Commit | Line | Data |
---|---|---|
fc2aa563 FT |
1 | """WSGI handler for serving chained WSGI modules from physical files |
2 | ||
7ed9b82b FT |
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. | |
10 | ||
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. | |
18 | ||
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 | |
22 | details. | |
fc2aa563 FT |
23 | |
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 | |
7ed9b82b FT |
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. | |
fc2aa563 FT |
34 | """ |
35 | ||
c06db49a | 36 | import os, threading, types |
173e0e9e | 37 | import wsgiutil |
c06db49a | 38 | |
fc2aa563 FT |
39 | __all__ = ["application", "wmain", "getmod", "cachedmod"] |
40 | ||
f677567f | 41 | class cachedmod(object): |
fc2aa563 FT |
42 | """Cache entry for modules loaded by getmod() |
43 | ||
44 | Instances of this class are returned by the getmod() | |
45 | function. They contain three data attributes: | |
46 | * mod - The loaded module | |
47 | * lock - A threading.Lock object, which can be used for | |
48 | manipulating this instance in a thread-safe manner | |
49 | * mtime - The time the file was last modified | |
50 | ||
51 | Additional data attributes can be arbitrarily added for recording | |
52 | any meta-data about the module. | |
53 | """ | |
7fe08a6f | 54 | def __init__(self, mod = None, mtime = -1): |
14ef1e0e FT |
55 | self.lock = threading.Lock() |
56 | self.mod = mod | |
57 | self.mtime = mtime | |
58 | ||
c06db49a FT |
59 | modcache = {} |
60 | cachelock = threading.Lock() | |
61 | ||
62 | def mangle(path): | |
63 | ret = "" | |
64 | for c in path: | |
65 | if c.isalnum(): | |
66 | ret += c | |
67 | else: | |
68 | ret += "_" | |
69 | return ret | |
70 | ||
71 | def getmod(path): | |
fc2aa563 FT |
72 | """Load the given file as a module, caching it appropriately |
73 | ||
74 | The given file is loaded and compiled into a Python module. The | |
75 | compiled module is cached and returned upon subsequent requests | |
76 | for the same file, unless the file has changed (as determined by | |
77 | its mtime), in which case the cached module is discarded and the | |
78 | new file contents are reloaded in its place. | |
79 | ||
80 | The return value is an instance of the cachedmod class, which can | |
81 | be used for locking purposes and for storing arbitrary meta-data | |
82 | about the module. See its documentation for details. | |
83 | """ | |
c06db49a FT |
84 | sb = os.stat(path) |
85 | cachelock.acquire() | |
86 | try: | |
87 | if path in modcache: | |
14ef1e0e | 88 | entry = modcache[path] |
7fe08a6f FT |
89 | else: |
90 | entry = cachedmod() | |
91 | modcache[path] = entry | |
c06db49a FT |
92 | finally: |
93 | cachelock.release() | |
7fe08a6f FT |
94 | entry.lock.acquire() |
95 | try: | |
96 | if entry.mod is None or sb.st_mtime > entry.mtime: | |
97 | f = open(path, "r") | |
98 | try: | |
99 | text = f.read() | |
100 | finally: | |
101 | f.close() | |
102 | code = compile(text, path, "exec") | |
103 | mod = types.ModuleType(mangle(path)) | |
104 | mod.__file__ = path | |
105 | exec code in mod.__dict__ | |
106 | entry.mod = mod | |
107 | entry.mtime = sb.st_mtime | |
108 | return entry | |
109 | finally: | |
110 | entry.lock.release() | |
c06db49a | 111 | |
e9817fee FT |
112 | class handler(object): |
113 | def __init__(self): | |
114 | self.lock = threading.Lock() | |
115 | self.handlers = {} | |
116 | self.exts = {} | |
117 | self.addext("wsgi", "chain") | |
118 | self.addext("wsgi2", "chain") | |
119 | ||
120 | def resolve(self, name): | |
121 | self.lock.acquire() | |
122 | try: | |
123 | if name in self.handlers: | |
124 | return self.handlers[name] | |
125 | p = name.rfind('.') | |
126 | if p < 0: | |
127 | return globals()[name] | |
128 | mname = name[:p] | |
129 | hname = name[p + 1:] | |
130 | mod = __import__(mname, fromlist = ["dummy"]) | |
131 | ret = getattr(mod, hname) | |
132 | self.handlers[name] = ret | |
133 | return ret | |
134 | finally: | |
135 | self.lock.release() | |
136 | ||
137 | def addext(self, ext, handler): | |
138 | self.exts[ext] = self.resolve(handler) | |
139 | ||
140 | def handle(self, env, startreq): | |
141 | if not "SCRIPT_FILENAME" in env: | |
142 | return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.") | |
143 | path = env["SCRIPT_FILENAME"] | |
7ed9b82b | 144 | if not os.access(path, os.R_OK): |
e9817fee | 145 | return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.") |
7ed9b82b FT |
146 | if "HTTP_X_ASH_PYTHON_HANDLER" in env: |
147 | handler = self.resolve(env["HTTP_X_ASH_PYTHON_HANDLER"]) | |
148 | else: | |
149 | base = os.path.basename(path) | |
150 | p = base.rfind('.') | |
151 | if p < 0: | |
152 | return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.") | |
153 | ext = base[p + 1:] | |
154 | if not ext in self.exts: | |
155 | return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.") | |
156 | handler = self.exts[ext] | |
157 | return handler(env, startreq) | |
e9817fee FT |
158 | |
159 | def wmain(*argv): | |
160 | """Main function for ashd(7)-compatible WSGI handlers | |
161 | ||
162 | Returns the `application' function. If any arguments are given, | |
163 | they are parsed according to the module documentation. | |
164 | """ | |
165 | ret = handler() | |
166 | for arg in argv: | |
167 | if arg[0] == '.': | |
168 | p = arg.index('=') | |
169 | ret.addext(arg[1:p], arg[p + 1:]) | |
170 | return ret.handle | |
171 | ||
9b417336 | 172 | def chain(env, startreq): |
7ed9b82b FT |
173 | """Chain-loading WSGI handler |
174 | ||
175 | This handler loads requested files, compiles them and loads them | |
176 | into their own modules. The compiled modules are cached and reused | |
177 | until the file is modified, in which case the previous module is | |
178 | discarded and the new file contents are loaded into a new module | |
179 | in its place. When chaining such modules, an object named `wmain' | |
180 | is first looked for and called with no arguments if found. The | |
181 | object it returns is then used as the WSGI application object for | |
182 | that module, which is reused until the module is reloaded. If | |
183 | `wmain' is not found, an object named `application' is looked for | |
184 | instead. If found, it is used directly as the WSGI application | |
185 | object. | |
186 | """ | |
9b417336 | 187 | path = env["SCRIPT_FILENAME"] |
c06db49a | 188 | mod = getmod(path) |
14ef1e0e FT |
189 | entry = None |
190 | if mod is not None: | |
191 | mod.lock.acquire() | |
192 | try: | |
193 | if hasattr(mod, "entry"): | |
194 | entry = mod.entry | |
195 | else: | |
196 | if hasattr(mod.mod, "wmain"): | |
adb11d5f | 197 | entry = mod.mod.wmain() |
14ef1e0e FT |
198 | elif hasattr(mod.mod, "application"): |
199 | entry = mod.mod.application | |
200 | mod.entry = entry | |
201 | finally: | |
202 | mod.lock.release() | |
203 | if entry is not None: | |
204 | return entry(env, startreq) | |
36ea06a6 | 205 | return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "Invalid WSGI handler.") |
c06db49a | 206 | |
e9817fee | 207 | application = handler().handle |