Add support to put a patchset into a subdirectory.

patch.py

 # coding=utf8
 # Copyright (c) 2011 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.
 """Utility functions to handle patches."""
 
+import posixpath
+import os
 import re
 
 
 class UnsupportedPatchFormat(Exception):
   def __init__(self, filename, status):
     super(UnsupportedPatchFormat, self).__init__(filename, status)
     self.filename = filename
     self.status = status
 
   def __str__(self):
     out = 'Can\'t process patch for file %s.' % self.filename
     if self.status:
       out += '\n%s' % self.status
     return out
 
 
 class FilePatchBase(object):
-  """Defines a single file being modified."""
+  """Defines a single file being modified.
+
+  '/' is always used instead of os.sep for consistency.
+  """
   is_delete = False
   is_binary = False
 
+  def __init__(self, filename):
+    self.filename = None
+    self._set_filename(filename)
+
+  def _set_filename(self, filename):
+    self.filename = filename.replace('\\', '/')
+    # Blacklist a few characters for simplicity.
+    for i in ('%', '$', '..', '\'', '"'):
+      if i in self.filename:
+        self._fail('Can\'t use \'%s\' in filename.' % i)
+    for i in ('/', 'CON', 'COM'):
+      if self.filename.startswith(i):
+        self._fail('Filename can\'t start with \'%s\'.' % i)
+
   def get(self):
     raise NotImplementedError('Nothing to grab')
 
+  def set_relpath(self, relpath):
+    if not relpath:
+      return
+    relpath = relpath.replace('\\', '/')
+    if relpath[0] == '/':
+      self._fail('Relative path starts with %s' % relpath[0])
+    self._set_filename(posixpath.join(relpath, self.filename))
+
+  def _fail(self, msg):
+    raise UnsupportedPatchFormat(self.filename, msg)
+
 
 class FilePatchDelete(FilePatchBase):
   """Deletes a file."""
   is_delete = True
 
   def __init__(self, filename, is_binary):
-    super(FilePatchDelete, self).__init__()
-    self.filename = filename
+    super(FilePatchDelete, self).__init__(filename)
     self.is_binary = is_binary
 
   def get(self):
     raise NotImplementedError('Nothing to grab')
 
 
 class FilePatchBinary(FilePatchBase):
   """Content of a new binary file."""
   is_binary = True
 
   def __init__(self, filename, data, svn_properties):
-    super(FilePatchBinary, self).__init__()
-    self.filename = filename
+    super(FilePatchBinary, self).__init__(filename)
     self.data = data
     self.svn_properties = svn_properties or []
 
   def get(self):
     return self.data
 
 
 class FilePatchDiff(FilePatchBase):
   """Patch for a single file."""
 
   def __init__(self, filename, diff, svn_properties):
-    super(FilePatchDiff, self).__init__()
-    self.filename = filename
-    self.diff = diff
+    super(FilePatchDiff, self).__init__(filename)
+    self.diff_header, self.diff_hunks = self._split_header(diff)
     self.svn_properties = svn_properties or []
-    self.is_git_diff = self._is_git_diff(diff)
+    self.is_git_diff = self._is_git_diff_header(self.diff_header)
+    self.patchlevel = 0
     if self.is_git_diff:
-      self.patchlevel = 1
-      self._verify_git_patch(filename, diff)
+      self._verify_git_header()
       assert not svn_properties
     else:
-      self.patchlevel = 0
-      self._verify_svn_patch(filename, diff)
+      self._verify_svn_header()
 
   def get(self):
-    return self.diff
+    return self.diff_header + self.diff_hunks
+
+  def set_relpath(self, relpath):
+    old_filename = self.filename
+    super(FilePatchDiff, self).set_relpath(relpath)
+    # Update the header too.
+    self.diff_header = self.diff_header.replace(old_filename, self.filename)
+
+  def _split_header(self, diff):
+    """Splits a diff in two: the header and the hunks."""
+    header = []
+    hunks = diff.splitlines(True)
+    while hunks:
+      header.append(hunks.pop(0))
+      if header[-1].startswith('--- '):
+        break
+    else:
+      # Some diff may not have a ---/+++ set like a git rename with no change or
+      # a svn diff with only property change.
+      pass
+
+    if hunks:
+      if not hunks[0].startswith('+++ '):
+        self._fail('Inconsistent header')
+      header.append(hunks.pop(0))
+      if hunks:
+        if not hunks[0].startswith('@@ '):
+          self._fail('Inconsistent hunk header')
+
+    # Mangle any \\ in the header to /.
+    header_lines = ('Index:', 'diff', 'copy', 'rename', '+++', '---')
+    basename = os.path.basename(self.filename)
+    for i in xrange(len(header)):
+      if (header[i].split(' ', 1)[0] in header_lines or
+          header[i].endswith(basename)):
+        header[i] = header[i].replace('\\', '/')
+    return ''.join(header), ''.join(hunks)
 
   @staticmethod
-  def _is_git_diff(diff):
-    """Returns True if the diff for a single files was generated with gt.
-
-    Expects the following format:
-
-    Index: <filename>
-    diff --git a/<filename> b/<filename>
-    <filemode changes>
-    <index>
-    --- <filename>
-    +++ <filename>
-    <hunks>
-
-    Index: is a rietveld specific line.
-    """
+  def _is_git_diff_header(diff_header):
+    """Returns True if the diff for a single files was generated with git."""
     # Delete: http://codereview.chromium.org/download/issue6368055_22_29.diff
     # Rename partial change:
     # http://codereview.chromium.org/download/issue6250123_3013_6010.diff
     # Rename no change:
     # http://codereview.chromium.org/download/issue6287022_3001_4010.diff
-    return any(l.startswith('diff --git') for l in diff.splitlines()[:3])
+    return any(l.startswith('diff --git') for l in diff_header.splitlines())
 
-  @staticmethod
-  def _verify_git_patch(filename, diff):
-    lines = diff.splitlines()
-    # First fine the git diff header:
+  def mangle(self, string):
+    """Mangle a file path."""
+    return '/'.join(string.replace('\\', '/').split('/')[self.patchlevel:])
+
+  def _verify_git_header(self):
+    """Sanity checks the header.
+
+    Expects the following format:
+
+    <garbagge>
+    diff --git (|a/)<filename> (|b/)<filename>
+    <similarity>
+    <filemode changes>
+    <index>
+    <copy|rename from>
+    <copy|rename to>
+    --- <filename>
+    +++ <filename>
+
+    Everything is optional except the diff --git line.
+    """
+    lines = self.diff_header.splitlines()
+
+    # Verify the diff --git line.
+    old = None
+    new = None
     while lines:
-      line = lines.pop(0)
-      match = re.match(r'^diff \-\-git a\/(.*?) b\/(.*)$', line)
-      if match:
-        a = match.group(1)
-        b = match.group(2)
-        if a != filename and a != 'dev/null':
-          raise UnsupportedPatchFormat(
-              filename, 'Unexpected git diff input name.')
-        if b != filename and b != 'dev/null':
-          raise UnsupportedPatchFormat(
-              filename, 'Unexpected git diff output name.')
-        if a == 'dev/null' and b == 'dev/null':
-          raise UnsupportedPatchFormat(
-              filename, 'Unexpected /dev/null git diff.')
+      match = re.match(r'^diff \-\-git (.*?) (.*)$', lines.pop(0))
+      if not match:
+        continue
+      old = match.group(1).replace('\\', '/')
+      new = match.group(2).replace('\\', '/')
+      if old.startswith('a/') and new.startswith('b/'):
+        self.patchlevel = 1
+        old = old[2:]
+        new = new[2:]
+      # The rename is about the new file so the old file can be anything.
+      if new not in (self.filename, 'dev/null'):
+        self._fail('Unexpected git diff output name %s.' % new)
+      if old == 'dev/null' and new == 'dev/null':
+        self._fail('Unexpected /dev/null git diff.')
+      break
+
+    if not old or not new:
+      self._fail('Unexpected git diff; couldn\'t find git header.')
+
+    # Handle these:
+    # rename from <>
+    # rename to <>
+    # copy from <>
+    # copy to <>
+    while lines:
+      if lines[0].startswith('--- '):
         break
+      match = re.match(r'^(rename|copy) from (.+)$', lines.pop(0))
+      if not match:
+        continue
+      if old != match.group(2):
+        self._fail('Unexpected git diff input name for %s.' % match.group(1))
+      if not lines:
+        self._fail('Missing git diff output name for %s.' % match.group(1))
+      match = re.match(r'^(rename|copy) to (.+)$', lines.pop(0))
+      if not match:
+        self._fail('Missing git diff output name for %s.' % match.group(1))
+      if new != match.group(2):
+        self._fail('Unexpected git diff output name for %s.' % match.group(1))
+
+    # Handle ---/+++
+    while lines:
+      match = re.match(r'^--- (.*)$', lines.pop(0))
+      if not match:
+        continue
+      if old != self.mangle(match.group(1)) and match.group(1) != '/dev/null':
+        self._fail('Unexpected git diff: %s != %s.' % (old, match.group(1)))
+      if not lines:
+        self._fail('Missing git diff output name.')
+      match = re.match(r'^\+\+\+ (.*)$', lines.pop(0))
+      if not match:
+        self._fail('Unexpected git diff: --- not following +++.')
+      if new != self.mangle(match.group(1)) and '/dev/null' != match.group(1):
+        self._fail('Unexpected git diff: %s != %s.' % (new, match.group(1)))
+      assert not lines, '_split_header() is broken'
+      break
+
+  def _verify_svn_header(self):
+    """Sanity checks the header.
+
+    A svn diff can contain only property changes, in that case there will be no
+    proper header. To make things worse, this property change header is
+    localized.
+    """
+    lines = self.diff_header.splitlines()
+    while lines:
+      match = re.match(r'^--- ([^\t]+).*$', lines.pop(0))
+      if not match:
+        continue
+      if match.group(1) not in (self.filename, '/dev/null'):
+        self._fail('Unexpected diff: %s.' % match.group(1))
+      match = re.match(r'^\+\+\+ ([^\t]+).*$', lines.pop(0))
+      if not match:
+        self._fail('Unexpected diff: --- not following +++.')
+      if match.group(1) not in (self.filename, '/dev/null'):
+        self._fail('Unexpected diff: %s.' % match.group(1))
+      assert not lines, '_split_header() is broken'
+      break
     else:
-      raise UnsupportedPatchFormat(
-          filename, 'Unexpected git diff; couldn\'t find git header.')
-
-    while lines:
-      line = lines.pop(0)
-      match = re.match(r'^--- a/(.*)$', line)
-      if match:
-        if a != match.group(1):
-          raise UnsupportedPatchFormat(
-              filename, 'Unexpected git diff: %s != %s.' % (a, match.group(1)))
-        match = re.match(r'^\+\+\+ b/(.*)$', lines.pop(0))
-        if not match:
-          raise UnsupportedPatchFormat(
-              filename, 'Unexpected git diff: --- not following +++.')
-        if b != match.group(1):
-          raise UnsupportedPatchFormat(
-              filename, 'Unexpected git diff: %s != %s.' % (b, match.group(1)))
-        break
-    # Don't fail if the patch header is not found, the diff could be a
-    # file-mode-change-only diff.
-
-  @staticmethod
-  def _verify_svn_patch(filename, diff):
-    lines = diff.splitlines()
-    while lines:
-      line = lines.pop(0)
-      match = re.match(r'^--- ([^\t]+).*$', line)
-      if match:
-        if match.group(1) not in (filename, '/dev/null'):
-          raise UnsupportedPatchFormat(
-              filename,
-              'Unexpected diff: %s != %s.' % (filename, match.group(1)))
-        # Grab next line.
-        line2 = lines.pop(0)
-        match = re.match(r'^\+\+\+ ([^\t]+).*$', line2)
-        if not match:
-          raise UnsupportedPatchFormat(
-              filename,
-              'Unexpected diff: --- not following +++.:\n%s\n%s' % (
-                  line, line2))
-        if match.group(1) not in (filename, '/dev/null'):
-          raise UnsupportedPatchFormat(
-              filename,
-              'Unexpected diff: %s != %s.' % (filename, match.group(1)))
-        break
-    # Don't fail if the patch header is not found, the diff could be a
-    # svn-property-change-only diff.
+      # Cheap check to make sure the file name is at least mentioned in the
+      # 'diff' header. That the only remaining invariant.
+      if not self.filename in self.diff_header:
+        self._fail('Diff seems corrupted.')
 
 
 class PatchSet(object):
   """A list of FilePatch* objects."""
 
   def __init__(self, patches):
     self.patches = patches
 
+  def set_relpath(self, relpath):
+    """Used to offset the patch into a subdirectory."""
+    for patch in self.patches:
+      patch.set_relpath(relpath)
+
   def __iter__(self):
     for patch in self.patches:
       yield patch
 
   @property
   def filenames(self):
     return [p.filename for p in self.patches]