view tests/test-hgweb-non-interactive.t @ 26375:3686fa2b8eee

windows: insert file positioning call between reads and writes

fopen() and fdopen() have a unique-to-Windows requirement that
transitions between read and write operations in files opened
in modes r+, w+, and a+ perform a file positioning call
(fsetpos, fseek, or rewind) in between. While the MSDN docs don't
say what will happen if this is not done, observations reveal
that Python raises an IOError with errno 0. Furthermore, I
/think/ this behavior isn't deterministic. But I can reproduce
it reliably with subsequent patches applied that open revlogs
in a+ mode and perform both reads and writes.

This patch introduces a proxy class for file handles opened
in r+, w+, and a+ mode on Windows. The class intercepts calls
and audits whether a file positioning function has been called
between read and write operations. If not, a dummy, no-op seek
to the current file position is performed. This appears to be
sufficient to "trick" Windows into allowing transitions between
read and writes without raising errors.

Tests if hgweb can run without touching sys.stdin, as is required
by the WSGI standard and strictly implemented by mod_wsgi.

  $ hg init repo
  $ cd repo
  $ echo foo > bar
  $ hg add bar
  $ hg commit -m "test"
  $ cat > request.py <<EOF
  > from mercurial import dispatch
  > from mercurial.hgweb.hgweb_mod import hgweb
  > from mercurial.ui import ui
  > from mercurial import hg
  > from StringIO import StringIO
  > import os, sys
  > 
  > class FileLike(object):
  >     def __init__(self, real):
  >         self.real = real
  >     def fileno(self):
  >         print >> sys.__stdout__, 'FILENO'
  >         return self.real.fileno()
  >     def read(self):
  >         print >> sys.__stdout__, 'READ'
  >         return self.real.read()
  >     def readline(self):
  >         print >> sys.__stdout__, 'READLINE'
  >         return self.real.readline()
  > 
  > sys.stdin = FileLike(sys.stdin)
  > errors = StringIO()
  > input = StringIO()
  > output = StringIO()
  > 
  > def startrsp(status, headers):
  >     print '---- STATUS'
  >     print status
  >     print '---- HEADERS'
  >     print [i for i in headers if i[0] != 'ETag']
  >     print '---- DATA'
  >     return output.write
  > 
  > env = {
  >     'wsgi.version': (1, 0),
  >     'wsgi.url_scheme': 'http',
  >     'wsgi.errors': errors,
  >     'wsgi.input': input,
  >     'wsgi.multithread': False,
  >     'wsgi.multiprocess': False,
  >     'wsgi.run_once': False,
  >     'REQUEST_METHOD': 'GET',
  >     'SCRIPT_NAME': '',
  >     'PATH_INFO': '',
  >     'QUERY_STRING': '',
  >     'SERVER_NAME': '127.0.0.1',
  >     'SERVER_PORT': os.environ['HGPORT'],
  >     'SERVER_PROTOCOL': 'HTTP/1.0'
  > }
  > 
  > i = hgweb('.')
  > for c in i(env, startrsp):
  >     pass
  > print '---- ERRORS'
  > print errors.getvalue()
  > print '---- OS.ENVIRON wsgi variables'
  > print sorted([x for x in os.environ if x.startswith('wsgi')])
  > print '---- request.ENVIRON wsgi variables'
  > with i._obtainrepo() as repo:
  >     print sorted([x for x in repo.ui.environ if x.startswith('wsgi')])
  > EOF
  $ python request.py
  ---- STATUS
  200 Script output follows
  ---- HEADERS
  [('Content-Type', 'text/html; charset=ascii')]
  ---- DATA
  ---- ERRORS
  
  ---- OS.ENVIRON wsgi variables
  []
  ---- request.ENVIRON wsgi variables
  ['wsgi.errors', 'wsgi.input', 'wsgi.multiprocess', 'wsgi.multithread', 'wsgi.run_once', 'wsgi.url_scheme', 'wsgi.version']

  $ cd ..