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9d13f5c4 | 1 | /* Specialized bits of code needed to support construction and |
2 | destruction of file-scope objects in C++ code. | |
997d68fe | 3 | Copyright (C) 1991, 94, 95, 96, 97, 1998 Free Software Foundation, Inc. |
31dcf09a | 4 | Contributed by Ron Guilmette (rfg@monkeys.com). |
9d13f5c4 | 5 | |
6 | This file is part of GNU CC. | |
7 | ||
8 | GNU CC is free software; you can redistribute it and/or modify | |
9 | it under the terms of the GNU General Public License as published by | |
10 | the Free Software Foundation; either version 2, or (at your option) | |
11 | any later version. | |
12 | ||
13 | GNU CC is distributed in the hope that it will be useful, | |
14 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | GNU General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with GNU CC; see the file COPYING. If not, write to | |
8d62a21c | 20 | the Free Software Foundation, 59 Temple Place - Suite 330, |
21 | Boston, MA 02111-1307, USA. */ | |
9d13f5c4 | 22 | |
23 | /* As a special exception, if you link this library with files | |
24 | compiled with GCC to produce an executable, this does not cause | |
25 | the resulting executable to be covered by the GNU General Public License. | |
26 | This exception does not however invalidate any other reasons why | |
27 | the executable file might be covered by the GNU General Public License. */ | |
28 | ||
29 | /* This file is a bit like libgcc1.c/libgcc2.c in that it is compiled | |
30 | multiple times and yields multiple .o files. | |
31 | ||
32 | This file is useful on target machines where the object file format | |
33 | supports multiple "user-defined" sections (e.g. COFF, ELF, ROSE). On | |
34 | such systems, this file allows us to avoid running collect (or any | |
35 | other such slow and painful kludge). Additionally, if the target | |
36 | system supports a .init section, this file allows us to support the | |
37 | linking of C++ code with a non-C++ main program. | |
38 | ||
39 | Note that if INIT_SECTION_ASM_OP is defined in the tm.h file, then | |
40 | this file *will* make use of the .init section. If that symbol is | |
41 | not defined however, then the .init section will not be used. | |
42 | ||
5dd605c6 | 43 | Currently, only ELF and COFF are supported. It is likely however that |
44 | ROSE could also be supported, if someone was willing to do the work to | |
45 | make whatever (small?) adaptations are needed. (Some work may be | |
46 | needed on the ROSE assembler and linker also.) | |
9d13f5c4 | 47 | |
48 | This file must be compiled with gcc. */ | |
49 | ||
50 | /* It is incorrect to include config.h here, because this file is being | |
51 | compiled for the target, and hence definitions concerning only the host | |
52 | do not apply. */ | |
53 | ||
54 | #include "tm.h" | |
d757b8c9 | 55 | #include "defaults.h" |
ad87de1e | 56 | #include <stddef.h> |
57 | #include "frame.h" | |
9d13f5c4 | 58 | |
5c61dffd | 59 | #ifndef OBJECT_FORMAT_MACHO |
60 | ||
b7c87ff2 | 61 | /* Provide default definitions for the pseudo-ops used to switch to the |
62 | .ctors and .dtors sections. | |
63 | ||
64 | Note that we want to give these sections the SHF_WRITE attribute | |
65 | because these sections will actually contain data (i.e. tables of | |
66 | addresses of functions in the current root executable or shared library | |
67 | file) and, in the case of a shared library, the relocatable addresses | |
68 | will have to be properly resolved/relocated (and then written into) by | |
69 | the dynamic linker when it actually attaches the given shared library | |
70 | to the executing process. (Note that on SVR4, you may wish to use the | |
71 | `-z text' option to the ELF linker, when building a shared library, as | |
72 | an additional check that you are doing everything right. But if you do | |
73 | use the `-z text' option when building a shared library, you will get | |
74 | errors unless the .ctors and .dtors sections are marked as writable | |
75 | via the SHF_WRITE attribute.) */ | |
76 | ||
9d13f5c4 | 77 | #ifndef CTORS_SECTION_ASM_OP |
b7c87ff2 | 78 | #define CTORS_SECTION_ASM_OP ".section\t.ctors,\"aw\"" |
9d13f5c4 | 79 | #endif |
80 | #ifndef DTORS_SECTION_ASM_OP | |
b7c87ff2 | 81 | #define DTORS_SECTION_ASM_OP ".section\t.dtors,\"aw\"" |
9d13f5c4 | 82 | #endif |
d757b8c9 | 83 | #if !defined (EH_FRAME_SECTION_ASM_OP) && defined (DWARF2_UNWIND_INFO) && defined(ASM_OUTPUT_SECTION_NAME) |
84 | #define EH_FRAME_SECTION_ASM_OP ".section\t.eh_frame,\"aw\"" | |
85 | #endif | |
9d13f5c4 | 86 | |
b7c87ff2 | 87 | #ifdef OBJECT_FORMAT_ELF |
88 | ||
89 | /* Declare a pointer to void function type. */ | |
90 | typedef void (*func_ptr) (void); | |
91 | #define STATIC static | |
92 | ||
93 | #else /* OBJECT_FORMAT_ELF */ | |
94 | ||
9d13f5c4 | 95 | #include "gbl-ctors.h" |
96 | ||
97 | #ifndef ON_EXIT | |
98 | #define ON_EXIT(a, b) | |
99 | #endif | |
b7c87ff2 | 100 | #define STATIC |
101 | ||
102 | #endif /* OBJECT_FORMAT_ELF */ | |
9d13f5c4 | 103 | |
104 | #ifdef CRT_BEGIN | |
105 | ||
106 | #ifdef INIT_SECTION_ASM_OP | |
107 | ||
b7c87ff2 | 108 | #ifdef OBJECT_FORMAT_ELF |
109 | ||
110 | /* Run all the global destructors on exit from the program. */ | |
111 | ||
112 | /* Some systems place the number of pointers in the first word of the | |
113 | table. On SVR4 however, that word is -1. In all cases, the table is | |
114 | null-terminated. On SVR4, we start from the beginning of the list and | |
115 | invoke each per-compilation-unit destructor routine in order | |
116 | until we find that null. | |
117 | ||
118 | Note that this function MUST be static. There will be one of these | |
119 | functions in each root executable and one in each shared library, but | |
120 | although they all have the same code, each one is unique in that it | |
121 | refers to one particular associated `__DTOR_LIST__' which belongs to the | |
113f9ca7 | 122 | same particular root executable or shared library file. |
123 | ||
124 | On some systems, this routine is run more than once from the .fini, | |
125 | when exit is called recursively, so we arrange to remember where in | |
126 | the list we left off processing, and we resume at that point, | |
127 | should we be re-invoked. */ | |
b7c87ff2 | 128 | |
d757b8c9 | 129 | static char __EH_FRAME_BEGIN__[]; |
b7c87ff2 | 130 | static func_ptr __DTOR_LIST__[]; |
131 | static void | |
132 | __do_global_dtors_aux () | |
133 | { | |
113f9ca7 | 134 | static func_ptr *p = __DTOR_LIST__ + 1; |
dade0711 | 135 | static int completed = 0; |
136 | ||
137 | if (completed) | |
138 | return; | |
139 | ||
113f9ca7 | 140 | while (*p) |
141 | { | |
142 | p++; | |
143 | (*(p-1)) (); | |
144 | } | |
d757b8c9 | 145 | |
146 | #ifdef EH_FRAME_SECTION_ASM_OP | |
c4fa4c4d | 147 | __deregister_frame_info (__EH_FRAME_BEGIN__); |
d757b8c9 | 148 | #endif |
dade0711 | 149 | completed = 1; |
b7c87ff2 | 150 | } |
151 | ||
dade0711 | 152 | |
b7c87ff2 | 153 | /* Stick a call to __do_global_dtors_aux into the .fini section. */ |
a92771b8 | 154 | |
ebd9163c | 155 | static void __attribute__ ((__unused__)) |
b7c87ff2 | 156 | fini_dummy () |
157 | { | |
158 | asm (FINI_SECTION_ASM_OP); | |
159 | __do_global_dtors_aux (); | |
160 | #ifdef FORCE_FINI_SECTION_ALIGN | |
161 | FORCE_FINI_SECTION_ALIGN; | |
162 | #endif | |
163 | asm (TEXT_SECTION_ASM_OP); | |
164 | } | |
165 | ||
d757b8c9 | 166 | #ifdef EH_FRAME_SECTION_ASM_OP |
c4fa4c4d | 167 | /* Stick a call to __register_frame_info into the .init section. For some |
168 | reason calls with no arguments work more reliably in .init, so stick the | |
169 | call in another function. */ | |
d757b8c9 | 170 | |
171 | static void | |
172 | frame_dummy () | |
173 | { | |
ad87de1e | 174 | static struct object object; |
c4fa4c4d | 175 | __register_frame_info (__EH_FRAME_BEGIN__, &object); |
d757b8c9 | 176 | } |
177 | ||
ebd9163c | 178 | static void __attribute__ ((__unused__)) |
d757b8c9 | 179 | init_dummy () |
180 | { | |
181 | asm (INIT_SECTION_ASM_OP); | |
182 | frame_dummy (); | |
183 | #ifdef FORCE_INIT_SECTION_ALIGN | |
184 | FORCE_INIT_SECTION_ALIGN; | |
185 | #endif | |
186 | asm (TEXT_SECTION_ASM_OP); | |
187 | } | |
188 | #endif /* EH_FRAME_SECTION_ASM_OP */ | |
189 | ||
b7c87ff2 | 190 | #else /* OBJECT_FORMAT_ELF */ |
191 | ||
b13ae905 | 192 | /* The function __do_global_ctors_aux is compiled twice (once in crtbegin.o |
d8fa92ab | 193 | and once in crtend.o). It must be declared static to avoid a link |
b13ae905 | 194 | error. Here, we define __do_global_ctors as an externally callable |
195 | function. It is externally callable so that __main can invoke it when | |
196 | INVOKE__main is defined. This has the additional effect of forcing cc1 | |
197 | to switch to the .text section. */ | |
a92771b8 | 198 | |
ee45242a | 199 | static void __do_global_ctors_aux (); |
84b64a19 | 200 | void __do_global_ctors () |
201 | { | |
202 | #ifdef INVOKE__main /* If __main won't actually call __do_global_ctors | |
203 | then it doesn't matter what's inside the function. | |
204 | The inside of __do_global_ctors_aux is called | |
205 | automatically in that case. | |
206 | And the Alliant fx2800 linker crashes | |
207 | on this reference. So prevent the crash. */ | |
208 | __do_global_ctors_aux (); | |
209 | #endif | |
210 | } | |
9d13f5c4 | 211 | |
212 | asm (INIT_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ | |
213 | ||
3c67709e | 214 | /* On some svr4 systems, the initial .init section preamble code provided in |
215 | crti.o may do something, such as bump the stack, which we have to | |
216 | undo before we reach the function prologue code for __do_global_ctors | |
217 | (directly below). For such systems, define the macro INIT_SECTION_PREAMBLE | |
a92771b8 | 218 | to expand into the code needed to undo the actions of the crti.o file. */ |
3c67709e | 219 | |
220 | #ifdef INIT_SECTION_PREAMBLE | |
221 | INIT_SECTION_PREAMBLE; | |
222 | #endif | |
223 | ||
9d13f5c4 | 224 | /* A routine to invoke all of the global constructors upon entry to the |
225 | program. We put this into the .init section (for systems that have | |
226 | such a thing) so that we can properly perform the construction of | |
227 | file-scope static-storage C++ objects within shared libraries. */ | |
228 | ||
229 | static void | |
b13ae905 | 230 | __do_global_ctors_aux () /* prologue goes in .init section */ |
9d13f5c4 | 231 | { |
635d52b7 | 232 | #ifdef FORCE_INIT_SECTION_ALIGN |
233 | FORCE_INIT_SECTION_ALIGN; /* Explicit align before switch to .text */ | |
234 | #endif | |
9d13f5c4 | 235 | asm (TEXT_SECTION_ASM_OP); /* don't put epilogue and body in .init */ |
236 | DO_GLOBAL_CTORS_BODY; | |
237 | ON_EXIT (__do_global_dtors, 0); | |
238 | } | |
239 | ||
b7c87ff2 | 240 | #endif /* OBJECT_FORMAT_ELF */ |
8313a782 | 241 | |
242 | #else /* defined(INIT_SECTION_ASM_OP) */ | |
243 | ||
4e04a2df | 244 | #ifdef HAS_INIT_SECTION |
8313a782 | 245 | /* This case is used by the Irix 6 port, which supports named sections but |
246 | not an SVR4-style .fini section. __do_global_dtors can be non-static | |
d757b8c9 | 247 | in this case because we protect it with -hidden_symbol. */ |
248 | ||
249 | static char __EH_FRAME_BEGIN__[]; | |
8313a782 | 250 | static func_ptr __DTOR_LIST__[]; |
251 | void | |
252 | __do_global_dtors () | |
253 | { | |
254 | func_ptr *p; | |
255 | for (p = __DTOR_LIST__ + 1; *p; p++) | |
256 | (*p) (); | |
d757b8c9 | 257 | |
258 | #ifdef EH_FRAME_SECTION_ASM_OP | |
c4fa4c4d | 259 | __deregister_frame_info (__EH_FRAME_BEGIN__); |
d757b8c9 | 260 | #endif |
8313a782 | 261 | } |
72ac783d | 262 | |
263 | #ifdef EH_FRAME_SECTION_ASM_OP | |
264 | /* Define a function here to call __register_frame. crtend.o is linked in | |
265 | after libgcc.a, and hence can't call libgcc.a functions directly. That | |
266 | can lead to unresolved function references. */ | |
267 | void | |
268 | __frame_dummy () | |
269 | { | |
270 | static struct object object; | |
271 | __register_frame_info (__EH_FRAME_BEGIN__, &object); | |
272 | } | |
273 | #endif | |
4e04a2df | 274 | #endif |
8313a782 | 275 | |
9d13f5c4 | 276 | #endif /* defined(INIT_SECTION_ASM_OP) */ |
277 | ||
278 | /* Force cc1 to switch to .data section. */ | |
cd03a192 | 279 | static func_ptr force_to_data[0] __attribute__ ((__unused__)) = { }; |
9d13f5c4 | 280 | |
b7c87ff2 | 281 | /* NOTE: In order to be able to support SVR4 shared libraries, we arrange |
282 | to have one set of symbols { __CTOR_LIST__, __DTOR_LIST__, __CTOR_END__, | |
283 | __DTOR_END__ } per root executable and also one set of these symbols | |
284 | per shared library. So in any given whole process image, we may have | |
285 | multiple definitions of each of these symbols. In order to prevent | |
286 | these definitions from conflicting with one another, and in order to | |
287 | ensure that the proper lists are used for the initialization/finalization | |
288 | of each individual shared library (respectively), we give these symbols | |
289 | only internal (i.e. `static') linkage, and we also make it a point to | |
290 | refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__ | |
291 | symbol in crtbegin.o, where they are defined. */ | |
292 | ||
9d13f5c4 | 293 | /* The -1 is a flag to __do_global_[cd]tors |
294 | indicating that this table does not start with a count of elements. */ | |
b13ae905 | 295 | #ifdef CTOR_LIST_BEGIN |
296 | CTOR_LIST_BEGIN; | |
297 | #else | |
9d13f5c4 | 298 | asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
cd03a192 | 299 | STATIC func_ptr __CTOR_LIST__[1] __attribute__ ((__unused__)) |
300 | = { (func_ptr) (-1) }; | |
b13ae905 | 301 | #endif |
9d13f5c4 | 302 | |
b13ae905 | 303 | #ifdef DTOR_LIST_BEGIN |
304 | DTOR_LIST_BEGIN; | |
305 | #else | |
9d13f5c4 | 306 | asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
b7c87ff2 | 307 | STATIC func_ptr __DTOR_LIST__[1] = { (func_ptr) (-1) }; |
b13ae905 | 308 | #endif |
9d13f5c4 | 309 | |
d757b8c9 | 310 | #ifdef EH_FRAME_SECTION_ASM_OP |
311 | /* Stick a label at the beginning of the frame unwind info so we can register | |
312 | and deregister it with the exception handling library code. */ | |
313 | ||
314 | asm (EH_FRAME_SECTION_ASM_OP); | |
315 | #ifdef INIT_SECTION_ASM_OP | |
316 | STATIC | |
317 | #endif | |
318 | char __EH_FRAME_BEGIN__[] = { }; | |
319 | #endif /* EH_FRAME_SECTION_ASM_OP */ | |
320 | ||
9d13f5c4 | 321 | #endif /* defined(CRT_BEGIN) */ |
322 | ||
323 | #ifdef CRT_END | |
324 | ||
325 | #ifdef INIT_SECTION_ASM_OP | |
326 | ||
b7c87ff2 | 327 | #ifdef OBJECT_FORMAT_ELF |
9d13f5c4 | 328 | |
b7c87ff2 | 329 | static func_ptr __CTOR_END__[]; |
330 | static void | |
331 | __do_global_ctors_aux () | |
332 | { | |
333 | func_ptr *p; | |
334 | for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--) | |
335 | (*p) (); | |
336 | } | |
337 | ||
338 | /* Stick a call to __do_global_ctors_aux into the .init section. */ | |
a92771b8 | 339 | |
ebd9163c | 340 | static void __attribute__ ((__unused__)) |
b7c87ff2 | 341 | init_dummy () |
342 | { | |
343 | asm (INIT_SECTION_ASM_OP); | |
344 | __do_global_ctors_aux (); | |
345 | #ifdef FORCE_INIT_SECTION_ALIGN | |
346 | FORCE_INIT_SECTION_ALIGN; | |
347 | #endif | |
348 | asm (TEXT_SECTION_ASM_OP); | |
baf8c510 | 349 | |
ad87de1e | 350 | /* This is a kludge. The i386 GNU/Linux dynamic linker needs ___brk_addr, |
31dcf09a | 351 | __environ and atexit (). We have to make sure they are in the .dynsym |
352 | section. We accomplish it by making a dummy call here. This | |
a92771b8 | 353 | code is never reached. */ |
baf8c510 | 354 | |
31dcf09a | 355 | #if defined(__linux__) && defined(__PIC__) && defined(__i386__) |
baf8c510 | 356 | { |
357 | extern void *___brk_addr; | |
358 | extern char **__environ; | |
359 | ||
360 | ___brk_addr = __environ; | |
361 | atexit (); | |
362 | } | |
363 | #endif | |
b7c87ff2 | 364 | } |
365 | ||
366 | #else /* OBJECT_FORMAT_ELF */ | |
367 | ||
368 | /* Stick the real initialization code, followed by a normal sort of | |
369 | function epilogue at the very end of the .init section for this | |
370 | entire root executable file or for this entire shared library file. | |
371 | ||
372 | Note that we use some tricks here to get *just* the body and just | |
373 | a function epilogue (but no function prologue) into the .init | |
c3418f42 | 374 | section of the crtend.o file. Specifically, we switch to the .text |
b7c87ff2 | 375 | section, start to define a function, and then we switch to the .init |
376 | section just before the body code. | |
377 | ||
378 | Earlier on, we put the corresponding function prologue into the .init | |
379 | section of the crtbegin.o file (which will be linked in first). | |
380 | ||
381 | Note that we want to invoke all constructors for C++ file-scope static- | |
382 | storage objects AFTER any other possible initialization actions which | |
383 | may be performed by the code in the .init section contributions made by | |
384 | other libraries, etc. That's because those other initializations may | |
385 | include setup operations for very primitive things (e.g. initializing | |
386 | the state of the floating-point coprocessor, etc.) which should be done | |
a92771b8 | 387 | before we start to execute any of the user's code. */ |
9d13f5c4 | 388 | |
389 | static void | |
b13ae905 | 390 | __do_global_ctors_aux () /* prologue goes in .text section */ |
9d13f5c4 | 391 | { |
392 | asm (INIT_SECTION_ASM_OP); | |
393 | DO_GLOBAL_CTORS_BODY; | |
394 | ON_EXIT (__do_global_dtors, 0); | |
997d68fe | 395 | } /* epilogue and body go in .init section */ |
396 | ||
220345e0 | 397 | #ifdef FORCE_INIT_SECTION_ALIGN |
997d68fe | 398 | FORCE_INIT_SECTION_ALIGN; |
220345e0 | 399 | #endif |
997d68fe | 400 | |
401 | asm (TEXT_SECTION_ASM_OP); | |
9d13f5c4 | 402 | |
b7c87ff2 | 403 | #endif /* OBJECT_FORMAT_ELF */ |
404 | ||
8313a782 | 405 | #else /* defined(INIT_SECTION_ASM_OP) */ |
406 | ||
4e04a2df | 407 | #ifdef HAS_INIT_SECTION |
8313a782 | 408 | /* This case is used by the Irix 6 port, which supports named sections but |
409 | not an SVR4-style .init section. __do_global_ctors can be non-static | |
d757b8c9 | 410 | in this case because we protect it with -hidden_symbol. */ |
8313a782 | 411 | static func_ptr __CTOR_END__[]; |
ebd9163c | 412 | #ifdef EH_FRAME_SECTION_ASM_OP |
413 | extern void __frame_dummy (void); | |
414 | #endif | |
8313a782 | 415 | void |
416 | __do_global_ctors () | |
417 | { | |
418 | func_ptr *p; | |
d757b8c9 | 419 | #ifdef EH_FRAME_SECTION_ASM_OP |
72ac783d | 420 | __frame_dummy (); |
d757b8c9 | 421 | #endif |
8313a782 | 422 | for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--) |
423 | (*p) (); | |
424 | } | |
4e04a2df | 425 | #endif |
8313a782 | 426 | |
9d13f5c4 | 427 | #endif /* defined(INIT_SECTION_ASM_OP) */ |
428 | ||
429 | /* Force cc1 to switch to .data section. */ | |
cd03a192 | 430 | static func_ptr force_to_data[0] __attribute__ ((__unused__)) = { }; |
9d13f5c4 | 431 | |
b7c87ff2 | 432 | /* Put a word containing zero at the end of each of our two lists of function |
433 | addresses. Note that the words defined here go into the .ctors and .dtors | |
434 | sections of the crtend.o file, and since that file is always linked in | |
435 | last, these words naturally end up at the very ends of the two lists | |
436 | contained in these two sections. */ | |
437 | ||
b13ae905 | 438 | #ifdef CTOR_LIST_END |
439 | CTOR_LIST_END; | |
440 | #else | |
9d13f5c4 | 441 | asm (CTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
b7c87ff2 | 442 | STATIC func_ptr __CTOR_END__[1] = { (func_ptr) 0 }; |
b13ae905 | 443 | #endif |
9d13f5c4 | 444 | |
b13ae905 | 445 | #ifdef DTOR_LIST_END |
446 | DTOR_LIST_END; | |
447 | #else | |
9d13f5c4 | 448 | asm (DTORS_SECTION_ASM_OP); /* cc1 doesn't know that we are switching! */ |
cd03a192 | 449 | STATIC func_ptr __DTOR_END__[1] __attribute__ ((__unused__)) |
450 | = { (func_ptr) 0 }; | |
b13ae905 | 451 | #endif |
9d13f5c4 | 452 | |
d757b8c9 | 453 | #ifdef EH_FRAME_SECTION_ASM_OP |
454 | /* Terminate the frame unwind info section with a 4byte 0 as a sentinel; | |
455 | this would be the 'length' field in a real FDE. */ | |
456 | ||
457 | typedef unsigned int ui32 __attribute__ ((mode (SI))); | |
458 | asm (EH_FRAME_SECTION_ASM_OP); | |
cd03a192 | 459 | STATIC ui32 __FRAME_END__[] __attribute__ ((__unused__)) = { 0 }; |
d757b8c9 | 460 | #endif /* EH_FRAME_SECTION */ |
461 | ||
9d13f5c4 | 462 | #endif /* defined(CRT_END) */ |
5c61dffd | 463 | |
464 | #else /* OBJECT_FORMAT_MACHO */ | |
465 | ||
466 | /* For Mach-O format executables, we assume that the system's runtime is | |
467 | smart enough to handle constructors and destructors, but doesn't have | |
468 | an init section (if it can't even handle constructors/destructors | |
469 | you should be using INVOKE__main, not crtstuff). All we need to do | |
470 | is install/deinstall the frame information for exceptions. We do this | |
471 | by putting a constructor in crtbegin.o and a destructor in crtend.o. | |
472 | ||
473 | crtend.o also puts in the terminating zero in the frame information | |
474 | segment. */ | |
475 | ||
476 | /* The crtstuff for other object formats use the symbol __EH_FRAME_BEGIN__ | |
477 | to figure out the start of the exception frame, but here we use | |
478 | getsectbynamefromheader to find this value. Either method would work, | |
479 | but this method avoids creating any global symbols, which seems | |
480 | cleaner. */ | |
481 | ||
482 | #include <mach-o/ldsyms.h> | |
483 | extern const struct section * | |
484 | getsectbynamefromheader (const struct mach_header *, | |
485 | const char *, const char *); | |
486 | ||
487 | #ifdef CRT_BEGIN | |
488 | ||
489 | static void __reg_frame_ctor () __attribute__ ((constructor)); | |
490 | ||
491 | static void | |
492 | __reg_frame_ctor () | |
493 | { | |
494 | static struct object object; | |
495 | const struct section *eh_frame; | |
496 | ||
497 | eh_frame = getsectbynamefromheader (&_mh_execute_header, | |
498 | "__TEXT", "__eh_frame"); | |
499 | __register_frame_info ((void *) eh_frame->addr, &object); | |
500 | } | |
501 | ||
502 | #endif /* CRT_BEGIN */ | |
503 | ||
504 | #ifdef CRT_END | |
505 | ||
506 | static void __dereg_frame_dtor () __attribute__ ((destructor)); | |
507 | ||
508 | static | |
509 | void __dereg_frame_dtor () | |
510 | { | |
511 | const struct section *eh_frame; | |
512 | ||
513 | eh_frame = getsectbynamefromheader (&_mh_execute_header, | |
514 | "__TEXT", "__eh_frame"); | |
515 | __deregister_frame_info ((void *) eh_frame->addr); | |
516 | } | |
517 | ||
518 | /* Terminate the frame section with a final zero. */ | |
519 | ||
520 | /* Force cc1 to switch to .data section. */ | |
521 | static void * force_to_data[0] __attribute__ ((__unused__)) = { }; | |
522 | ||
523 | typedef unsigned int ui32 __attribute__ ((mode (SI))); | |
524 | asm (EH_FRAME_SECTION_ASM_OP); | |
525 | static ui32 __FRAME_END__[] __attribute__ ((__unused__)) = { 0 }; | |
526 | ||
527 | #endif /* CRT_END */ | |
528 | ||
529 | #endif /* OBJECT_FORMAT_MACHO */ | |
530 |