Use git apply for applying patch files (issue #1825)

tools/git_util.py

@@ -4,14 +4,21 @@
 
 from exec_util import exec_cmd
 import os
+import sys
+
+if sys.platform == 'win32':
+  # Force use of the git version bundled with depot_tools.
+  git_exe = 'git.bat'
+else:
+  git_exe = 'git'
 
 def is_checkout(path):
   """ Returns true if the path represents a git checkout. """
-  return os.path.exists(os.path.join(path, '.git'))
+  return os.path.isdir(os.path.join(path, '.git'))
 
 def get_hash(path = '.', branch = 'HEAD'):
   """ Returns the git hash for the specified branch/tag/hash. """
-  cmd = "git rev-parse %s" % branch
+  cmd = "%s rev-parse %s" % (git_exe, branch)
   result = exec_cmd(cmd, path)
   if result['out'] != '':
     return result['out'].strip()
@@ -19,7 +26,7 @@ def get_hash(path = '.', branch = 'HEAD'):
 
 def get_url(path = '.'):
   """ Returns the origin url for the specified path. """
-  cmd = "git config --get remote.origin.url"
+  cmd = "%s config --get remote.origin.url" % git_exe
   result = exec_cmd(cmd, path)
   if result['out'] != '':
     return result['out'].strip()
@@ -27,7 +34,7 @@ def get_url(path = '.'):
 
 def get_commit_number(path = '.', branch = 'HEAD'):
   """ Returns the number of commits in the specified branch/tag/hash. """
-  cmd = "git rev-list --count %s" % branch
+  cmd = "%s rev-list --count %s" % (git_exe, branch)
   result = exec_cmd(cmd, path)
   if result['out'] != '':
     return result['out'].strip()
@@ -37,3 +44,64 @@ def get_changed_files(path = '.'):
   """ Retrieves the list of changed files. """
   # not implemented
   return []
+
+def write_indented_output(output):
+  """ Apply a fixed amount of intent to lines before printing. """
+  if output == '':
+    return
+  for line in output.split('\n'):
+    line = line.strip()
+    if len(line) == 0:
+      continue
+    sys.stdout.write('\t%s\n' % line)
+
+def git_apply_patch_file(patch_path, patch_dir):
+  """ Apply |patch_path| to files in |patch_dir|. """
+  patch_name = os.path.basename(patch_path)
+  sys.stdout.write('\nApply %s in %s\n' % (patch_name, patch_dir))
+
+  if not os.path.isfile(patch_path):
+    sys.stdout.write('... patch file does not exist.\n')
+    return 'fail'
+
+  patch_string = open(patch_path, 'rb').read()
+  if sys.platform == 'win32':
+    # Convert the patch to Unix line endings. This is necessary to avoid
+    # whitespace errors with git apply.
+    patch_string = patch_string.replace('\r\n', '\n')
+
+  # Git apply fails silently if not run relative to a respository root.
+  if not is_checkout(patch_dir):
+    sys.stdout.write('... patch directory is not a repository root.\n')
+    return 'fail'
+
+  # Output patch contents.
+  cmd = '%s apply -p0 --numstat' % git_exe
+  result = exec_cmd(cmd, patch_dir, patch_string)
+  write_indented_output(result['out'].replace('<stdin>', patch_name))
+
+  # Reverse check to see if the patch has already been applied.
+  cmd = '%s apply -p0 --reverse --check' % git_exe
+  result = exec_cmd(cmd, patch_dir, patch_string)
+  if result['err'].find('error:') < 0:
+    sys.stdout.write('... already applied (skipping).\n')
+    return 'skip'
+
+  # Normal check to see if the patch can be applied cleanly.
+  cmd = '%s apply -p0 --check' % git_exe
+  result = exec_cmd(cmd, patch_dir, patch_string)
+  if result['err'].find('error:') >= 0:
+    sys.stdout.write('... failed to apply:\n')
+    write_indented_output(result['err'].replace('<stdin>', patch_name))
+    return 'fail'
+
+  # Apply the patch file. This should always succeed because the previous
+  # command succeeded.
+  cmd = '%s apply -p0' % git_exe
+  result = exec_cmd(cmd, patch_dir, patch_string)
+  if result['err'] == '':
+    sys.stdout.write('... successfully applied.\n')
+  else:
+    sys.stdout.write('... successfully applied (with warnings):\n')
+    write_indented_output(result['err'].replace('<stdin>', patch_name))
+  return 'apply'