gdb/solib-darwin.c

   1 /* Handle Darwin shared libraries for GDB, the GNU Debugger.
   2
   3    Copyright (C) 2009-2012 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 "gdb_assert.h"
  34
  35 #include "solist.h"
  36 #include "solib.h"
  37 #include "solib-svr4.h"
  38
  39 #include "bfd-target.h"
  40 #include "elf-bfd.h"
  41 #include "exec.h"
  42 #include "auxv.h"
  43 #include "exceptions.h"
  44 #include "mach-o.h"
  45 #include "mach-o/external.h"
  46
  47 struct gdb_dyld_image_info
  48 {
  49   /* Base address (which corresponds to the Mach-O header).  */
  50   CORE_ADDR mach_header;
  51   /* Image file path.  */
  52   CORE_ADDR file_path;
  53   /* st.m_time of image file.  */
  54   unsigned long mtime;
  55 };
  56
  57 /* Content of inferior dyld_all_image_infos structure.
  58    See /usr/include/mach-o/dyld_images.h for the documentation.  */
  59 struct gdb_dyld_all_image_infos
  60 {
  61   /* Version (1).  */
  62   unsigned int version;
  63   /* Number of images.  */
  64   unsigned int count;
  65   /* Image description.  */
  66   CORE_ADDR info;
  67   /* Notifier (function called when a library is added or removed).  */
  68   CORE_ADDR notifier;
  69 };
  70
  71 /* Current all_image_infos version.  */
  72 #define DYLD_VERSION_MIN 1
  73 #define DYLD_VERSION_MAX 12
  74
  75 /* Per PSPACE specific data.  */
  76 struct darwin_info
  77 {
  78   /* Address of structure dyld_all_image_infos in inferior.  */
  79   CORE_ADDR all_image_addr;
  80
  81   /* Gdb copy of dyld_all_info_infos.  */
  82   struct gdb_dyld_all_image_infos all_image;
  83 };
  84
  85 /* Per-program-space data key.  */
  86 static const struct program_space_data *solib_darwin_pspace_data;
  87
  88 static void
  89 darwin_pspace_data_cleanup (struct program_space *pspace, void *arg)
  90 {
  91   struct darwin_info *info;
  92
  93   info = program_space_data (pspace, solib_darwin_pspace_data);
  94   xfree (info);
  95 }
  96
  97 /* Get the current darwin data.  If none is found yet, add it now.  This
  98    function always returns a valid object.  */
  99
 100 static struct darwin_info *
 101 get_darwin_info (void)
 102 {
 103   struct darwin_info *info;
 104
 105   info = program_space_data (current_program_space, solib_darwin_pspace_data);
 106   if (info != NULL)
 107     return info;
 108
 109   info = XZALLOC (struct darwin_info);
 110   set_program_space_data (current_program_space,
 111                           solib_darwin_pspace_data, info);
 112   return info;
 113 }
 114
 115 /* Return non-zero if the version in dyld_all_image is known.  */
 116
 117 static int
 118 darwin_dyld_version_ok (const struct darwin_info *info)
 119 {
 120   return info->all_image.version >= DYLD_VERSION_MIN
 121     && info->all_image.version <= DYLD_VERSION_MAX;
 122 }
 123
 124 /* Read dyld_all_image from inferior.  */
 125
 126 static void
 127 darwin_load_image_infos (struct darwin_info *info)
 128 {
 129   gdb_byte buf[24];
 130   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 131   struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
 132   int len;
 133
 134   /* If the structure address is not known, don't continue.  */
 135   if (info->all_image_addr == 0)
 136     return;
 137
 138   /* The structure has 4 fields: version (4 bytes), count (4 bytes),
 139      info (pointer) and notifier (pointer).  */
 140   len = 4 + 4 + 2 * ptr_type->length;
 141   gdb_assert (len <= sizeof (buf));
 142   memset (&info->all_image, 0, sizeof (info->all_image));
 143
 144   /* Read structure raw bytes from target.  */
 145   if (target_read_memory (info->all_image_addr, buf, len))
 146     return;
 147
 148   /* Extract the fields.  */
 149   info->all_image.version = extract_unsigned_integer (buf, 4, byte_order);
 150   if (!darwin_dyld_version_ok (info))
 151     return;
 152
 153   info->all_image.count = extract_unsigned_integer (buf + 4, 4, byte_order);
 154   info->all_image.info = extract_typed_address (buf + 8, ptr_type);
 155   info->all_image.notifier = extract_typed_address
 156     (buf + 8 + ptr_type->length, ptr_type);
 157 }
 158
 159 /* Link map info to include in an allocated so_list entry.  */
 160
 161 struct lm_info
 162 {
 163   /* The target location of lm.  */
 164   CORE_ADDR lm_addr;
 165 };
 166
 167 struct darwin_so_list
 168 {
 169   /* Common field.  */
 170   struct so_list sl;
 171   /* Darwin specific data.  */
 172   struct lm_info li;
 173 };
 174
 175 /* Lookup the value for a specific symbol.  */
 176
 177 static CORE_ADDR
 178 lookup_symbol_from_bfd (bfd *abfd, char *symname)
 179 {
 180   long storage_needed;
 181   asymbol **symbol_table;
 182   unsigned int number_of_symbols;
 183   unsigned int i;
 184   CORE_ADDR symaddr = 0;
 185
 186   storage_needed = bfd_get_symtab_upper_bound (abfd);
 187
 188   if (storage_needed <= 0)
 189     return 0;
 190
 191   symbol_table = (asymbol **) xmalloc (storage_needed);
 192   number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table);
 193
 194   for (i = 0; i < number_of_symbols; i++)
 195     {
 196       asymbol *sym = symbol_table[i];
 197
 198       if (strcmp (sym->name, symname) == 0
 199           && (sym->section->flags & (SEC_CODE | SEC_DATA)) != 0)
 200         {
 201           /* BFD symbols are section relative.  */
 202           symaddr = sym->value + sym->section->vma;
 203           break;
 204         }
 205     }
 206   xfree (symbol_table);
 207
 208   return symaddr;
 209 }
 210
 211 /* Return program interpreter string.  */
 212
 213 static gdb_byte *
 214 find_program_interpreter (void)
 215 {
 216   gdb_byte *buf = NULL;
 217
 218   /* If we have an exec_bfd, get the interpreter from the load commands.  */
 219   if (exec_bfd)
 220     {
 221       bfd_mach_o_load_command *cmd;
 222
 223       if (bfd_mach_o_lookup_command (exec_bfd,
 224                                      BFD_MACH_O_LC_LOAD_DYLINKER, &cmd) == 1)
 225         return cmd->command.dylinker.name_str;
 226     }
 227
 228   /* If we didn't find it, read from memory.
 229      FIXME: todo.  */
 230   return buf;
 231 }
 232
 233 /*  Not used.  I don't see how the main symbol file can be found: the
 234     interpreter name is needed and it is known from the executable file.
 235     Note that darwin-nat.c implements pid_to_exec_file.  */
 236
 237 static int
 238 open_symbol_file_object (void *from_ttyp)
 239 {
 240   return 0;
 241 }
 242
 243 /* Build a list of currently loaded shared objects.  See solib-svr4.c.  */
 244
 245 static struct so_list *
 246 darwin_current_sos (void)
 247 {
 248   struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
 249   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 250   int ptr_len = TYPE_LENGTH (ptr_type);
 251   unsigned int image_info_size;
 252   struct so_list *head = NULL;
 253   struct so_list *tail = NULL;
 254   int i;
 255   struct darwin_info *info = get_darwin_info ();
 256
 257   /* Be sure image infos are loaded.  */
 258   darwin_load_image_infos (info);
 259
 260   if (!darwin_dyld_version_ok (info))
 261     return NULL;
 262
 263   image_info_size = ptr_len * 3;
 264
 265   /* Read infos for each solib.
 266      The first entry was rumored to be the executable itself, but this is not
 267      true when a large number of shared libraries are used (table expanded ?).
 268      We now check all entries, but discard executable images.  */
 269   for (i = 0; i < info->all_image.count; i++)
 270     {
 271       CORE_ADDR iinfo = info->all_image.info + i * image_info_size;
 272       char buf[image_info_size];
 273       CORE_ADDR load_addr;
 274       CORE_ADDR path_addr;
 275       struct mach_o_header_external hdr;
 276       unsigned long hdr_val;
 277       char *file_path;
 278       int errcode;
 279       struct darwin_so_list *dnew;
 280       struct so_list *new;
 281       struct cleanup *old_chain;
 282
 283       /* Read image info from inferior.  */
 284       if (target_read_memory (iinfo, buf, image_info_size))
 285         break;
 286
 287       load_addr = extract_typed_address (buf, ptr_type);
 288       path_addr = extract_typed_address (buf + ptr_len, ptr_type);
 289
 290       /* Read Mach-O header from memory.  */
 291       if (target_read_memory (load_addr, (char *) &hdr, sizeof (hdr) - 4))
 292         break;
 293       /* Discard wrong magic numbers.  Shouldn't happen.  */
 294       hdr_val = extract_unsigned_integer
 295         (hdr.magic, sizeof (hdr.magic), byte_order);
 296       if (hdr_val != BFD_MACH_O_MH_MAGIC && hdr_val != BFD_MACH_O_MH_MAGIC_64)
 297         continue;
 298       /* Discard executable.  Should happen only once.  */
 299       hdr_val = extract_unsigned_integer
 300         (hdr.filetype, sizeof (hdr.filetype), byte_order);
 301       if (hdr_val == BFD_MACH_O_MH_EXECUTE)
 302         continue;
 303
 304       target_read_string (path_addr, &file_path,
 305                           SO_NAME_MAX_PATH_SIZE - 1, &errcode);
 306       if (errcode)
 307         break;
 308
 309       /* Create and fill the new so_list element.  */
 310       dnew = XZALLOC (struct darwin_so_list);
 311       new = &dnew->sl;
 312       old_chain = make_cleanup (xfree, dnew);
 313
 314       new->lm_info = &dnew->li;
 315
 316       strncpy (new->so_name, file_path, SO_NAME_MAX_PATH_SIZE - 1);
 317       new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
 318       strcpy (new->so_original_name, new->so_name);
 319       xfree (file_path);
 320       new->lm_info->lm_addr = load_addr;
 321
 322       if (head == NULL)
 323         head = new;
 324       else
 325         tail->next = new;
 326       tail = new;
 327
 328       discard_cleanups (old_chain);
 329     }
 330
 331   return head;
 332 }
 333
 334 /* Return 1 if PC lies in the dynamic symbol resolution code of the
 335    run time loader.  */
 336
 337 static int
 338 darwin_in_dynsym_resolve_code (CORE_ADDR pc)
 339 {
 340   return 0;
 341 }
 342
 343
 344 /* No special symbol handling.  */
 345
 346 static void
 347 darwin_special_symbol_handling (void)
 348 {
 349 }
 350
 351 /* A wrapper for bfd_mach_o_fat_extract that handles reference
 352    counting properly.  This will either return NULL, or return a new
 353    reference to a BFD.  */
 354
 355 static bfd *
 356 gdb_bfd_mach_o_fat_extract (bfd *abfd, bfd_format format,
 357                             const bfd_arch_info_type *arch)
 358 {
 359   bfd *result = bfd_mach_o_fat_extract (abfd, format, arch);
 360
 361   if (result == NULL)
 362     return NULL;
 363
 364   if (result == abfd)
 365     gdb_bfd_ref (result);
 366   else
 367     gdb_bfd_mark_parent (result, abfd);
 368
 369   return result;
 370 }
 371
 372 /* Extract dyld_all_image_addr when the process was just created, assuming the
 373    current PC is at the entry of the dynamic linker.  */
 374
 375 static void
 376 darwin_solib_get_all_image_info_addr_at_init (struct darwin_info *info)
 377 {
 378   gdb_byte *interp_name;
 379   CORE_ADDR load_addr = 0;
 380   bfd *dyld_bfd = NULL;
 381   struct cleanup *cleanup;
 382
 383   /* This method doesn't work with an attached process.  */
 384   if (current_inferior ()->attach_flag)
 385     return;
 386
 387   /* Find the program interpreter.  */
 388   interp_name = find_program_interpreter ();
 389   if (!interp_name)
 390     return;
 391
 392   cleanup = make_cleanup (null_cleanup, NULL);
 393
 394   /* Create a bfd for the interpreter.  */
 395   dyld_bfd = gdb_bfd_open (interp_name, gnutarget, -1);
 396   if (dyld_bfd)
 397     {
 398       bfd *sub;
 399
 400       make_cleanup_bfd_unref (dyld_bfd);
 401       sub = gdb_bfd_mach_o_fat_extract (dyld_bfd, bfd_object,
 402                                         gdbarch_bfd_arch_info (target_gdbarch ()));
 403       if (sub)
 404         {
 405           dyld_bfd = sub;
 406           make_cleanup_bfd_unref (sub);
 407         }
 408       else
 409         dyld_bfd = NULL;
 410     }
 411   if (!dyld_bfd)
 412     {
 413       do_cleanups (cleanup);
 414       return;
 415     }
 416
 417   /* We find the dynamic linker's base address by examining
 418      the current pc (which should point at the entry point for the
 419      dynamic linker) and subtracting the offset of the entry point.  */
 420   load_addr = (regcache_read_pc (get_current_regcache ())
 421                - bfd_get_start_address (dyld_bfd));
 422
 423   /* Now try to set a breakpoint in the dynamic linker.  */
 424   info->all_image_addr =
 425     lookup_symbol_from_bfd (dyld_bfd, "_dyld_all_image_infos");
 426
 427   do_cleanups (cleanup);
 428
 429   if (info->all_image_addr == 0)
 430     return;
 431
 432   info->all_image_addr += load_addr;
 433 }
 434
 435 /* Extract dyld_all_image_addr reading it from
 436    TARGET_OBJECT_DARWIN_DYLD_INFO.  */
 437
 438 static void
 439 darwin_solib_read_all_image_info_addr (struct darwin_info *info)
 440 {
 441   gdb_byte buf[8 + 8 + 4];
 442   LONGEST len;
 443   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 444
 445   len = target_read (&current_target, TARGET_OBJECT_DARWIN_DYLD_INFO, NULL,
 446                      buf, 0, sizeof (buf));
 447   if (len != sizeof (buf))
 448     return;
 449
 450   info->all_image_addr = extract_unsigned_integer (buf, 8, byte_order);
 451 }
 452
 453 /* Shared library startup support.  See documentation in solib-svr4.c.  */
 454
 455 static void
 456 darwin_solib_create_inferior_hook (int from_tty)
 457 {
 458   struct darwin_info *info = get_darwin_info ();
 459
 460   info->all_image_addr = 0;
 461
 462   darwin_solib_read_all_image_info_addr (info);
 463
 464   if (info->all_image_addr == 0)
 465     darwin_solib_get_all_image_info_addr_at_init (info);
 466
 467   if (info->all_image_addr == 0)
 468     return;
 469
 470   darwin_load_image_infos (info);
 471
 472   if (darwin_dyld_version_ok (info))
 473     create_solib_event_breakpoint (target_gdbarch (), info->all_image.notifier);
 474 }
 475
 476 static void
 477 darwin_clear_solib (void)
 478 {
 479   struct darwin_info *info = get_darwin_info ();
 480
 481   info->all_image_addr = 0;
 482   info->all_image.version = 0;
 483 }
 484
 485 static void
 486 darwin_free_so (struct so_list *so)
 487 {
 488 }
 489
 490 /* The section table is built from bfd sections using bfd VMAs.
 491    Relocate these VMAs according to solib info.  */
 492
 493 static void
 494 darwin_relocate_section_addresses (struct so_list *so,
 495                                    struct target_section *sec)
 496 {
 497   sec->addr += so->lm_info->lm_addr;
 498   sec->endaddr += so->lm_info->lm_addr;
 499
 500   /* Best effort to set addr_high/addr_low.  This is used only by
 501      'info sharedlibary'.  */
 502   if (so->addr_high == 0)
 503     {
 504       so->addr_low = sec->addr;
 505       so->addr_high = sec->endaddr;
 506     }
 507   if (sec->endaddr > so->addr_high)
 508     so->addr_high = sec->endaddr;
 509   if (sec->addr < so->addr_low)
 510     so->addr_low = sec->addr;
 511 }
 512 \f
 513 static struct symbol *
 514 darwin_lookup_lib_symbol (const struct objfile *objfile,
 515                           const char *name,
 516                           const domain_enum domain)
 517 {
 518   return NULL;
 519 }
 520
 521 static bfd *
 522 darwin_bfd_open (char *pathname)
 523 {
 524   char *found_pathname;
 525   int found_file;
 526   bfd *abfd;
 527   bfd *res;
 528
 529   /* Search for shared library file.  */
 530   found_pathname = solib_find (pathname, &found_file);
 531   if (found_pathname == NULL)
 532     perror_with_name (pathname);
 533
 534   /* Open bfd for shared library.  */
 535   abfd = solib_bfd_fopen (found_pathname, found_file);
 536
 537   res = gdb_bfd_mach_o_fat_extract (abfd, bfd_object,
 538                                     gdbarch_bfd_arch_info (target_gdbarch ()));
 539   if (!res)
 540     {
 541       make_cleanup_bfd_unref (abfd);
 542       error (_("`%s': not a shared-library: %s"),
 543              bfd_get_filename (abfd), bfd_errmsg (bfd_get_error ()));
 544     }
 545
 546   gdb_bfd_unref (abfd);
 547   return res;
 548 }
 549
 550 struct target_so_ops darwin_so_ops;
 551
 552 /* -Wmissing-prototypes */
 553 extern initialize_file_ftype _initialize_darwin_solib;
 554
 555 void
 556 _initialize_darwin_solib (void)
 557 {
 558   solib_darwin_pspace_data
 559     = register_program_space_data_with_cleanup (NULL,
 560                                                 darwin_pspace_data_cleanup);
 561
 562   darwin_so_ops.relocate_section_addresses = darwin_relocate_section_addresses;
 563   darwin_so_ops.free_so = darwin_free_so;
 564   darwin_so_ops.clear_solib = darwin_clear_solib;
 565   darwin_so_ops.solib_create_inferior_hook = darwin_solib_create_inferior_hook;
 566   darwin_so_ops.special_symbol_handling = darwin_special_symbol_handling;
 567   darwin_so_ops.current_sos = darwin_current_sos;
 568   darwin_so_ops.open_symbol_file_object = open_symbol_file_object;
 569   darwin_so_ops.in_dynsym_resolve_code = darwin_in_dynsym_resolve_code;
 570   darwin_so_ops.lookup_lib_global_symbol = darwin_lookup_lib_symbol;
 571   darwin_so_ops.bfd_open = darwin_bfd_open;
 572 }