1 /* Handle SunOS and SVR4 shared libraries for GDB, the GNU Debugger.
2 Copyright 1990, 1991, 1992 Free Software Foundation, Inc.
4 This file is part of GDB.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
23 #include <sys/types.h>
27 #include <sys/param.h>
30 #ifndef SVR4_SHARED_LIBS
31 /* SunOS shared libs need the nlist structure. */
46 #define MAX_PATH_SIZE 256 /* FIXME: Should be dynamic */
48 /* On SVR4 systems, for the initial implementation, use main() as the
49 "startup mapping complete" breakpoint address. The models for SunOS
50 and SVR4 dynamic linking debugger support are different in that SunOS
51 hits one breakpoint when all mapping is complete while using the SVR4
52 debugger support takes two breakpoint hits for each file mapped, and
53 there is no way to know when the "last" one is hit. Both these
54 mechanisms should be tied to a "breakpoint service routine" that
55 gets automatically executed whenever one of the breakpoints indicating
56 a change in mapping is hit. This is a future enhancement. (FIXME) */
58 #define BKPT_AT_MAIN 1
60 /* local data declarations */
62 #ifndef SVR4_SHARED_LIBS
64 #define DEBUG_BASE "_DYNAMIC"
65 #define LM_ADDR(so) ((so) -> lm.lm_addr)
66 #define LM_NEXT(so) ((so) -> lm.lm_next)
67 #define LM_NAME(so) ((so) -> lm.lm_name)
68 static struct link_dynamic dynamic_copy
;
69 static struct link_dynamic_2 ld_2_copy
;
70 static struct ld_debug debug_copy
;
71 static CORE_ADDR debug_addr
;
72 static CORE_ADDR flag_addr
;
74 #else /* SVR4_SHARED_LIBS */
76 #define DEBUG_BASE "_r_debug"
77 #define LM_ADDR(so) ((so) -> lm.l_addr)
78 #define LM_NEXT(so) ((so) -> lm.l_next)
79 #define LM_NAME(so) ((so) -> lm.l_name)
80 static struct r_debug debug_copy
;
81 char shadow_contents
[BREAKPOINT_MAX
]; /* Stash old bkpt addr contents */
83 #endif /* !SVR4_SHARED_LIBS */
86 struct so_list
*next
; /* next structure in linked list */
87 struct link_map lm
; /* copy of link map from inferior */
88 struct link_map
*lmaddr
; /* addr in inferior lm was read from */
89 CORE_ADDR lmend
; /* upper addr bound of mapped object */
90 char so_name
[MAX_PATH_SIZE
]; /* shared object lib name (FIXME) */
91 char symbols_loaded
; /* flag: symbols read in yet? */
92 char from_tty
; /* flag: print msgs? */
93 bfd
*so_bfd
; /* bfd for so_name */
94 struct objfile
*objfile
; /* objfile for loaded lib */
95 struct section_table
*sections
;
96 struct section_table
*sections_end
;
97 struct section_table
*textsection
;
100 static struct so_list
*so_list_head
; /* List of known shared objects */
101 static CORE_ADDR debug_base
; /* Base of dynamic linker structures */
102 static CORE_ADDR breakpoint_addr
; /* Address where end bkpt is set */
105 fdmatch
PARAMS ((int, int)); /* In libiberty */
107 /* Local function prototypes */
110 special_symbol_handling
PARAMS ((struct so_list
*));
113 sharedlibrary_command
PARAMS ((char *, int));
116 enable_break
PARAMS ((void));
119 disable_break
PARAMS ((void));
122 info_sharedlibrary_command
PARAMS ((char *, int));
125 symbol_add_stub
PARAMS ((char *));
127 static struct so_list
*
128 find_solib
PARAMS ((struct so_list
*));
130 static struct link_map
*
131 first_link_map_member
PARAMS ((void));
134 locate_base
PARAMS ((void));
137 solib_map_sections
PARAMS ((struct so_list
*));
139 #ifdef SVR4_SHARED_LIBS
142 look_for_base
PARAMS ((int, CORE_ADDR
));
145 bfd_lookup_symbol
PARAMS ((bfd
*, char *));
150 solib_add_common_symbols
PARAMS ((struct rtc_symb
*, struct objfile
*));
158 solib_map_sections -- open bfd and build sections for shared lib
162 static void solib_map_sections (struct so_list *so)
166 Given a pointer to one of the shared objects in our list
167 of mapped objects, use the recorded name to open a bfd
168 descriptor for the object, build a section table, and then
169 relocate all the section addresses by the base address at
170 which the shared object was mapped.
174 In most (all?) cases the shared object file name recorded in the
175 dynamic linkage tables will be a fully qualified pathname. For
176 cases where it isn't, do we really mimic the systems search
177 mechanism correctly in the below code (particularly the tilde
182 solib_map_sections (so
)
186 char *scratch_pathname
;
188 struct section_table
*p
;
190 filename
= tilde_expand (so
-> so_name
);
191 make_cleanup (free
, filename
);
193 scratch_chan
= openp (getenv ("PATH"), 1, filename
, O_RDONLY
, 0,
195 if (scratch_chan
< 0)
197 scratch_chan
= openp (getenv ("LD_LIBRARY_PATH"), 1, filename
,
198 O_RDONLY
, 0, &scratch_pathname
);
200 if (scratch_chan
< 0)
202 perror_with_name (filename
);
205 so
-> so_bfd
= bfd_fdopenr (scratch_pathname
, NULL
, scratch_chan
);
208 error ("Could not open `%s' as an executable file: %s",
209 scratch_pathname
, bfd_errmsg (bfd_error
));
211 if (!bfd_check_format (so
-> so_bfd
, bfd_object
))
213 error ("\"%s\": not in executable format: %s.",
214 scratch_pathname
, bfd_errmsg (bfd_error
));
216 if (build_section_table (so
-> so_bfd
, &so
-> sections
, &so
-> sections_end
))
218 error ("Can't find the file sections in `%s': %s",
219 exec_bfd
-> filename
, bfd_errmsg (bfd_error
));
222 for (p
= so
-> sections
; p
< so
-> sections_end
; p
++)
224 /* Relocate the section binding addresses as recorded in the shared
225 object's file by the base address to which the object was actually
227 p
-> addr
+= (CORE_ADDR
) LM_ADDR (so
);
228 p
-> endaddr
+= (CORE_ADDR
) LM_ADDR (so
);
229 so
-> lmend
= (CORE_ADDR
) max (p
-> endaddr
, so
-> lmend
);
230 if (strcmp (p
-> sec_ptr
-> name
, ".text") == 0)
232 so
-> textsection
= p
;
237 /* Read all dynamically loaded common symbol definitions from the inferior
238 and add them to the minimal symbol table for the shared library objfile. */
240 #ifndef SVR4_SHARED_LIBS
243 solib_add_common_symbols (rtc_symp
, objfile
)
244 struct rtc_symb
*rtc_symp
;
245 struct objfile
*objfile
;
247 struct rtc_symb inferior_rtc_symb
;
248 struct nlist inferior_rtc_nlist
;
253 init_minimal_symbol_collection ();
254 make_cleanup (discard_minimal_symbols
, 0);
258 read_memory ((CORE_ADDR
) rtc_symp
,
259 (char *) &inferior_rtc_symb
,
260 sizeof (inferior_rtc_symb
));
261 read_memory ((CORE_ADDR
) inferior_rtc_symb
.rtc_sp
,
262 (char *) &inferior_rtc_nlist
,
263 sizeof(inferior_rtc_nlist
));
264 if (inferior_rtc_nlist
.n_type
== N_COMM
)
266 /* FIXME: The length of the symbol name is not available, but in the
267 current implementation the common symbol is allocated immediately
268 behind the name of the symbol. */
269 len
= inferior_rtc_nlist
.n_value
- inferior_rtc_nlist
.n_un
.n_strx
;
271 origname
= name
= xmalloc (len
);
272 read_memory ((CORE_ADDR
) inferior_rtc_nlist
.n_un
.n_name
, name
, len
);
274 /* Don't enter the symbol twice if the target is re-run. */
276 #ifdef NAMES_HAVE_UNDERSCORE
282 /* FIXME: Do we really want to exclude symbols which happen
283 to match symbols for other locations in the inferior's
284 address space, even when they are in different linkage units? */
285 if (lookup_minimal_symbol (name
, (struct objfile
*) NULL
) == NULL
)
287 name
= obsavestring (name
, strlen (name
),
288 &objfile
-> symbol_obstack
);
289 prim_record_minimal_symbol (name
, inferior_rtc_nlist
.n_value
,
294 rtc_symp
= inferior_rtc_symb
.rtc_next
;
297 /* Install any minimal symbols that have been collected as the current
298 minimal symbols for this objfile. */
300 install_minimal_symbols (objfile
);
303 #endif /* SVR4_SHARED_LIBS */
305 #ifdef SVR4_SHARED_LIBS
311 bfd_lookup_symbol -- lookup the value for a specific symbol
315 CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname)
319 An expensive way to lookup the value of a single symbol for
320 bfd's that are only temporary anyway. This is used by the
321 shared library support to find the address of the debugger
322 interface structures in the shared library.
324 Note that 0 is specifically allowed as an error return (no
327 FIXME: See if there is a less "expensive" way of doing this.
328 Also see if there is already another bfd or gdb function
329 that specifically does this, and if so, use it.
333 bfd_lookup_symbol (abfd
, symname
)
337 unsigned int storage_needed
;
339 asymbol
**symbol_table
;
340 unsigned int number_of_symbols
;
342 struct cleanup
*back_to
;
343 CORE_ADDR symaddr
= 0;
345 storage_needed
= get_symtab_upper_bound (abfd
);
347 if (storage_needed
> 0)
349 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
350 back_to
= make_cleanup (free
, (PTR
)symbol_table
);
351 number_of_symbols
= bfd_canonicalize_symtab (abfd
, symbol_table
);
353 for (i
= 0; i
< number_of_symbols
; i
++)
355 sym
= *symbol_table
++;
356 if (strcmp (sym
-> name
, symname
) == 0)
358 symaddr
= sym
-> value
;
362 do_cleanups (back_to
);
371 look_for_base -- examine file for each mapped address segment
375 static int look_for_base (int fd, CORE_ADDR baseaddr)
379 This function is passed to proc_iterate_over_mappings, which
380 causes it to get called once for each mapped address space, with
381 an open file descriptor for the file mapped to that space, and the
382 base address of that mapped space.
384 Our job is to find the symbol DEBUG_BASE in the file that this
385 fd is open on, if it exists, and if so, initialize the dynamic
386 linker structure base address debug_base.
388 Note that this is a computationally expensive proposition, since
389 we basically have to open a bfd on every call, so we specifically
390 avoid opening the exec file.
394 look_for_base (fd
, baseaddr
)
401 /* If the fd is -1, then there is no file that corresponds to this
402 mapped memory segment, so skip it. Also, if the fd corresponds
403 to the exec file, skip it as well. */
405 if ((fd
== -1) || fdmatch (fileno ((FILE *)(exec_bfd
-> iostream
)), fd
))
410 /* Try to open whatever random file this fd corresponds to. Note that
411 we have no way currently to find the filename. Don't gripe about
412 any problems we might have, just fail. */
414 if ((interp_bfd
= bfd_fdopenr ("unnamed", NULL
, fd
)) == NULL
)
418 if (!bfd_check_format (interp_bfd
, bfd_object
))
420 bfd_close (interp_bfd
);
424 /* Now try to find our DEBUG_BASE symbol in this file, which we at
425 least know to be a valid ELF executable or shared library. */
427 if ((address
= bfd_lookup_symbol (interp_bfd
, DEBUG_BASE
)) == 0)
429 bfd_close (interp_bfd
);
433 /* Eureka! We found the symbol. But now we may need to relocate it
434 by the base address. If the symbol's value is less than the base
435 address of the shared library, then it hasn't yet been relocated
436 by the dynamic linker, and we have to do it ourself. FIXME: Note
437 that we make the assumption that the first segment that corresponds
438 to the shared library has the base address to which the library
441 if (address
< baseaddr
)
445 debug_base
= address
;
446 bfd_close (interp_bfd
);
456 locate_base -- locate the base address of dynamic linker structs
460 CORE_ADDR locate_base (void)
464 For both the SunOS and SVR4 shared library implementations, if the
465 inferior executable has been linked dynamically, there is a single
466 address somewhere in the inferior's data space which is the key to
467 locating all of the dynamic linker's runtime structures. This
468 address is the value of the symbol defined by the macro DEBUG_BASE.
469 The job of this function is to find and return that address, or to
470 return 0 if there is no such address (the executable is statically
473 For SunOS, the job is almost trivial, since the dynamic linker and
474 all of it's structures are statically linked to the executable at
475 link time. Thus the symbol for the address we are looking for has
476 already been added to the minimal symbol table for the executable's
477 objfile at the time the symbol file's symbols were read, and all we
478 have to do is look it up there. Note that we explicitly do NOT want
479 to find the copies in the shared library.
481 The SVR4 version is much more complicated because the dynamic linker
482 and it's structures are located in the shared C library, which gets
483 run as the executable's "interpreter" by the kernel. We have to go
484 to a lot more work to discover the address of DEBUG_BASE. Because
485 of this complexity, we cache the value we find and return that value
486 on subsequent invocations. Note there is no copy in the executable
489 Note that we can assume nothing about the process state at the time
490 we need to find this address. We may be stopped on the first instruc-
491 tion of the interpreter (C shared library), the first instruction of
492 the executable itself, or somewhere else entirely (if we attached
493 to the process for example).
501 #ifndef SVR4_SHARED_LIBS
503 struct minimal_symbol
*msymbol
;
504 CORE_ADDR address
= 0;
506 /* For SunOS, we want to limit the search for DEBUG_BASE to the executable
507 being debugged, since there is a duplicate named symbol in the shared
508 library. We don't want the shared library versions. */
510 msymbol
= lookup_minimal_symbol (DEBUG_BASE
, symfile_objfile
);
511 if ((msymbol
!= NULL
) && (msymbol
-> address
!= 0))
513 address
= msymbol
-> address
;
517 #else /* SVR4_SHARED_LIBS */
519 /* Check to see if we have a currently valid address, and if so, avoid
520 doing all this work again and just return the cached address. If
521 we have no cached address, ask the /proc support interface to iterate
522 over the list of mapped address segments, calling look_for_base() for
523 each segment. When we are done, we will have either found the base
528 proc_iterate_over_mappings (look_for_base
);
532 #endif /* !SVR4_SHARED_LIBS */
536 static struct link_map
*
537 first_link_map_member ()
539 struct link_map
*lm
= NULL
;
541 #ifndef SVR4_SHARED_LIBS
543 read_memory (debug_base
, (char *) &dynamic_copy
, sizeof (dynamic_copy
));
544 if (dynamic_copy
.ld_version
>= 2)
546 /* It is a version that we can deal with, so read in the secondary
547 structure and find the address of the link map list from it. */
548 read_memory ((CORE_ADDR
) dynamic_copy
.ld_un
.ld_2
, (char *) &ld_2_copy
,
549 sizeof (struct link_dynamic_2
));
550 lm
= ld_2_copy
.ld_loaded
;
553 #else /* SVR4_SHARED_LIBS */
555 read_memory (debug_base
, (char *) &debug_copy
, sizeof (struct r_debug
));
556 lm
= debug_copy
.r_map
;
558 #endif /* !SVR4_SHARED_LIBS */
567 find_solib -- step through list of shared objects
571 struct so_list *find_solib (struct so_list *so_list_ptr)
575 This module contains the routine which finds the names of any
576 loaded "images" in the current process. The argument in must be
577 NULL on the first call, and then the returned value must be passed
578 in on subsequent calls. This provides the capability to "step" down
579 the list of loaded objects. On the last object, a NULL value is
582 The arg and return value are "struct link_map" pointers, as defined
586 static struct so_list
*
587 find_solib (so_list_ptr
)
588 struct so_list
*so_list_ptr
; /* Last lm or NULL for first one */
590 struct so_list
*so_list_next
= NULL
;
591 struct link_map
*lm
= NULL
;
594 if (so_list_ptr
== NULL
)
596 /* We are setting up for a new scan through the loaded images. */
597 if ((so_list_next
= so_list_head
) == NULL
)
599 /* We have not already read in the dynamic linking structures
600 from the inferior, lookup the address of the base structure. */
601 debug_base
= locate_base ();
604 /* Read the base structure in and find the address of the first
605 link map list member. */
606 lm
= first_link_map_member ();
612 /* We have been called before, and are in the process of walking
613 the shared library list. Advance to the next shared object. */
614 if ((lm
= LM_NEXT (so_list_ptr
)) == NULL
)
616 /* We have hit the end of the list, so check to see if any were
617 added, but be quiet if we can't read from the target any more. */
618 int status
= target_read_memory ((CORE_ADDR
) so_list_ptr
-> lmaddr
,
619 (char *) &(so_list_ptr
-> lm
),
620 sizeof (struct link_map
));
623 lm
= LM_NEXT (so_list_ptr
);
630 so_list_next
= so_list_ptr
-> next
;
632 if ((so_list_next
== NULL
) && (lm
!= NULL
))
634 /* Get next link map structure from inferior image and build a local
635 abbreviated load_map structure */
636 new = (struct so_list
*) xmalloc (sizeof (struct so_list
));
637 (void) memset ((char *) new, 0, sizeof (struct so_list
));
639 /* Add the new node as the next node in the list, or as the root
640 node if this is the first one. */
641 if (so_list_ptr
!= NULL
)
643 so_list_ptr
-> next
= new;
650 read_memory ((CORE_ADDR
) lm
, (char *) &(new -> lm
),
651 sizeof (struct link_map
));
652 /* For the SVR4 version, there is one entry that has no name
653 (for the inferior executable) since it is not a shared object. */
654 if (LM_NAME (new) != 0)
656 if (!target_read_string((CORE_ADDR
) LM_NAME (new), new -> so_name
,
658 error ("find_solib: Can't read pathname for load map\n");
659 new -> so_name
[MAX_PATH_SIZE
- 1] = 0;
660 solib_map_sections (new);
663 return (so_list_next
);
666 /* A small stub to get us past the arg-passing pinhole of catch_errors. */
669 symbol_add_stub (arg
)
672 register struct so_list
*so
= (struct so_list
*) arg
; /* catch_errs bogon */
674 so
-> objfile
= symbol_file_add (so
-> so_name
, so
-> from_tty
,
675 (unsigned int) so
-> textsection
-> addr
,
684 solib_add -- add a shared library file to the symtab and section list
688 void solib_add (char *arg_string, int from_tty,
689 struct target_ops *target)
696 solib_add (arg_string
, from_tty
, target
)
699 struct target_ops
*target
;
701 register struct so_list
*so
= NULL
; /* link map state variable */
706 if ((re_err
= re_comp (arg_string
? arg_string
: ".")) != NULL
)
708 error ("Invalid regexp: %s", re_err
);
711 /* Getting new symbols may change our opinion about what is
713 reinit_frame_cache ();
715 while ((so
= find_solib (so
)) != NULL
)
717 if (so
-> so_name
[0] && re_exec (so
-> so_name
))
719 if (so
-> symbols_loaded
)
723 printf ("Symbols already loaded for %s\n", so
-> so_name
);
728 catch_errors (symbol_add_stub
, (char *) so
,
729 "Error while reading shared library symbols:\n");
731 special_symbol_handling (so
);
732 so
-> symbols_loaded
= 1;
733 so
-> from_tty
= from_tty
;
738 /* Now add the shared library sections to the section table of the
739 specified target, if any. */
742 /* Count how many new section_table entries there are. */
745 while ((so
= find_solib (so
)) != NULL
)
747 if (so
-> so_name
[0])
749 count
+= so
-> sections_end
- so
-> sections
;
755 /* Reallocate the target's section table including the new size. */
756 if (target
-> to_sections
)
758 old
= target
-> to_sections_end
- target
-> to_sections
;
759 target
-> to_sections
= (struct section_table
*)
760 realloc ((char *)target
-> to_sections
,
761 (sizeof (struct section_table
)) * (count
+ old
));
766 target
-> to_sections
= (struct section_table
*)
767 malloc ((sizeof (struct section_table
)) * count
);
769 target
-> to_sections_end
= target
-> to_sections
+ (count
+ old
);
771 /* Add these section table entries to the target's table. */
772 while ((so
= find_solib (so
)) != NULL
)
774 if (so
-> so_name
[0])
776 count
= so
-> sections_end
- so
-> sections
;
777 (void) memcpy ((char *) (target
-> to_sections
+ old
),
779 (sizeof (struct section_table
)) * count
);
791 info_sharedlibrary_command -- code for "info sharedlibrary"
795 static void info_sharedlibrary_command ()
799 Walk through the shared library list and print information
800 about each attached library.
804 info_sharedlibrary_command (ignore
, from_tty
)
808 register struct so_list
*so
= NULL
; /* link map state variable */
811 if (exec_bfd
== NULL
)
813 printf ("No exec file.\n");
816 while ((so
= find_solib (so
)) != NULL
)
818 if (so
-> so_name
[0])
822 printf("%-12s%-12s%-12s%s\n", "From", "To", "Syms Read",
823 "Shared Object Library");
826 printf ("%-12s", local_hex_string_custom ((int) LM_ADDR (so
), "08"));
827 printf ("%-12s", local_hex_string_custom (so
-> lmend
, "08"));
828 printf ("%-12s", so
-> symbols_loaded
? "Yes" : "No");
829 printf ("%s\n", so
-> so_name
);
832 if (so_list_head
== NULL
)
834 printf ("No shared libraries loaded at this time.\n");
842 solib_address -- check to see if an address is in a shared lib
846 int solib_address (CORE_ADDR address)
850 Provides a hook for other gdb routines to discover whether or
851 not a particular address is within the mapped address space of
852 a shared library. Any address between the base mapping address
853 and the first address beyond the end of the last mapping, is
854 considered to be within the shared library address space, for
857 For example, this routine is called at one point to disable
858 breakpoints which are in shared libraries that are not currently
863 solib_address (address
)
866 register struct so_list
*so
= 0; /* link map state variable */
868 while ((so
= find_solib (so
)) != NULL
)
870 if (so
-> so_name
[0])
872 if ((address
>= (CORE_ADDR
) LM_ADDR (so
)) &&
873 (address
< (CORE_ADDR
) so
-> lmend
))
882 /* Called by free_all_symtabs */
887 struct so_list
*next
;
891 if (so_list_head
-> sections
)
893 free ((PTR
)so_list_head
-> sections
);
895 if (so_list_head
-> so_bfd
)
897 bfd_close (so_list_head
-> so_bfd
);
899 next
= so_list_head
-> next
;
900 free((PTR
)so_list_head
);
910 disable_break -- remove the "mapping changed" breakpoint
914 static int disable_break ()
918 Removes the breakpoint that gets hit when the dynamic linker
919 completes a mapping change.
928 #ifndef SVR4_SHARED_LIBS
932 /* Read the debugger structure from the inferior to retrieve the
933 address of the breakpoint and the original contents of the
934 breakpoint address. Remove the breakpoint by writing the original
937 read_memory (debug_addr
, (char *) &debug_copy
, sizeof (debug_copy
));
939 /* Set `in_debugger' to zero now. */
941 write_memory (flag_addr
, (char *) &in_debugger
, sizeof (in_debugger
));
943 breakpoint_addr
= (CORE_ADDR
) debug_copy
.ldd_bp_addr
;
944 write_memory (breakpoint_addr
, (char *) &debug_copy
.ldd_bp_inst
,
945 sizeof (debug_copy
.ldd_bp_inst
));
947 #else /* SVR4_SHARED_LIBS */
949 /* Note that breakpoint address and original contents are in our address
950 space, so we just need to write the original contents back. */
952 if (memory_remove_breakpoint (breakpoint_addr
, shadow_contents
) != 0)
957 #endif /* !SVR4_SHARED_LIBS */
959 /* For the SVR4 version, we always know the breakpoint address. For the
960 SunOS version we don't know it until the above code is executed.
961 Grumble if we are stopped anywhere besides the breakpoint address. */
963 if (stop_pc
!= breakpoint_addr
)
965 warning ("stopped at unknown breakpoint while handling shared libraries");
975 enable_break -- arrange for dynamic linker to hit breakpoint
979 int enable_break (void)
983 Both the SunOS and the SVR4 dynamic linkers have, as part of their
984 debugger interface, support for arranging for the inferior to hit
985 a breakpoint after mapping in the shared libraries. This function
986 enables that breakpoint.
988 For SunOS, there is a special flag location (in_debugger) which we
989 set to 1. When the dynamic linker sees this flag set, it will set
990 a breakpoint at a location known only to itself, after saving the
991 original contents of that place and the breakpoint address itself,
992 in it's own internal structures. When we resume the inferior, it
993 will eventually take a SIGTRAP when it runs into the breakpoint.
994 We handle this (in a different place) by restoring the contents of
995 the breakpointed location (which is only known after it stops),
996 chasing around to locate the shared libraries that have been
997 loaded, then resuming.
999 For SVR4, the debugger interface structure contains a member (r_brk)
1000 which is statically initialized at the time the shared library is
1001 built, to the offset of a function (_r_debug_state) which is guaran-
1002 teed to be called once before mapping in a library, and again when
1003 the mapping is complete. At the time we are examining this member,
1004 it contains only the unrelocated offset of the function, so we have
1005 to do our own relocation. Later, when the dynamic linker actually
1006 runs, it relocates r_brk to be the actual address of _r_debug_state().
1008 The debugger interface structure also contains an enumeration which
1009 is set to either RT_ADD or RT_DELETE prior to changing the mapping,
1010 depending upon whether or not the library is being mapped or unmapped,
1011 and then set to RT_CONSISTENT after the library is mapped/unmapped.
1018 #ifndef SVR4_SHARED_LIBS
1023 /* Get link_dynamic structure */
1025 j
= target_read_memory (debug_base
, (char *) &dynamic_copy
,
1026 sizeof (dynamic_copy
));
1033 /* Calc address of debugger interface structure */
1035 debug_addr
= (CORE_ADDR
) dynamic_copy
.ldd
;
1037 /* Calc address of `in_debugger' member of debugger interface structure */
1039 flag_addr
= debug_addr
+ (CORE_ADDR
) ((char *) &debug_copy
.ldd_in_debugger
-
1040 (char *) &debug_copy
);
1042 /* Write a value of 1 to this member. */
1046 write_memory (flag_addr
, (char *) &in_debugger
, sizeof (in_debugger
));
1048 #else /* SVR4_SHARED_LIBS */
1052 struct minimal_symbol
*msymbol
;
1054 msymbol
= lookup_minimal_symbol ("main", symfile_objfile
);
1055 if ((msymbol
!= NULL
) && (msymbol
-> address
!= 0))
1057 breakpoint_addr
= msymbol
-> address
;
1064 if (target_insert_breakpoint (breakpoint_addr
, shadow_contents
) != 0)
1069 #else /* !BKPT_AT_MAIN */
1071 struct symtab_and_line sal
;
1073 /* Read the debugger interface structure directly. */
1075 read_memory (debug_base
, (char *) &debug_copy
, sizeof (debug_copy
));
1077 /* Set breakpoint at the debugger interface stub routine that will
1078 be called just prior to each mapping change and again after the
1079 mapping change is complete. Set up the (nonexistent) handler to
1080 deal with hitting these breakpoints. (FIXME). */
1082 warning ("'%s': line %d: missing SVR4 support code", __FILE__
, __LINE__
);
1084 #endif /* BKPT_AT_MAIN */
1086 #endif /* !SVR4_SHARED_LIBS */
1095 solib_create_inferior_hook -- shared library startup support
1099 void solib_create_inferior_hook()
1103 When gdb starts up the inferior, it nurses it along (through the
1104 shell) until it is ready to execute it's first instruction. At this
1105 point, this function gets called via expansion of the macro
1106 SOLIB_CREATE_INFERIOR_HOOK.
1108 For both SunOS shared libraries, and SVR4 shared libraries, we
1109 can arrange to cooperate with the dynamic linker to discover the
1110 names of shared libraries that are dynamically linked, and the
1111 base addresses to which they are linked.
1113 This function is responsible for discovering those names and
1114 addresses, and saving sufficient information about them to allow
1115 their symbols to be read at a later time.
1119 Between enable_break() and disable_break(), this code does not
1120 properly handle hitting breakpoints which the user might have
1121 set in the startup code or in the dynamic linker itself. Proper
1122 handling will probably have to wait until the implementation is
1123 changed to use the "breakpoint handler function" method.
1125 Also, what if child has exit()ed? Must exit loop somehow.
1129 solib_create_inferior_hook()
1132 if ((debug_base
= locate_base ()) == 0)
1134 /* Can't find the symbol or the executable is statically linked. */
1138 if (!enable_break ())
1140 warning ("shared library handler failed to enable breakpoint");
1144 /* Now run the target. It will eventually hit the breakpoint, at
1145 which point all of the libraries will have been mapped in and we
1146 can go groveling around in the dynamic linker structures to find
1147 out what we need to know about them. */
1149 clear_proceed_status ();
1150 stop_soon_quietly
= 1;
1154 target_resume (0, stop_signal
);
1155 wait_for_inferior ();
1157 while (stop_signal
!= SIGTRAP
);
1158 stop_soon_quietly
= 0;
1160 /* We are now either at the "mapping complete" breakpoint (or somewhere
1161 else, a condition we aren't prepared to deal with anyway), so adjust
1162 the PC as necessary after a breakpoint, disable the breakpoint, and
1163 add any shared libraries that were mapped in. */
1165 if (DECR_PC_AFTER_BREAK
)
1167 stop_pc
-= DECR_PC_AFTER_BREAK
;
1168 write_register (PC_REGNUM
, stop_pc
);
1171 if (!disable_break ())
1173 warning ("shared library handler failed to disable breakpoint");
1176 solib_add ((char *) 0, 0, (struct target_ops
*) 0);
1183 special_symbol_handling -- additional shared library symbol handling
1187 void special_symbol_handling (struct so_list *so)
1191 Once the symbols from a shared object have been loaded in the usual
1192 way, we are called to do any system specific symbol handling that
1195 For Suns, this consists of grunging around in the dynamic linkers
1196 structures to find symbol definitions for "common" symbols and
1197 adding them to the minimal symbol table for the corresponding
1203 special_symbol_handling (so
)
1206 #ifndef SVR4_SHARED_LIBS
1209 if (debug_addr
== 0)
1211 /* Get link_dynamic structure */
1213 j
= target_read_memory (debug_base
, (char *) &dynamic_copy
,
1214 sizeof (dynamic_copy
));
1221 /* Calc address of debugger interface structure */
1222 /* FIXME, this needs work for cross-debugging of core files
1223 (byteorder, size, alignment, etc). */
1225 debug_addr
= (CORE_ADDR
) dynamic_copy
.ldd
;
1228 /* Read the debugger structure from the inferior, just to make sure
1229 we have a current copy. */
1231 j
= target_read_memory (debug_addr
, (char *) &debug_copy
,
1232 sizeof (debug_copy
));
1234 return; /* unreadable */
1236 /* Get common symbol definitions for the loaded object. */
1238 if (debug_copy
.ldd_cp
)
1240 solib_add_common_symbols (debug_copy
.ldd_cp
, so
-> objfile
);
1243 #endif /* !SVR4_SHARED_LIBS */
1251 sharedlibrary_command -- handle command to explicitly add library
1255 static void sharedlibrary_command (char *args, int from_tty)
1262 sharedlibrary_command (args
, from_tty
)
1267 solib_add (args
, from_tty
, (struct target_ops
*) 0);
1274 add_com ("sharedlibrary", class_files
, sharedlibrary_command
,
1275 "Load shared object library symbols for files matching REGEXP.");
1276 add_info ("sharedlibrary", info_sharedlibrary_command
,
1277 "Status of loaded shared object libraries.");