gdb/solib-darwin.c

   1 /* Handle Darwin shared libraries for GDB, the GNU Debugger.
   2
   3    Copyright (C) 2009-2017 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 "mach-o.h"
  42 #include "mach-o/external.h"
  43
  44 struct gdb_dyld_image_info
  45 {
  46   /* Base address (which corresponds to the Mach-O header).  */
  47   CORE_ADDR mach_header;
  48   /* Image file path.  */
  49   CORE_ADDR file_path;
  50   /* st.m_time of image file.  */
  51   unsigned long mtime;
  52 };
  53
  54 /* Content of inferior dyld_all_image_infos structure.
  55    See /usr/include/mach-o/dyld_images.h for the documentation.  */
  56 struct gdb_dyld_all_image_infos
  57 {
  58   /* Version (1).  */
  59   unsigned int version;
  60   /* Number of images.  */
  61   unsigned int count;
  62   /* Image description.  */
  63   CORE_ADDR info;
  64   /* Notifier (function called when a library is added or removed).  */
  65   CORE_ADDR notifier;
  66 };
  67
  68 /* Current all_image_infos version.  */
  69 #define DYLD_VERSION_MIN 1
  70 #define DYLD_VERSION_MAX 14
  71
  72 /* Per PSPACE specific data.  */
  73 struct darwin_info
  74 {
  75   /* Address of structure dyld_all_image_infos in inferior.  */
  76   CORE_ADDR all_image_addr;
  77
  78   /* Gdb copy of dyld_all_info_infos.  */
  79   struct gdb_dyld_all_image_infos all_image;
  80 };
  81
  82 /* Per-program-space data key.  */
  83 static const struct program_space_data *solib_darwin_pspace_data;
  84
  85 static void
  86 darwin_pspace_data_cleanup (struct program_space *pspace, void *arg)
  87 {
  88   xfree (arg);
  89 }
  90
  91 /* Get the current darwin data.  If none is found yet, add it now.  This
  92    function always returns a valid object.  */
  93
  94 static struct darwin_info *
  95 get_darwin_info (void)
  96 {
  97   struct darwin_info *info;
  98
  99   info = (struct darwin_info *) program_space_data (current_program_space,
 100                                                     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 * TYPE_LENGTH (ptr_type);
 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 + TYPE_LENGTH (ptr_type), 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 *newobj;
 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       newobj = &dnew->sl;
 307       old_chain = make_cleanup (xfree, dnew);
 308
 309       newobj->lm_info = &dnew->li;
 310
 311       strncpy (newobj->so_name, file_path, SO_NAME_MAX_PATH_SIZE - 1);
 312       newobj->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
 313       strcpy (newobj->so_original_name, newobj->so_name);
 314       xfree (file_path);
 315       newobj->lm_info->lm_addr = load_addr;
 316
 317       if (head == NULL)
 318         head = newobj;
 319       else
 320         tail->next = newobj;
 321       tail = newobj;
 322
 323       discard_cleanups (old_chain);
 324     }
 325
 326   return head;
 327 }
 328
 329 /* Check LOAD_ADDR points to a Mach-O executable header.  Return LOAD_ADDR
 330    in case of success, 0 in case of failure.  */
 331
 332 static CORE_ADDR
 333 darwin_validate_exec_header (CORE_ADDR load_addr)
 334 {
 335   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 336   struct mach_o_header_external hdr;
 337   unsigned long hdr_val;
 338
 339   /* Read Mach-O header from memory.  */
 340   if (target_read_memory (load_addr, (gdb_byte *) &hdr, sizeof (hdr) - 4))
 341     return 0;
 342
 343   /* Discard wrong magic numbers.  Shouldn't happen.  */
 344   hdr_val = extract_unsigned_integer
 345     (hdr.magic, sizeof (hdr.magic), byte_order);
 346   if (hdr_val != BFD_MACH_O_MH_MAGIC && hdr_val != BFD_MACH_O_MH_MAGIC_64)
 347     return 0;
 348
 349   /* Check executable.  */
 350   hdr_val = extract_unsigned_integer
 351     (hdr.filetype, sizeof (hdr.filetype), byte_order);
 352   if (hdr_val == BFD_MACH_O_MH_EXECUTE)
 353     return load_addr;
 354
 355   return 0;
 356 }
 357
 358 /* Get the load address of the executable using dyld list of images.
 359    We assume that the dyld info are correct (which is wrong if the target
 360    is stopped at the first instruction).  */
 361
 362 static CORE_ADDR
 363 darwin_read_exec_load_addr_from_dyld (struct darwin_info *info)
 364 {
 365   struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
 366   int ptr_len = TYPE_LENGTH (ptr_type);
 367   unsigned int image_info_size = ptr_len * 3;
 368   int i;
 369
 370   /* Read infos for each solib.  One of them should be the executable.  */
 371   for (i = 0; i < info->all_image.count; i++)
 372     {
 373       CORE_ADDR iinfo = info->all_image.info + i * image_info_size;
 374       gdb_byte buf[image_info_size];
 375       CORE_ADDR load_addr;
 376
 377       /* Read image info from inferior.  */
 378       if (target_read_memory (iinfo, buf, image_info_size))
 379         break;
 380
 381       load_addr = extract_typed_address (buf, ptr_type);
 382       if (darwin_validate_exec_header (load_addr) == load_addr)
 383         return load_addr;
 384     }
 385
 386   return 0;
 387 }
 388
 389 /* Get the load address of the executable when the PC is at the dyld
 390    entry point using parameter passed by the kernel (at SP). */
 391
 392 static CORE_ADDR
 393 darwin_read_exec_load_addr_at_init (struct darwin_info *info)
 394 {
 395   struct gdbarch *gdbarch = target_gdbarch ();
 396   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 397   int addr_size = gdbarch_addr_bit (gdbarch) / 8;
 398   ULONGEST load_ptr_addr;
 399   ULONGEST load_addr;
 400   gdb_byte buf[8];
 401
 402   /* Get SP.  */
 403   if (regcache_cooked_read_unsigned (get_current_regcache (),
 404                                      gdbarch_sp_regnum (gdbarch),
 405                                      &load_ptr_addr) != REG_VALID)
 406     return 0;
 407
 408   /* Read value at SP (image load address).  */
 409   if (target_read_memory (load_ptr_addr, buf, addr_size))
 410     return 0;
 411
 412   load_addr = extract_unsigned_integer (buf, addr_size, byte_order);
 413
 414   return darwin_validate_exec_header (load_addr);
 415 }
 416
 417 /* Return 1 if PC lies in the dynamic symbol resolution code of the
 418    run time loader.  */
 419
 420 static int
 421 darwin_in_dynsym_resolve_code (CORE_ADDR pc)
 422 {
 423   return 0;
 424 }
 425
 426 /* A wrapper for bfd_mach_o_fat_extract that handles reference
 427    counting properly.  This will either return NULL, or return a new
 428    reference to a BFD.  */
 429
 430 static gdb_bfd_ref_ptr
 431 gdb_bfd_mach_o_fat_extract (bfd *abfd, bfd_format format,
 432                             const bfd_arch_info_type *arch)
 433 {
 434   bfd *result = bfd_mach_o_fat_extract (abfd, format, arch);
 435
 436   if (result == NULL)
 437     return NULL;
 438
 439   if (result == abfd)
 440     gdb_bfd_ref (result);
 441   else
 442     gdb_bfd_mark_parent (result, abfd);
 443
 444   return gdb_bfd_ref_ptr (result);
 445 }
 446
 447 /* Extract dyld_all_image_addr when the process was just created, assuming the
 448    current PC is at the entry of the dynamic linker.  */
 449
 450 static void
 451 darwin_solib_get_all_image_info_addr_at_init (struct darwin_info *info)
 452 {
 453   char *interp_name;
 454   CORE_ADDR load_addr = 0;
 455
 456   /* This method doesn't work with an attached process.  */
 457   if (current_inferior ()->attach_flag)
 458     return;
 459
 460   /* Find the program interpreter.  */
 461   interp_name = find_program_interpreter ();
 462   if (!interp_name)
 463     return;
 464
 465   /* Create a bfd for the interpreter.  */
 466   gdb_bfd_ref_ptr dyld_bfd (gdb_bfd_open (interp_name, gnutarget, -1));
 467   if (dyld_bfd != NULL)
 468     {
 469       gdb_bfd_ref_ptr sub
 470         (gdb_bfd_mach_o_fat_extract (dyld_bfd.get (), bfd_object,
 471                                      gdbarch_bfd_arch_info (target_gdbarch ())));
 472       if (sub != NULL)
 473         dyld_bfd = sub;
 474       else
 475         dyld_bfd.release ();
 476     }
 477   if (dyld_bfd == NULL)
 478     return;
 479
 480   /* We find the dynamic linker's base address by examining
 481      the current pc (which should point at the entry point for the
 482      dynamic linker) and subtracting the offset of the entry point.  */
 483   load_addr = (regcache_read_pc (get_current_regcache ())
 484                - bfd_get_start_address (dyld_bfd.get ()));
 485
 486   /* Now try to set a breakpoint in the dynamic linker.  */
 487   info->all_image_addr =
 488     lookup_symbol_from_bfd (dyld_bfd.get (), "_dyld_all_image_infos");
 489
 490   if (info->all_image_addr == 0)
 491     return;
 492
 493   info->all_image_addr += load_addr;
 494 }
 495
 496 /* Extract dyld_all_image_addr reading it from
 497    TARGET_OBJECT_DARWIN_DYLD_INFO.  */
 498
 499 static void
 500 darwin_solib_read_all_image_info_addr (struct darwin_info *info)
 501 {
 502   gdb_byte buf[8];
 503   LONGEST len;
 504   struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
 505
 506   /* Sanity check.  */
 507   if (TYPE_LENGTH (ptr_type) > sizeof (buf))
 508     return;
 509
 510   len = target_read (&current_target, TARGET_OBJECT_DARWIN_DYLD_INFO, NULL,
 511                      buf, 0, TYPE_LENGTH (ptr_type));
 512   if (len <= 0)
 513     return;
 514
 515   /* The use of BIG endian is intended, as BUF is a raw stream of bytes.  This
 516       makes the support of remote protocol easier.  */
 517   info->all_image_addr = extract_unsigned_integer (buf, len, BFD_ENDIAN_BIG);
 518 }
 519
 520 /* Shared library startup support.  See documentation in solib-svr4.c.  */
 521
 522 static void
 523 darwin_solib_create_inferior_hook (int from_tty)
 524 {
 525   struct darwin_info *info = get_darwin_info ();
 526   CORE_ADDR load_addr;
 527
 528   info->all_image_addr = 0;
 529
 530   darwin_solib_read_all_image_info_addr (info);
 531
 532   if (info->all_image_addr == 0)
 533     darwin_solib_get_all_image_info_addr_at_init (info);
 534
 535   if (info->all_image_addr == 0)
 536     return;
 537
 538   darwin_load_image_infos (info);
 539
 540   if (!darwin_dyld_version_ok (info))
 541     {
 542       warning (_("unhandled dyld version (%d)"), info->all_image.version);
 543       return;
 544     }
 545
 546   /* Add the breakpoint which is hit by dyld when the list of solib is
 547      modified.  */
 548   create_solib_event_breakpoint (target_gdbarch (), info->all_image.notifier);
 549
 550   if (info->all_image.count != 0)
 551     {
 552       /* Possible relocate the main executable (PIE).  */
 553       load_addr = darwin_read_exec_load_addr_from_dyld (info);
 554     }
 555   else
 556     {
 557       /* Possible issue:
 558          Do not break on the notifier if dyld is not initialized (deduced from
 559          count == 0).  In that case, dyld hasn't relocated itself and the
 560          notifier may point to a wrong address.  */
 561
 562       load_addr = darwin_read_exec_load_addr_at_init (info);
 563     }
 564
 565   if (load_addr != 0 && symfile_objfile != NULL)
 566     {
 567       CORE_ADDR vmaddr;
 568
 569       /* Find the base address of the executable.  */
 570       vmaddr = bfd_mach_o_get_base_address (exec_bfd);
 571
 572       /* Relocate.  */
 573       if (vmaddr != load_addr)
 574         objfile_rebase (symfile_objfile, load_addr - vmaddr);
 575     }
 576 }
 577
 578 static void
 579 darwin_clear_solib (void)
 580 {
 581   struct darwin_info *info = get_darwin_info ();
 582
 583   info->all_image_addr = 0;
 584   info->all_image.version = 0;
 585 }
 586
 587 static void
 588 darwin_free_so (struct so_list *so)
 589 {
 590 }
 591
 592 /* The section table is built from bfd sections using bfd VMAs.
 593    Relocate these VMAs according to solib info.  */
 594
 595 static void
 596 darwin_relocate_section_addresses (struct so_list *so,
 597                                    struct target_section *sec)
 598 {
 599   sec->addr += so->lm_info->lm_addr;
 600   sec->endaddr += so->lm_info->lm_addr;
 601
 602   /* Best effort to set addr_high/addr_low.  This is used only by
 603      'info sharedlibary'.  */
 604   if (so->addr_high == 0)
 605     {
 606       so->addr_low = sec->addr;
 607       so->addr_high = sec->endaddr;
 608     }
 609   if (sec->endaddr > so->addr_high)
 610     so->addr_high = sec->endaddr;
 611   if (sec->addr < so->addr_low)
 612     so->addr_low = sec->addr;
 613 }
 614 \f
 615 static struct block_symbol
 616 darwin_lookup_lib_symbol (struct objfile *objfile,
 617                           const char *name,
 618                           const domain_enum domain)
 619 {
 620   return (struct block_symbol) {NULL, NULL};
 621 }
 622
 623 static gdb_bfd_ref_ptr
 624 darwin_bfd_open (char *pathname)
 625 {
 626   char *found_pathname;
 627   int found_file;
 628
 629   /* Search for shared library file.  */
 630   found_pathname = solib_find (pathname, &found_file);
 631   if (found_pathname == NULL)
 632     perror_with_name (pathname);
 633
 634   /* Open bfd for shared library.  */
 635   gdb_bfd_ref_ptr abfd (solib_bfd_fopen (found_pathname, found_file));
 636
 637   gdb_bfd_ref_ptr res
 638     (gdb_bfd_mach_o_fat_extract (abfd.get (), bfd_object,
 639                                  gdbarch_bfd_arch_info (target_gdbarch ())));
 640   if (res == NULL)
 641     error (_("`%s': not a shared-library: %s"),
 642            bfd_get_filename (abfd.get ()), bfd_errmsg (bfd_get_error ()));
 643
 644   /* The current filename for fat-binary BFDs is a name generated
 645      by BFD, usually a string containing the name of the architecture.
 646      Reset its value to the actual filename.  */
 647   xfree (bfd_get_filename (res.get ()));
 648   res->filename = xstrdup (pathname);
 649
 650   return res;
 651 }
 652
 653 struct target_so_ops darwin_so_ops;
 654
 655 /* -Wmissing-prototypes */
 656 extern initialize_file_ftype _initialize_darwin_solib;
 657
 658 void
 659 _initialize_darwin_solib (void)
 660 {
 661   solib_darwin_pspace_data
 662     = register_program_space_data_with_cleanup (NULL,
 663                                                 darwin_pspace_data_cleanup);
 664
 665   darwin_so_ops.relocate_section_addresses = darwin_relocate_section_addresses;
 666   darwin_so_ops.free_so = darwin_free_so;
 667   darwin_so_ops.clear_solib = darwin_clear_solib;
 668   darwin_so_ops.solib_create_inferior_hook = darwin_solib_create_inferior_hook;
 669   darwin_so_ops.current_sos = darwin_current_sos;
 670   darwin_so_ops.open_symbol_file_object = open_symbol_file_object;
 671   darwin_so_ops.in_dynsym_resolve_code = darwin_in_dynsym_resolve_code;
 672   darwin_so_ops.lookup_lib_global_symbol = darwin_lookup_lib_symbol;
 673   darwin_so_ops.bfd_open = darwin_bfd_open;
 674 }