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1 | /* loader-preopen.c -- emulate dynamic linking using preloaded_symbols |
2 | ||
3 | Copyright (C) 1998, 1999, 2000, 2004, 2006, | |
4 | 2007, 2008 Free Software Foundation, Inc. | |
5 | Written by Thomas Tanner, 1998 | |
6 | ||
7 | NOTE: The canonical source of this file is maintained with the | |
8 | GNU Libtool package. Report bugs to bug-libtool@gnu.org. | |
9 | ||
10 | GNU Libltdl is free software; you can redistribute it and/or | |
11 | modify it under the terms of the GNU Lesser General Public | |
12 | License as published by the Free Software Foundation; either | |
13 | version 2 of the License, or (at your option) any later version. | |
14 | ||
15 | As a special exception to the GNU Lesser General Public License, | |
16 | if you distribute this file as part of a program or library that | |
17 | is built using GNU Libtool, you may include this file under the | |
18 | same distribution terms that you use for the rest of that program. | |
19 | ||
20 | GNU Libltdl is distributed in the hope that it will be useful, | |
21 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
22 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
23 | GNU Lesser General Public License for more details. | |
24 | ||
25 | You should have received a copy of the GNU Lesser General Public | |
26 | License along with GNU Libltdl; see the file COPYING.LIB. If not, a | |
27 | copy can be downloaded from http://www.gnu.org/licenses/lgpl.html, | |
28 | or obtained by writing to the Free Software Foundation, Inc., | |
29 | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. | |
30 | */ | |
31 | ||
32 | #include "lt__private.h" | |
33 | #include "lt_dlloader.h" | |
34 | ||
35 | /* Use the preprocessor to rename non-static symbols to avoid namespace | |
36 | collisions when the loader code is statically linked into libltdl. | |
37 | Use the "<module_name>_LTX_" prefix so that the symbol addresses can | |
38 | be fetched from the preloaded symbol list by lt_dlsym(): */ | |
39 | #define get_vtable preopen_LTX_get_vtable | |
40 | ||
41 | LT_BEGIN_C_DECLS | |
42 | LT_SCOPE lt_dlvtable *get_vtable (lt_user_data loader_data); | |
43 | LT_END_C_DECLS | |
44 | ||
45 | ||
46 | /* Boilerplate code to set up the vtable for hooking this loader into | |
47 | libltdl's loader list: */ | |
48 | static int vl_init (lt_user_data loader_data); | |
49 | static int vl_exit (lt_user_data loader_data); | |
50 | static lt_module vm_open (lt_user_data loader_data, const char *filename, | |
51 | lt_dladvise advise); | |
52 | static int vm_close (lt_user_data loader_data, lt_module module); | |
53 | static void * vm_sym (lt_user_data loader_data, lt_module module, | |
54 | const char *symbolname); | |
55 | ||
56 | static lt_dlvtable *vtable = 0; | |
57 | ||
58 | /* Return the vtable for this loader, only the name and sym_prefix | |
59 | attributes (plus the virtual function implementations, obviously) | |
60 | change between loaders. */ | |
61 | lt_dlvtable * | |
62 | get_vtable (lt_user_data loader_data) | |
63 | { | |
64 | if (!vtable) | |
65 | { | |
66 | vtable = (lt_dlvtable *) lt__zalloc (sizeof *vtable); | |
67 | } | |
68 | ||
69 | if (vtable && !vtable->name) | |
70 | { | |
71 | vtable->name = "lt_preopen"; | |
72 | vtable->sym_prefix = 0; | |
73 | vtable->module_open = vm_open; | |
74 | vtable->module_close = vm_close; | |
75 | vtable->find_sym = vm_sym; | |
76 | vtable->dlloader_init = vl_init; | |
77 | vtable->dlloader_exit = vl_exit; | |
78 | vtable->dlloader_data = loader_data; | |
79 | vtable->priority = LT_DLLOADER_PREPEND; | |
80 | } | |
81 | ||
82 | if (vtable && (vtable->dlloader_data != loader_data)) | |
83 | { | |
84 | LT__SETERROR (INIT_LOADER); | |
85 | return 0; | |
86 | } | |
87 | ||
88 | return vtable; | |
89 | } | |
90 | ||
91 | ||
92 | ||
93 | /* --- IMPLEMENTATION --- */ | |
94 | ||
95 | ||
96 | /* Wrapper type to chain together symbol lists of various origins. */ | |
97 | typedef struct symlist_chain | |
98 | { | |
99 | struct symlist_chain *next; | |
100 | const lt_dlsymlist *symlist; | |
101 | } symlist_chain; | |
102 | ||
103 | ||
104 | static int add_symlist (const lt_dlsymlist *symlist); | |
105 | static int free_symlists (void); | |
106 | ||
107 | /* The start of the symbol lists chain. */ | |
108 | static symlist_chain *preloaded_symlists = 0; | |
109 | ||
110 | /* A symbol list preloaded before lt_init() was called. */ | |
111 | static const lt_dlsymlist *default_preloaded_symbols = 0; | |
112 | ||
113 | ||
114 | /* A function called through the vtable to initialise this loader. */ | |
115 | static int | |
116 | vl_init (lt_user_data LT__UNUSED loader_data) | |
117 | { | |
118 | int errors = 0; | |
119 | ||
120 | preloaded_symlists = 0; | |
121 | if (default_preloaded_symbols) | |
122 | { | |
123 | errors = lt_dlpreload (default_preloaded_symbols); | |
124 | } | |
125 | ||
126 | return errors; | |
127 | } | |
128 | ||
129 | ||
130 | /* A function called through the vtable when this loader is no | |
131 | longer needed by the application. */ | |
132 | static int | |
133 | vl_exit (lt_user_data LT__UNUSED loader_data) | |
134 | { | |
135 | vtable = NULL; | |
136 | free_symlists (); | |
137 | return 0; | |
138 | } | |
139 | ||
140 | ||
141 | /* A function called through the vtable to open a module with this | |
142 | loader. Returns an opaque representation of the newly opened | |
143 | module for processing with this loader's other vtable functions. */ | |
144 | static lt_module | |
145 | vm_open (lt_user_data LT__UNUSED loader_data, const char *filename, | |
146 | lt_dladvise LT__UNUSED advise) | |
147 | { | |
148 | symlist_chain *lists; | |
149 | lt_module module = 0; | |
150 | ||
151 | if (!preloaded_symlists) | |
152 | { | |
153 | LT__SETERROR (NO_SYMBOLS); | |
154 | goto done; | |
155 | } | |
156 | ||
157 | /* Can't use NULL as the reflective symbol header, as NULL is | |
158 | used to mark the end of the entire symbol list. Self-dlpreopened | |
159 | symbols follow this magic number, chosen to be an unlikely | |
160 | clash with a real module name. */ | |
161 | if (!filename) | |
162 | { | |
163 | filename = "@PROGRAM@"; | |
164 | } | |
165 | ||
166 | for (lists = preloaded_symlists; lists; lists = lists->next) | |
167 | { | |
168 | const lt_dlsymlist *symbol; | |
169 | for (symbol= lists->symlist; symbol->name; ++symbol) | |
170 | { | |
171 | if (!symbol->address && streq (symbol->name, filename)) | |
172 | { | |
173 | /* If the next symbol's name and address is 0, it means | |
174 | the module just contains the originator and no symbols. | |
175 | In this case we pretend that we never saw the module and | |
176 | hope that some other loader will be able to load the module | |
177 | and have access to its symbols */ | |
178 | const lt_dlsymlist *next_symbol = symbol +1; | |
179 | if (next_symbol->address && next_symbol->name) | |
180 | { | |
181 | module = (lt_module) lists->symlist; | |
182 | goto done; | |
183 | } | |
184 | } | |
185 | } | |
186 | } | |
187 | ||
188 | LT__SETERROR (FILE_NOT_FOUND); | |
189 | ||
190 | done: | |
191 | return module; | |
192 | } | |
193 | ||
194 | ||
195 | /* A function called through the vtable when a particular module | |
196 | should be unloaded. */ | |
197 | static int | |
198 | vm_close (lt_user_data LT__UNUSED loader_data, lt_module LT__UNUSED module) | |
199 | { | |
200 | /* Just to silence gcc -Wall */ | |
201 | module = 0; | |
202 | return 0; | |
203 | } | |
204 | ||
205 | ||
206 | /* A function called through the vtable to get the address of | |
207 | a symbol loaded from a particular module. */ | |
208 | static void * | |
209 | vm_sym (lt_user_data LT__UNUSED loader_data, lt_module module, const char *name) | |
210 | { | |
211 | lt_dlsymlist *symbol = (lt_dlsymlist*) module; | |
212 | ||
213 | symbol +=2; /* Skip header (originator then libname). */ | |
214 | ||
215 | while (symbol->name) | |
216 | { | |
217 | if (streq (symbol->name, name)) | |
218 | { | |
219 | return symbol->address; | |
220 | } | |
221 | ||
222 | ++symbol; | |
223 | } | |
224 | ||
225 | LT__SETERROR (SYMBOL_NOT_FOUND); | |
226 | ||
227 | return 0; | |
228 | } | |
229 | ||
230 | ||
231 | ||
232 | /* --- HELPER FUNCTIONS --- */ | |
233 | ||
234 | ||
235 | /* The symbol lists themselves are not allocated from the heap, but | |
236 | we can unhook them and free up the chain of links between them. */ | |
237 | static int | |
238 | free_symlists (void) | |
239 | { | |
240 | symlist_chain *lists; | |
241 | ||
242 | lists = preloaded_symlists; | |
243 | while (lists) | |
244 | { | |
245 | symlist_chain *next = lists->next; | |
246 | FREE (lists); | |
247 | lists = next; | |
248 | } | |
249 | preloaded_symlists = 0; | |
250 | ||
251 | return 0; | |
252 | } | |
253 | ||
254 | /* Add a new symbol list to the global chain. */ | |
255 | static int | |
256 | add_symlist (const lt_dlsymlist *symlist) | |
257 | { | |
258 | symlist_chain *lists; | |
259 | int errors = 0; | |
260 | ||
261 | /* Search for duplicate entries: */ | |
262 | for (lists = preloaded_symlists; | |
263 | lists && lists->symlist != symlist; lists = lists->next) | |
264 | /*NOWORK*/; | |
265 | ||
266 | /* Don't add the same list twice: */ | |
267 | if (!lists) | |
268 | { | |
269 | symlist_chain *tmp = (symlist_chain *) lt__zalloc (sizeof *tmp); | |
270 | ||
271 | if (tmp) | |
272 | { | |
273 | tmp->symlist = symlist; | |
274 | tmp->next = preloaded_symlists; | |
275 | preloaded_symlists = tmp; | |
276 | } | |
277 | else | |
278 | { | |
279 | ++errors; | |
280 | } | |
281 | } | |
282 | ||
283 | return errors; | |
284 | } | |
285 | ||
286 | ||
287 | ||
288 | /* --- PRELOADING API CALL IMPLEMENTATIONS --- */ | |
289 | ||
290 | ||
291 | /* Save a default symbol list for later. */ | |
292 | int | |
293 | lt_dlpreload_default (const lt_dlsymlist *preloaded) | |
294 | { | |
295 | default_preloaded_symbols = preloaded; | |
296 | return 0; | |
297 | } | |
298 | ||
299 | ||
300 | /* Add a symbol list to the global chain, or with a NULL argument, | |
301 | revert to just the default list. */ | |
302 | int | |
303 | lt_dlpreload (const lt_dlsymlist *preloaded) | |
304 | { | |
305 | int errors = 0; | |
306 | ||
307 | if (preloaded) | |
308 | { | |
309 | errors = add_symlist (preloaded); | |
310 | } | |
311 | else | |
312 | { | |
313 | free_symlists(); | |
314 | ||
315 | if (default_preloaded_symbols) | |
316 | { | |
317 | errors = lt_dlpreload (default_preloaded_symbols); | |
318 | } | |
319 | } | |
320 | ||
321 | return errors; | |
322 | } | |
323 | ||
324 | ||
325 | /* Open all the preloaded modules from the named originator, executing | |
326 | a callback for each one. If ORIGINATOR is NULL, then call FUNC for | |
327 | each preloaded module from the program itself. */ | |
328 | int | |
329 | lt_dlpreload_open (const char *originator, lt_dlpreload_callback_func *func) | |
330 | { | |
331 | symlist_chain *list; | |
332 | int errors = 0; | |
333 | int found = 0; | |
334 | ||
335 | /* For each symlist in the chain... */ | |
336 | for (list = preloaded_symlists; list; list = list->next) | |
337 | { | |
338 | /* ...that was preloaded by the requesting ORIGINATOR... */ | |
339 | if ((originator && streq (list->symlist->name, originator)) | |
340 | || (!originator && streq (list->symlist->name, "@PROGRAM@"))) | |
341 | { | |
342 | const lt_dlsymlist *symbol; | |
343 | unsigned int idx = 0; | |
344 | ||
345 | ++found; | |
346 | ||
347 | /* ...load the symbols per source compilation unit: | |
348 | (we preincrement the index to skip over the originator entry) */ | |
349 | while ((symbol = &list->symlist[++idx])->name != 0) | |
350 | { | |
351 | if ((symbol->address == 0) | |
352 | && (strneq (symbol->name, "@PROGRAM@"))) | |
353 | { | |
354 | lt_dlhandle handle = lt_dlopen (symbol->name); | |
355 | if (handle == 0) | |
356 | { | |
357 | ++errors; | |
358 | } | |
359 | else | |
360 | { | |
361 | errors += (*func) (handle); | |
362 | } | |
363 | } | |
364 | } | |
365 | } | |
366 | } | |
367 | ||
368 | if (!found) | |
369 | { | |
370 | LT__SETERROR(CANNOT_OPEN); | |
371 | ++errors; | |
372 | } | |
373 | ||
374 | return errors; | |
375 | } |