gdb/solib-darwin.c

   1 /* Handle Darwin shared libraries for GDB, the GNU Debugger.
   2
   3    Copyright (C) 2009-2014 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 "symtab.h"
  23 #include "bfd.h"
  24 #include "symfile.h"
  25 #include "objfiles.h"
  26 #include "gdbcore.h"
  27 #include "target.h"
  28 #include "inferior.h"
  29 #include "regcache.h"
  30 #include "gdbthread.h"
  31 #include "gdb_bfd.h"
  32
  33 #include "solist.h"
  34 #include "solib.h"
  35 #include "solib-svr4.h"
  36
  37 #include "bfd-target.h"
  38 #include "elf-bfd.h"
  39 #include "exec.h"
  40 #include "auxv.h"
  41 #include "exceptions.h"
  42 #include "mach-o.h"
  43 #include "mach-o/external.h"
  44
  45 struct gdb_dyld_image_info
  46 {
  47   /* Base address (which corresponds to the Mach-O header).  */
  48   CORE_ADDR mach_header;
  49   /* Image file path.  */
  50   CORE_ADDR file_path;
  51   /* st.m_time of image file.  */
  52   unsigned long mtime;
  53 };
  54
  55 /* Content of inferior dyld_all_image_infos structure.
  56    See /usr/include/mach-o/dyld_images.h for the documentation.  */
  57 struct gdb_dyld_all_image_infos
  58 {
  59   /* Version (1).  */
  60   unsigned int version;
  61   /* Number of images.  */
  62   unsigned int count;
  63   /* Image description.  */
  64   CORE_ADDR info;
  65   /* Notifier (function called when a library is added or removed).  */
  66   CORE_ADDR notifier;
  67 };
  68
  69 /* Current all_image_infos version.  */
  70 #define DYLD_VERSION_MIN 1
  71 #define DYLD_VERSION_MAX 14
  72
  73 /* Per PSPACE specific data.  */
  74 struct darwin_info
  75 {
  76   /* Address of structure dyld_all_image_infos in inferior.  */
  77   CORE_ADDR all_image_addr;
  78
  79   /* Gdb copy of dyld_all_info_infos.  */
  80   struct gdb_dyld_all_image_infos all_image;
  81 };
  82
  83 /* Per-program-space data key.  */
  84 static const struct program_space_data *solib_darwin_pspace_data;
  85
  86 static void
  87 darwin_pspace_data_cleanup (struct program_space *pspace, void *arg)
  88 {
  89   xfree (arg);
  90 }
  91
  92 /* Get the current darwin data.  If none is found yet, add it now.  This
  93    function always returns a valid object.  */
  94
  95 static struct darwin_info *
  96 get_darwin_info (void)
  97 {
  98   struct darwin_info *info;
  99
 100   info = program_space_data (current_program_space, solib_darwin_pspace_data);
 101   if (info != NULL)
 102     return info;
 103
 104   info = XCNEW (struct darwin_info);
 105   set_program_space_data (current_program_space,
 106                           solib_darwin_pspace_data, info);
 107   return info;
 108 }
 109
 110 /* Return non-zero if the version in dyld_all_image is known.  */
 111
 112 static int
 113 darwin_dyld_version_ok (const struct darwin_info *info)
 114 {
 115   return info->all_image.version >= DYLD_VERSION_MIN
 116     && info->all_image.version <= DYLD_VERSION_MAX;
 117 }
 118
 119 /* Read dyld_all_image from inferior.  */
 120
 121 static void
 122 darwin_load_image_infos (struct darwin_info *info)
 123 {
 124   gdb_byte buf[24];
 125   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 126   struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
 127   int len;
 128
 129   /* If the structure address is not known, don't continue.  */
 130   if (info->all_image_addr == 0)
 131     return;
 132
 133   /* The structure has 4 fields: version (4 bytes), count (4 bytes),
 134      info (pointer) and notifier (pointer).  */
 135   len = 4 + 4 + 2 * ptr_type->length;
 136   gdb_assert (len <= sizeof (buf));
 137   memset (&info->all_image, 0, sizeof (info->all_image));
 138
 139   /* Read structure raw bytes from target.  */
 140   if (target_read_memory (info->all_image_addr, buf, len))
 141     return;
 142
 143   /* Extract the fields.  */
 144   info->all_image.version = extract_unsigned_integer (buf, 4, byte_order);
 145   if (!darwin_dyld_version_ok (info))
 146     return;
 147
 148   info->all_image.count = extract_unsigned_integer (buf + 4, 4, byte_order);
 149   info->all_image.info = extract_typed_address (buf + 8, ptr_type);
 150   info->all_image.notifier = extract_typed_address
 151     (buf + 8 + ptr_type->length, ptr_type);
 152 }
 153
 154 /* Link map info to include in an allocated so_list entry.  */
 155
 156 struct lm_info
 157 {
 158   /* The target location of lm.  */
 159   CORE_ADDR lm_addr;
 160 };
 161
 162 struct darwin_so_list
 163 {
 164   /* Common field.  */
 165   struct so_list sl;
 166   /* Darwin specific data.  */
 167   struct lm_info li;
 168 };
 169
 170 /* Lookup the value for a specific symbol.  */
 171
 172 static CORE_ADDR
 173 lookup_symbol_from_bfd (bfd *abfd, char *symname)
 174 {
 175   long storage_needed;
 176   asymbol **symbol_table;
 177   unsigned int number_of_symbols;
 178   unsigned int i;
 179   CORE_ADDR symaddr = 0;
 180
 181   storage_needed = bfd_get_symtab_upper_bound (abfd);
 182
 183   if (storage_needed <= 0)
 184     return 0;
 185
 186   symbol_table = (asymbol **) xmalloc (storage_needed);
 187   number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table);
 188
 189   for (i = 0; i < number_of_symbols; i++)
 190     {
 191       asymbol *sym = symbol_table[i];
 192
 193       if (strcmp (sym->name, symname) == 0
 194           && (sym->section->flags & (SEC_CODE | SEC_DATA)) != 0)
 195         {
 196           /* BFD symbols are section relative.  */
 197           symaddr = sym->value + sym->section->vma;
 198           break;
 199         }
 200     }
 201   xfree (symbol_table);
 202
 203   return symaddr;
 204 }
 205
 206 /* Return program interpreter string.  */
 207
 208 static char *
 209 find_program_interpreter (void)
 210 {
 211   char *buf = NULL;
 212
 213   /* If we have an exec_bfd, get the interpreter from the load commands.  */
 214   if (exec_bfd)
 215     {
 216       bfd_mach_o_load_command *cmd;
 217
 218       if (bfd_mach_o_lookup_command (exec_bfd,
 219                                      BFD_MACH_O_LC_LOAD_DYLINKER, &cmd) == 1)
 220         return cmd->command.dylinker.name_str;
 221     }
 222
 223   /* If we didn't find it, read from memory.
 224      FIXME: todo.  */
 225   return buf;
 226 }
 227
 228 /*  Not used.  I don't see how the main symbol file can be found: the
 229     interpreter name is needed and it is known from the executable file.
 230     Note that darwin-nat.c implements pid_to_exec_file.  */
 231
 232 static int
 233 open_symbol_file_object (void *from_ttyp)
 234 {
 235   return 0;
 236 }
 237
 238 /* Build a list of currently loaded shared objects.  See solib-svr4.c.  */
 239
 240 static struct so_list *
 241 darwin_current_sos (void)
 242 {
 243   struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
 244   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 245   int ptr_len = TYPE_LENGTH (ptr_type);
 246   unsigned int image_info_size;
 247   struct so_list *head = NULL;
 248   struct so_list *tail = NULL;
 249   int i;
 250   struct darwin_info *info = get_darwin_info ();
 251
 252   /* Be sure image infos are loaded.  */
 253   darwin_load_image_infos (info);
 254
 255   if (!darwin_dyld_version_ok (info))
 256     return NULL;
 257
 258   image_info_size = ptr_len * 3;
 259
 260   /* Read infos for each solib.
 261      The first entry was rumored to be the executable itself, but this is not
 262      true when a large number of shared libraries are used (table expanded ?).
 263      We now check all entries, but discard executable images.  */
 264   for (i = 0; i < info->all_image.count; i++)
 265     {
 266       CORE_ADDR iinfo = info->all_image.info + i * image_info_size;
 267       gdb_byte buf[image_info_size];
 268       CORE_ADDR load_addr;
 269       CORE_ADDR path_addr;
 270       struct mach_o_header_external hdr;
 271       unsigned long hdr_val;
 272       char *file_path;
 273       int errcode;
 274       struct darwin_so_list *dnew;
 275       struct so_list *new;
 276       struct cleanup *old_chain;
 277
 278       /* Read image info from inferior.  */
 279       if (target_read_memory (iinfo, buf, image_info_size))
 280         break;
 281
 282       load_addr = extract_typed_address (buf, ptr_type);
 283       path_addr = extract_typed_address (buf + ptr_len, ptr_type);
 284
 285       /* Read Mach-O header from memory.  */
 286       if (target_read_memory (load_addr, (gdb_byte *) &hdr, sizeof (hdr) - 4))
 287         break;
 288       /* Discard wrong magic numbers.  Shouldn't happen.  */
 289       hdr_val = extract_unsigned_integer
 290         (hdr.magic, sizeof (hdr.magic), byte_order);
 291       if (hdr_val != BFD_MACH_O_MH_MAGIC && hdr_val != BFD_MACH_O_MH_MAGIC_64)
 292         continue;
 293       /* Discard executable.  Should happen only once.  */
 294       hdr_val = extract_unsigned_integer
 295         (hdr.filetype, sizeof (hdr.filetype), byte_order);
 296       if (hdr_val == BFD_MACH_O_MH_EXECUTE)
 297         continue;
 298
 299       target_read_string (path_addr, &file_path,
 300                           SO_NAME_MAX_PATH_SIZE - 1, &errcode);
 301       if (errcode)
 302         break;
 303
 304       /* Create and fill the new so_list element.  */
 305       dnew = XCNEW (struct darwin_so_list);
 306       new = &dnew->sl;
 307       old_chain = make_cleanup (xfree, dnew);
 308
 309       new->lm_info = &dnew->li;
 310
 311       strncpy (new->so_name, file_path, SO_NAME_MAX_PATH_SIZE - 1);
 312       new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
 313       strcpy (new->so_original_name, new->so_name);
 314       xfree (file_path);
 315       new->lm_info->lm_addr = load_addr;
 316
 317       if (head == NULL)
 318         head = new;
 319       else
 320         tail->next = new;
 321       tail = new;
 322
 323       discard_cleanups (old_chain);
 324     }
 325
 326   return head;
 327 }
 328
 329 /* Get the load address of the executable.  We assume that the dyld info are
 330    correct.  */
 331
 332 static CORE_ADDR
 333 darwin_read_exec_load_addr (struct darwin_info *info)
 334 {
 335   struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
 336   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 337   int ptr_len = TYPE_LENGTH (ptr_type);
 338   unsigned int image_info_size = ptr_len * 3;
 339   int i;
 340
 341   /* Read infos for each solib.  One of them should be the executable.  */
 342   for (i = 0; i < info->all_image.count; i++)
 343     {
 344       CORE_ADDR iinfo = info->all_image.info + i * image_info_size;
 345       gdb_byte buf[image_info_size];
 346       CORE_ADDR load_addr;
 347       struct mach_o_header_external hdr;
 348       unsigned long hdr_val;
 349
 350       /* Read image info from inferior.  */
 351       if (target_read_memory (iinfo, buf, image_info_size))
 352         break;
 353
 354       load_addr = extract_typed_address (buf, ptr_type);
 355
 356       /* Read Mach-O header from memory.  */
 357       if (target_read_memory (load_addr, (gdb_byte *) &hdr, sizeof (hdr) - 4))
 358         break;
 359       /* Discard wrong magic numbers.  Shouldn't happen.  */
 360       hdr_val = extract_unsigned_integer
 361         (hdr.magic, sizeof (hdr.magic), byte_order);
 362       if (hdr_val != BFD_MACH_O_MH_MAGIC && hdr_val != BFD_MACH_O_MH_MAGIC_64)
 363         continue;
 364       /* Check executable.  */
 365       hdr_val = extract_unsigned_integer
 366         (hdr.filetype, sizeof (hdr.filetype), byte_order);
 367       if (hdr_val == BFD_MACH_O_MH_EXECUTE)
 368         return load_addr;
 369     }
 370
 371   return 0;
 372 }
 373
 374 /* Return 1 if PC lies in the dynamic symbol resolution code of the
 375    run time loader.  */
 376
 377 static int
 378 darwin_in_dynsym_resolve_code (CORE_ADDR pc)
 379 {
 380   return 0;
 381 }
 382
 383
 384 /* No special symbol handling.  */
 385
 386 static void
 387 darwin_special_symbol_handling (void)
 388 {
 389 }
 390
 391 /* A wrapper for bfd_mach_o_fat_extract that handles reference
 392    counting properly.  This will either return NULL, or return a new
 393    reference to a BFD.  */
 394
 395 static bfd *
 396 gdb_bfd_mach_o_fat_extract (bfd *abfd, bfd_format format,
 397                             const bfd_arch_info_type *arch)
 398 {
 399   bfd *result = bfd_mach_o_fat_extract (abfd, format, arch);
 400
 401   if (result == NULL)
 402     return NULL;
 403
 404   if (result == abfd)
 405     gdb_bfd_ref (result);
 406   else
 407     gdb_bfd_mark_parent (result, abfd);
 408
 409   return result;
 410 }
 411
 412 /* Extract dyld_all_image_addr when the process was just created, assuming the
 413    current PC is at the entry of the dynamic linker.  */
 414
 415 static void
 416 darwin_solib_get_all_image_info_addr_at_init (struct darwin_info *info)
 417 {
 418   char *interp_name;
 419   CORE_ADDR load_addr = 0;
 420   bfd *dyld_bfd = NULL;
 421   struct cleanup *cleanup;
 422
 423   /* This method doesn't work with an attached process.  */
 424   if (current_inferior ()->attach_flag)
 425     return;
 426
 427   /* Find the program interpreter.  */
 428   interp_name = find_program_interpreter ();
 429   if (!interp_name)
 430     return;
 431
 432   cleanup = make_cleanup (null_cleanup, NULL);
 433
 434   /* Create a bfd for the interpreter.  */
 435   dyld_bfd = gdb_bfd_open (interp_name, gnutarget, -1);
 436   if (dyld_bfd)
 437     {
 438       bfd *sub;
 439
 440       make_cleanup_bfd_unref (dyld_bfd);
 441       sub = gdb_bfd_mach_o_fat_extract (dyld_bfd, bfd_object,
 442                                         gdbarch_bfd_arch_info (target_gdbarch ()));
 443       if (sub)
 444         {
 445           dyld_bfd = sub;
 446           make_cleanup_bfd_unref (sub);
 447         }
 448       else
 449         dyld_bfd = NULL;
 450     }
 451   if (!dyld_bfd)
 452     {
 453       do_cleanups (cleanup);
 454       return;
 455     }
 456
 457   /* We find the dynamic linker's base address by examining
 458      the current pc (which should point at the entry point for the
 459      dynamic linker) and subtracting the offset of the entry point.  */
 460   load_addr = (regcache_read_pc (get_current_regcache ())
 461                - bfd_get_start_address (dyld_bfd));
 462
 463   /* Now try to set a breakpoint in the dynamic linker.  */
 464   info->all_image_addr =
 465     lookup_symbol_from_bfd (dyld_bfd, "_dyld_all_image_infos");
 466
 467   do_cleanups (cleanup);
 468
 469   if (info->all_image_addr == 0)
 470     return;
 471
 472   info->all_image_addr += load_addr;
 473 }
 474
 475 /* Extract dyld_all_image_addr reading it from
 476    TARGET_OBJECT_DARWIN_DYLD_INFO.  */
 477
 478 static void
 479 darwin_solib_read_all_image_info_addr (struct darwin_info *info)
 480 {
 481   gdb_byte buf[8 + 8 + 4];
 482   LONGEST len;
 483   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 484
 485   len = target_read (&current_target, TARGET_OBJECT_DARWIN_DYLD_INFO, NULL,
 486                      buf, 0, sizeof (buf));
 487   if (len != sizeof (buf))
 488     return;
 489
 490   info->all_image_addr = extract_unsigned_integer (buf, 8, byte_order);
 491 }
 492
 493 /* Shared library startup support.  See documentation in solib-svr4.c.  */
 494
 495 static void
 496 darwin_solib_create_inferior_hook (int from_tty)
 497 {
 498   struct darwin_info *info = get_darwin_info ();
 499   CORE_ADDR load_addr;
 500
 501   info->all_image_addr = 0;
 502
 503   darwin_solib_read_all_image_info_addr (info);
 504
 505   if (info->all_image_addr == 0)
 506     darwin_solib_get_all_image_info_addr_at_init (info);
 507
 508   if (info->all_image_addr == 0)
 509     return;
 510
 511   darwin_load_image_infos (info);
 512
 513   if (!darwin_dyld_version_ok (info))
 514     {
 515       warning (_("unhandled dyld version (%d)"), info->all_image.version);
 516       return;
 517     }
 518
 519   create_solib_event_breakpoint (target_gdbarch (), info->all_image.notifier);
 520
 521   /* Possible relocate the main executable (PIE).  */
 522   load_addr = darwin_read_exec_load_addr (info);
 523   if (load_addr != 0 && symfile_objfile != NULL)
 524     {
 525       CORE_ADDR vmaddr;
 526
 527       /* Find the base address of the executable.  */
 528       vmaddr = bfd_mach_o_get_base_address (exec_bfd);
 529
 530       /* Relocate.  */
 531       if (vmaddr != load_addr)
 532         objfile_rebase (symfile_objfile, load_addr - vmaddr);
 533     }
 534 }
 535
 536 static void
 537 darwin_clear_solib (void)
 538 {
 539   struct darwin_info *info = get_darwin_info ();
 540
 541   info->all_image_addr = 0;
 542   info->all_image.version = 0;
 543 }
 544
 545 static void
 546 darwin_free_so (struct so_list *so)
 547 {
 548 }
 549
 550 /* The section table is built from bfd sections using bfd VMAs.
 551    Relocate these VMAs according to solib info.  */
 552
 553 static void
 554 darwin_relocate_section_addresses (struct so_list *so,
 555                                    struct target_section *sec)
 556 {
 557   sec->addr += so->lm_info->lm_addr;
 558   sec->endaddr += so->lm_info->lm_addr;
 559
 560   /* Best effort to set addr_high/addr_low.  This is used only by
 561      'info sharedlibary'.  */
 562   if (so->addr_high == 0)
 563     {
 564       so->addr_low = sec->addr;
 565       so->addr_high = sec->endaddr;
 566     }
 567   if (sec->endaddr > so->addr_high)
 568     so->addr_high = sec->endaddr;
 569   if (sec->addr < so->addr_low)
 570     so->addr_low = sec->addr;
 571 }
 572 \f
 573 static struct symbol *
 574 darwin_lookup_lib_symbol (const struct objfile *objfile,
 575                           const char *name,
 576                           const domain_enum domain)
 577 {
 578   return NULL;
 579 }
 580
 581 static bfd *
 582 darwin_bfd_open (char *pathname)
 583 {
 584   char *found_pathname;
 585   int found_file;
 586   bfd *abfd;
 587   bfd *res;
 588
 589   /* Search for shared library file.  */
 590   found_pathname = solib_find (pathname, &found_file);
 591   if (found_pathname == NULL)
 592     perror_with_name (pathname);
 593
 594   /* Open bfd for shared library.  */
 595   abfd = solib_bfd_fopen (found_pathname, found_file);
 596
 597   res = gdb_bfd_mach_o_fat_extract (abfd, bfd_object,
 598                                     gdbarch_bfd_arch_info (target_gdbarch ()));
 599   if (!res)
 600     {
 601       make_cleanup_bfd_unref (abfd);
 602       error (_("`%s': not a shared-library: %s"),
 603              bfd_get_filename (abfd), bfd_errmsg (bfd_get_error ()));
 604     }
 605
 606   /* The current filename for fat-binary BFDs is a name generated
 607      by BFD, usually a string containing the name of the architecture.
 608      Reset its value to the actual filename.  */
 609   xfree (bfd_get_filename (res));
 610   res->filename = xstrdup (pathname);
 611
 612   gdb_bfd_unref (abfd);
 613   return res;
 614 }
 615
 616 struct target_so_ops darwin_so_ops;
 617
 618 /* -Wmissing-prototypes */
 619 extern initialize_file_ftype _initialize_darwin_solib;
 620
 621 void
 622 _initialize_darwin_solib (void)
 623 {
 624   solib_darwin_pspace_data
 625     = register_program_space_data_with_cleanup (NULL,
 626                                                 darwin_pspace_data_cleanup);
 627
 628   darwin_so_ops.relocate_section_addresses = darwin_relocate_section_addresses;
 629   darwin_so_ops.free_so = darwin_free_so;
 630   darwin_so_ops.clear_solib = darwin_clear_solib;
 631   darwin_so_ops.solib_create_inferior_hook = darwin_solib_create_inferior_hook;
 632   darwin_so_ops.special_symbol_handling = darwin_special_symbol_handling;
 633   darwin_so_ops.current_sos = darwin_current_sos;
 634   darwin_so_ops.open_symbol_file_object = open_symbol_file_object;
 635   darwin_so_ops.in_dynsym_resolve_code = darwin_in_dynsym_resolve_code;
 636   darwin_so_ops.lookup_lib_global_symbol = darwin_lookup_lib_symbol;
 637   darwin_so_ops.bfd_open = darwin_bfd_open;
 638 }