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 `.wsgi3' 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, importlib, getopt
37 from . import wsgiutil
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.
89 entry = modcache[path]
91 entry = [threading.Lock(), None]
92 modcache[path] = entry
94 if entry[1] is None or sb.st_mtime > entry[1].mtime:
95 with open(path, "rb") as f:
97 code = compile(text, path, "exec")
98 mod = types.ModuleType(mangle(path))
100 exec(code, mod.__dict__)
101 entry[1] = cachedmod(mod, sb.st_mtime)
104 class handler(object):
106 self.lock = threading.Lock()
109 self.addext("wsgi", "chain")
110 self.addext("wsgi3", "chain")
112 def resolve(self, name):
114 if name in self.handlers:
115 return self.handlers[name]
118 return globals()[name]
121 mod = importlib.import_module(mname)
122 ret = getattr(mod, hname)
123 self.handlers[name] = ret
126 def addext(self, ext, handler):
127 self.exts[ext] = self.resolve(handler)
129 def handle(self, env, startreq):
130 if not "SCRIPT_FILENAME" in env:
131 return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.")
132 path = env["SCRIPT_FILENAME"]
133 if not os.access(path, os.R_OK):
134 return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.")
135 if "HTTP_X_ASH_PYTHON_HANDLER" in env:
136 handler = self.resolve(env["HTTP_X_ASH_PYTHON_HANDLER"])
138 base = os.path.basename(path)
141 return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.")
143 if not ext in self.exts:
144 return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.")
145 handler = self.exts[ext]
146 return handler(env, startreq)
149 """Main function for ashd(7)-compatible WSGI handlers
151 Returns the `application' function. If any arguments are given,
152 they are parsed according to the module documentation.
157 opts, args = getopt.getopt(argv, "-V")
160 import wsgiref.validate
161 ret = wsgiref.validate.validator(ret)
166 hnd.addext(arg[1:p], arg[p + 1:])
169 def chain(env, startreq):
170 """Chain-loading WSGI handler
172 This handler loads requested files, compiles them and loads them
173 into their own modules. The compiled modules are cached and reused
174 until the file is modified, in which case the previous module is
175 discarded and the new file contents are loaded into a new module
176 in its place. When chaining such modules, an object named `wmain'
177 is first looked for and called with no arguments if found. The
178 object it returns is then used as the WSGI application object for
179 that module, which is reused until the module is reloaded. If
180 `wmain' is not found, an object named `application' is looked for
181 instead. If found, it is used directly as the WSGI application
184 path = env["SCRIPT_FILENAME"]
188 log.error("Exception occurred when loading %s" % path, exc_info=sys.exc_info())
189 return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "Could not load WSGI handler.")
193 if hasattr(mod, "entry"):
196 if hasattr(mod.mod, "wmain"):
197 entry = mod.mod.wmain()
198 elif hasattr(mod.mod, "application"):
199 entry = mod.mod.application
201 if entry is not None:
202 return entry(env, startreq)
203 return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "Invalid WSGI handler.")
205 application = handler().handle