1 /* Read ELF (Executable and Linking Format) object files for GDB.
2 
3    Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
4    2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
5 
6    Written by Fred Fish at Cygnus Support.
7 
8    This file is part of GDB.
9 
10    This program is free software; you can redistribute it and/or modify
11    it under the terms of the GNU General Public License as published by
12    the Free Software Foundation; either version 2 of the License, or
13    (at your option) any later version.
14 
15    This program is distributed in the hope that it will be useful,
16    but WITHOUT ANY WARRANTY; without even the implied warranty of
17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18    GNU General Public License for more details.
19 
20    You should have received a copy of the GNU General Public License
21    along with this program; if not, write to the Free Software
22    Foundation, Inc., 59 Temple Place - Suite 330,
23    Boston, MA 02111-1307, USA.  */
24 
25 #include "defs.h"
26 #include "bfd.h"
27 #include "gdb_string.h"
28 #include "elf-bfd.h"
29 #include "elf/mips.h"
30 #include "symtab.h"
31 #include "symfile.h"
32 #include "objfiles.h"
33 #include "buildsym.h"
34 #include "stabsread.h"
35 #include "gdb-stabs.h"
36 #include "complaints.h"
37 #include "demangle.h"
38 
39 extern void _initialize_elfread (void);
40 
41 /* The struct elfinfo is available only during ELF symbol table and
42    psymtab reading.  It is destroyed at the completion of psymtab-reading.
43    It's local to elf_symfile_read.  */
44 
45 struct elfinfo
46   {
47     file_ptr dboffset;		/* Offset to dwarf debug section */
48     unsigned int dbsize;	/* Size of dwarf debug section */
49     file_ptr lnoffset;		/* Offset to dwarf line number section */
50     unsigned int lnsize;	/* Size of dwarf line number section */
51     asection *stabsect;		/* Section pointer for .stab section */
52     asection *stabindexsect;	/* Section pointer for .stab.index section */
53     asection *mdebugsect;	/* Section pointer for .mdebug section */
54   };
55 
56 static void free_elfinfo (void *);
57 
58 /* We are called once per section from elf_symfile_read.  We
59    need to examine each section we are passed, check to see
60    if it is something we are interested in processing, and
61    if so, stash away some access information for the section.
62 
63    For now we recognize the dwarf debug information sections and
64    line number sections from matching their section names.  The
65    ELF definition is no real help here since it has no direct
66    knowledge of DWARF (by design, so any debugging format can be
67    used).
68 
69    We also recognize the ".stab" sections used by the Sun compilers
70    released with Solaris 2.
71 
72    FIXME: The section names should not be hardwired strings (what
73    should they be?  I don't think most object file formats have enough
74    section flags to specify what kind of debug section it is
75    -kingdon).  */
76 
77 static void
elf_locate_sections(bfd * ignore_abfd,asection * sectp,void * eip)78 elf_locate_sections (bfd *ignore_abfd, asection *sectp, void *eip)
79 {
80   struct elfinfo *ei;
81 
82   ei = (struct elfinfo *) eip;
83   if (strcmp (sectp->name, ".debug") == 0)
84     {
85       ei->dboffset = sectp->filepos;
86       ei->dbsize = bfd_get_section_size (sectp);
87     }
88   else if (strcmp (sectp->name, ".line") == 0)
89     {
90       ei->lnoffset = sectp->filepos;
91       ei->lnsize = bfd_get_section_size (sectp);
92     }
93   else if (strcmp (sectp->name, ".stab") == 0)
94     {
95       ei->stabsect = sectp;
96     }
97   else if (strcmp (sectp->name, ".stab.index") == 0)
98     {
99       ei->stabindexsect = sectp;
100     }
101   else if (strcmp (sectp->name, ".mdebug") == 0)
102     {
103       ei->mdebugsect = sectp;
104     }
105 }
106 
107 static struct minimal_symbol *
record_minimal_symbol(char * name,CORE_ADDR address,enum minimal_symbol_type ms_type,asection * bfd_section,struct objfile * objfile)108 record_minimal_symbol (char *name, CORE_ADDR address,
109 		       enum minimal_symbol_type ms_type,
110 		       asection *bfd_section, struct objfile *objfile)
111 {
112   if (ms_type == mst_text || ms_type == mst_file_text)
113     address = SMASH_TEXT_ADDRESS (address);
114 
115   return prim_record_minimal_symbol_and_info
116     (name, address, ms_type, NULL, bfd_section->index, bfd_section, objfile);
117 }
118 
119 /*
120 
121    LOCAL FUNCTION
122 
123    elf_symtab_read -- read the symbol table of an ELF file
124 
125    SYNOPSIS
126 
127    void elf_symtab_read (struct objfile *objfile, int dynamic)
128 
129    DESCRIPTION
130 
131    Given an objfile and a flag that specifies whether or not the objfile
132    is for an executable or not (may be shared library for example), add
133    all the global function and data symbols to the minimal symbol table.
134 
135    In stabs-in-ELF, as implemented by Sun, there are some local symbols
136    defined in the ELF symbol table, which can be used to locate
137    the beginnings of sections from each ".o" file that was linked to
138    form the executable objfile.  We gather any such info and record it
139    in data structures hung off the objfile's private data.
140 
141  */
142 
143 static void
elf_symtab_read(struct objfile * objfile,int dynamic)144 elf_symtab_read (struct objfile *objfile, int dynamic)
145 {
146   long storage_needed;
147   asymbol *sym;
148   asymbol **symbol_table;
149   long number_of_symbols;
150   long i;
151   struct cleanup *back_to;
152   CORE_ADDR symaddr;
153   CORE_ADDR offset;
154   enum minimal_symbol_type ms_type;
155   /* If sectinfo is nonNULL, it contains section info that should end up
156      filed in the objfile.  */
157   struct stab_section_info *sectinfo = NULL;
158   /* If filesym is nonzero, it points to a file symbol, but we haven't
159      seen any section info for it yet.  */
160   asymbol *filesym = 0;
161 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
162   /* Name of filesym, as saved on the objfile_obstack.  */
163   char *filesymname = obsavestring ("", 0, &objfile->objfile_obstack);
164 #endif
165   struct dbx_symfile_info *dbx = objfile->deprecated_sym_stab_info;
166   int stripped = (bfd_get_symcount (objfile->obfd) == 0);
167 
168   if (dynamic)
169     {
170       storage_needed = bfd_get_dynamic_symtab_upper_bound (objfile->obfd);
171 
172       /* Nothing to be done if there is no dynamic symtab.  */
173       if (storage_needed < 0)
174 	return;
175     }
176   else
177     {
178       storage_needed = bfd_get_symtab_upper_bound (objfile->obfd);
179       if (storage_needed < 0)
180 	error (_("Can't read symbols from %s: %s"), bfd_get_filename (objfile->obfd),
181 	       bfd_errmsg (bfd_get_error ()));
182     }
183   if (storage_needed > 0)
184     {
185       symbol_table = (asymbol **) xmalloc (storage_needed);
186       back_to = make_cleanup (xfree, symbol_table);
187       if (dynamic)
188 	number_of_symbols = bfd_canonicalize_dynamic_symtab (objfile->obfd,
189 							     symbol_table);
190       else
191 	number_of_symbols = bfd_canonicalize_symtab (objfile->obfd, symbol_table);
192       if (number_of_symbols < 0)
193 	error (_("Can't read symbols from %s: %s"), bfd_get_filename (objfile->obfd),
194 	       bfd_errmsg (bfd_get_error ()));
195 
196       for (i = 0; i < number_of_symbols; i++)
197 	{
198 	  sym = symbol_table[i];
199 	  if (sym->name == NULL || *sym->name == '\0')
200 	    {
201 	      /* Skip names that don't exist (shouldn't happen), or names
202 	         that are null strings (may happen). */
203 	      continue;
204 	    }
205 
206           offset = ANOFFSET (objfile->section_offsets, sym->section->index);
207 	  if (dynamic
208 	      && sym->section == &bfd_und_section
209 	      && (sym->flags & BSF_FUNCTION))
210 	    {
211 	      struct minimal_symbol *msym;
212 
213 	      /* Symbol is a reference to a function defined in
214 	         a shared library.
215 	         If its value is non zero then it is usually the address
216 	         of the corresponding entry in the procedure linkage table,
217 	         plus the desired section offset.
218 	         If its value is zero then the dynamic linker has to resolve
219 	         the symbol. We are unable to find any meaningful address
220 	         for this symbol in the executable file, so we skip it.  */
221 	      symaddr = sym->value;
222 	      if (symaddr == 0)
223 		continue;
224 	      symaddr += offset;
225 	      msym = record_minimal_symbol
226 		((char *) sym->name, symaddr,
227 		 mst_solib_trampoline, sym->section, objfile);
228 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
229 	      if (msym != NULL)
230 		msym->filename = filesymname;
231 #endif
232 	      continue;
233 	    }
234 
235 	  /* If it is a nonstripped executable, do not enter dynamic
236 	     symbols, as the dynamic symbol table is usually a subset
237 	     of the main symbol table.  */
238 	  if (dynamic && !stripped)
239 	    continue;
240 	  if (sym->flags & BSF_FILE)
241 	    {
242 	      /* STT_FILE debugging symbol that helps stabs-in-elf debugging.
243 	         Chain any old one onto the objfile; remember new sym.  */
244 	      if (sectinfo != NULL)
245 		{
246 		  sectinfo->next = dbx->stab_section_info;
247 		  dbx->stab_section_info = sectinfo;
248 		  sectinfo = NULL;
249 		}
250 	      filesym = sym;
251 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
252 	      filesymname =
253 		obsavestring ((char *) filesym->name, strlen (filesym->name),
254 			      &objfile->objfile_obstack);
255 #endif
256 	    }
257 	  else if (sym->flags & BSF_SECTION_SYM)
258 	    continue;
259 	  else if (sym->flags & (BSF_GLOBAL | BSF_LOCAL | BSF_WEAK))
260 	    {
261 	      struct minimal_symbol *msym;
262 
263 	      /* Select global/local/weak symbols.  Note that bfd puts abs
264 	         symbols in their own section, so all symbols we are
265 	         interested in will have a section. */
266 	      /* Bfd symbols are section relative. */
267 	      symaddr = sym->value + sym->section->vma;
268 	      /* Relocate all non-absolute symbols by the section offset.  */
269 	      if (sym->section != &bfd_abs_section)
270 		{
271 		  symaddr += offset;
272 		}
273 	      /* For non-absolute symbols, use the type of the section
274 	         they are relative to, to intuit text/data.  Bfd provides
275 	         no way of figuring this out for absolute symbols. */
276 	      if (sym->section == &bfd_abs_section)
277 		{
278 		  /* This is a hack to get the minimal symbol type
279 		     right for Irix 5, which has absolute addresses
280 		     with special section indices for dynamic symbols. */
281 		  unsigned short shndx =
282 		  ((elf_symbol_type *) sym)->internal_elf_sym.st_shndx;
283 
284 		  switch (shndx)
285 		    {
286 		    case SHN_MIPS_TEXT:
287 		      ms_type = mst_text;
288 		      break;
289 		    case SHN_MIPS_DATA:
290 		      ms_type = mst_data;
291 		      break;
292 		    case SHN_MIPS_ACOMMON:
293 		      ms_type = mst_bss;
294 		      break;
295 		    default:
296 		      ms_type = mst_abs;
297 		    }
298 
299 		  /* If it is an Irix dynamic symbol, skip section name
300 		     symbols, relocate all others by section offset. */
301 		  if (ms_type != mst_abs)
302 		    {
303 		      if (sym->name[0] == '.')
304 			continue;
305 		      symaddr += offset;
306 		    }
307 		}
308 	      else if (sym->section->flags & SEC_CODE)
309 		{
310 		  if (sym->flags & BSF_GLOBAL)
311 		    {
312 		      ms_type = mst_text;
313 		    }
314 		  else if ((sym->name[0] == '.' && sym->name[1] == 'L')
315 			   || ((sym->flags & BSF_LOCAL)
316 			       && sym->name[0] == '$'
317 			       && sym->name[1] == 'L'))
318 		    /* Looks like a compiler-generated label.  Skip
319 		       it.  The assembler should be skipping these (to
320 		       keep executables small), but apparently with
321 		       gcc on the (deleted) delta m88k SVR4, it loses.
322 		       So to have us check too should be harmless (but
323 		       I encourage people to fix this in the assembler
324 		       instead of adding checks here).  */
325 		    continue;
326 		  else
327 		    {
328 		      ms_type = mst_file_text;
329 		    }
330 		}
331 	      else if (sym->section->flags & SEC_ALLOC)
332 		{
333 		  if (sym->flags & (BSF_GLOBAL | BSF_WEAK))
334 		    {
335 		      if (sym->section->flags & SEC_LOAD)
336 			{
337 			  ms_type = mst_data;
338 			}
339 		      else
340 			{
341 			  ms_type = mst_bss;
342 			}
343 		    }
344 		  else if (sym->flags & BSF_LOCAL)
345 		    {
346 		      /* Named Local variable in a Data section.
347 		         Check its name for stabs-in-elf.  */
348 		      int special_local_sect;
349 		      if (strcmp ("Bbss.bss", sym->name) == 0)
350 			special_local_sect = SECT_OFF_BSS (objfile);
351 		      else if (strcmp ("Ddata.data", sym->name) == 0)
352 			special_local_sect = SECT_OFF_DATA (objfile);
353 		      else if (strcmp ("Drodata.rodata", sym->name) == 0)
354 			special_local_sect = SECT_OFF_RODATA (objfile);
355 		      else
356 			special_local_sect = -1;
357 		      if (special_local_sect >= 0)
358 			{
359 			  /* Found a special local symbol.  Allocate a
360 			     sectinfo, if needed, and fill it in.  */
361 			  if (sectinfo == NULL)
362 			    {
363 			      int max_index;
364 			      size_t size;
365 
366 			      max_index
367 				= max (SECT_OFF_BSS (objfile),
368 				       max (SECT_OFF_DATA (objfile),
369 					    SECT_OFF_RODATA (objfile)));
370 
371                               /* max_index is the largest index we'll
372                                  use into this array, so we must
373                                  allocate max_index+1 elements for it.
374                                  However, 'struct stab_section_info'
375                                  already includes one element, so we
376                                  need to allocate max_index aadditional
377                                  elements.  */
378 			      size = (sizeof (struct stab_section_info)
379 				      + (sizeof (CORE_ADDR)
380 					 * max_index));
381 			      sectinfo = (struct stab_section_info *)
382 				xmalloc (size);
383 			      memset (sectinfo, 0, size);
384 			      sectinfo->num_sections = max_index;
385 			      if (filesym == NULL)
386 				{
387 				  complaint (&symfile_complaints,
388 					     _("elf/stab section information %s without a preceding file symbol"),
389 					     sym->name);
390 				}
391 			      else
392 				{
393 				  sectinfo->filename =
394 				    (char *) filesym->name;
395 				}
396 			    }
397 			  if (sectinfo->sections[special_local_sect] != 0)
398 			    complaint (&symfile_complaints,
399 				       _("duplicated elf/stab section information for %s"),
400 				       sectinfo->filename);
401 			  /* BFD symbols are section relative.  */
402 			  symaddr = sym->value + sym->section->vma;
403 			  /* Relocate non-absolute symbols by the
404                              section offset.  */
405 			  if (sym->section != &bfd_abs_section)
406 			    symaddr += offset;
407 			  sectinfo->sections[special_local_sect] = symaddr;
408 			  /* The special local symbols don't go in the
409 			     minimal symbol table, so ignore this one.  */
410 			  continue;
411 			}
412 		      /* Not a special stabs-in-elf symbol, do regular
413 		         symbol processing.  */
414 		      if (sym->section->flags & SEC_LOAD)
415 			{
416 			  ms_type = mst_file_data;
417 			}
418 		      else
419 			{
420 			  ms_type = mst_file_bss;
421 			}
422 		    }
423 		  else
424 		    {
425 		      ms_type = mst_unknown;
426 		    }
427 		}
428 	      else
429 		{
430 		  /* FIXME:  Solaris2 shared libraries include lots of
431 		     odd "absolute" and "undefined" symbols, that play
432 		     hob with actions like finding what function the PC
433 		     is in.  Ignore them if they aren't text, data, or bss.  */
434 		  /* ms_type = mst_unknown; */
435 		  continue;	/* Skip this symbol. */
436 		}
437 	      msym = record_minimal_symbol
438 		((char *) sym->name, symaddr,
439 		 ms_type, sym->section, objfile);
440 	      if (msym)
441 	      {
442 		/* Pass symbol size field in via BFD.  FIXME!!!  */
443 		unsigned long size = ((elf_symbol_type *) sym)->internal_elf_sym.st_size;
444 		MSYMBOL_SIZE(msym) = size;
445 	      }
446 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
447 	      if (msym != NULL)
448 		msym->filename = filesymname;
449 #endif
450 	      ELF_MAKE_MSYMBOL_SPECIAL (sym, msym);
451 	    }
452 	}
453       do_cleanups (back_to);
454     }
455 }
456 
457 /* Scan and build partial symbols for a symbol file.
458    We have been initialized by a call to elf_symfile_init, which
459    currently does nothing.
460 
461    SECTION_OFFSETS is a set of offsets to apply to relocate the symbols
462    in each section.  We simplify it down to a single offset for all
463    symbols.  FIXME.
464 
465    MAINLINE is true if we are reading the main symbol
466    table (as opposed to a shared lib or dynamically loaded file).
467 
468    This function only does the minimum work necessary for letting the
469    user "name" things symbolically; it does not read the entire symtab.
470    Instead, it reads the external and static symbols and puts them in partial
471    symbol tables.  When more extensive information is requested of a
472    file, the corresponding partial symbol table is mutated into a full
473    fledged symbol table by going back and reading the symbols
474    for real.
475 
476    We look for sections with specific names, to tell us what debug
477    format to look for:  FIXME!!!
478 
479    dwarf_build_psymtabs() builds psymtabs for DWARF symbols;
480    elfstab_build_psymtabs() handles STABS symbols;
481    mdebug_build_psymtabs() handles ECOFF debugging information.
482 
483    Note that ELF files have a "minimal" symbol table, which looks a lot
484    like a COFF symbol table, but has only the minimal information necessary
485    for linking.  We process this also, and use the information to
486    build gdb's minimal symbol table.  This gives us some minimal debugging
487    capability even for files compiled without -g.  */
488 
489 static void
elf_symfile_read(struct objfile * objfile,int mainline)490 elf_symfile_read (struct objfile *objfile, int mainline)
491 {
492   bfd *abfd = objfile->obfd;
493   struct elfinfo ei;
494   struct cleanup *back_to;
495   CORE_ADDR offset;
496 
497   init_minimal_symbol_collection ();
498   back_to = make_cleanup_discard_minimal_symbols ();
499 
500   memset ((char *) &ei, 0, sizeof (ei));
501 
502   /* Allocate struct to keep track of the symfile */
503   objfile->deprecated_sym_stab_info = (struct dbx_symfile_info *)
504     xmalloc (sizeof (struct dbx_symfile_info));
505   memset ((char *) objfile->deprecated_sym_stab_info, 0, sizeof (struct dbx_symfile_info));
506   make_cleanup (free_elfinfo, (void *) objfile);
507 
508   /* Process the normal ELF symbol table first.  This may write some
509      chain of info into the dbx_symfile_info in objfile->deprecated_sym_stab_info,
510      which can later be used by elfstab_offset_sections.  */
511 
512   elf_symtab_read (objfile, 0);
513 
514   /* Add the dynamic symbols.  */
515 
516   elf_symtab_read (objfile, 1);
517 
518   /* Install any minimal symbols that have been collected as the current
519      minimal symbols for this objfile.  The debug readers below this point
520      should not generate new minimal symbols; if they do it's their
521      responsibility to install them.  "mdebug" appears to be the only one
522      which will do this.  */
523 
524   install_minimal_symbols (objfile);
525   do_cleanups (back_to);
526 
527   /* Now process debugging information, which is contained in
528      special ELF sections. */
529 
530   /* If we are reinitializing, or if we have never loaded syms yet,
531      set table to empty.  MAINLINE is cleared so that *_read_psymtab
532      functions do not all also re-initialize the psymbol table. */
533   if (mainline)
534     {
535       init_psymbol_list (objfile, 0);
536       mainline = 0;
537     }
538 
539   /* We first have to find them... */
540   bfd_map_over_sections (abfd, elf_locate_sections, (void *) & ei);
541 
542   /* ELF debugging information is inserted into the psymtab in the
543      order of least informative first - most informative last.  Since
544      the psymtab table is searched `most recent insertion first' this
545      increases the probability that more detailed debug information
546      for a section is found.
547 
548      For instance, an object file might contain both .mdebug (XCOFF)
549      and .debug_info (DWARF2) sections then .mdebug is inserted first
550      (searched last) and DWARF2 is inserted last (searched first).  If
551      we don't do this then the XCOFF info is found first - for code in
552      an included file XCOFF info is useless. */
553 
554   if (ei.mdebugsect)
555     {
556       const struct ecoff_debug_swap *swap;
557 
558       /* .mdebug section, presumably holding ECOFF debugging
559          information.  */
560       swap = get_elf_backend_data (abfd)->elf_backend_ecoff_debug_swap;
561       if (swap)
562 	elfmdebug_build_psymtabs (objfile, swap, ei.mdebugsect);
563     }
564   if (ei.stabsect)
565     {
566       asection *str_sect;
567 
568       /* Stab sections have an associated string table that looks like
569          a separate section.  */
570       str_sect = bfd_get_section_by_name (abfd, ".stabstr");
571 
572       /* FIXME should probably warn about a stab section without a stabstr.  */
573       if (str_sect)
574 	elfstab_build_psymtabs (objfile,
575 				mainline,
576 				ei.stabsect,
577 				str_sect->filepos,
578 				bfd_section_size (abfd, str_sect));
579     }
580   if (dwarf2_has_info (objfile))
581     {
582       /* DWARF 2 sections */
583       dwarf2_build_psymtabs (objfile, mainline);
584     }
585   else if (ei.dboffset && ei.lnoffset)
586     {
587       /* DWARF sections */
588       dwarf_build_psymtabs (objfile,
589 			    mainline,
590 			    ei.dboffset, ei.dbsize,
591 			    ei.lnoffset, ei.lnsize);
592     }
593 
594   /* FIXME: kettenis/20030504: This still needs to be integrated with
595      dwarf2read.c in a better way.  */
596   dwarf2_build_frame_info (objfile);
597 }
598 
599 /* This cleans up the objfile's deprecated_sym_stab_info pointer, and
600    the chain of stab_section_info's, that might be dangling from
601    it.  */
602 
603 static void
free_elfinfo(void * objp)604 free_elfinfo (void *objp)
605 {
606   struct objfile *objfile = (struct objfile *) objp;
607   struct dbx_symfile_info *dbxinfo = objfile->deprecated_sym_stab_info;
608   struct stab_section_info *ssi, *nssi;
609 
610   ssi = dbxinfo->stab_section_info;
611   while (ssi)
612     {
613       nssi = ssi->next;
614       xfree (ssi);
615       ssi = nssi;
616     }
617 
618   dbxinfo->stab_section_info = 0;	/* Just say No mo info about this.  */
619 }
620 
621 
622 /* Initialize anything that needs initializing when a completely new symbol
623    file is specified (not just adding some symbols from another file, e.g. a
624    shared library).
625 
626    We reinitialize buildsym, since we may be reading stabs from an ELF file.  */
627 
628 static void
elf_new_init(struct objfile * ignore)629 elf_new_init (struct objfile *ignore)
630 {
631   stabsread_new_init ();
632   buildsym_new_init ();
633 }
634 
635 /* Perform any local cleanups required when we are done with a particular
636    objfile.  I.E, we are in the process of discarding all symbol information
637    for an objfile, freeing up all memory held for it, and unlinking the
638    objfile struct from the global list of known objfiles. */
639 
640 static void
elf_symfile_finish(struct objfile * objfile)641 elf_symfile_finish (struct objfile *objfile)
642 {
643   if (objfile->deprecated_sym_stab_info != NULL)
644     {
645       xfree (objfile->deprecated_sym_stab_info);
646     }
647 }
648 
649 /* ELF specific initialization routine for reading symbols.
650 
651    It is passed a pointer to a struct sym_fns which contains, among other
652    things, the BFD for the file whose symbols are being read, and a slot for
653    a pointer to "private data" which we can fill with goodies.
654 
655    For now at least, we have nothing in particular to do, so this function is
656    just a stub. */
657 
658 static void
elf_symfile_init(struct objfile * objfile)659 elf_symfile_init (struct objfile *objfile)
660 {
661   /* ELF objects may be reordered, so set OBJF_REORDERED.  If we
662      find this causes a significant slowdown in gdb then we could
663      set it in the debug symbol readers only when necessary.  */
664   objfile->flags |= OBJF_REORDERED;
665 }
666 
667 /* When handling an ELF file that contains Sun STABS debug info,
668    some of the debug info is relative to the particular chunk of the
669    section that was generated in its individual .o file.  E.g.
670    offsets to static variables are relative to the start of the data
671    segment *for that module before linking*.  This information is
672    painfully squirreled away in the ELF symbol table as local symbols
673    with wierd names.  Go get 'em when needed.  */
674 
675 void
elfstab_offset_sections(struct objfile * objfile,struct partial_symtab * pst)676 elfstab_offset_sections (struct objfile *objfile, struct partial_symtab *pst)
677 {
678   char *filename = pst->filename;
679   struct dbx_symfile_info *dbx = objfile->deprecated_sym_stab_info;
680   struct stab_section_info *maybe = dbx->stab_section_info;
681   struct stab_section_info *questionable = 0;
682   int i;
683   char *p;
684 
685   /* The ELF symbol info doesn't include path names, so strip the path
686      (if any) from the psymtab filename.  */
687   while (0 != (p = strchr (filename, '/')))
688     filename = p + 1;
689 
690   /* FIXME:  This linear search could speed up significantly
691      if it was chained in the right order to match how we search it,
692      and if we unchained when we found a match. */
693   for (; maybe; maybe = maybe->next)
694     {
695       if (filename[0] == maybe->filename[0]
696 	  && strcmp (filename, maybe->filename) == 0)
697 	{
698 	  /* We found a match.  But there might be several source files
699 	     (from different directories) with the same name.  */
700 	  if (0 == maybe->found)
701 	    break;
702 	  questionable = maybe;	/* Might use it later.  */
703 	}
704     }
705 
706   if (maybe == 0 && questionable != 0)
707     {
708       complaint (&symfile_complaints,
709 		 _("elf/stab section information questionable for %s"), filename);
710       maybe = questionable;
711     }
712 
713   if (maybe)
714     {
715       /* Found it!  Allocate a new psymtab struct, and fill it in.  */
716       maybe->found++;
717       pst->section_offsets = (struct section_offsets *)
718 	obstack_alloc (&objfile->objfile_obstack,
719 		       SIZEOF_N_SECTION_OFFSETS (objfile->num_sections));
720       for (i = 0; i < maybe->num_sections; i++)
721 	(pst->section_offsets)->offsets[i] = maybe->sections[i];
722       return;
723     }
724 
725   /* We were unable to find any offsets for this file.  Complain.  */
726   if (dbx->stab_section_info)	/* If there *is* any info, */
727     complaint (&symfile_complaints,
728 	       _("elf/stab section information missing for %s"), filename);
729 }
730 
731 /* Register that we are able to handle ELF object file formats.  */
732 
733 static struct sym_fns elf_sym_fns =
734 {
735   bfd_target_elf_flavour,
736   elf_new_init,			/* sym_new_init: init anything gbl to entire symtab */
737   elf_symfile_init,		/* sym_init: read initial info, setup for sym_read() */
738   elf_symfile_read,		/* sym_read: read a symbol file into symtab */
739   elf_symfile_finish,		/* sym_finish: finished with file, cleanup */
740   default_symfile_offsets,	/* sym_offsets:  Translate ext. to int. relocation */
741   NULL				/* next: pointer to next struct sym_fns */
742 };
743 
744 void
_initialize_elfread(void)745 _initialize_elfread (void)
746 {
747   add_symtab_fns (&elf_sym_fns);
748 }
749