1 """WSGI handler for serving chained WSGI modules from physical files
3 The WSGI handler in this module ensures that the SCRIPT_FILENAME
4 variable is properly set in every request and points out a file that
5 exists and is readable. It then dispatches the request in one of two
6 ways: If the header X-Ash-Python-Handler is set in the request, its
7 value is used as the name of a handler object to dispatch the request
8 to; otherwise, the file extension of the SCRIPT_FILENAME is used to
9 determine the handler object.
11 The name of a handler object is specified as a string, which is split
12 along its last constituent dot. The part left of the dot is the name
13 of a module, which is imported; and the part right of the dot is the
14 name of an object in that module, which should be a callable adhering
15 to the WSGI specification. Alternatively, the module part may be
16 omitted (such that the name is a string with no dots), in which case
17 the handler object is looked up from this module.
19 By default, this module will handle files with the extensions `.wsgi'
20 or `.wsgi2' using the `chain' handler, which chainloads such files and
21 runs them as independent WSGI applications. See its documentation for
24 This module itself contains both an `application' and a `wmain'
25 object. If this module is used by ashd-wsgi(1) or scgi-wsgi(1) so that
26 its wmain function is called, arguments can be specified to it to
27 install handlers for other file extensions. Such arguments take the
28 form `.EXT=HANDLER', where EXT is the file extension to be handled,
29 and HANDLER is a handler name, as described above. For example, the
30 argument `.fpy=my.module.foohandler' can be given to pass requests for
31 `.fpy' files to the function `foohandler' in the module `my.module'
32 (which must, of course, be importable). When writing such handler
33 functions, you may want to use the getmod() function in this module.
36 import sys, os, threading, types, logging, getopt
39 __all__ = ["application", "wmain", "getmod", "cachedmod", "chain"]
41 log = logging.getLogger("wsgidir")
43 class cachedmod(object):
44 """Cache entry for modules loaded by getmod()
46 Instances of this class are returned by the getmod()
47 function. They contain three data attributes:
48 * mod - The loaded module
49 * lock - A threading.Lock object, which can be used for
50 manipulating this instance in a thread-safe manner
51 * mtime - The time the file was last modified
53 Additional data attributes can be arbitrarily added for recording
54 any meta-data about the module.
56 def __init__(self, mod = None, mtime = -1):
57 self.lock = threading.Lock()
62 cachelock = threading.Lock()
74 """Load the given file as a module, caching it appropriately
76 The given file is loaded and compiled into a Python module. The
77 compiled module is cached and returned upon subsequent requests
78 for the same file, unless the file has changed (as determined by
79 its mtime), in which case the cached module is discarded and the
80 new file contents are reloaded in its place.
82 The return value is an instance of the cachedmod class, which can
83 be used for locking purposes and for storing arbitrary meta-data
84 about the module. See its documentation for details.
90 entry = modcache[path]
92 entry = [threading.Lock(), None]
93 modcache[path] = entry
98 if entry[1] is None or sb.st_mtime > entry[1].mtime:
104 code = compile(text, path, "exec")
105 mod = types.ModuleType(mangle(path))
107 exec code in mod.__dict__
108 entry[1] = cachedmod(mod, sb.st_mtime)
113 class handler(object):
115 self.lock = threading.Lock()
118 self.addext("wsgi", "chain")
119 self.addext("wsgi2", "chain")
121 def resolve(self, name):
124 if name in self.handlers:
125 return self.handlers[name]
128 return globals()[name]
131 mod = __import__(mname, fromlist = ["dummy"])
132 ret = getattr(mod, hname)
133 self.handlers[name] = ret
138 def addext(self, ext, handler):
139 self.exts[ext] = self.resolve(handler)
141 def handle(self, env, startreq):
142 if not "SCRIPT_FILENAME" in env:
143 return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.")
144 path = env["SCRIPT_FILENAME"]
145 if not os.access(path, os.R_OK):
146 return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.")
147 if "HTTP_X_ASH_PYTHON_HANDLER" in env:
148 handler = self.resolve(env["HTTP_X_ASH_PYTHON_HANDLER"])
150 base = os.path.basename(path)
153 return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.")
155 if not ext in self.exts:
156 return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.")
157 handler = self.exts[ext]
158 return handler(env, startreq)
161 """Main function for ashd(7)-compatible WSGI handlers
163 Returns the `application' function. If any arguments are given,
164 they are parsed according to the module documentation.
169 opts, args = getopt.getopt(argv, "V")
172 import wsgiref.validate
173 ret = wsgiref.validate.validator(ret)
178 hnd.addext(arg[1:p], arg[p + 1:])
181 def chain(env, startreq):
182 """Chain-loading WSGI handler
184 This handler loads requested files, compiles them and loads them
185 into their own modules. The compiled modules are cached and reused
186 until the file is modified, in which case the previous module is
187 discarded and the new file contents are loaded into a new module
188 in its place. When chaining such modules, an object named `wmain'
189 is first looked for and called with no arguments if found. The
190 object it returns is then used as the WSGI application object for
191 that module, which is reused until the module is reloaded. If
192 `wmain' is not found, an object named `application' is looked for
193 instead. If found, it is used directly as the WSGI application
196 path = env["SCRIPT_FILENAME"]
200 log.error("Exception occurred when loading %s" % path, exc_info=sys.exc_info())
201 return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "Could not load WSGI handler.")
206 if hasattr(mod, "entry"):
209 if hasattr(mod.mod, "wmain"):
210 entry = mod.mod.wmain()
211 elif hasattr(mod.mod, "application"):
212 entry = mod.mod.application
216 if entry is not None:
217 return entry(env, startreq)
218 return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "Invalid WSGI handler.")
220 application = handler().handle