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 some runtime startup
49 symbol as the "startup mapping complete" breakpoint address. The models
50 for SunOS and SVR4 dynamic linking debugger support are different in that
51 SunOS 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_SYMBOL 1
60 static char *bkpt_names
[] = {
61 #ifdef SOLIB_BKPT_NAME
62 SOLIB_BKPT_NAME
, /* Prefer configured name if it exists. */
69 /* local data declarations */
71 #ifndef SVR4_SHARED_LIBS
73 #define DEBUG_BASE "_DYNAMIC"
74 #define LM_ADDR(so) ((so) -> lm.lm_addr)
75 #define LM_NEXT(so) ((so) -> lm.lm_next)
76 #define LM_NAME(so) ((so) -> lm.lm_name)
77 static struct link_dynamic dynamic_copy
;
78 static struct link_dynamic_2 ld_2_copy
;
79 static struct ld_debug debug_copy
;
80 static CORE_ADDR debug_addr
;
81 static CORE_ADDR flag_addr
;
83 #else /* SVR4_SHARED_LIBS */
85 #define DEBUG_BASE "_r_debug"
86 #define LM_ADDR(so) ((so) -> lm.l_addr)
87 #define LM_NEXT(so) ((so) -> lm.l_next)
88 #define LM_NAME(so) ((so) -> lm.l_name)
89 static struct r_debug debug_copy
;
90 char shadow_contents
[BREAKPOINT_MAX
]; /* Stash old bkpt addr contents */
92 #endif /* !SVR4_SHARED_LIBS */
95 struct so_list
*next
; /* next structure in linked list */
96 struct link_map lm
; /* copy of link map from inferior */
97 struct link_map
*lmaddr
; /* addr in inferior lm was read from */
98 CORE_ADDR lmend
; /* upper addr bound of mapped object */
99 char so_name
[MAX_PATH_SIZE
]; /* shared object lib name (FIXME) */
100 char symbols_loaded
; /* flag: symbols read in yet? */
101 char from_tty
; /* flag: print msgs? */
102 struct objfile
*objfile
; /* objfile for loaded lib */
103 struct section_table
*sections
;
104 struct section_table
*sections_end
;
105 struct section_table
*textsection
;
109 static struct so_list
*so_list_head
; /* List of known shared objects */
110 static CORE_ADDR debug_base
; /* Base of dynamic linker structures */
111 static CORE_ADDR breakpoint_addr
; /* Address where end bkpt is set */
114 fdmatch
PARAMS ((int, int)); /* In libiberty */
116 /* Local function prototypes */
119 special_symbol_handling
PARAMS ((struct so_list
*));
122 sharedlibrary_command
PARAMS ((char *, int));
125 enable_break
PARAMS ((void));
128 disable_break
PARAMS ((void));
131 info_sharedlibrary_command
PARAMS ((char *, int));
134 symbol_add_stub
PARAMS ((char *));
136 static struct so_list
*
137 find_solib
PARAMS ((struct so_list
*));
139 static struct link_map
*
140 first_link_map_member
PARAMS ((void));
143 locate_base
PARAMS ((void));
146 solib_map_sections
PARAMS ((struct so_list
*));
148 #ifdef SVR4_SHARED_LIBS
151 look_for_base
PARAMS ((int, CORE_ADDR
));
154 bfd_lookup_symbol
PARAMS ((bfd
*, char *));
159 solib_add_common_symbols
PARAMS ((struct rtc_symb
*, struct objfile
*));
167 solib_map_sections -- open bfd and build sections for shared lib
171 static void solib_map_sections (struct so_list *so)
175 Given a pointer to one of the shared objects in our list
176 of mapped objects, use the recorded name to open a bfd
177 descriptor for the object, build a section table, and then
178 relocate all the section addresses by the base address at
179 which the shared object was mapped.
183 In most (all?) cases the shared object file name recorded in the
184 dynamic linkage tables will be a fully qualified pathname. For
185 cases where it isn't, do we really mimic the systems search
186 mechanism correctly in the below code (particularly the tilde
191 solib_map_sections (so
)
195 char *scratch_pathname
;
197 struct section_table
*p
;
198 struct cleanup
*old_chain
;
201 filename
= tilde_expand (so
-> so_name
);
202 old_chain
= make_cleanup (free
, filename
);
204 scratch_chan
= openp (getenv ("PATH"), 1, filename
, O_RDONLY
, 0,
206 if (scratch_chan
< 0)
208 scratch_chan
= openp (getenv ("LD_LIBRARY_PATH"), 1, filename
,
209 O_RDONLY
, 0, &scratch_pathname
);
211 if (scratch_chan
< 0)
213 perror_with_name (filename
);
215 /* Leave scratch_pathname allocated. bfd->name will point to it. */
217 abfd
= bfd_fdopenr (scratch_pathname
, NULL
, scratch_chan
);
220 close (scratch_chan
);
221 error ("Could not open `%s' as an executable file: %s",
222 scratch_pathname
, bfd_errmsg (bfd_error
));
224 /* Leave bfd open, core_xfer_memory and "info files" need it. */
226 abfd
-> cacheable
= true;
228 if (!bfd_check_format (abfd
, bfd_object
))
230 error ("\"%s\": not in executable format: %s.",
231 scratch_pathname
, bfd_errmsg (bfd_error
));
233 if (build_section_table (abfd
, &so
-> sections
, &so
-> sections_end
))
235 error ("Can't find the file sections in `%s': %s",
236 bfd_get_filename (exec_bfd
), bfd_errmsg (bfd_error
));
239 for (p
= so
-> sections
; p
< so
-> sections_end
; p
++)
241 /* Relocate the section binding addresses as recorded in the shared
242 object's file by the base address to which the object was actually
244 p
-> addr
+= (CORE_ADDR
) LM_ADDR (so
);
245 p
-> endaddr
+= (CORE_ADDR
) LM_ADDR (so
);
246 so
-> lmend
= (CORE_ADDR
) max (p
-> endaddr
, so
-> lmend
);
247 if (STREQ (p
-> sec_ptr
-> name
, ".text"))
249 so
-> textsection
= p
;
253 /* Free the file names, close the file now. */
254 do_cleanups (old_chain
);
257 /* Read all dynamically loaded common symbol definitions from the inferior
258 and add them to the minimal symbol table for the shared library objfile. */
260 #ifndef SVR4_SHARED_LIBS
263 solib_add_common_symbols (rtc_symp
, objfile
)
264 struct rtc_symb
*rtc_symp
;
265 struct objfile
*objfile
;
267 struct rtc_symb inferior_rtc_symb
;
268 struct nlist inferior_rtc_nlist
;
273 init_minimal_symbol_collection ();
274 make_cleanup (discard_minimal_symbols
, 0);
278 read_memory ((CORE_ADDR
) rtc_symp
,
279 (char *) &inferior_rtc_symb
,
280 sizeof (inferior_rtc_symb
));
281 read_memory ((CORE_ADDR
) inferior_rtc_symb
.rtc_sp
,
282 (char *) &inferior_rtc_nlist
,
283 sizeof(inferior_rtc_nlist
));
284 if (inferior_rtc_nlist
.n_type
== N_COMM
)
286 /* FIXME: The length of the symbol name is not available, but in the
287 current implementation the common symbol is allocated immediately
288 behind the name of the symbol. */
289 len
= inferior_rtc_nlist
.n_value
- inferior_rtc_nlist
.n_un
.n_strx
;
291 origname
= name
= xmalloc (len
);
292 read_memory ((CORE_ADDR
) inferior_rtc_nlist
.n_un
.n_name
, name
, len
);
294 /* Don't enter the symbol twice if the target is re-run. */
296 if (name
[0] == bfd_get_symbol_leading_char (objfile
->obfd
))
301 /* FIXME: Do we really want to exclude symbols which happen
302 to match symbols for other locations in the inferior's
303 address space, even when they are in different linkage units? */
304 if (lookup_minimal_symbol (name
, (struct objfile
*) NULL
) == NULL
)
306 name
= obsavestring (name
, strlen (name
),
307 &objfile
-> symbol_obstack
);
308 prim_record_minimal_symbol (name
, inferior_rtc_nlist
.n_value
,
313 rtc_symp
= inferior_rtc_symb
.rtc_next
;
316 /* Install any minimal symbols that have been collected as the current
317 minimal symbols for this objfile. */
319 install_minimal_symbols (objfile
);
322 #endif /* SVR4_SHARED_LIBS */
324 #ifdef SVR4_SHARED_LIBS
330 bfd_lookup_symbol -- lookup the value for a specific symbol
334 CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname)
338 An expensive way to lookup the value of a single symbol for
339 bfd's that are only temporary anyway. This is used by the
340 shared library support to find the address of the debugger
341 interface structures in the shared library.
343 Note that 0 is specifically allowed as an error return (no
346 FIXME: See if there is a less "expensive" way of doing this.
347 Also see if there is already another bfd or gdb function
348 that specifically does this, and if so, use it.
352 bfd_lookup_symbol (abfd
, symname
)
356 unsigned int storage_needed
;
358 asymbol
**symbol_table
;
359 unsigned int number_of_symbols
;
361 struct cleanup
*back_to
;
362 CORE_ADDR symaddr
= 0;
364 storage_needed
= get_symtab_upper_bound (abfd
);
366 if (storage_needed
> 0)
368 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
369 back_to
= make_cleanup (free
, (PTR
)symbol_table
);
370 number_of_symbols
= bfd_canonicalize_symtab (abfd
, symbol_table
);
372 for (i
= 0; i
< number_of_symbols
; i
++)
374 sym
= *symbol_table
++;
375 if (STREQ (sym
-> name
, symname
))
377 /* Bfd symbols are section relative. */
378 symaddr
= sym
-> value
+ sym
-> section
-> vma
;
382 do_cleanups (back_to
);
391 look_for_base -- examine file for each mapped address segment
395 static int look_for_base (int fd, CORE_ADDR baseaddr)
399 This function is passed to proc_iterate_over_mappings, which
400 causes it to get called once for each mapped address space, with
401 an open file descriptor for the file mapped to that space, and the
402 base address of that mapped space.
404 Our job is to find the symbol DEBUG_BASE in the file that this
405 fd is open on, if it exists, and if so, initialize the dynamic
406 linker structure base address debug_base.
408 Note that this is a computationally expensive proposition, since
409 we basically have to open a bfd on every call, so we specifically
410 avoid opening the exec file.
414 look_for_base (fd
, baseaddr
)
421 /* If the fd is -1, then there is no file that corresponds to this
422 mapped memory segment, so skip it. Also, if the fd corresponds
423 to the exec file, skip it as well. */
425 if ((fd
== -1) || fdmatch (fileno ((FILE *)(exec_bfd
-> iostream
)), fd
))
430 /* Try to open whatever random file this fd corresponds to. Note that
431 we have no way currently to find the filename. Don't gripe about
432 any problems we might have, just fail. */
434 if ((interp_bfd
= bfd_fdopenr ("unnamed", NULL
, fd
)) == NULL
)
438 if (!bfd_check_format (interp_bfd
, bfd_object
))
440 bfd_close (interp_bfd
);
444 /* Now try to find our DEBUG_BASE symbol in this file, which we at
445 least know to be a valid ELF executable or shared library. */
447 if ((address
= bfd_lookup_symbol (interp_bfd
, DEBUG_BASE
)) == 0)
449 bfd_close (interp_bfd
);
453 /* Eureka! We found the symbol. But now we may need to relocate it
454 by the base address. If the symbol's value is less than the base
455 address of the shared library, then it hasn't yet been relocated
456 by the dynamic linker, and we have to do it ourself. FIXME: Note
457 that we make the assumption that the first segment that corresponds
458 to the shared library has the base address to which the library
461 if (address
< baseaddr
)
465 debug_base
= address
;
466 bfd_close (interp_bfd
);
476 locate_base -- locate the base address of dynamic linker structs
480 CORE_ADDR locate_base (void)
484 For both the SunOS and SVR4 shared library implementations, if the
485 inferior executable has been linked dynamically, there is a single
486 address somewhere in the inferior's data space which is the key to
487 locating all of the dynamic linker's runtime structures. This
488 address is the value of the symbol defined by the macro DEBUG_BASE.
489 The job of this function is to find and return that address, or to
490 return 0 if there is no such address (the executable is statically
493 For SunOS, the job is almost trivial, since the dynamic linker and
494 all of it's structures are statically linked to the executable at
495 link time. Thus the symbol for the address we are looking for has
496 already been added to the minimal symbol table for the executable's
497 objfile at the time the symbol file's symbols were read, and all we
498 have to do is look it up there. Note that we explicitly do NOT want
499 to find the copies in the shared library.
501 The SVR4 version is much more complicated because the dynamic linker
502 and it's structures are located in the shared C library, which gets
503 run as the executable's "interpreter" by the kernel. We have to go
504 to a lot more work to discover the address of DEBUG_BASE. Because
505 of this complexity, we cache the value we find and return that value
506 on subsequent invocations. Note there is no copy in the executable
509 Note that we can assume nothing about the process state at the time
510 we need to find this address. We may be stopped on the first instruc-
511 tion of the interpreter (C shared library), the first instruction of
512 the executable itself, or somewhere else entirely (if we attached
513 to the process for example).
521 #ifndef SVR4_SHARED_LIBS
523 struct minimal_symbol
*msymbol
;
524 CORE_ADDR address
= 0;
526 /* For SunOS, we want to limit the search for DEBUG_BASE to the executable
527 being debugged, since there is a duplicate named symbol in the shared
528 library. We don't want the shared library versions. */
530 msymbol
= lookup_minimal_symbol (DEBUG_BASE
, symfile_objfile
);
531 if ((msymbol
!= NULL
) && (SYMBOL_VALUE_ADDRESS (msymbol
) != 0))
533 address
= SYMBOL_VALUE_ADDRESS (msymbol
);
537 #else /* SVR4_SHARED_LIBS */
539 /* Check to see if we have a currently valid address, and if so, avoid
540 doing all this work again and just return the cached address. If
541 we have no cached address, ask the /proc support interface to iterate
542 over the list of mapped address segments, calling look_for_base() for
543 each segment. When we are done, we will have either found the base
548 proc_iterate_over_mappings (look_for_base
);
552 #endif /* !SVR4_SHARED_LIBS */
560 first_link_map_member -- locate first member in dynamic linker's map
564 static struct link_map *first_link_map_member (void)
568 Read in a copy of the first member in the inferior's dynamic
569 link map from the inferior's dynamic linker structures, and return
570 a pointer to the copy in our address space.
573 static struct link_map
*
574 first_link_map_member ()
576 struct link_map
*lm
= NULL
;
578 #ifndef SVR4_SHARED_LIBS
580 read_memory (debug_base
, (char *) &dynamic_copy
, sizeof (dynamic_copy
));
581 if (dynamic_copy
.ld_version
>= 2)
583 /* It is a version that we can deal with, so read in the secondary
584 structure and find the address of the link map list from it. */
585 read_memory ((CORE_ADDR
) dynamic_copy
.ld_un
.ld_2
, (char *) &ld_2_copy
,
586 sizeof (struct link_dynamic_2
));
587 lm
= ld_2_copy
.ld_loaded
;
590 #else /* SVR4_SHARED_LIBS */
592 read_memory (debug_base
, (char *) &debug_copy
, sizeof (struct r_debug
));
593 /* FIXME: Perhaps we should validate the info somehow, perhaps by
594 checking r_version for a known version number, or r_state for
596 lm
= debug_copy
.r_map
;
598 #endif /* !SVR4_SHARED_LIBS */
607 find_solib -- step through list of shared objects
611 struct so_list *find_solib (struct so_list *so_list_ptr)
615 This module contains the routine which finds the names of any
616 loaded "images" in the current process. The argument in must be
617 NULL on the first call, and then the returned value must be passed
618 in on subsequent calls. This provides the capability to "step" down
619 the list of loaded objects. On the last object, a NULL value is
622 The arg and return value are "struct link_map" pointers, as defined
626 static struct so_list
*
627 find_solib (so_list_ptr
)
628 struct so_list
*so_list_ptr
; /* Last lm or NULL for first one */
630 struct so_list
*so_list_next
= NULL
;
631 struct link_map
*lm
= NULL
;
634 if (so_list_ptr
== NULL
)
636 /* We are setting up for a new scan through the loaded images. */
637 if ((so_list_next
= so_list_head
) == NULL
)
639 /* We have not already read in the dynamic linking structures
640 from the inferior, lookup the address of the base structure. */
641 debug_base
= locate_base ();
644 /* Read the base structure in and find the address of the first
645 link map list member. */
646 lm
= first_link_map_member ();
652 /* We have been called before, and are in the process of walking
653 the shared library list. Advance to the next shared object. */
654 if ((lm
= LM_NEXT (so_list_ptr
)) == NULL
)
656 /* We have hit the end of the list, so check to see if any were
657 added, but be quiet if we can't read from the target any more. */
658 int status
= target_read_memory ((CORE_ADDR
) so_list_ptr
-> lmaddr
,
659 (char *) &(so_list_ptr
-> lm
),
660 sizeof (struct link_map
));
663 lm
= LM_NEXT (so_list_ptr
);
670 so_list_next
= so_list_ptr
-> next
;
672 if ((so_list_next
== NULL
) && (lm
!= NULL
))
674 /* Get next link map structure from inferior image and build a local
675 abbreviated load_map structure */
676 new = (struct so_list
*) xmalloc (sizeof (struct so_list
));
677 memset ((char *) new, 0, sizeof (struct so_list
));
679 /* Add the new node as the next node in the list, or as the root
680 node if this is the first one. */
681 if (so_list_ptr
!= NULL
)
683 so_list_ptr
-> next
= new;
690 read_memory ((CORE_ADDR
) lm
, (char *) &(new -> lm
),
691 sizeof (struct link_map
));
692 /* For the SVR4 version, there is one entry that has no name
693 (for the inferior executable) since it is not a shared object. */
694 if (LM_NAME (new) != 0)
696 if (!target_read_string((CORE_ADDR
) LM_NAME (new), new -> so_name
,
698 error ("find_solib: Can't read pathname for load map\n");
699 new -> so_name
[MAX_PATH_SIZE
- 1] = 0;
700 solib_map_sections (new);
703 return (so_list_next
);
706 /* A small stub to get us past the arg-passing pinhole of catch_errors. */
709 symbol_add_stub (arg
)
712 register struct so_list
*so
= (struct so_list
*) arg
; /* catch_errs bogon */
714 so
-> objfile
= symbol_file_add (so
-> so_name
, so
-> from_tty
,
715 (unsigned int) so
-> textsection
-> addr
,
724 solib_add -- add a shared library file to the symtab and section list
728 void solib_add (char *arg_string, int from_tty,
729 struct target_ops *target)
736 solib_add (arg_string
, from_tty
, target
)
739 struct target_ops
*target
;
741 register struct so_list
*so
= NULL
; /* link map state variable */
746 if ((re_err
= re_comp (arg_string
? arg_string
: ".")) != NULL
)
748 error ("Invalid regexp: %s", re_err
);
751 /* Getting new symbols may change our opinion about what is
753 reinit_frame_cache ();
755 while ((so
= find_solib (so
)) != NULL
)
757 if (so
-> so_name
[0] && re_exec (so
-> so_name
))
759 so
-> from_tty
= from_tty
;
760 if (so
-> symbols_loaded
)
764 printf ("Symbols already loaded for %s\n", so
-> so_name
);
767 else if (catch_errors
768 (symbol_add_stub
, (char *) so
,
769 "Error while reading shared library symbols:\n",
772 special_symbol_handling (so
);
773 so
-> symbols_loaded
= 1;
778 /* Now add the shared library sections to the section table of the
779 specified target, if any. */
782 /* Count how many new section_table entries there are. */
785 while ((so
= find_solib (so
)) != NULL
)
787 if (so
-> so_name
[0])
789 count
+= so
-> sections_end
- so
-> sections
;
795 /* Reallocate the target's section table including the new size. */
796 if (target
-> to_sections
)
798 old
= target
-> to_sections_end
- target
-> to_sections
;
799 target
-> to_sections
= (struct section_table
*)
800 realloc ((char *)target
-> to_sections
,
801 (sizeof (struct section_table
)) * (count
+ old
));
806 target
-> to_sections
= (struct section_table
*)
807 malloc ((sizeof (struct section_table
)) * count
);
809 target
-> to_sections_end
= target
-> to_sections
+ (count
+ old
);
811 /* Add these section table entries to the target's table. */
812 while ((so
= find_solib (so
)) != NULL
)
814 if (so
-> so_name
[0])
816 count
= so
-> sections_end
- so
-> sections
;
817 memcpy ((char *) (target
-> to_sections
+ old
),
819 (sizeof (struct section_table
)) * count
);
831 info_sharedlibrary_command -- code for "info sharedlibrary"
835 static void info_sharedlibrary_command ()
839 Walk through the shared library list and print information
840 about each attached library.
844 info_sharedlibrary_command (ignore
, from_tty
)
848 register struct so_list
*so
= NULL
; /* link map state variable */
851 if (exec_bfd
== NULL
)
853 printf ("No exec file.\n");
856 while ((so
= find_solib (so
)) != NULL
)
858 if (so
-> so_name
[0])
862 printf("%-12s%-12s%-12s%s\n", "From", "To", "Syms Read",
863 "Shared Object Library");
866 printf ("%-12s", local_hex_string_custom ((int) LM_ADDR (so
), "08"));
867 printf ("%-12s", local_hex_string_custom (so
-> lmend
, "08"));
868 printf ("%-12s", so
-> symbols_loaded
? "Yes" : "No");
869 printf ("%s\n", so
-> so_name
);
872 if (so_list_head
== NULL
)
874 printf ("No shared libraries loaded at this time.\n");
882 solib_address -- check to see if an address is in a shared lib
886 int solib_address (CORE_ADDR address)
890 Provides a hook for other gdb routines to discover whether or
891 not a particular address is within the mapped address space of
892 a shared library. Any address between the base mapping address
893 and the first address beyond the end of the last mapping, is
894 considered to be within the shared library address space, for
897 For example, this routine is called at one point to disable
898 breakpoints which are in shared libraries that are not currently
903 solib_address (address
)
906 register struct so_list
*so
= 0; /* link map state variable */
908 while ((so
= find_solib (so
)) != NULL
)
910 if (so
-> so_name
[0])
912 if ((address
>= (CORE_ADDR
) LM_ADDR (so
)) &&
913 (address
< (CORE_ADDR
) so
-> lmend
))
922 /* Called by free_all_symtabs */
927 struct so_list
*next
;
932 if (so_list_head
-> sections
)
934 free ((PTR
)so_list_head
-> sections
);
936 if (so_list_head
-> bfd
)
938 bfd_filename
= bfd_get_filename (so_list_head
-> bfd
);
939 bfd_close (so_list_head
-> bfd
);
942 /* This happens for the executable on SVR4. */
945 next
= so_list_head
-> next
;
947 free ((PTR
)bfd_filename
);
948 free ((PTR
)so_list_head
);
958 disable_break -- remove the "mapping changed" breakpoint
962 static int disable_break ()
966 Removes the breakpoint that gets hit when the dynamic linker
967 completes a mapping change.
976 #ifndef SVR4_SHARED_LIBS
980 /* Read the debugger structure from the inferior to retrieve the
981 address of the breakpoint and the original contents of the
982 breakpoint address. Remove the breakpoint by writing the original
985 read_memory (debug_addr
, (char *) &debug_copy
, sizeof (debug_copy
));
987 /* Set `in_debugger' to zero now. */
989 write_memory (flag_addr
, (char *) &in_debugger
, sizeof (in_debugger
));
991 breakpoint_addr
= (CORE_ADDR
) debug_copy
.ldd_bp_addr
;
992 write_memory (breakpoint_addr
, (char *) &debug_copy
.ldd_bp_inst
,
993 sizeof (debug_copy
.ldd_bp_inst
));
995 #else /* SVR4_SHARED_LIBS */
997 /* Note that breakpoint address and original contents are in our address
998 space, so we just need to write the original contents back. */
1000 if (memory_remove_breakpoint (breakpoint_addr
, shadow_contents
) != 0)
1005 #endif /* !SVR4_SHARED_LIBS */
1007 /* For the SVR4 version, we always know the breakpoint address. For the
1008 SunOS version we don't know it until the above code is executed.
1009 Grumble if we are stopped anywhere besides the breakpoint address. */
1011 if (stop_pc
!= breakpoint_addr
)
1013 warning ("stopped at unknown breakpoint while handling shared libraries");
1023 enable_break -- arrange for dynamic linker to hit breakpoint
1027 int enable_break (void)
1031 Both the SunOS and the SVR4 dynamic linkers have, as part of their
1032 debugger interface, support for arranging for the inferior to hit
1033 a breakpoint after mapping in the shared libraries. This function
1034 enables that breakpoint.
1036 For SunOS, there is a special flag location (in_debugger) which we
1037 set to 1. When the dynamic linker sees this flag set, it will set
1038 a breakpoint at a location known only to itself, after saving the
1039 original contents of that place and the breakpoint address itself,
1040 in it's own internal structures. When we resume the inferior, it
1041 will eventually take a SIGTRAP when it runs into the breakpoint.
1042 We handle this (in a different place) by restoring the contents of
1043 the breakpointed location (which is only known after it stops),
1044 chasing around to locate the shared libraries that have been
1045 loaded, then resuming.
1047 For SVR4, the debugger interface structure contains a member (r_brk)
1048 which is statically initialized at the time the shared library is
1049 built, to the offset of a function (_r_debug_state) which is guaran-
1050 teed to be called once before mapping in a library, and again when
1051 the mapping is complete. At the time we are examining this member,
1052 it contains only the unrelocated offset of the function, so we have
1053 to do our own relocation. Later, when the dynamic linker actually
1054 runs, it relocates r_brk to be the actual address of _r_debug_state().
1056 The debugger interface structure also contains an enumeration which
1057 is set to either RT_ADD or RT_DELETE prior to changing the mapping,
1058 depending upon whether or not the library is being mapped or unmapped,
1059 and then set to RT_CONSISTENT after the library is mapped/unmapped.
1067 #ifndef SVR4_SHARED_LIBS
1072 /* Get link_dynamic structure */
1074 j
= target_read_memory (debug_base
, (char *) &dynamic_copy
,
1075 sizeof (dynamic_copy
));
1082 /* Calc address of debugger interface structure */
1084 debug_addr
= (CORE_ADDR
) dynamic_copy
.ldd
;
1086 /* Calc address of `in_debugger' member of debugger interface structure */
1088 flag_addr
= debug_addr
+ (CORE_ADDR
) ((char *) &debug_copy
.ldd_in_debugger
-
1089 (char *) &debug_copy
);
1091 /* Write a value of 1 to this member. */
1094 write_memory (flag_addr
, (char *) &in_debugger
, sizeof (in_debugger
));
1097 #else /* SVR4_SHARED_LIBS */
1099 #ifdef BKPT_AT_SYMBOL
1101 struct minimal_symbol
*msymbol
;
1103 CORE_ADDR bkpt_addr
;
1105 /* Scan through the list of symbols, trying to look up the symbol and
1106 set a breakpoint there. Terminate loop when we/if we succeed. */
1108 breakpoint_addr
= 0;
1109 for (bkpt_namep
= bkpt_names
; *bkpt_namep
!= NULL
; bkpt_namep
++)
1111 msymbol
= lookup_minimal_symbol (*bkpt_namep
, symfile_objfile
);
1112 if ((msymbol
!= NULL
) && (SYMBOL_VALUE_ADDRESS (msymbol
) != 0))
1114 bkpt_addr
= SYMBOL_VALUE_ADDRESS (msymbol
);
1115 if (target_insert_breakpoint (bkpt_addr
, shadow_contents
) == 0)
1117 breakpoint_addr
= bkpt_addr
;
1124 #else /* !BKPT_AT_SYMBOL */
1126 struct symtab_and_line sal
;
1128 /* Read the debugger interface structure directly. */
1130 read_memory (debug_base
, (char *) &debug_copy
, sizeof (debug_copy
));
1132 /* Set breakpoint at the debugger interface stub routine that will
1133 be called just prior to each mapping change and again after the
1134 mapping change is complete. Set up the (nonexistent) handler to
1135 deal with hitting these breakpoints. (FIXME). */
1137 warning ("'%s': line %d: missing SVR4 support code", __FILE__
, __LINE__
);
1140 #endif /* BKPT_AT_SYMBOL */
1142 #endif /* !SVR4_SHARED_LIBS */
1151 solib_create_inferior_hook -- shared library startup support
1155 void solib_create_inferior_hook()
1159 When gdb starts up the inferior, it nurses it along (through the
1160 shell) until it is ready to execute it's first instruction. At this
1161 point, this function gets called via expansion of the macro
1162 SOLIB_CREATE_INFERIOR_HOOK.
1164 For SunOS executables, this first instruction is typically the
1165 one at "_start", or a similar text label, regardless of whether
1166 the executable is statically or dynamically linked. The runtime
1167 startup code takes care of dynamically linking in any shared
1168 libraries, once gdb allows the inferior to continue.
1170 For SVR4 executables, this first instruction is either the first
1171 instruction in the dynamic linker (for dynamically linked
1172 executables) or the instruction at "start" for statically linked
1173 executables. For dynamically linked executables, the system
1174 first exec's /lib/libc.so.N, which contains the dynamic linker,
1175 and starts it running. The dynamic linker maps in any needed
1176 shared libraries, maps in the actual user executable, and then
1177 jumps to "start" in the user executable.
1179 For both SunOS shared libraries, and SVR4 shared libraries, we
1180 can arrange to cooperate with the dynamic linker to discover the
1181 names of shared libraries that are dynamically linked, and the
1182 base addresses to which they are linked.
1184 This function is responsible for discovering those names and
1185 addresses, and saving sufficient information about them to allow
1186 their symbols to be read at a later time.
1190 Between enable_break() and disable_break(), this code does not
1191 properly handle hitting breakpoints which the user might have
1192 set in the startup code or in the dynamic linker itself. Proper
1193 handling will probably have to wait until the implementation is
1194 changed to use the "breakpoint handler function" method.
1196 Also, what if child has exit()ed? Must exit loop somehow.
1200 solib_create_inferior_hook()
1202 /* If we are using the BKPT_AT_SYMBOL code, then we don't need the base
1203 yet. In fact, in the case of a SunOS4 executable being run on
1204 Solaris, we can't get it yet. find_solib will get it when it needs
1206 #if !(defined (SVR4_SHARED_LIBS) && defined (BKPT_AT_SYMBOL))
1207 if ((debug_base
= locate_base ()) == 0)
1209 /* Can't find the symbol or the executable is statically linked. */
1214 if (!enable_break ())
1216 warning ("shared library handler failed to enable breakpoint");
1220 /* Now run the target. It will eventually hit the breakpoint, at
1221 which point all of the libraries will have been mapped in and we
1222 can go groveling around in the dynamic linker structures to find
1223 out what we need to know about them. */
1225 clear_proceed_status ();
1226 stop_soon_quietly
= 1;
1230 target_resume (0, stop_signal
);
1231 wait_for_inferior ();
1233 while (stop_signal
!= SIGTRAP
);
1234 stop_soon_quietly
= 0;
1236 /* We are now either at the "mapping complete" breakpoint (or somewhere
1237 else, a condition we aren't prepared to deal with anyway), so adjust
1238 the PC as necessary after a breakpoint, disable the breakpoint, and
1239 add any shared libraries that were mapped in. */
1241 if (DECR_PC_AFTER_BREAK
)
1243 stop_pc
-= DECR_PC_AFTER_BREAK
;
1244 write_register (PC_REGNUM
, stop_pc
);
1247 if (!disable_break ())
1249 warning ("shared library handler failed to disable breakpoint");
1252 solib_add ((char *) 0, 0, (struct target_ops
*) 0);
1259 special_symbol_handling -- additional shared library symbol handling
1263 void special_symbol_handling (struct so_list *so)
1267 Once the symbols from a shared object have been loaded in the usual
1268 way, we are called to do any system specific symbol handling that
1271 For Suns, this consists of grunging around in the dynamic linkers
1272 structures to find symbol definitions for "common" symbols and
1273 adding them to the minimal symbol table for the corresponding
1279 special_symbol_handling (so
)
1282 #ifndef SVR4_SHARED_LIBS
1285 if (debug_addr
== 0)
1287 /* Get link_dynamic structure */
1289 j
= target_read_memory (debug_base
, (char *) &dynamic_copy
,
1290 sizeof (dynamic_copy
));
1297 /* Calc address of debugger interface structure */
1298 /* FIXME, this needs work for cross-debugging of core files
1299 (byteorder, size, alignment, etc). */
1301 debug_addr
= (CORE_ADDR
) dynamic_copy
.ldd
;
1304 /* Read the debugger structure from the inferior, just to make sure
1305 we have a current copy. */
1307 j
= target_read_memory (debug_addr
, (char *) &debug_copy
,
1308 sizeof (debug_copy
));
1310 return; /* unreadable */
1312 /* Get common symbol definitions for the loaded object. */
1314 if (debug_copy
.ldd_cp
)
1316 solib_add_common_symbols (debug_copy
.ldd_cp
, so
-> objfile
);
1319 #endif /* !SVR4_SHARED_LIBS */
1327 sharedlibrary_command -- handle command to explicitly add library
1331 static void sharedlibrary_command (char *args, int from_tty)
1338 sharedlibrary_command (args
, from_tty
)
1343 solib_add (args
, from_tty
, (struct target_ops
*) 0);
1350 add_com ("sharedlibrary", class_files
, sharedlibrary_command
,
1351 "Load shared object library symbols for files matching REGEXP.");
1352 add_info ("sharedlibrary", info_sharedlibrary_command
,
1353 "Status of loaded shared object libraries.");