Fix -Wmisleading-indentation warning in top.c
[deliverable/binutils-gdb.git] / gdb / osabi.c
1 /* OS ABI variant handling for GDB.
2
3 Copyright (C) 2001-2019 Free Software Foundation, Inc.
4
5 This file is part of GDB.
6
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
11
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
19
20 #include "defs.h"
21
22 #include "osabi.h"
23 #include "arch-utils.h"
24 #include "gdbcmd.h"
25 #include "command.h"
26
27 #include "elf-bfd.h"
28
29 #ifndef GDB_OSABI_DEFAULT
30 #define GDB_OSABI_DEFAULT GDB_OSABI_UNKNOWN
31 #endif
32
33 /* State for the "set osabi" command. */
34 static enum { osabi_auto, osabi_default, osabi_user } user_osabi_state;
35 static enum gdb_osabi user_selected_osabi;
36 static const char *gdb_osabi_available_names[GDB_OSABI_INVALID + 3] = {
37 "auto",
38 "default",
39 "none",
40 NULL
41 };
42 static const char *set_osabi_string;
43
44 /* Names associated with each osabi. */
45
46 struct osabi_names
47 {
48 /* The "pretty" name. */
49
50 const char *pretty;
51
52 /* The triplet regexp, or NULL if not known. */
53
54 const char *regexp;
55 };
56
57 /* This table matches the indices assigned to enum gdb_osabi. Keep
58 them in sync. */
59 static const struct osabi_names gdb_osabi_names[] =
60 {
61 { "unknown", NULL },
62 { "none", NULL },
63
64 { "SVR4", NULL },
65 { "GNU/Hurd", NULL },
66 { "Solaris", NULL },
67 { "GNU/Linux", "linux(-gnu[^-]*)?" },
68 { "FreeBSD", NULL },
69 { "NetBSD", NULL },
70 { "OpenBSD", NULL },
71 { "WindowsCE", NULL },
72 { "DJGPP", NULL },
73 { "QNX-Neutrino", NULL },
74 { "Cygwin", NULL },
75 { "AIX", NULL },
76 { "DICOS", NULL },
77 { "Darwin", NULL },
78 { "Symbian", NULL },
79 { "OpenVMS", NULL },
80 { "LynxOS178", NULL },
81 { "Newlib", NULL },
82 { "SDE", NULL },
83 { "PikeOS", NULL },
84
85 { "<invalid>", NULL }
86 };
87
88 const char *
89 gdbarch_osabi_name (enum gdb_osabi osabi)
90 {
91 if (osabi >= GDB_OSABI_UNKNOWN && osabi < GDB_OSABI_INVALID)
92 return gdb_osabi_names[osabi].pretty;
93
94 return gdb_osabi_names[GDB_OSABI_INVALID].pretty;
95 }
96
97 /* See osabi.h. */
98
99 const char *
100 osabi_triplet_regexp (enum gdb_osabi osabi)
101 {
102 if (osabi >= GDB_OSABI_UNKNOWN && osabi < GDB_OSABI_INVALID)
103 return gdb_osabi_names[osabi].regexp;
104
105 return gdb_osabi_names[GDB_OSABI_INVALID].regexp;
106 }
107
108 /* Lookup the OS ABI corresponding to the specified target description
109 string. */
110
111 enum gdb_osabi
112 osabi_from_tdesc_string (const char *name)
113 {
114 int i;
115
116 for (i = 0; i < ARRAY_SIZE (gdb_osabi_names); i++)
117 if (strcmp (name, gdb_osabi_names[i].pretty) == 0)
118 {
119 /* See note above: the name table matches the indices assigned
120 to enum gdb_osabi. */
121 enum gdb_osabi osabi = (enum gdb_osabi) i;
122
123 if (osabi == GDB_OSABI_INVALID)
124 return GDB_OSABI_UNKNOWN;
125 else
126 return osabi;
127 }
128
129 return GDB_OSABI_UNKNOWN;
130 }
131
132 /* Handler for a given architecture/OS ABI pair. There should be only
133 one handler for a given OS ABI each architecture family. */
134 struct gdb_osabi_handler
135 {
136 struct gdb_osabi_handler *next;
137 const struct bfd_arch_info *arch_info;
138 enum gdb_osabi osabi;
139 void (*init_osabi)(struct gdbarch_info, struct gdbarch *);
140 };
141
142 static struct gdb_osabi_handler *gdb_osabi_handler_list;
143
144 void
145 gdbarch_register_osabi (enum bfd_architecture arch, unsigned long machine,
146 enum gdb_osabi osabi,
147 void (*init_osabi)(struct gdbarch_info,
148 struct gdbarch *))
149 {
150 struct gdb_osabi_handler **handler_p;
151 const struct bfd_arch_info *arch_info = bfd_lookup_arch (arch, machine);
152 const char **name_ptr;
153
154 /* Registering an OS ABI handler for "unknown" is not allowed. */
155 if (osabi == GDB_OSABI_UNKNOWN)
156 {
157 internal_error
158 (__FILE__, __LINE__,
159 _("gdbarch_register_osabi: An attempt to register a handler for "
160 "OS ABI \"%s\" for architecture %s was made. The handler will "
161 "not be registered"),
162 gdbarch_osabi_name (osabi),
163 bfd_printable_arch_mach (arch, machine));
164 return;
165 }
166
167 gdb_assert (arch_info);
168
169 for (handler_p = &gdb_osabi_handler_list; *handler_p != NULL;
170 handler_p = &(*handler_p)->next)
171 {
172 if ((*handler_p)->arch_info == arch_info
173 && (*handler_p)->osabi == osabi)
174 {
175 internal_error
176 (__FILE__, __LINE__,
177 _("gdbarch_register_osabi: A handler for OS ABI \"%s\" "
178 "has already been registered for architecture %s"),
179 gdbarch_osabi_name (osabi),
180 arch_info->printable_name);
181 /* If user wants to continue, override previous definition. */
182 (*handler_p)->init_osabi = init_osabi;
183 return;
184 }
185 }
186
187 (*handler_p) = XNEW (struct gdb_osabi_handler);
188 (*handler_p)->next = NULL;
189 (*handler_p)->arch_info = arch_info;
190 (*handler_p)->osabi = osabi;
191 (*handler_p)->init_osabi = init_osabi;
192
193 /* Add this OS ABI to the list of enum values for "set osabi", if it isn't
194 already there. */
195 for (name_ptr = gdb_osabi_available_names; *name_ptr; name_ptr ++)
196 {
197 if (*name_ptr == gdbarch_osabi_name (osabi))
198 return;
199 }
200 *name_ptr++ = gdbarch_osabi_name (osabi);
201 *name_ptr = NULL;
202 }
203 \f
204
205 /* Sniffer to find the OS ABI for a given file's architecture and flavour.
206 It is legal to have multiple sniffers for each arch/flavour pair, to
207 disambiguate one OS's a.out from another, for example. The first sniffer
208 to return something other than GDB_OSABI_UNKNOWN wins, so a sniffer should
209 be careful to claim a file only if it knows for sure what it is. */
210 struct gdb_osabi_sniffer
211 {
212 struct gdb_osabi_sniffer *next;
213 enum bfd_architecture arch; /* bfd_arch_unknown == wildcard */
214 enum bfd_flavour flavour;
215 enum gdb_osabi (*sniffer)(bfd *);
216 };
217
218 static struct gdb_osabi_sniffer *gdb_osabi_sniffer_list;
219
220 void
221 gdbarch_register_osabi_sniffer (enum bfd_architecture arch,
222 enum bfd_flavour flavour,
223 enum gdb_osabi (*sniffer_fn)(bfd *))
224 {
225 struct gdb_osabi_sniffer *sniffer;
226
227 sniffer = XNEW (struct gdb_osabi_sniffer);
228 sniffer->arch = arch;
229 sniffer->flavour = flavour;
230 sniffer->sniffer = sniffer_fn;
231
232 sniffer->next = gdb_osabi_sniffer_list;
233 gdb_osabi_sniffer_list = sniffer;
234 }
235 \f
236
237 enum gdb_osabi
238 gdbarch_lookup_osabi (bfd *abfd)
239 {
240 struct gdb_osabi_sniffer *sniffer;
241 enum gdb_osabi osabi, match;
242 int match_specific;
243
244 /* If we aren't in "auto" mode, return the specified OS ABI. */
245 if (user_osabi_state == osabi_user)
246 return user_selected_osabi;
247
248 /* If we don't have a binary, just return unknown. The caller may
249 have other sources the OSABI can be extracted from, e.g., the
250 target description. */
251 if (abfd == NULL)
252 return GDB_OSABI_UNKNOWN;
253
254 match = GDB_OSABI_UNKNOWN;
255 match_specific = 0;
256
257 for (sniffer = gdb_osabi_sniffer_list; sniffer != NULL;
258 sniffer = sniffer->next)
259 {
260 if ((sniffer->arch == bfd_arch_unknown /* wildcard */
261 || sniffer->arch == bfd_get_arch (abfd))
262 && sniffer->flavour == bfd_get_flavour (abfd))
263 {
264 osabi = (*sniffer->sniffer) (abfd);
265 if (osabi < GDB_OSABI_UNKNOWN || osabi >= GDB_OSABI_INVALID)
266 {
267 internal_error
268 (__FILE__, __LINE__,
269 _("gdbarch_lookup_osabi: invalid OS ABI (%d) from sniffer "
270 "for architecture %s flavour %d"),
271 (int) osabi,
272 bfd_printable_arch_mach (bfd_get_arch (abfd), 0),
273 (int) bfd_get_flavour (abfd));
274 }
275 else if (osabi != GDB_OSABI_UNKNOWN)
276 {
277 /* A specific sniffer always overrides a generic sniffer.
278 Croak on multiple match if the two matches are of the
279 same class. If the user wishes to continue, we'll use
280 the first match. */
281 if (match != GDB_OSABI_UNKNOWN)
282 {
283 if ((match_specific && sniffer->arch != bfd_arch_unknown)
284 || (!match_specific && sniffer->arch == bfd_arch_unknown))
285 {
286 internal_error
287 (__FILE__, __LINE__,
288 _("gdbarch_lookup_osabi: multiple %sspecific OS ABI "
289 "match for architecture %s flavour %d: first "
290 "match \"%s\", second match \"%s\""),
291 match_specific ? "" : "non-",
292 bfd_printable_arch_mach (bfd_get_arch (abfd), 0),
293 (int) bfd_get_flavour (abfd),
294 gdbarch_osabi_name (match),
295 gdbarch_osabi_name (osabi));
296 }
297 else if (sniffer->arch != bfd_arch_unknown)
298 {
299 match = osabi;
300 match_specific = 1;
301 }
302 }
303 else
304 {
305 match = osabi;
306 if (sniffer->arch != bfd_arch_unknown)
307 match_specific = 1;
308 }
309 }
310 }
311 }
312
313 return match;
314 }
315
316
317 /* Return non-zero if architecture A can run code written for
318 architecture B. */
319 static int
320 can_run_code_for (const struct bfd_arch_info *a, const struct bfd_arch_info *b)
321 {
322 /* BFD's 'A->compatible (A, B)' functions return zero if A and B are
323 incompatible. But if they are compatible, it returns the 'more
324 featureful' of the two arches. That is, if A can run code
325 written for B, but B can't run code written for A, then it'll
326 return A.
327
328 struct bfd_arch_info objects are singletons: that is, there's
329 supposed to be exactly one instance for a given machine. So you
330 can tell whether two are equivalent by comparing pointers. */
331 return (a == b || a->compatible (a, b) == a);
332 }
333
334
335 void
336 gdbarch_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch)
337 {
338 struct gdb_osabi_handler *handler;
339
340 gdb_assert (info.osabi != GDB_OSABI_UNKNOWN);
341
342 for (handler = gdb_osabi_handler_list; handler != NULL;
343 handler = handler->next)
344 {
345 if (handler->osabi != info.osabi)
346 continue;
347
348 /* If the architecture described by ARCH_INFO can run code for
349 the architecture we registered the handler for, then the
350 handler is applicable. Note, though, that if the handler is
351 for an architecture that is a superset of ARCH_INFO, we can't
352 use that --- it would be perfectly correct for it to install
353 gdbarch methods that refer to registers / instructions /
354 other facilities ARCH_INFO doesn't have.
355
356 NOTE: kettenis/20021027: There may be more than one machine
357 type that is compatible with the desired machine type. Right
358 now we simply return the first match, which is fine for now.
359 However, we might want to do something smarter in the future. */
360 /* NOTE: cagney/2003-10-23: The code for "a can_run_code_for b"
361 is implemented using BFD's compatible method (a->compatible
362 (b) == a -- the lowest common denominator between a and b is
363 a). That method's definition of compatible may not be as you
364 expect. For instance the test "amd64 can run code for i386"
365 (or more generally "64-bit ISA can run code for the 32-bit
366 ISA"). BFD doesn't normally consider 32-bit and 64-bit
367 "compatible" so it doesn't succeed. */
368 if (can_run_code_for (info.bfd_arch_info, handler->arch_info))
369 {
370 (*handler->init_osabi) (info, gdbarch);
371 return;
372 }
373 }
374
375 if (info.osabi == GDB_OSABI_NONE)
376 {
377 /* Don't complain about no OSABI. Assume the user knows
378 what they are doing. */
379 return;
380 }
381
382 warning
383 ("A handler for the OS ABI \"%s\" is not built into this configuration\n"
384 "of GDB. Attempting to continue with the default %s settings.\n",
385 gdbarch_osabi_name (info.osabi),
386 info.bfd_arch_info->printable_name);
387 }
388 \f
389 /* Limit on the amount of data to be read. */
390 #define MAX_NOTESZ 128
391
392 /* Return non-zero if NOTE matches NAME, DESCSZ and TYPE. If
393 *SECTSIZE is non-zero, then this reads that many bytes from
394 the start of the section and clears *SECTSIZE. */
395
396 static int
397 check_note (bfd *abfd, asection *sect, char *note, unsigned int *sectsize,
398 const char *name, unsigned long descsz, unsigned long type)
399 {
400 unsigned long notesz;
401
402 if (*sectsize)
403 {
404 if (!bfd_get_section_contents (abfd, sect, note, 0, *sectsize))
405 return 0;
406 *sectsize = 0;
407 }
408
409 /* Calculate the size of this note. */
410 notesz = strlen (name) + 1;
411 notesz = ((notesz + 3) & ~3);
412 notesz += descsz;
413 notesz = ((notesz + 3) & ~3);
414
415 /* If this assertion triggers, increase MAX_NOTESZ. */
416 gdb_assert (notesz <= MAX_NOTESZ);
417
418 /* Check whether SECT is big enough to contain the complete note. */
419 if (notesz > bfd_section_size (sect))
420 return 0;
421
422 /* Check the note name. */
423 if (bfd_h_get_32 (abfd, note) != (strlen (name) + 1)
424 || strcmp (note + 12, name) != 0)
425 return 0;
426
427 /* Check the descriptor size. */
428 if (bfd_h_get_32 (abfd, note + 4) != descsz)
429 return 0;
430
431 /* Check the note type. */
432 if (bfd_h_get_32 (abfd, note + 8) != type)
433 return 0;
434
435 return 1;
436 }
437
438 /* Generic sniffer for ELF flavoured files. */
439
440 void
441 generic_elf_osabi_sniff_abi_tag_sections (bfd *abfd, asection *sect, void *obj)
442 {
443 enum gdb_osabi *osabi = (enum gdb_osabi *) obj;
444 const char *name;
445 unsigned int sectsize;
446 char *note;
447
448 name = bfd_section_name (sect);
449 sectsize = bfd_section_size (sect);
450
451 /* Limit the amount of data to read. */
452 if (sectsize > MAX_NOTESZ)
453 sectsize = MAX_NOTESZ;
454
455 /* We lazily read the section data here. Since we use
456 BFD_DECOMPRESS, we can't use bfd_get_section_contents on a
457 compressed section. But, since note sections are not compressed,
458 deferring the reading until we recognize the section avoids any
459 error. */
460 note = (char *) alloca (sectsize);
461
462 /* .note.ABI-tag notes, used by GNU/Linux and FreeBSD. */
463 if (strcmp (name, ".note.ABI-tag") == 0)
464 {
465 /* GNU. */
466 if (check_note (abfd, sect, note, &sectsize, "GNU", 16, NT_GNU_ABI_TAG))
467 {
468 unsigned int abi_tag = bfd_h_get_32 (abfd, note + 16);
469
470 switch (abi_tag)
471 {
472 case GNU_ABI_TAG_LINUX:
473 *osabi = GDB_OSABI_LINUX;
474 break;
475
476 case GNU_ABI_TAG_HURD:
477 *osabi = GDB_OSABI_HURD;
478 break;
479
480 case GNU_ABI_TAG_SOLARIS:
481 *osabi = GDB_OSABI_SOLARIS;
482 break;
483
484 case GNU_ABI_TAG_FREEBSD:
485 *osabi = GDB_OSABI_FREEBSD;
486 break;
487
488 case GNU_ABI_TAG_NETBSD:
489 *osabi = GDB_OSABI_NETBSD;
490 break;
491
492 default:
493 warning (_("GNU ABI tag value %u unrecognized."), abi_tag);
494 break;
495 }
496 return;
497 }
498
499 /* FreeBSD. */
500 if (check_note (abfd, sect, note, &sectsize, "FreeBSD", 4,
501 NT_FREEBSD_ABI_TAG))
502 {
503 /* There is no need to check the version yet. */
504 *osabi = GDB_OSABI_FREEBSD;
505 return;
506 }
507
508 return;
509 }
510
511 /* .note.netbsd.ident notes, used by NetBSD. */
512 if (strcmp (name, ".note.netbsd.ident") == 0
513 && check_note (abfd, sect, note, &sectsize, "NetBSD", 4, NT_NETBSD_IDENT))
514 {
515 /* There is no need to check the version yet. */
516 *osabi = GDB_OSABI_NETBSD;
517 return;
518 }
519
520 /* .note.openbsd.ident notes, used by OpenBSD. */
521 if (strcmp (name, ".note.openbsd.ident") == 0
522 && check_note (abfd, sect, note, &sectsize, "OpenBSD", 4,
523 NT_OPENBSD_IDENT))
524 {
525 /* There is no need to check the version yet. */
526 *osabi = GDB_OSABI_OPENBSD;
527 return;
528 }
529
530 /* .note.netbsdcore.procinfo notes, used by NetBSD. */
531 if (strcmp (name, ".note.netbsdcore.procinfo") == 0)
532 {
533 *osabi = GDB_OSABI_NETBSD;
534 return;
535 }
536 }
537
538 static enum gdb_osabi
539 generic_elf_osabi_sniffer (bfd *abfd)
540 {
541 unsigned int elfosabi;
542 enum gdb_osabi osabi = GDB_OSABI_UNKNOWN;
543
544 elfosabi = elf_elfheader (abfd)->e_ident[EI_OSABI];
545
546 switch (elfosabi)
547 {
548 case ELFOSABI_NONE:
549 case ELFOSABI_GNU:
550 case ELFOSABI_HPUX:
551 /* When the EI_OSABI field in the ELF header is ELFOSABI_NONE
552 (0), then the ELF structures in the file are conforming to
553 the base specification for that machine (there are no
554 OS-specific extensions). In order to determine the real OS
555 in use, we must look for OS-specific notes.
556
557 The same applies for ELFOSABI_GNU: this can mean GNU/Hurd,
558 GNU/Linux, and possibly more. */
559
560 /* And likewise ELFOSABI_HPUX. For some reason the default
561 value for the EI_OSABI field is ELFOSABI_HPUX for all PA-RISC
562 targets (with the exception of GNU/Linux). */
563 bfd_map_over_sections (abfd,
564 generic_elf_osabi_sniff_abi_tag_sections,
565 &osabi);
566 break;
567
568 case ELFOSABI_FREEBSD:
569 osabi = GDB_OSABI_FREEBSD;
570 break;
571
572 case ELFOSABI_NETBSD:
573 osabi = GDB_OSABI_NETBSD;
574 break;
575
576 case ELFOSABI_SOLARIS:
577 osabi = GDB_OSABI_SOLARIS;
578 break;
579
580 case ELFOSABI_OPENVMS:
581 osabi = GDB_OSABI_OPENVMS;
582 break;
583 }
584
585 if (osabi == GDB_OSABI_UNKNOWN)
586 {
587 /* The FreeBSD folks have been naughty; they stored the string
588 "FreeBSD" in the padding of the e_ident field of the ELF
589 header to "brand" their ELF binaries in FreeBSD 3.x. */
590 if (memcmp (&elf_elfheader (abfd)->e_ident[8],
591 "FreeBSD", sizeof ("FreeBSD")) == 0)
592 osabi = GDB_OSABI_FREEBSD;
593 }
594
595 return osabi;
596 }
597 \f
598 static void
599 set_osabi (const char *args, int from_tty, struct cmd_list_element *c)
600 {
601 struct gdbarch_info info;
602
603 if (strcmp (set_osabi_string, "auto") == 0)
604 user_osabi_state = osabi_auto;
605 else if (strcmp (set_osabi_string, "default") == 0)
606 {
607 user_selected_osabi = GDB_OSABI_DEFAULT;
608 user_osabi_state = osabi_user;
609 }
610 else
611 {
612 int i;
613
614 for (i = 1; i < GDB_OSABI_INVALID; i++)
615 {
616 enum gdb_osabi osabi = (enum gdb_osabi) i;
617
618 if (strcmp (set_osabi_string, gdbarch_osabi_name (osabi)) == 0)
619 {
620 user_selected_osabi = osabi;
621 user_osabi_state = osabi_user;
622 break;
623 }
624 }
625 if (i == GDB_OSABI_INVALID)
626 internal_error (__FILE__, __LINE__,
627 _("Invalid OS ABI \"%s\" passed to command handler."),
628 set_osabi_string);
629 }
630
631 /* NOTE: At some point (true multiple architectures) we'll need to be more
632 graceful here. */
633 gdbarch_info_init (&info);
634 if (! gdbarch_update_p (info))
635 internal_error (__FILE__, __LINE__, _("Updating OS ABI failed."));
636 }
637
638 static void
639 show_osabi (struct ui_file *file, int from_tty, struct cmd_list_element *c,
640 const char *value)
641 {
642 if (user_osabi_state == osabi_auto)
643 fprintf_filtered (file,
644 _("The current OS ABI is \"auto\" "
645 "(currently \"%s\").\n"),
646 gdbarch_osabi_name (gdbarch_osabi (get_current_arch ())));
647 else
648 fprintf_filtered (file, _("The current OS ABI is \"%s\".\n"),
649 gdbarch_osabi_name (user_selected_osabi));
650
651 if (GDB_OSABI_DEFAULT != GDB_OSABI_UNKNOWN)
652 fprintf_filtered (file, _("The default OS ABI is \"%s\".\n"),
653 gdbarch_osabi_name (GDB_OSABI_DEFAULT));
654 }
655
656 void
657 _initialize_gdb_osabi (void)
658 {
659 if (strcmp (gdb_osabi_names[GDB_OSABI_INVALID].pretty, "<invalid>") != 0)
660 internal_error
661 (__FILE__, __LINE__,
662 _("_initialize_gdb_osabi: gdb_osabi_names[] is inconsistent"));
663
664 /* Register a generic sniffer for ELF flavoured files. */
665 gdbarch_register_osabi_sniffer (bfd_arch_unknown,
666 bfd_target_elf_flavour,
667 generic_elf_osabi_sniffer);
668
669 /* Register the "set osabi" command. */
670 add_setshow_enum_cmd ("osabi", class_support, gdb_osabi_available_names,
671 &set_osabi_string,
672 _("Set OS ABI of target."),
673 _("Show OS ABI of target."),
674 NULL, set_osabi, show_osabi,
675 &setlist, &showlist);
676 user_osabi_state = osabi_auto;
677 }
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