Very basic starter presubmit script for Chromium, as requested by maruel....

PRESUBMIT.py

Index: PRESUBMIT.py
===================================================================
--- PRESUBMIT.py	(revision 0)
+++ PRESUBMIT.py	(revision 0)
@@ -0,0 +1,73 @@
+#!/usr/bin/python
+# Copyright (c) 2009 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.
+
+"""Top-level presubmit script for Chromium.
+
+See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts for
+details on the presubmit API built into gcl.
+"""
+
+
+import os
+
+
+# Files with these extensions will be considered source files
+SOURCE_FILE_EXTENSIONS = ['.c', '.cc', '.cpp', '.h', '.m', '.mm', '.py']
+
+
+def ReadFile(path):
+  """Given a path, returns the full contents of the file.
+  
+  Reads files in binary format.
+  """
+  fo = open(path, 'rb')
+  try:
+    contents = fo.read()
+  finally:
+    fo.close()
+  return contents
+
+
+# Seam for unit testing
+_ReadFile = ReadFile
+
+
+def CheckChangeOnUpload(input_api, output_api):
+  return (CheckNoCrOrTabs(input_api, output_api) +
+          input_api.canned_checks.CheckDoNotSubmit(input_api, output_api))
+
+
+def CheckChangeOnCommit(input_api, output_api):
+  # No extra checks on commit for now
+  return CheckChangeOnUpload(input_api, output_api)
+
+
+def CheckNoCrOrTabs(input_api, output_api):
+  """Reports an error if source files use CR (or CRLF) or TAB.
+  """
+  cr_files = []
+  tab_files = []
+  results = []
+  
+  for f in input_api.AffectedTextFiles(include_deletes=False):
+    path = f.LocalPath()
+    root, ext = os.path.splitext(path)
+    if ext in SOURCE_FILE_EXTENSIONS:
+      # Need to read the file ourselves since AffectedFile.NewContents()
+      # will normalize line endings.
+      contents = _ReadFile(path)
+      if '\r' in contents:
+        cr_files.append(path)
+      if '\t' in contents:
+        tab_files.append(path)
+  if cr_files:
+    results.append(output_api.PresubmitError(
+        'Found CR (or CRLF) line ending in these files, please use only LF:',
+        items=cr_files))
+  if tab_files:
+    results.append(output_api.PresubmitError(
+        'Found tabs in the following files, please use spaces',
+        items=tab_files))
+  return results