1/* Handle SunOS shared libraries for GDB, the GNU Debugger. 2 Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 3 2001, 2004 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#include "bcache.h" 43#include "regcache.h" 44 45/* Link map info to include in an allocated so_list entry */ 46 47struct lm_info 48 { 49 /* Pointer to copy of link map from inferior. The type is char * 50 rather than void *, so that we may use byte offsets to find the 51 various fields without the need for a cast. */ 52 char *lm; 53 }; 54 55 56/* Symbols which are used to locate the base of the link map structures. */ 57 58static char *debug_base_symbols[] = 59{ 60 "_DYNAMIC", 61 "_DYNAMIC__MGC", 62 NULL 63}; 64 65static char *main_name_list[] = 66{ 67 "main_$main", 68 NULL 69}; 70 71/* Macro to extract an address from a solib structure. When GDB is 72 configured for some 32-bit targets (e.g. Solaris 2.7 sparc), BFD is 73 configured to handle 64-bit targets, so CORE_ADDR is 64 bits. We 74 have to extract only the significant bits of addresses to get the 75 right address when accessing the core file BFD. 76 77 Assume that the address is unsigned. */ 78 79#define SOLIB_EXTRACT_ADDRESS(MEMBER) \ 80 extract_unsigned_integer (&(MEMBER), sizeof (MEMBER)) 81 82/* local data declarations */ 83 84static struct link_dynamic dynamic_copy; 85static struct link_dynamic_2 ld_2_copy; 86static struct ld_debug debug_copy; 87static CORE_ADDR debug_addr; 88static CORE_ADDR flag_addr; 89 90#ifndef offsetof 91#define offsetof(TYPE, MEMBER) ((unsigned long) &((TYPE *)0)->MEMBER) 92#endif 93#define fieldsize(TYPE, MEMBER) (sizeof (((TYPE *)0)->MEMBER)) 94 95/* link map access functions */ 96 97static CORE_ADDR 98LM_ADDR (struct so_list *so) 99{ 100 int lm_addr_offset = offsetof (struct link_map, lm_addr); 101 int lm_addr_size = fieldsize (struct link_map, lm_addr); 102 103 return (CORE_ADDR) extract_signed_integer (so->lm_info->lm + lm_addr_offset, 104 lm_addr_size); 105} 106 107static CORE_ADDR 108LM_NEXT (struct so_list *so) 109{ 110 int lm_next_offset = offsetof (struct link_map, lm_next); 111 int lm_next_size = fieldsize (struct link_map, lm_next); 112 113 /* Assume that the address is unsigned. */ 114 return extract_unsigned_integer (so->lm_info->lm + lm_next_offset, 115 lm_next_size); 116} 117 118static CORE_ADDR 119LM_NAME (struct so_list *so) 120{ 121 int lm_name_offset = offsetof (struct link_map, lm_name); 122 int lm_name_size = fieldsize (struct link_map, lm_name); 123 124 /* Assume that the address is unsigned. */ 125 return extract_unsigned_integer (so->lm_info->lm + lm_name_offset, 126 lm_name_size); 127} 128 129static CORE_ADDR debug_base; /* Base of dynamic linker structures */ 130 131/* Local function prototypes */ 132 133static int match_main (char *); 134 135/* Allocate the runtime common object file. */ 136 137static void 138allocate_rt_common_objfile (void) 139{ 140 struct objfile *objfile; 141 struct objfile *last_one; 142 143 objfile = (struct objfile *) xmalloc (sizeof (struct objfile)); 144 memset (objfile, 0, sizeof (struct objfile)); 145 objfile->md = NULL; 146 objfile->psymbol_cache = bcache_xmalloc (); 147 objfile->macro_cache = bcache_xmalloc (); 148 obstack_init (&objfile->objfile_obstack); 149 objfile->name = mstrsave (objfile->md, "rt_common"); 150 151 /* Add this file onto the tail of the linked list of other such files. */ 152 153 objfile->next = NULL; 154 if (object_files == NULL) 155 object_files = objfile; 156 else 157 { 158 for (last_one = object_files; 159 last_one->next; 160 last_one = last_one->next); 161 last_one->next = objfile; 162 } 163 164 rt_common_objfile = objfile; 165} 166 167/* Read all dynamically loaded common symbol definitions from the inferior 168 and put them into the minimal symbol table for the runtime common 169 objfile. */ 170 171static void 172solib_add_common_symbols (CORE_ADDR rtc_symp) 173{ 174 struct rtc_symb inferior_rtc_symb; 175 struct nlist inferior_rtc_nlist; 176 int len; 177 char *name; 178 179 /* Remove any runtime common symbols from previous runs. */ 180 181 if (rt_common_objfile != NULL && rt_common_objfile->minimal_symbol_count) 182 { 183 obstack_free (&rt_common_objfile->objfile_obstack, 0); 184 obstack_init (&rt_common_objfile->objfile_obstack); 185 rt_common_objfile->minimal_symbol_count = 0; 186 rt_common_objfile->msymbols = NULL; 187 terminate_minimal_symbol_table (rt_common_objfile); 188 } 189 190 init_minimal_symbol_collection (); 191 make_cleanup_discard_minimal_symbols (); 192 193 while (rtc_symp) 194 { 195 read_memory (rtc_symp, 196 (char *) &inferior_rtc_symb, 197 sizeof (inferior_rtc_symb)); 198 read_memory (SOLIB_EXTRACT_ADDRESS (inferior_rtc_symb.rtc_sp), 199 (char *) &inferior_rtc_nlist, 200 sizeof (inferior_rtc_nlist)); 201 if (inferior_rtc_nlist.n_type == N_COMM) 202 { 203 /* FIXME: The length of the symbol name is not available, but in the 204 current implementation the common symbol is allocated immediately 205 behind the name of the symbol. */ 206 len = inferior_rtc_nlist.n_value - inferior_rtc_nlist.n_un.n_strx; 207 208 name = xmalloc (len); 209 read_memory (SOLIB_EXTRACT_ADDRESS (inferior_rtc_nlist.n_un.n_name), 210 name, len); 211 212 /* Allocate the runtime common objfile if necessary. */ 213 if (rt_common_objfile == NULL) 214 allocate_rt_common_objfile (); 215 216 prim_record_minimal_symbol (name, inferior_rtc_nlist.n_value, 217 mst_bss, rt_common_objfile); 218 xfree (name); 219 } 220 rtc_symp = SOLIB_EXTRACT_ADDRESS (inferior_rtc_symb.rtc_next); 221 } 222 223 /* Install any minimal symbols that have been collected as the current 224 minimal symbols for the runtime common objfile. */ 225 226 install_minimal_symbols (rt_common_objfile); 227} 228 229 230/* 231 232 LOCAL FUNCTION 233 234 locate_base -- locate the base address of dynamic linker structs 235 236 SYNOPSIS 237 238 CORE_ADDR locate_base (void) 239 240 DESCRIPTION 241 242 For both the SunOS and SVR4 shared library implementations, if the 243 inferior executable has been linked dynamically, there is a single 244 address somewhere in the inferior's data space which is the key to 245 locating all of the dynamic linker's runtime structures. This 246 address is the value of the debug base symbol. The job of this 247 function is to find and return that address, or to return 0 if there 248 is no such address (the executable is statically linked for example). 249 250 For SunOS, the job is almost trivial, since the dynamic linker and 251 all of it's structures are statically linked to the executable at 252 link time. Thus the symbol for the address we are looking for has 253 already been added to the minimal symbol table for the executable's 254 objfile at the time the symbol file's symbols were read, and all we 255 have to do is look it up there. Note that we explicitly do NOT want 256 to find the copies in the shared library. 257 258 The SVR4 version is a bit more complicated because the address 259 is contained somewhere in the dynamic info section. We have to go 260 to a lot more work to discover the address of the debug base symbol. 261 Because of this complexity, we cache the value we find and return that 262 value on subsequent invocations. Note there is no copy in the 263 executable symbol tables. 264 265 */ 266 267static CORE_ADDR 268locate_base (void) 269{ 270 struct minimal_symbol *msymbol; 271 CORE_ADDR address = 0; 272 char **symbolp; 273 274 /* For SunOS, we want to limit the search for the debug base symbol to the 275 executable being debugged, since there is a duplicate named symbol in the 276 shared library. We don't want the shared library versions. */ 277 278 for (symbolp = debug_base_symbols; *symbolp != NULL; symbolp++) 279 { 280 msymbol = lookup_minimal_symbol (*symbolp, NULL, symfile_objfile); 281 if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0)) 282 { 283 address = SYMBOL_VALUE_ADDRESS (msymbol); 284 return (address); 285 } 286 } 287 return (0); 288} 289 290/* 291 292 LOCAL FUNCTION 293 294 first_link_map_member -- locate first member in dynamic linker's map 295 296 SYNOPSIS 297 298 static CORE_ADDR first_link_map_member (void) 299 300 DESCRIPTION 301 302 Find the first element in the inferior's dynamic link map, and 303 return its address in the inferior. This function doesn't copy the 304 link map entry itself into our address space; current_sos actually 305 does the reading. */ 306 307static CORE_ADDR 308first_link_map_member (void) 309{ 310 CORE_ADDR lm = 0; 311 312 read_memory (debug_base, (char *) &dynamic_copy, sizeof (dynamic_copy)); 313 if (dynamic_copy.ld_version >= 2) 314 { 315 /* It is a version that we can deal with, so read in the secondary 316 structure and find the address of the link map list from it. */ 317 read_memory (SOLIB_EXTRACT_ADDRESS (dynamic_copy.ld_un.ld_2), 318 (char *) &ld_2_copy, sizeof (struct link_dynamic_2)); 319 lm = SOLIB_EXTRACT_ADDRESS (ld_2_copy.ld_loaded); 320 } 321 return (lm); 322} 323 324static int 325open_symbol_file_object (void *from_ttyp) 326{ 327 return 1; 328} 329 330 331/* LOCAL FUNCTION 332 333 current_sos -- build a list of currently loaded shared objects 334 335 SYNOPSIS 336 337 struct so_list *current_sos () 338 339 DESCRIPTION 340 341 Build a list of `struct so_list' objects describing the shared 342 objects currently loaded in the inferior. This list does not 343 include an entry for the main executable file. 344 345 Note that we only gather information directly available from the 346 inferior --- we don't examine any of the shared library files 347 themselves. The declaration of `struct so_list' says which fields 348 we provide values for. */ 349 350static struct so_list * 351sunos_current_sos (void) 352{ 353 CORE_ADDR lm; 354 struct so_list *head = 0; 355 struct so_list **link_ptr = &head; 356 int errcode; 357 char *buffer; 358 359 /* Make sure we've looked up the inferior's dynamic linker's base 360 structure. */ 361 if (! debug_base) 362 { 363 debug_base = locate_base (); 364 365 /* If we can't find the dynamic linker's base structure, this 366 must not be a dynamically linked executable. Hmm. */ 367 if (! debug_base) 368 return 0; 369 } 370 371 /* Walk the inferior's link map list, and build our list of 372 `struct so_list' nodes. */ 373 lm = first_link_map_member (); 374 while (lm) 375 { 376 struct so_list *new 377 = (struct so_list *) xmalloc (sizeof (struct so_list)); 378 struct cleanup *old_chain = make_cleanup (xfree, new); 379 380 memset (new, 0, sizeof (*new)); 381 382 new->lm_info = xmalloc (sizeof (struct lm_info)); 383 make_cleanup (xfree, new->lm_info); 384 385 new->lm_info->lm = xmalloc (sizeof (struct link_map)); 386 make_cleanup (xfree, new->lm_info->lm); 387 memset (new->lm_info->lm, 0, sizeof (struct link_map)); 388 389 read_memory (lm, new->lm_info->lm, sizeof (struct link_map)); 390 391 lm = LM_NEXT (new); 392 393 /* Extract this shared object's name. */ 394 target_read_string (LM_NAME (new), &buffer, 395 SO_NAME_MAX_PATH_SIZE - 1, &errcode); 396 if (errcode != 0) 397 { 398 warning ("current_sos: Can't read pathname for load map: %s\n", 399 safe_strerror (errcode)); 400 } 401 else 402 { 403 strncpy (new->so_name, buffer, SO_NAME_MAX_PATH_SIZE - 1); 404 new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0'; 405 xfree (buffer); 406 strcpy (new->so_original_name, new->so_name); 407 } 408 409 /* If this entry has no name, or its name matches the name 410 for the main executable, don't include it in the list. */ 411 if (! new->so_name[0] 412 || match_main (new->so_name)) 413 free_so (new); 414 else 415 { 416 new->next = 0; 417 *link_ptr = new; 418 link_ptr = &new->next; 419 } 420 421 discard_cleanups (old_chain); 422 } 423 424 return head; 425} 426 427 428/* On some systems, the only way to recognize the link map entry for 429 the main executable file is by looking at its name. Return 430 non-zero iff SONAME matches one of the known main executable names. */ 431 432static int 433match_main (char *soname) 434{ 435 char **mainp; 436 437 for (mainp = main_name_list; *mainp != NULL; mainp++) 438 { 439 if (strcmp (soname, *mainp) == 0) 440 return (1); 441 } 442 443 return (0); 444} 445 446 447static int 448sunos_in_dynsym_resolve_code (CORE_ADDR pc) 449{ 450 return 0; 451} 452 453/* 454 455 LOCAL FUNCTION 456 457 disable_break -- remove the "mapping changed" breakpoint 458 459 SYNOPSIS 460 461 static int disable_break () 462 463 DESCRIPTION 464 465 Removes the breakpoint that gets hit when the dynamic linker 466 completes a mapping change. 467 468 */ 469 470static int 471disable_break (void) 472{ 473 CORE_ADDR breakpoint_addr; /* Address where end bkpt is set */ 474 475 int in_debugger = 0; 476 477 /* Read the debugger structure from the inferior to retrieve the 478 address of the breakpoint and the original contents of the 479 breakpoint address. Remove the breakpoint by writing the original 480 contents back. */ 481 482 read_memory (debug_addr, (char *) &debug_copy, sizeof (debug_copy)); 483 484 /* Set `in_debugger' to zero now. */ 485 486 write_memory (flag_addr, (char *) &in_debugger, sizeof (in_debugger)); 487 488 breakpoint_addr = SOLIB_EXTRACT_ADDRESS (debug_copy.ldd_bp_addr); 489 write_memory (breakpoint_addr, (char *) &debug_copy.ldd_bp_inst, 490 sizeof (debug_copy.ldd_bp_inst)); 491 492 /* For the SVR4 version, we always know the breakpoint address. For the 493 SunOS version we don't know it until the above code is executed. 494 Grumble if we are stopped anywhere besides the breakpoint address. */ 495 496 if (stop_pc != breakpoint_addr) 497 { 498 warning ("stopped at unknown breakpoint while handling shared libraries"); 499 } 500 501 return 1; 502} 503 504 505/* 506 507 LOCAL FUNCTION 508 509 enable_break -- arrange for dynamic linker to hit breakpoint 510 511 SYNOPSIS 512 513 int enable_break (void) 514 515 DESCRIPTION 516 517 Both the SunOS and the SVR4 dynamic linkers have, as part of their 518 debugger interface, support for arranging for the inferior to hit 519 a breakpoint after mapping in the shared libraries. This function 520 enables that breakpoint. 521 522 For SunOS, there is a special flag location (in_debugger) which we 523 set to 1. When the dynamic linker sees this flag set, it will set 524 a breakpoint at a location known only to itself, after saving the 525 original contents of that place and the breakpoint address itself, 526 in it's own internal structures. When we resume the inferior, it 527 will eventually take a SIGTRAP when it runs into the breakpoint. 528 We handle this (in a different place) by restoring the contents of 529 the breakpointed location (which is only known after it stops), 530 chasing around to locate the shared libraries that have been 531 loaded, then resuming. 532 533 For SVR4, the debugger interface structure contains a member (r_brk) 534 which is statically initialized at the time the shared library is 535 built, to the offset of a function (_r_debug_state) which is guaran- 536 teed to be called once before mapping in a library, and again when 537 the mapping is complete. At the time we are examining this member, 538 it contains only the unrelocated offset of the function, so we have 539 to do our own relocation. Later, when the dynamic linker actually 540 runs, it relocates r_brk to be the actual address of _r_debug_state(). 541 542 The debugger interface structure also contains an enumeration which 543 is set to either RT_ADD or RT_DELETE prior to changing the mapping, 544 depending upon whether or not the library is being mapped or unmapped, 545 and then set to RT_CONSISTENT after the library is mapped/unmapped. 546 */ 547 548static int 549enable_break (void) 550{ 551 int success = 0; 552 int j; 553 int in_debugger; 554 555 /* Get link_dynamic structure */ 556 557 j = target_read_memory (debug_base, (char *) &dynamic_copy, 558 sizeof (dynamic_copy)); 559 if (j) 560 { 561 /* unreadable */ 562 return (0); 563 } 564 565 /* Calc address of debugger interface structure */ 566 567 debug_addr = SOLIB_EXTRACT_ADDRESS (dynamic_copy.ldd); 568 569 /* Calc address of `in_debugger' member of debugger interface structure */ 570 571 flag_addr = debug_addr + (CORE_ADDR) ((char *) &debug_copy.ldd_in_debugger - 572 (char *) &debug_copy); 573 574 /* Write a value of 1 to this member. */ 575 576 in_debugger = 1; 577 write_memory (flag_addr, (char *) &in_debugger, sizeof (in_debugger)); 578 success = 1; 579 580 return (success); 581} 582 583/* 584 585 LOCAL FUNCTION 586 587 special_symbol_handling -- additional shared library symbol handling 588 589 SYNOPSIS 590 591 void special_symbol_handling () 592 593 DESCRIPTION 594 595 Once the symbols from a shared object have been loaded in the usual 596 way, we are called to do any system specific symbol handling that 597 is needed. 598 599 For SunOS4, this consists of grunging around in the dynamic 600 linkers structures to find symbol definitions for "common" symbols 601 and adding them to the minimal symbol table for the runtime common 602 objfile. 603 604 */ 605 606static void 607sunos_special_symbol_handling (void) 608{ 609 int j; 610 611 if (debug_addr == 0) 612 { 613 /* Get link_dynamic structure */ 614 615 j = target_read_memory (debug_base, (char *) &dynamic_copy, 616 sizeof (dynamic_copy)); 617 if (j) 618 { 619 /* unreadable */ 620 return; 621 } 622 623 /* Calc address of debugger interface structure */ 624 /* FIXME, this needs work for cross-debugging of core files 625 (byteorder, size, alignment, etc). */ 626 627 debug_addr = SOLIB_EXTRACT_ADDRESS (dynamic_copy.ldd); 628 } 629 630 /* Read the debugger structure from the inferior, just to make sure 631 we have a current copy. */ 632 633 j = target_read_memory (debug_addr, (char *) &debug_copy, 634 sizeof (debug_copy)); 635 if (j) 636 return; /* unreadable */ 637 638 /* Get common symbol definitions for the loaded object. */ 639 640 if (debug_copy.ldd_cp) 641 { 642 solib_add_common_symbols (SOLIB_EXTRACT_ADDRESS (debug_copy.ldd_cp)); 643 } 644} 645 646/* Relocate the main executable. This function should be called upon 647 stopping the inferior process at the entry point to the program. 648 The entry point from BFD is compared to the PC and if they are 649 different, the main executable is relocated by the proper amount. 650 651 As written it will only attempt to relocate executables which 652 lack interpreter sections. It seems likely that only dynamic 653 linker executables will get relocated, though it should work 654 properly for a position-independent static executable as well. */ 655 656static void 657sunos_relocate_main_executable (void) 658{ 659 asection *interp_sect; 660 CORE_ADDR pc = read_pc (); 661 662 /* Decide if the objfile needs to be relocated. As indicated above, 663 we will only be here when execution is stopped at the beginning 664 of the program. Relocation is necessary if the address at which 665 we are presently stopped differs from the start address stored in 666 the executable AND there's no interpreter section. The condition 667 regarding the interpreter section is very important because if 668 there *is* an interpreter section, execution will begin there 669 instead. When there is an interpreter section, the start address 670 is (presumably) used by the interpreter at some point to start 671 execution of the program. 672 673 If there is an interpreter, it is normal for it to be set to an 674 arbitrary address at the outset. The job of finding it is 675 handled in enable_break(). 676 677 So, to summarize, relocations are necessary when there is no 678 interpreter section and the start address obtained from the 679 executable is different from the address at which GDB is 680 currently stopped. 681 682 [ The astute reader will note that we also test to make sure that 683 the executable in question has the DYNAMIC flag set. It is my 684 opinion that this test is unnecessary (undesirable even). It 685 was added to avoid inadvertent relocation of an executable 686 whose e_type member in the ELF header is not ET_DYN. There may 687 be a time in the future when it is desirable to do relocations 688 on other types of files as well in which case this condition 689 should either be removed or modified to accomodate the new file 690 type. (E.g, an ET_EXEC executable which has been built to be 691 position-independent could safely be relocated by the OS if 692 desired. It is true that this violates the ABI, but the ABI 693 has been known to be bent from time to time.) - Kevin, Nov 2000. ] 694 */ 695 696 interp_sect = bfd_get_section_by_name (exec_bfd, ".interp"); 697 if (interp_sect == NULL 698 && (bfd_get_file_flags (exec_bfd) & DYNAMIC) != 0 699 && bfd_get_start_address (exec_bfd) != pc) 700 { 701 struct cleanup *old_chain; 702 struct section_offsets *new_offsets; 703 int i, changed; 704 CORE_ADDR displacement; 705 706 /* It is necessary to relocate the objfile. The amount to 707 relocate by is simply the address at which we are stopped 708 minus the starting address from the executable. 709 710 We relocate all of the sections by the same amount. This 711 behavior is mandated by recent editions of the System V ABI. 712 According to the System V Application Binary Interface, 713 Edition 4.1, page 5-5: 714 715 ... Though the system chooses virtual addresses for 716 individual processes, it maintains the segments' relative 717 positions. Because position-independent code uses relative 718 addressesing between segments, the difference between 719 virtual addresses in memory must match the difference 720 between virtual addresses in the file. The difference 721 between the virtual address of any segment in memory and 722 the corresponding virtual address in the file is thus a 723 single constant value for any one executable or shared 724 object in a given process. This difference is the base 725 address. One use of the base address is to relocate the 726 memory image of the program during dynamic linking. 727 728 The same language also appears in Edition 4.0 of the System V 729 ABI and is left unspecified in some of the earlier editions. */ 730 731 displacement = pc - bfd_get_start_address (exec_bfd); 732 changed = 0; 733 734 new_offsets = xcalloc (symfile_objfile->num_sections, 735 sizeof (struct section_offsets)); 736 old_chain = make_cleanup (xfree, new_offsets); 737 738 for (i = 0; i < symfile_objfile->num_sections; i++) 739 { 740 if (displacement != ANOFFSET (symfile_objfile->section_offsets, i)) 741 changed = 1; 742 new_offsets->offsets[i] = displacement; 743 } 744 745 if (changed) 746 objfile_relocate (symfile_objfile, new_offsets); 747 748 do_cleanups (old_chain); 749 } 750} 751 752/* 753 754 GLOBAL FUNCTION 755 756 sunos_solib_create_inferior_hook -- shared library startup support 757 758 SYNOPSIS 759 760 void sunos_solib_create_inferior_hook() 761 762 DESCRIPTION 763 764 When gdb starts up the inferior, it nurses it along (through the 765 shell) until it is ready to execute it's first instruction. At this 766 point, this function gets called via expansion of the macro 767 SOLIB_CREATE_INFERIOR_HOOK. 768 769 For SunOS executables, this first instruction is typically the 770 one at "_start", or a similar text label, regardless of whether 771 the executable is statically or dynamically linked. The runtime 772 startup code takes care of dynamically linking in any shared 773 libraries, once gdb allows the inferior to continue. 774 775 For SVR4 executables, this first instruction is either the first 776 instruction in the dynamic linker (for dynamically linked 777 executables) or the instruction at "start" for statically linked 778 executables. For dynamically linked executables, the system 779 first exec's /lib/libc.so.N, which contains the dynamic linker, 780 and starts it running. The dynamic linker maps in any needed 781 shared libraries, maps in the actual user executable, and then 782 jumps to "start" in the user executable. 783 784 For both SunOS shared libraries, and SVR4 shared libraries, we 785 can arrange to cooperate with the dynamic linker to discover the 786 names of shared libraries that are dynamically linked, and the 787 base addresses to which they are linked. 788 789 This function is responsible for discovering those names and 790 addresses, and saving sufficient information about them to allow 791 their symbols to be read at a later time. 792 793 FIXME 794 795 Between enable_break() and disable_break(), this code does not 796 properly handle hitting breakpoints which the user might have 797 set in the startup code or in the dynamic linker itself. Proper 798 handling will probably have to wait until the implementation is 799 changed to use the "breakpoint handler function" method. 800 801 Also, what if child has exit()ed? Must exit loop somehow. 802 */ 803 804static void 805sunos_solib_create_inferior_hook (void) 806{ 807 /* Relocate the main executable if necessary. */ 808 sunos_relocate_main_executable (); 809 810 if ((debug_base = locate_base ()) == 0) 811 { 812 /* Can't find the symbol or the executable is statically linked. */ 813 return; 814 } 815 816 if (!enable_break ()) 817 { 818 warning ("shared library handler failed to enable breakpoint"); 819 return; 820 } 821 822 /* SCO and SunOS need the loop below, other systems should be using the 823 special shared library breakpoints and the shared library breakpoint 824 service routine. 825 826 Now run the target. It will eventually hit the breakpoint, at 827 which point all of the libraries will have been mapped in and we 828 can go groveling around in the dynamic linker structures to find 829 out what we need to know about them. */ 830 831 clear_proceed_status (); 832 stop_soon = STOP_QUIETLY; 833 stop_signal = TARGET_SIGNAL_0; 834 do 835 { 836 target_resume (pid_to_ptid (-1), 0, stop_signal); 837 wait_for_inferior (); 838 } 839 while (stop_signal != TARGET_SIGNAL_TRAP); 840 stop_soon = NO_STOP_QUIETLY; 841 842 /* We are now either at the "mapping complete" breakpoint (or somewhere 843 else, a condition we aren't prepared to deal with anyway), so adjust 844 the PC as necessary after a breakpoint, disable the breakpoint, and 845 add any shared libraries that were mapped in. */ 846 847 if (DECR_PC_AFTER_BREAK) 848 { 849 stop_pc -= DECR_PC_AFTER_BREAK; 850 write_register (PC_REGNUM, stop_pc); 851 } 852 853 if (!disable_break ()) 854 { 855 warning ("shared library handler failed to disable breakpoint"); 856 } 857 858 solib_add ((char *) 0, 0, (struct target_ops *) 0, auto_solib_add); 859} 860 861static void 862sunos_clear_solib (void) 863{ 864 debug_base = 0; 865} 866 867static void 868sunos_free_so (struct so_list *so) 869{ 870 xfree (so->lm_info->lm); 871 xfree (so->lm_info); 872} 873 874static void 875sunos_relocate_section_addresses (struct so_list *so, 876 struct section_table *sec) 877{ 878 sec->addr += LM_ADDR (so); 879 sec->endaddr += LM_ADDR (so); 880} 881 882static struct target_so_ops sunos_so_ops; 883 884void 885_initialize_sunos_solib (void) 886{ 887 sunos_so_ops.relocate_section_addresses = sunos_relocate_section_addresses; 888 sunos_so_ops.free_so = sunos_free_so; 889 sunos_so_ops.clear_solib = sunos_clear_solib; 890 sunos_so_ops.solib_create_inferior_hook = sunos_solib_create_inferior_hook; 891 sunos_so_ops.special_symbol_handling = sunos_special_symbol_handling; 892 sunos_so_ops.current_sos = sunos_current_sos; 893 sunos_so_ops.open_symbol_file_object = open_symbol_file_object; 894 sunos_so_ops.in_dynsym_resolve_code = sunos_in_dynsym_resolve_code; 895 896 /* FIXME: Don't do this here. *_gdbarch_init() should set so_ops. */ 897 current_target_so_ops = &sunos_so_ops; 898} 899