[catapult] - Copy Telemetry's gsutilz over to third_party.

third_party/gsutil/third_party/protorpc/protorpc/wsgi/util.py

Index: third_party/gsutil/third_party/protorpc/protorpc/wsgi/util.py
diff --git a/third_party/gsutil/third_party/protorpc/protorpc/wsgi/util.py b/third_party/gsutil/third_party/protorpc/protorpc/wsgi/util.py
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+#!/usr/bin/env python
+#
+# Copyright 2011 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+"""WSGI utilities
+
+Small collection of helpful utilities for working with WSGI.
+"""
+import six
+
+__author__ = 'rafek@google.com (Rafe Kaplan)'
+
+import six.moves.http_client
+import re
+
+from .. import util
+
+__all__ = ['static_page',
+           'error',
+           'first_found',
+]
+
+_STATUS_PATTERN = re.compile('^(\d{3})\s')
+
+
+@util.positional(1)
+def static_page(content='',
+                status='200 OK',
+                content_type='text/html; charset=utf-8',
+                headers=None):
+  """Create a WSGI application that serves static content.
+
+  A static page is one that will be the same every time it receives a request.
+  It will always serve the same status, content and headers.
+
+  Args:
+    content: Content to serve in response to HTTP request.
+    status: Status to serve in response to HTTP request.  If string, status
+      is served as is without any error checking.  If integer, will look up
+      status message.  Otherwise, parameter is tuple (status, description):
+        status: Integer status of response.
+        description: Brief text description of response.
+    content_type: Convenient parameter for content-type header.  Will appear
+      before any content-type header that appears in 'headers' parameter.
+    headers: Dictionary of headers or iterable of tuples (name, value):
+      name: String name of header.
+      value: String value of header.
+
+  Returns:
+    WSGI application that serves static content.
+  """
+  if isinstance(status, six.integer_types):
+    status = '%d %s' % (status, six.moves.http_client.responses.get(status, 'Unknown Error'))
+  elif not isinstance(status, six.string_types):
+    status = '%d %s' % tuple(status)
+
+  if isinstance(headers, dict):
+    headers = six.iteritems(headers)
+
+  headers = [('content-length', str(len(content))),
+             ('content-type', content_type),
+            ] + list(headers or [])
+
+  # Ensure all headers are str.
+  for index, (key, value) in enumerate(headers):
+    if isinstance(value, six.text_type):
+      value = value.encode('utf-8')
+      headers[index] = key, value
+
+    if not isinstance(key, str):
+      raise TypeError('Header key must be str, found: %r' % (key,))
+
+    if not isinstance(value, str):
+      raise TypeError(
+          'Header %r must be type str or unicode, found: %r' % (key, value))
+
+  def static_page_application(environ, start_response):
+    start_response(status, headers)
+    return [content]
+
+  return static_page_application
+
+
+@util.positional(2)
+def error(status_code, status_message=None,
+          content_type='text/plain; charset=utf-8',
+          headers=None, content=None):
+  """Create WSGI application that statically serves an error page.
+
+  Creates a static error page specifically for non-200 HTTP responses.
+
+  Browsers such as Internet Explorer will display their own error pages for
+  error content responses smaller than 512 bytes.  For this reason all responses
+  are right-padded up to 512 bytes.
+
+  Error pages that are not provided will content will contain the standard HTTP
+  status message as their content.
+
+  Args:
+    status_code: Integer status code of error.
+    status_message: Status message.
+
+  Returns:
+    Static WSGI application that sends static error response.
+  """
+  if status_message is None:
+    status_message = six.moves.http_client.responses.get(status_code, 'Unknown Error')
+
+  if content is None:
+    content = status_message
+
+  content = util.pad_string(content)
+
+  return static_page(content,
+                     status=(status_code, status_message),
+                     content_type=content_type,
+                     headers=headers)
+
+
+def first_found(apps):
+  """Serve the first application that does not response with 404 Not Found.
+
+  If no application serves content, will respond with generic 404 Not Found.
+
+  Args:
+    apps: List of WSGI applications to search through.  Will serve the content
+      of the first of these that does not return a 404 Not Found.  Applications
+      in this list must not modify the environment or any objects in it if they
+      do not match.  Applications that do not obey this restriction can create
+      unpredictable results.
+
+  Returns:
+    Compound application that serves the contents of the first application that
+    does not response with 404 Not Found.
+  """
+  apps = tuple(apps)
+  not_found = error(six.moves.http_client.NOT_FOUND)
+
+  def first_found_app(environ, start_response):
+    """Compound application returned from the first_found function."""
+    final_result = {}  # Used in absence of Python local scoping.
+
+    def first_found_start_response(status, response_headers):
+      """Replacement for start_response as passed in to first_found_app.
+
+      Called by each application in apps instead of the real start response.
+      Checks the response status, and if anything other than 404, sets 'status'
+      and 'response_headers' in final_result.
+      """
+      status_match = _STATUS_PATTERN.match(status)
+      assert status_match, ('Status must be a string beginning '
+                            'with 3 digit number. Found: %s' % status)
+      status_code = status_match.group(0)
+      if int(status_code) == six.moves.http_client.NOT_FOUND:
+        return
+
+      final_result['status'] = status
+      final_result['response_headers'] = response_headers
+
+    for app in apps:
+      response = app(environ, first_found_start_response)
+      if final_result:
+        start_response(final_result['status'], final_result['response_headers'])
+        return response
+
+    return not_found(environ, start_response)
+  return first_found_app