gdb/solib-sunos.c

   1 /* Handle SunOS shared libraries for GDB, the GNU Debugger.
   2    Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000,
   3    2001
   4    Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program 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 of the License, or
  11    (at your option) any later version.
  12
  13    This program 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 this program; if not, write to the Free Software
  20    Foundation, Inc., 59 Temple Place - Suite 330,
  21    Boston, MA 02111-1307, USA.  */
  22
  23 #include "defs.h"
  24
  25 #include <sys/types.h>
  26 #include <signal.h>
  27 #include "gdb_string.h"
  28 #include <sys/param.h>
  29 #include <fcntl.h>
  30
  31  /* SunOS shared libs need the nlist structure.  */
  32 #include <a.out.h>
  33 #include <link.h>
  34
  35 #include "symtab.h"
  36 #include "bfd.h"
  37 #include "symfile.h"
  38 #include "objfiles.h"
  39 #include "gdbcore.h"
  40 #include "inferior.h"
  41 #include "solist.h"
  42
  43 /* Link map info to include in an allocated so_list entry */
  44
  45 struct lm_info
  46   {
  47     /* Pointer to copy of link map from inferior.  The type is char *
  48        rather than void *, so that we may use byte offsets to find the
  49        various fields without the need for a cast.  */
  50     char *lm;
  51   };
  52
  53
  54 /* Symbols which are used to locate the base of the link map structures. */
  55
  56 static char *debug_base_symbols[] =
  57 {
  58   "_DYNAMIC",
  59   "_DYNAMIC__MGC",
  60   NULL
  61 };
  62
  63 static char *main_name_list[] =
  64 {
  65   "main_$main",
  66   NULL
  67 };
  68
  69 /* Macro to extract an address from a solib structure.
  70    When GDB is configured for some 32-bit targets (e.g. Solaris 2.7
  71    sparc), BFD is configured to handle 64-bit targets, so CORE_ADDR is
  72    64 bits.  We have to extract only the significant bits of addresses
  73    to get the right address when accessing the core file BFD.  */
  74
  75 #define SOLIB_EXTRACT_ADDRESS(MEMBER) \
  76         extract_address (&(MEMBER), sizeof (MEMBER))
  77
  78 /* local data declarations */
  79
  80 static struct link_dynamic dynamic_copy;
  81 static struct link_dynamic_2 ld_2_copy;
  82 static struct ld_debug debug_copy;
  83 static CORE_ADDR debug_addr;
  84 static CORE_ADDR flag_addr;
  85
  86 #ifndef offsetof
  87 #define offsetof(TYPE, MEMBER) ((unsigned long) &((TYPE *)0)->MEMBER)
  88 #endif
  89 #define fieldsize(TYPE, MEMBER) (sizeof (((TYPE *)0)->MEMBER))
  90
  91 /* link map access functions */
  92
  93 static CORE_ADDR
  94 LM_ADDR (struct so_list *so)
  95 {
  96   int lm_addr_offset = offsetof (struct link_map, lm_addr);
  97   int lm_addr_size = fieldsize (struct link_map, lm_addr);
  98
  99   return (CORE_ADDR) extract_signed_integer (so->lm_info->lm + lm_addr_offset,
 100                                              lm_addr_size);
 101 }
 102
 103 static CORE_ADDR
 104 LM_NEXT (struct so_list *so)
 105 {
 106   int lm_next_offset = offsetof (struct link_map, lm_next);
 107   int lm_next_size = fieldsize (struct link_map, lm_next);
 108
 109   return extract_address (so->lm_info->lm + lm_next_offset, lm_next_size);
 110 }
 111
 112 static CORE_ADDR
 113 LM_NAME (struct so_list *so)
 114 {
 115   int lm_name_offset = offsetof (struct link_map, lm_name);
 116   int lm_name_size = fieldsize (struct link_map, lm_name);
 117
 118   return extract_address (so->lm_info->lm + lm_name_offset, lm_name_size);
 119 }
 120
 121 static CORE_ADDR debug_base;    /* Base of dynamic linker structures */
 122
 123 /* Local function prototypes */
 124
 125 static int match_main (char *);
 126
 127 /* Allocate the runtime common object file.  */
 128
 129 static void
 130 allocate_rt_common_objfile (void)
 131 {
 132   struct objfile *objfile;
 133   struct objfile *last_one;
 134
 135   objfile = (struct objfile *) xmalloc (sizeof (struct objfile));
 136   memset (objfile, 0, sizeof (struct objfile));
 137   objfile->md = NULL;
 138   obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0,
 139                               xmalloc, xfree);
 140   obstack_specify_allocation (&objfile->macro_cache.cache, 0, 0,
 141                               xmalloc, xfree);
 142   obstack_specify_allocation (&objfile->psymbol_obstack, 0, 0, xmalloc,
 143                               xfree);
 144   obstack_specify_allocation (&objfile->symbol_obstack, 0, 0, xmalloc,
 145                               xfree);
 146   obstack_specify_allocation (&objfile->type_obstack, 0, 0, xmalloc,
 147                               xfree);
 148   objfile->name = mstrsave (objfile->md, "rt_common");
 149
 150   /* Add this file onto the tail of the linked list of other such files. */
 151
 152   objfile->next = NULL;
 153   if (object_files == NULL)
 154     object_files = objfile;
 155   else
 156     {
 157       for (last_one = object_files;
 158            last_one->next;
 159            last_one = last_one->next);
 160       last_one->next = objfile;
 161     }
 162
 163   rt_common_objfile = objfile;
 164 }
 165
 166 /* Read all dynamically loaded common symbol definitions from the inferior
 167    and put them into the minimal symbol table for the runtime common
 168    objfile.  */
 169
 170 static void
 171 solib_add_common_symbols (CORE_ADDR rtc_symp)
 172 {
 173   struct rtc_symb inferior_rtc_symb;
 174   struct nlist inferior_rtc_nlist;
 175   int len;
 176   char *name;
 177
 178   /* Remove any runtime common symbols from previous runs.  */
 179
 180   if (rt_common_objfile != NULL && rt_common_objfile->minimal_symbol_count)
 181     {
 182       obstack_free (&rt_common_objfile->symbol_obstack, 0);
 183       obstack_specify_allocation (&rt_common_objfile->symbol_obstack, 0, 0,
 184                                   xmalloc, xfree);
 185       rt_common_objfile->minimal_symbol_count = 0;
 186       rt_common_objfile->msymbols = NULL;
 187     }
 188
 189   init_minimal_symbol_collection ();
 190   make_cleanup_discard_minimal_symbols ();
 191
 192   while (rtc_symp)
 193     {
 194       read_memory (rtc_symp,
 195                    (char *) &inferior_rtc_symb,
 196                    sizeof (inferior_rtc_symb));
 197       read_memory (SOLIB_EXTRACT_ADDRESS (inferior_rtc_symb.rtc_sp),
 198                    (char *) &inferior_rtc_nlist,
 199                    sizeof (inferior_rtc_nlist));
 200       if (inferior_rtc_nlist.n_type == N_COMM)
 201         {
 202           /* FIXME: The length of the symbol name is not available, but in the
 203              current implementation the common symbol is allocated immediately
 204              behind the name of the symbol. */
 205           len = inferior_rtc_nlist.n_value - inferior_rtc_nlist.n_un.n_strx;
 206
 207           name = xmalloc (len);
 208           read_memory (SOLIB_EXTRACT_ADDRESS (inferior_rtc_nlist.n_un.n_name),
 209                        name, len);
 210
 211           /* Allocate the runtime common objfile if necessary. */
 212           if (rt_common_objfile == NULL)
 213             allocate_rt_common_objfile ();
 214
 215           prim_record_minimal_symbol (name, inferior_rtc_nlist.n_value,
 216                                       mst_bss, rt_common_objfile);
 217           xfree (name);
 218         }
 219       rtc_symp = SOLIB_EXTRACT_ADDRESS (inferior_rtc_symb.rtc_next);
 220     }
 221
 222   /* Install any minimal symbols that have been collected as the current
 223      minimal symbols for the runtime common objfile.  */
 224
 225   install_minimal_symbols (rt_common_objfile);
 226 }
 227
 228
 229 /*
 230
 231    LOCAL FUNCTION
 232
 233    locate_base -- locate the base address of dynamic linker structs
 234
 235    SYNOPSIS
 236
 237    CORE_ADDR locate_base (void)
 238
 239    DESCRIPTION
 240
 241    For both the SunOS and SVR4 shared library implementations, if the
 242    inferior executable has been linked dynamically, there is a single
 243    address somewhere in the inferior's data space which is the key to
 244    locating all of the dynamic linker's runtime structures.  This
 245    address is the value of the debug base symbol.  The job of this
 246    function is to find and return that address, or to return 0 if there
 247    is no such address (the executable is statically linked for example).
 248
 249    For SunOS, the job is almost trivial, since the dynamic linker and
 250    all of it's structures are statically linked to the executable at
 251    link time.  Thus the symbol for the address we are looking for has
 252    already been added to the minimal symbol table for the executable's
 253    objfile at the time the symbol file's symbols were read, and all we
 254    have to do is look it up there.  Note that we explicitly do NOT want
 255    to find the copies in the shared library.
 256
 257    The SVR4 version is a bit more complicated because the address
 258    is contained somewhere in the dynamic info section.  We have to go
 259    to a lot more work to discover the address of the debug base symbol.
 260    Because of this complexity, we cache the value we find and return that
 261    value on subsequent invocations.  Note there is no copy in the
 262    executable symbol tables.
 263
 264  */
 265
 266 static CORE_ADDR
 267 locate_base (void)
 268 {
 269   struct minimal_symbol *msymbol;
 270   CORE_ADDR address = 0;
 271   char **symbolp;
 272
 273   /* For SunOS, we want to limit the search for the debug base symbol to the
 274      executable being debugged, since there is a duplicate named symbol in the
 275      shared library.  We don't want the shared library versions. */
 276
 277   for (symbolp = debug_base_symbols; *symbolp != NULL; symbolp++)
 278     {
 279       msymbol = lookup_minimal_symbol (*symbolp, NULL, symfile_objfile);
 280       if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0))
 281         {
 282           address = SYMBOL_VALUE_ADDRESS (msymbol);
 283           return (address);
 284         }
 285     }
 286   return (0);
 287 }
 288
 289 /*
 290
 291    LOCAL FUNCTION
 292
 293    first_link_map_member -- locate first member in dynamic linker's map
 294
 295    SYNOPSIS
 296
 297    static CORE_ADDR first_link_map_member (void)
 298
 299    DESCRIPTION
 300
 301    Find the first element in the inferior's dynamic link map, and
 302    return its address in the inferior.  This function doesn't copy the
 303    link map entry itself into our address space; current_sos actually
 304    does the reading.  */
 305
 306 static CORE_ADDR
 307 first_link_map_member (void)
 308 {
 309   CORE_ADDR lm = 0;
 310
 311   read_memory (debug_base, (char *) &dynamic_copy, sizeof (dynamic_copy));
 312   if (dynamic_copy.ld_version >= 2)
 313     {
 314       /* It is a version that we can deal with, so read in the secondary
 315          structure and find the address of the link map list from it. */
 316       read_memory (SOLIB_EXTRACT_ADDRESS (dynamic_copy.ld_un.ld_2),
 317                    (char *) &ld_2_copy, sizeof (struct link_dynamic_2));
 318       lm = SOLIB_EXTRACT_ADDRESS (ld_2_copy.ld_loaded);
 319     }
 320   return (lm);
 321 }
 322
 323 static int
 324 open_symbol_file_object (void *from_ttyp)
 325 {
 326   return 1;
 327 }
 328
 329
 330 /* LOCAL FUNCTION
 331
 332    current_sos -- build a list of currently loaded shared objects
 333
 334    SYNOPSIS
 335
 336    struct so_list *current_sos ()
 337
 338    DESCRIPTION
 339
 340    Build a list of `struct so_list' objects describing the shared
 341    objects currently loaded in the inferior.  This list does not
 342    include an entry for the main executable file.
 343
 344    Note that we only gather information directly available from the
 345    inferior --- we don't examine any of the shared library files
 346    themselves.  The declaration of `struct so_list' says which fields
 347    we provide values for.  */
 348
 349 static struct so_list *
 350 sunos_current_sos (void)
 351 {
 352   CORE_ADDR lm;
 353   struct so_list *head = 0;
 354   struct so_list **link_ptr = &head;
 355   int errcode;
 356   char *buffer;
 357
 358   /* Make sure we've looked up the inferior's dynamic linker's base
 359      structure.  */
 360   if (! debug_base)
 361     {
 362       debug_base = locate_base ();
 363
 364       /* If we can't find the dynamic linker's base structure, this
 365          must not be a dynamically linked executable.  Hmm.  */
 366       if (! debug_base)
 367         return 0;
 368     }
 369
 370   /* Walk the inferior's link map list, and build our list of
 371      `struct so_list' nodes.  */
 372   lm = first_link_map_member ();
 373   while (lm)
 374     {
 375       struct so_list *new
 376         = (struct so_list *) xmalloc (sizeof (struct so_list));
 377       struct cleanup *old_chain = make_cleanup (xfree, new);
 378
 379       memset (new, 0, sizeof (*new));
 380
 381       new->lm_info = xmalloc (sizeof (struct lm_info));
 382       make_cleanup (xfree, new->lm_info);
 383
 384       new->lm_info->lm = xmalloc (sizeof (struct link_map));
 385       make_cleanup (xfree, new->lm_info->lm);
 386       memset (new->lm_info->lm, 0, sizeof (struct link_map));
 387
 388       read_memory (lm, new->lm_info->lm, sizeof (struct link_map));
 389
 390       lm = LM_NEXT (new);
 391
 392       /* Extract this shared object's name.  */
 393       target_read_string (LM_NAME (new), &buffer,
 394                           SO_NAME_MAX_PATH_SIZE - 1, &errcode);
 395       if (errcode != 0)
 396         {
 397           warning ("current_sos: Can't read pathname for load map: %s\n",
 398                    safe_strerror (errcode));
 399         }
 400       else
 401         {
 402           strncpy (new->so_name, buffer, SO_NAME_MAX_PATH_SIZE - 1);
 403           new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
 404           xfree (buffer);
 405           strcpy (new->so_original_name, new->so_name);
 406         }
 407
 408       /* If this entry has no name, or its name matches the name
 409          for the main executable, don't include it in the list.  */
 410       if (! new->so_name[0]
 411           || match_main (new->so_name))
 412         free_so (new);
 413       else
 414         {
 415           new->next = 0;
 416           *link_ptr = new;
 417           link_ptr = &new->next;
 418         }
 419
 420       discard_cleanups (old_chain);
 421     }
 422
 423   return head;
 424 }
 425
 426
 427 /* On some systems, the only way to recognize the link map entry for
 428    the main executable file is by looking at its name.  Return
 429    non-zero iff SONAME matches one of the known main executable names.  */
 430
 431 static int
 432 match_main (char *soname)
 433 {
 434   char **mainp;
 435
 436   for (mainp = main_name_list; *mainp != NULL; mainp++)
 437     {
 438       if (strcmp (soname, *mainp) == 0)
 439         return (1);
 440     }
 441
 442   return (0);
 443 }
 444
 445
 446 static int
 447 sunos_in_dynsym_resolve_code (CORE_ADDR pc)
 448 {
 449   return 0;
 450 }
 451
 452 /*
 453
 454    LOCAL FUNCTION
 455
 456    disable_break -- remove the "mapping changed" breakpoint
 457
 458    SYNOPSIS
 459
 460    static int disable_break ()
 461
 462    DESCRIPTION
 463
 464    Removes the breakpoint that gets hit when the dynamic linker
 465    completes a mapping change.
 466
 467  */
 468
 469 static int
 470 disable_break (void)
 471 {
 472   CORE_ADDR breakpoint_addr;    /* Address where end bkpt is set */
 473
 474   int in_debugger = 0;
 475
 476   /* Read the debugger structure from the inferior to retrieve the
 477      address of the breakpoint and the original contents of the
 478      breakpoint address.  Remove the breakpoint by writing the original
 479      contents back. */
 480
 481   read_memory (debug_addr, (char *) &debug_copy, sizeof (debug_copy));
 482
 483   /* Set `in_debugger' to zero now. */
 484
 485   write_memory (flag_addr, (char *) &in_debugger, sizeof (in_debugger));
 486
 487   breakpoint_addr = SOLIB_EXTRACT_ADDRESS (debug_copy.ldd_bp_addr);
 488   write_memory (breakpoint_addr, (char *) &debug_copy.ldd_bp_inst,
 489                 sizeof (debug_copy.ldd_bp_inst));
 490
 491   /* For the SVR4 version, we always know the breakpoint address.  For the
 492      SunOS version we don't know it until the above code is executed.
 493      Grumble if we are stopped anywhere besides the breakpoint address. */
 494
 495   if (stop_pc != breakpoint_addr)
 496     {
 497       warning ("stopped at unknown breakpoint while handling shared libraries");
 498     }
 499
 500   return 1;
 501 }
 502
 503
 504 /*
 505
 506    LOCAL FUNCTION
 507
 508    enable_break -- arrange for dynamic linker to hit breakpoint
 509
 510    SYNOPSIS
 511
 512    int enable_break (void)
 513
 514    DESCRIPTION
 515
 516    Both the SunOS and the SVR4 dynamic linkers have, as part of their
 517    debugger interface, support for arranging for the inferior to hit
 518    a breakpoint after mapping in the shared libraries.  This function
 519    enables that breakpoint.
 520
 521    For SunOS, there is a special flag location (in_debugger) which we
 522    set to 1.  When the dynamic linker sees this flag set, it will set
 523    a breakpoint at a location known only to itself, after saving the
 524    original contents of that place and the breakpoint address itself,
 525    in it's own internal structures.  When we resume the inferior, it
 526    will eventually take a SIGTRAP when it runs into the breakpoint.
 527    We handle this (in a different place) by restoring the contents of
 528    the breakpointed location (which is only known after it stops),
 529    chasing around to locate the shared libraries that have been
 530    loaded, then resuming.
 531
 532    For SVR4, the debugger interface structure contains a member (r_brk)
 533    which is statically initialized at the time the shared library is
 534    built, to the offset of a function (_r_debug_state) which is guaran-
 535    teed to be called once before mapping in a library, and again when
 536    the mapping is complete.  At the time we are examining this member,
 537    it contains only the unrelocated offset of the function, so we have
 538    to do our own relocation.  Later, when the dynamic linker actually
 539    runs, it relocates r_brk to be the actual address of _r_debug_state().
 540
 541    The debugger interface structure also contains an enumeration which
 542    is set to either RT_ADD or RT_DELETE prior to changing the mapping,
 543    depending upon whether or not the library is being mapped or unmapped,
 544    and then set to RT_CONSISTENT after the library is mapped/unmapped.
 545  */
 546
 547 static int
 548 enable_break (void)
 549 {
 550   int success = 0;
 551   int j;
 552   int in_debugger;
 553
 554   /* Get link_dynamic structure */
 555
 556   j = target_read_memory (debug_base, (char *) &dynamic_copy,
 557                           sizeof (dynamic_copy));
 558   if (j)
 559     {
 560       /* unreadable */
 561       return (0);
 562     }
 563
 564   /* Calc address of debugger interface structure */
 565
 566   debug_addr = SOLIB_EXTRACT_ADDRESS (dynamic_copy.ldd);
 567
 568   /* Calc address of `in_debugger' member of debugger interface structure */
 569
 570   flag_addr = debug_addr + (CORE_ADDR) ((char *) &debug_copy.ldd_in_debugger -
 571                                         (char *) &debug_copy);
 572
 573   /* Write a value of 1 to this member.  */
 574
 575   in_debugger = 1;
 576   write_memory (flag_addr, (char *) &in_debugger, sizeof (in_debugger));
 577   success = 1;
 578
 579   return (success);
 580 }
 581
 582 /*
 583
 584    LOCAL FUNCTION
 585
 586    special_symbol_handling -- additional shared library symbol handling
 587
 588    SYNOPSIS
 589
 590    void special_symbol_handling ()
 591
 592    DESCRIPTION
 593
 594    Once the symbols from a shared object have been loaded in the usual
 595    way, we are called to do any system specific symbol handling that
 596    is needed.
 597
 598    For SunOS4, this consists of grunging around in the dynamic
 599    linkers structures to find symbol definitions for "common" symbols
 600    and adding them to the minimal symbol table for the runtime common
 601    objfile.
 602
 603  */
 604
 605 static void
 606 sunos_special_symbol_handling (void)
 607 {
 608   int j;
 609
 610   if (debug_addr == 0)
 611     {
 612       /* Get link_dynamic structure */
 613
 614       j = target_read_memory (debug_base, (char *) &dynamic_copy,
 615                               sizeof (dynamic_copy));
 616       if (j)
 617         {
 618           /* unreadable */
 619           return;
 620         }
 621
 622       /* Calc address of debugger interface structure */
 623       /* FIXME, this needs work for cross-debugging of core files
 624          (byteorder, size, alignment, etc).  */
 625
 626       debug_addr = SOLIB_EXTRACT_ADDRESS (dynamic_copy.ldd);
 627     }
 628
 629   /* Read the debugger structure from the inferior, just to make sure
 630      we have a current copy. */
 631
 632   j = target_read_memory (debug_addr, (char *) &debug_copy,
 633                           sizeof (debug_copy));
 634   if (j)
 635     return;                     /* unreadable */
 636
 637   /* Get common symbol definitions for the loaded object. */
 638
 639   if (debug_copy.ldd_cp)
 640     {
 641       solib_add_common_symbols (SOLIB_EXTRACT_ADDRESS (debug_copy.ldd_cp));
 642     }
 643 }
 644
 645 /* Relocate the main executable.  This function should be called upon
 646    stopping the inferior process at the entry point to the program.
 647    The entry point from BFD is compared to the PC and if they are
 648    different, the main executable is relocated by the proper amount.
 649
 650    As written it will only attempt to relocate executables which
 651    lack interpreter sections.  It seems likely that only dynamic
 652    linker executables will get relocated, though it should work
 653    properly for a position-independent static executable as well.  */
 654
 655 static void
 656 sunos_relocate_main_executable (void)
 657 {
 658   asection *interp_sect;
 659   CORE_ADDR pc = read_pc ();
 660
 661   /* Decide if the objfile needs to be relocated.  As indicated above,
 662      we will only be here when execution is stopped at the beginning
 663      of the program.  Relocation is necessary if the address at which
 664      we are presently stopped differs from the start address stored in
 665      the executable AND there's no interpreter section.  The condition
 666      regarding the interpreter section is very important because if
 667      there *is* an interpreter section, execution will begin there
 668      instead.  When there is an interpreter section, the start address
 669      is (presumably) used by the interpreter at some point to start
 670      execution of the program.
 671
 672      If there is an interpreter, it is normal for it to be set to an
 673      arbitrary address at the outset.  The job of finding it is
 674      handled in enable_break().
 675
 676      So, to summarize, relocations are necessary when there is no
 677      interpreter section and the start address obtained from the
 678      executable is different from the address at which GDB is
 679      currently stopped.
 680
 681      [ The astute reader will note that we also test to make sure that
 682        the executable in question has the DYNAMIC flag set.  It is my
 683        opinion that this test is unnecessary (undesirable even).  It
 684        was added to avoid inadvertent relocation of an executable
 685        whose e_type member in the ELF header is not ET_DYN.  There may
 686        be a time in the future when it is desirable to do relocations
 687        on other types of files as well in which case this condition
 688        should either be removed or modified to accomodate the new file
 689        type.  (E.g, an ET_EXEC executable which has been built to be
 690        position-independent could safely be relocated by the OS if
 691        desired.  It is true that this violates the ABI, but the ABI
 692        has been known to be bent from time to time.)  - Kevin, Nov 2000. ]
 693      */
 694
 695   interp_sect = bfd_get_section_by_name (exec_bfd, ".interp");
 696   if (interp_sect == NULL
 697       && (bfd_get_file_flags (exec_bfd) & DYNAMIC) != 0
 698       && bfd_get_start_address (exec_bfd) != pc)
 699     {
 700       struct cleanup *old_chain;
 701       struct section_offsets *new_offsets;
 702       int i, changed;
 703       CORE_ADDR displacement;
 704
 705       /* It is necessary to relocate the objfile.  The amount to
 706          relocate by is simply the address at which we are stopped
 707          minus the starting address from the executable.
 708
 709          We relocate all of the sections by the same amount.  This
 710          behavior is mandated by recent editions of the System V ABI.
 711          According to the System V Application Binary Interface,
 712          Edition 4.1, page 5-5:
 713
 714            ...  Though the system chooses virtual addresses for
 715            individual processes, it maintains the segments' relative
 716            positions.  Because position-independent code uses relative
 717            addressesing between segments, the difference between
 718            virtual addresses in memory must match the difference
 719            between virtual addresses in the file.  The difference
 720            between the virtual address of any segment in memory and
 721            the corresponding virtual address in the file is thus a
 722            single constant value for any one executable or shared
 723            object in a given process.  This difference is the base
 724            address.  One use of the base address is to relocate the
 725            memory image of the program during dynamic linking.
 726
 727          The same language also appears in Edition 4.0 of the System V
 728          ABI and is left unspecified in some of the earlier editions.  */
 729
 730       displacement = pc - bfd_get_start_address (exec_bfd);
 731       changed = 0;
 732
 733       new_offsets = xcalloc (symfile_objfile->num_sections,
 734                              sizeof (struct section_offsets));
 735       old_chain = make_cleanup (xfree, new_offsets);
 736
 737       for (i = 0; i < symfile_objfile->num_sections; i++)
 738         {
 739           if (displacement != ANOFFSET (symfile_objfile->section_offsets, i))
 740             changed = 1;
 741           new_offsets->offsets[i] = displacement;
 742         }
 743
 744       if (changed)
 745         objfile_relocate (symfile_objfile, new_offsets);
 746
 747       do_cleanups (old_chain);
 748     }
 749 }
 750
 751 /*
 752
 753    GLOBAL FUNCTION
 754
 755    sunos_solib_create_inferior_hook -- shared library startup support
 756
 757    SYNOPSIS
 758
 759    void sunos_solib_create_inferior_hook()
 760
 761    DESCRIPTION
 762
 763    When gdb starts up the inferior, it nurses it along (through the
 764    shell) until it is ready to execute it's first instruction.  At this
 765    point, this function gets called via expansion of the macro
 766    SOLIB_CREATE_INFERIOR_HOOK.
 767
 768    For SunOS executables, this first instruction is typically the
 769    one at "_start", or a similar text label, regardless of whether
 770    the executable is statically or dynamically linked.  The runtime
 771    startup code takes care of dynamically linking in any shared
 772    libraries, once gdb allows the inferior to continue.
 773
 774    For SVR4 executables, this first instruction is either the first
 775    instruction in the dynamic linker (for dynamically linked
 776    executables) or the instruction at "start" for statically linked
 777    executables.  For dynamically linked executables, the system
 778    first exec's /lib/libc.so.N, which contains the dynamic linker,
 779    and starts it running.  The dynamic linker maps in any needed
 780    shared libraries, maps in the actual user executable, and then
 781    jumps to "start" in the user executable.
 782
 783    For both SunOS shared libraries, and SVR4 shared libraries, we
 784    can arrange to cooperate with the dynamic linker to discover the
 785    names of shared libraries that are dynamically linked, and the
 786    base addresses to which they are linked.
 787
 788    This function is responsible for discovering those names and
 789    addresses, and saving sufficient information about them to allow
 790    their symbols to be read at a later time.
 791
 792    FIXME
 793
 794    Between enable_break() and disable_break(), this code does not
 795    properly handle hitting breakpoints which the user might have
 796    set in the startup code or in the dynamic linker itself.  Proper
 797    handling will probably have to wait until the implementation is
 798    changed to use the "breakpoint handler function" method.
 799
 800    Also, what if child has exit()ed?  Must exit loop somehow.
 801  */
 802
 803 static void
 804 sunos_solib_create_inferior_hook (void)
 805 {
 806   /* Relocate the main executable if necessary.  */
 807   sunos_relocate_main_executable ();
 808
 809   if ((debug_base = locate_base ()) == 0)
 810     {
 811       /* Can't find the symbol or the executable is statically linked. */
 812       return;
 813     }
 814
 815   if (!enable_break ())
 816     {
 817       warning ("shared library handler failed to enable breakpoint");
 818       return;
 819     }
 820
 821   /* SCO and SunOS need the loop below, other systems should be using the
 822      special shared library breakpoints and the shared library breakpoint
 823      service routine.
 824
 825      Now run the target.  It will eventually hit the breakpoint, at
 826      which point all of the libraries will have been mapped in and we
 827      can go groveling around in the dynamic linker structures to find
 828      out what we need to know about them. */
 829
 830   clear_proceed_status ();
 831   stop_soon_quietly = 1;
 832   stop_signal = TARGET_SIGNAL_0;
 833   do
 834     {
 835       target_resume (pid_to_ptid (-1), 0, stop_signal);
 836       wait_for_inferior ();
 837     }
 838   while (stop_signal != TARGET_SIGNAL_TRAP);
 839   stop_soon_quietly = 0;
 840
 841   /* We are now either at the "mapping complete" breakpoint (or somewhere
 842      else, a condition we aren't prepared to deal with anyway), so adjust
 843      the PC as necessary after a breakpoint, disable the breakpoint, and
 844      add any shared libraries that were mapped in. */
 845
 846   if (DECR_PC_AFTER_BREAK)
 847     {
 848       stop_pc -= DECR_PC_AFTER_BREAK;
 849       write_register (PC_REGNUM, stop_pc);
 850     }
 851
 852   if (!disable_break ())
 853     {
 854       warning ("shared library handler failed to disable breakpoint");
 855     }
 856
 857   solib_add ((char *) 0, 0, (struct target_ops *) 0, auto_solib_add);
 858 }
 859
 860 static void
 861 sunos_clear_solib (void)
 862 {
 863   debug_base = 0;
 864 }
 865
 866 static void
 867 sunos_free_so (struct so_list *so)
 868 {
 869   xfree (so->lm_info->lm);
 870   xfree (so->lm_info);
 871 }
 872
 873 static void
 874 sunos_relocate_section_addresses (struct so_list *so,
 875                                  struct section_table *sec)
 876 {
 877   sec->addr += LM_ADDR (so);
 878   sec->endaddr += LM_ADDR (so);
 879 }
 880
 881 static struct target_so_ops sunos_so_ops;
 882
 883 void
 884 _initialize_sunos_solib (void)
 885 {
 886   sunos_so_ops.relocate_section_addresses = sunos_relocate_section_addresses;
 887   sunos_so_ops.free_so = sunos_free_so;
 888   sunos_so_ops.clear_solib = sunos_clear_solib;
 889   sunos_so_ops.solib_create_inferior_hook = sunos_solib_create_inferior_hook;
 890   sunos_so_ops.special_symbol_handling = sunos_special_symbol_handling;
 891   sunos_so_ops.current_sos = sunos_current_sos;
 892   sunos_so_ops.open_symbol_file_object = open_symbol_file_object;
 893   sunos_so_ops.in_dynsym_resolve_code = sunos_in_dynsym_resolve_code;
 894
 895   /* FIXME: Don't do this here.  *_gdbarch_init() should set so_ops. */
 896   current_target_so_ops = &sunos_so_ops;
 897 }