def RunAndGetFileList(options, args, in_directory, file_list):
+    """Runs svn checkout, update, or status, output to stdout.
+
+    The first item in args must be either "checkout", "update", or "status".
+
+    svn's stdout is parsed to collect a list of files checked out or updated.
+    These files are appended to file_list.  svn's stdout is also printed to
+    sys.stdout as in Run.
+
+    Args:
+      options: command line options to gclient
+      args: A sequence of command line parameters to be passed to svn.
+      in_directory: The directory where svn is to be run.
+
+    Raises:
+      Error: An error occurred while running the svn command.
+    """
+    command = [SVN.COMMAND]
+    command.extend(args)
+
+    # svn update and svn checkout use the same pattern: the first three columns
+    # are for file status, property status, and lock status.  This is followed
+    # by two spaces, and then the path to the file.
+    update_pattern = '^...  (.*)$'
+
+    # The first three columns of svn status are the same as for svn update and
+    # svn checkout.  The next three columns indicate addition-with-history,
+    # switch, and remote lock status.  This is followed by one space, and then
+    # the path to the file.
+    status_pattern = '^...... (.*)$'
+
+    # args[0] must be a supported command.  This will blow up if it's something
+    # else, which is good.  Note that the patterns are only effective when
+    # these commands are used in their ordinary forms, the patterns are invalid
+    # for "svn status --show-updates", for example.
+    pattern = {
+          'checkout': update_pattern,
+          'status':   status_pattern,
+          'update':   update_pattern,
+        }[args[0]]
+
+    compiled_pattern = re.compile(pattern)
+
+    def CaptureMatchingLines(line):
+      match = compiled_pattern.search(line)
+      if match:
+        file_list.append(match.group(1))
+
+    SVN.RunAndFilterOutput(args,
+                            in_directory,
+                            options.verbose,
+                            True,
+                            CaptureMatchingLines)
+
+  @staticmethod
+  def RunAndFilterOutput(args,
+                         in_directory,
+                         print_messages,
+                         print_stdout,
+                         filter):
+    """Runs svn checkout, update, status, or diff, optionally outputting
+    to stdout.
+
+    The first item in args must be either "checkout", "update",
+    "status", or "diff".
+
+    svn's stdout is passed line-by-line to the given filter function. If
+    print_stdout is true, it is also printed to sys.stdout as in Run.
+
+    Args:
+      args: A sequence of command line parameters to be passed to svn.
+      in_directory: The directory where svn is to be run.
+      print_messages: Whether to print status messages to stdout about
+        which Subversion commands are being run.
+      print_stdout: Whether to forward Subversion's output to stdout.
+      filter: A function taking one argument (a string) which will be
+        passed each line (with the ending newline character removed) of
+        Subversion's output for filtering.
+
+    Raises:
+      Error: An error occurred while running the svn command.
+    """
+    command = [SVN.COMMAND]
+    command.extend(args)
+
+    gclient_utils.SubprocessCallAndFilter(command,
+                                          in_directory,
+                                          print_messages,
+                                          print_stdout,
+                                          filter=filter)
+
+  @staticmethod
+  def CaptureInfo(relpath, in_directory=None, print_error=True):
+    """Returns a dictionary from the svn info output for the given file.
+
+    Args:
+      relpath: The directory where the working copy resides relative to
+        the directory given by in_directory.
+      in_directory: The directory where svn is to be run.
+    """
+    output = SVN.Capture(["info", "--xml", relpath], in_directory, print_error)
+    dom = gclient_utils.ParseXML(output)
+    result = {}
+    if dom:
+      GetNamedNodeText = gclient_utils.GetNamedNodeText
+      GetNodeNamedAttributeText = gclient_utils.GetNodeNamedAttributeText
+      def C(item, f):
+        if item is not None: return f(item)
+      # /info/entry/
+      #   url
+      #   reposityory/(root|uuid)
+      #   wc-info/(schedule|depth)
+      #   commit/(author|date)
+      # str() the results because they may be returned as Unicode, which
+      # interferes with the higher layers matching up things in the deps
+      # dictionary.
+      # TODO(maruel): Fix at higher level instead (!)
+      result['Repository Root'] = C(GetNamedNodeText(dom, 'root'), str)
+      result['URL'] = C(GetNamedNodeText(dom, 'url'), str)
+      result['UUID'] = C(GetNamedNodeText(dom, 'uuid'), str)
+      result['Revision'] = C(GetNodeNamedAttributeText(dom, 'entry',
+                                                       'revision'),
+                             int)
+      result['Node Kind'] = C(GetNodeNamedAttributeText(dom, 'entry', 'kind'),
+                              str)
+      # Differs across versions.
+      if result['Node Kind'] == 'dir':

[M-A Ruel, 2009/11/13 21:41:07]

This is new and simplify the expectations.

+        result['Node Kind'] = 'directory'
+      result['Schedule'] = C(GetNamedNodeText(dom, 'schedule'), str)
+      result['Path'] = C(GetNodeNamedAttributeText(dom, 'entry', 'path'), str)
+      result['Copied From URL'] = C(GetNamedNodeText(dom, 'copy-from-url'), str)
+      result['Copied From Rev'] = C(GetNamedNodeText(dom, 'copy-from-rev'), str)
+    return result
+
+  @staticmethod
+  def CaptureHeadRevision(url):
+    """Get the head revision of a SVN repository.
+
+    Returns:
+      Int head revision
+    """
+    info = SVN.Capture(["info", "--xml", url], os.getcwd())
+    dom = xml.dom.minidom.parseString(info)
+    return dom.getElementsByTagName('entry')[0].getAttribute('revision')
+
+  @staticmethod
+  def CaptureStatus(files):
+    """Returns the svn 1.5 svn status emulated output.
+
+    @files can be a string (one file) or a list of files.
+
+    Returns an array of (status, file) tuples."""
+    command = ["status", "--xml"]
+    if not files:
+      pass
+    elif isinstance(files, basestring):
+      command.append(files)
+    else:
+      command.extend(files)
+
+    status_letter = {
+      None: ' ',
+      '': ' ',
+      'added': 'A',
+      'conflicted': 'C',
+      'deleted': 'D',
+      'external': 'X',
+      'ignored': 'I',
+      'incomplete': '!',
+      'merged': 'G',
+      'missing': '!',
+      'modified': 'M',
+      'none': ' ',
+      'normal': ' ',
+      'obstructed': '~',
+      'replaced': 'R',
+      'unversioned': '?',
+    }
+    dom = gclient_utils.ParseXML(SVN.Capture(command))
+    results = []
+    if dom:
+      # /status/target/entry/(wc-status|commit|author|date)
+      for target in dom.getElementsByTagName('target'):
+        #base_path = target.getAttribute('path')
+        for entry in target.getElementsByTagName('entry'):
+          file_path = entry.getAttribute('path')
+          wc_status = entry.getElementsByTagName('wc-status')
+          assert len(wc_status) == 1
+          # Emulate svn 1.5 status ouput...
+          statuses = [' '] * 7
+          # Col 0
+          xml_item_status = wc_status[0].getAttribute('item')
+          if xml_item_status in status_letter:
+            statuses[0] = status_letter[xml_item_status]
+          else:
+            raise Exception('Unknown item status "%s"; please implement me!' %
+                            xml_item_status)
+          # Col 1
+          xml_props_status = wc_status[0].getAttribute('props')
+          if xml_props_status == 'modified':
+            statuses[1] = 'M'
+          elif xml_props_status == 'conflicted':
+            statuses[1] = 'C'
+          elif (not xml_props_status or xml_props_status == 'none' or
+                xml_props_status == 'normal'):
+            pass
+          else:
+            raise Exception('Unknown props status "%s"; please implement me!' %
+                            xml_props_status)
+          # Col 2
+          if wc_status[0].getAttribute('wc-locked') == 'true':
+            statuses[2] = 'L'
+          # Col 3
+          if wc_status[0].getAttribute('copied') == 'true':
+            statuses[3] = '+'
+          # Col 4
+          if wc_status[0].getAttribute('switched') == 'true':
+            statuses[4] = 'S'
+          # TODO(maruel): Col 5 and 6
+          item = (''.join(statuses), file_path)
+          results.append(item)
+    return results
+
+  @staticmethod
+  def IsMoved(filename):
+    """Determine if a file has been added through svn mv"""
+    info = SVN.CaptureInfo(filename)
+    return (info.get('Copied From URL') and
+            info.get('Copied From Rev') and
+            info.get('Schedule') == 'add')
+
+  @staticmethod
+  def GetFileProperty(file, property_name):
+    """Returns the value of an SVN property for the given file.
+
+    Args:
+      file: The file to check
+      property_name: The name of the SVN property, e.g. "svn:mime-type"
+
+    Returns:
+      The value of the property, which will be the empty string if the property
+      is not set on the file.  If the file is not under version control, the
+      empty string is also returned.
+    """
+    output = SVN.Run(["propget", property_name, file], None)
+    if (output.startswith("svn: ") and
+        output.endswith("is not under version control")):
+      return ""
+    else:
+      return output
+
+  @staticmethod
+  def DiffItem(filename):

[M-A Ruel, 2009/11/13 21:41:07]

Extracted from trychange.py

+    """Diff a single file"""
+    # Use svn info output instead of os.path.isdir because the latter fails
+    # when the file is deleted.
+    if SVN.CaptureInfo(filename).get("Node Kind") == "directory":
+      return None
+    # If the user specified a custom diff command in their svn config file,
+    # then it'll be used when we do svn diff, which we don't want to happen
+    # since we want the unified diff.  Using --diff-cmd=diff doesn't always
+    # work, since they can have another diff executable in their path that
+    # gives different line endings.  So we use a bogus temp directory as the
+    # config directory, which gets around these problems.
+    if sys.platform.startswith("win"):
+      parent_dir = tempfile.gettempdir()
+    else:
+      parent_dir = sys.path[0]  # tempdir is not secure.
+    bogus_dir = os.path.join(parent_dir, "temp_svn_config")
+    if not os.path.exists(bogus_dir):
+      os.mkdir(bogus_dir)
+    # Grabs the diff data.
+    data = SVN.Capture(["diff", "--config-dir", bogus_dir, filename], None)
+
+    # We know the diff will be incorrectly formatted. Fix it.
+    if SVN.IsMoved(filename):
+      # The file is "new" in the patch sense. Generate a homebrew diff.
+      # We can't use ReadFile() since it's not using binary mode.
+      file_handle = open(filename, 'rb')
+      file_content = file_handle.read()
+      file_handle.close()
+      # Prepend '+' to every lines.
+      file_content = ['+' + i for i in file_content.splitlines(True)]
+      nb_lines = len(file_content)
+      # We need to use / since patch on unix will fail otherwise.
+      filename = filename.replace('\\', '/')
+      data = "Index: %s\n" % filename
+      data += ("============================================================="
+               "======\n")
+      # Note: Should we use /dev/null instead?
+      data += "--- %s\n" % filename
+      data += "+++ %s\n" % filename
+      data += "@@ -0,0 +1,%d @@\n" % nb_lines
+      data += ''.join(file_content)
+    return data