1 ;;;; support for dynamically loading foreign object files and
2 ;;;; resolving symbols therein
4 ;;;; This software is part of the SBCL system. See the README file for
7 ;;;; This software is derived from the CMU CL system, which was
8 ;;;; written at Carnegie Mellon University and released into the
9 ;;;; public domain. The software is in the public domain and is
10 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
11 ;;;; files for more information.
13 (in-package "SB-ALIEN") ; (SB-ALIEN, not SB!ALIEN, since we're in warm load.)
15 ;;; SEMI-KLUDGE: Preferable would be to use something like O_NOFOLLOW
16 ;;; which will refuse to open() a file if it is a symlink; but I've
17 ;;; been told that is a FreeBSD/Linux-only thing. Meanwhile, this will
18 ;;; make our filenames a lot less predictable.
19 ;;; (The man file for open() says O_EXCL should treat even a symlink as
20 ;;; an existing file. I wonder if it really does that.)
21 ;;; Also, no more dependence on ASCII character ordering.
23 (defun generate-random-string (&optional (len 6))
24 (let* ((characters "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
25 (num (length characters))
26 (string (make-string len)))
27 (dotimes (i len string)
29 (char characters (random num))))))
31 (defun pick-temporary-file-name (&optional
32 (base "/tmp/sbcl-tmp-~D~A"))
33 (let ((code (generate-random-string)))
35 (let ((name (format nil base (sb-unix:unix-getpid) code)))
36 (multiple-value-bind (fd errno)
37 (sb-unix:unix-open name
38 (logior sb-unix:o_wronly
42 (cond ((not (null fd))
43 (sb-unix:unix-close fd)
45 ((not (= errno sb-unix:eexist))
46 (simple-file-perror "couldn't create temporary file ~S"
50 (setf code (generate-random-string)))))))))
52 ;;; On any OS where we don't support foreign object file loading, any
53 ;;; query of a foreign symbol value is answered with "no definition
55 #-(or linux sunos FreeBSD OpenBSD darwin)
56 (defun get-dynamic-foreign-symbol-address (symbol)
57 (declare (type simple-string symbol) (ignore symbol))
60 ;;; dlsym()-based implementation of GET-DYNAMIC-FOREIGN-SYMBOL-ADDRESS
61 ;;; and functions (e.g. LOAD-FOREIGN) which affect it. This should
62 ;;; work on any ELF system with dlopen(3) and dlsym(3)
63 ;;; It also works on OpenBSD, which isn't ELF, but is otherwise modern
64 ;;; enough to have a fairly well working dlopen/dlsym implementation.
65 #-(or linux sunos FreeBSD OpenBSD darwin)
66 (macrolet ((define-unsupported-fun (fun-name)
67 `(defun ,fun-name (&rest rest)
68 "unsupported on this system"
69 (declare (ignore rest))
70 (error 'unsupported-operator :name ',fun-name))))
71 (define-unsupported-fun load-1-foreign)
72 (define-unsupported-fun load-foreign))
73 #+(or linux sunos FreeBSD OpenBSD darwin)
76 ;;; flags for dlopen()
77 (defconstant rtld-lazy 1) ; lazy function call binding?
78 (defconstant rtld-now 2) ; immediate function call binding?
79 (defconstant rtld-global #x100) ; symbols of loaded obj file
80 ; (and its dependencies) made
81 ; visible (as though the
82 ; obj file were linked directly
85 ;;; a list of handles returned from dlopen(3) (or possibly some
86 ;;; bogus value temporarily during initialization)
87 (defvar *handles-from-dlopen* nil)
89 ;;; Dynamically loaded stuff isn't there upon restoring from a save.
90 ;;; Clearing the variable this way was originally done primarily for
91 ;;; Irix, which resolves tzname at runtime, resulting in
92 ;;; *HANDLES-FROM-DLOPEN* (which was then called *TABLES-FROM-DLOPEN*)
93 ;;; being set in the saved core image, resulting in havoc upon
94 ;;; restart; but it seems harmless and tidy for other OSes too.
96 ;;; Of course, it can be inconvenient that dynamically loaded stuff
97 ;;; goes away when we save and restore. However,
98 ;;; (1) trying to avoid it by system programming here could open a
99 ;;; huge can of worms, since e.g. now we would need to worry about
100 ;;; libraries possibly being in different locations (file locations
101 ;;; or memory locations) at restore time than at save time; and
102 ;;; (2) by the time the application programmer is so deep into the
103 ;;; the use of hard core extension features as to be doing
104 ;;; dynamic loading of foreign files and saving/restoring cores,
105 ;;; he probably has the sophistication to write his own after-save
106 ;;; code to reload the libraries without much difficulty.
108 ;;; dan 2001.05.10 suspects that objection (1) is bogus for
109 ;;; dlsym()-enabled systems
111 (push (lambda () (setq *handles-from-dlopen* nil))
112 *after-save-initializations*)
114 (defvar *dso-linker* "/usr/bin/ld")
115 (defvar *dso-linker-options*
116 #-darwin '("-shared" "-o")
117 #+darwin '("-bundle" "-o"))
119 (sb-alien:define-alien-routine dlopen system-area-pointer
120 (file sb-alien:c-string) (mode sb-alien:int))
121 (sb-alien:define-alien-routine dlsym system-area-pointer
122 (lib system-area-pointer)
123 (name sb-alien:c-string))
124 (sb-alien:define-alien-routine dlerror sb-alien:c-string)
126 ;;; Ensure that we've opened our own binary so we can dynamically resolve
127 ;;; symbols in the C runtime.
129 ;;; Old comment: This used to happen only in
130 ;;; GET-DYNAMIC-FOREIGN-SYMBOL-ADDRESS, and only if no libraries were
131 ;;; dlopen()ed already, but that didn't work if something was
132 ;;; dlopen()ed before any problem global vars were used. So now we do
133 ;;; this in any function that can add to the *HANDLES-FROM-DLOPEN*, as
134 ;;; well as in GET-DYNAMIC-FOREIGN-SYMBOL-ADDRESS.
136 ;;; FIXME: It would work just as well to do it once at startup, actually.
137 ;;; Then at least we know it's done. -dan 2001.05.10
138 (defun ensure-runtime-symbol-table-opened ()
139 (unless *handles-from-dlopen*
140 ;; Prevent recursive call if dlopen() isn't defined.
141 (setf *handles-from-dlopen* (int-sap 0))
142 (setf *handles-from-dlopen* (list (dlopen nil rtld-lazy)))
143 (when (zerop (sb-sys:sap-int (first *handles-from-dlopen*)))
144 (error "can't open our own binary's symbol table: ~S" (dlerror)))))
146 (defun load-1-foreign (file)
147 "the primitive upon which the more general LOAD-FOREIGN is built: load
148 a single foreign object file
150 To use LOAD-1-FOREIGN, at the Unix command line do this:
151 echo 'int summish(int x, int y) { return 1 + x + y; }' > /tmp/ffi-test.c
152 make /tmp/ffi-test.o # i.e. cc -c -o /tmp/ffi-test.o /tmp/ffi-test.c
153 ld -shared -o /tmp/ffi-test.so /tmp/ffi-test.o
154 then in SBCL do this:
155 (LOAD-1-FOREIGN \"/tmp/ffi-test.so\")
156 (DEFINE-ALIEN-ROUTINE SUMMISH INT (X INT) (Y INT))
157 Now running (SUMMISH 10 20) should return 31.
159 (ensure-runtime-symbol-table-opened)
160 ;; Note: We use RTLD-GLOBAL so that it can find all the symbols
161 ;; previously loaded. We use RTLD-NOW so that dlopen() will fail if
162 ;; not all symbols are defined.
163 (let* ((real-file (or (unix-namestring file) file))
164 (sap (dlopen real-file (logior rtld-now rtld-global))))
165 (if (zerop (sap-int sap))
166 (error "can't open object ~S: ~S" real-file (dlerror))
167 (pushnew sap *handles-from-dlopen* :test #'sap=)))
170 (defun get-dynamic-foreign-symbol-address (symbol)
171 (ensure-runtime-symbol-table-opened)
172 ;; Find the symbol in any of the loaded object files. Search in
173 ;; reverse order of loading, so that later loadings take precedence.
175 ;; FIXME: The way that we use PUSHNEW SAP in LOAD-1-FOREIGN means
176 ;; that the list isn't guaranteed to be in reverse order of loading,
177 ;; at least not if a file is loaded more than once. Is this the
178 ;; right thing? (In what cases does it matter?)
179 (dolist (handle (reverse *handles-from-dlopen*))
180 ;; KLUDGE: We implicitly exclude the possibility that the variable
181 ;; could actually be NULL, but the man page for dlsym(3)
182 ;; recommends doing a more careful test. -- WHN 20000825
183 (let ((possible-result (sap-int (dlsym handle symbol))))
184 (unless (zerop possible-result)
185 (return possible-result)))))
187 ;;; Dan Barlow's quick summary from IRC 2003-06-21:
188 ;;; fwiw, load-foreign does random stuff with ld so that you can use
189 ;;; it with static libraries
190 ;;; if you have shared objects, load-1-foreign will do fine
192 ;;; I think my position on this matter is consistent with Tim Moore's:
193 ;;; use (cmucl equivalent of) load-1-foreign, load-foreign is arse
194 ;;; though he may say ass
195 (defun load-foreign (files
198 ;; FIXME: The old documentation said
199 ;; The BASE-FILE argument is used to specify a
200 ;; file to use as the starting place for
201 ;; defined symbols. The default is the C start
203 ;; But the code ignored the BASE-FILE argument.
205 ;; (DECLARE (IGNORE BASE-FILE))
207 ;; dlopen() remembers the name of an object,
208 ;; when dlopen()ing the same name twice, the
209 ;; old object is reused.
210 ;; So I deleted all reference to BASE-FILE,
211 ;; including the now-bogus reference to the
212 ;; BASE-FILE argument in the documentation. But
213 ;; are there any other subtleties of the new code
214 ;; which need to be documented in its place?
216 (environment (if env-p
217 (unix-environment-sbcl-from-cmu env)
221 "LOAD-FOREIGN loads a list of C object files into a running Lisp. The FILES
222 argument should be a single file or a list of files. The files may be
223 specified as namestrings or as pathnames. The libraries argument should be a
224 list of library files as would be specified to ld. They will be searched in
225 the order given. The default is just \"-lc\", i.e., the C library. The
226 ENVIRONMENT argument is a list of SIMPLE-STRINGs corresponding to the Unix
227 environment (\"man environ\") definitions for the invocation of the linker.
228 The default is the environment that Lisp is itself running in. Instead of
229 using the ENVIRONMENT argument, it is also possible to use the ENV argument,
230 using the older, lossy CMU CL representation."
231 (when (and env-p environment-p)
232 (error "can't specify :ENV and :ENVIRONMENT simultaneously"))
233 (let ((output-file (pick-temporary-file-name
234 (concatenate 'string "/tmp/~D~A" (string (gensym)))))
235 (error-output (make-string-output-stream)))
237 (/show "running" *dso-linker*)
240 (let ((proc (sb-ext:run-program
242 (append *dso-linker-options*
244 (append (mapcar (lambda (name)
245 (unix-namestring name nil))
250 :environment environment
255 (error "could not run ~A" *dso-linker*))
256 (unless (zerop (sb-ext:process-exit-code proc))
257 (sb-sys:serve-all-events 0)
258 (error "~A failed:~%~A" *dso-linker*
259 (get-output-stream-string error-output)))
260 (load-1-foreign output-file))
261 #-sb-show (sb-unix:unix-unlink output-file)
262 #+sb-show (/show "not unlinking" output-file)))) ; so we can look at it