gdb/dwarf2/section.c

   1 /* DWARF 2 low-level section code
   2
   3    Copyright (C) 1994-2020 Free Software Foundation, Inc.
   4
   5    Adapted by Gary Funck (gary@intrepid.com), Intrepid Technology,
   6    Inc.  with support from Florida State University (under contract
   7    with the Ada Joint Program Office), and Silicon Graphics, Inc.
   8    Initial contribution by Brent Benson, Harris Computer Systems, Inc.,
   9    based on Fred Fish's (Cygnus Support) implementation of DWARF 1
  10    support.
  11
  12    This file is part of GDB.
  13
  14    This program is free software; you can redistribute it and/or modify
  15    it under the terms of the GNU General Public License as published by
  16    the Free Software Foundation; either version 3 of the License, or
  17    (at your option) any later version.
  18
  19    This program is distributed in the hope that it will be useful,
  20    but WITHOUT ANY WARRANTY; without even the implied warranty of
  21    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22    GNU General Public License for more details.
  23
  24    You should have received a copy of the GNU General Public License
  25    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  26
  27 #include "defs.h"
  28 #include "dwarf2/section.h"
  29 #include "gdb_bfd.h"
  30 #include "objfiles.h"
  31
  32 struct dwarf2_section_info *
  33 dwarf2_section_info::get_containing_section () const
  34 {
  35   gdb_assert (is_virtual);
  36   return s.containing_section;
  37 }
  38
  39 struct bfd *
  40 dwarf2_section_info::get_bfd_owner () const
  41 {
  42   const dwarf2_section_info *section = this;
  43   if (is_virtual)
  44     {
  45       section = get_containing_section ();
  46       gdb_assert (!section->is_virtual);
  47     }
  48   return section->s.section->owner;
  49 }
  50
  51 asection *
  52 dwarf2_section_info::get_bfd_section () const
  53 {
  54   const dwarf2_section_info *section = this;
  55   if (section->is_virtual)
  56     {
  57       section = get_containing_section ();
  58       gdb_assert (!section->is_virtual);
  59     }
  60   return section->s.section;
  61 }
  62
  63 const char *
  64 dwarf2_section_info::get_name () const
  65 {
  66   asection *sectp = get_bfd_section ();
  67
  68   gdb_assert (sectp != NULL);
  69   return bfd_section_name (sectp);
  70 }
  71
  72 const char *
  73 dwarf2_section_info::get_file_name () const
  74 {
  75   bfd *abfd = get_bfd_owner ();
  76
  77   return bfd_get_filename (abfd);
  78 }
  79
  80 int
  81 dwarf2_section_info::get_id () const
  82 {
  83   asection *sectp = get_bfd_section ();
  84
  85   if (sectp == NULL)
  86     return 0;
  87   return sectp->id;
  88 }
  89
  90 int
  91 dwarf2_section_info::get_flags () const
  92 {
  93   asection *sectp = get_bfd_section ();
  94
  95   gdb_assert (sectp != NULL);
  96   return bfd_section_flags (sectp);
  97 }
  98
  99 bool
 100 dwarf2_section_info::empty () const
 101 {
 102   if (is_virtual)
 103     return size == 0;
 104   return s.section == NULL || size == 0;
 105 }
 106
 107 void
 108 dwarf2_section_info::read (struct objfile *objfile)
 109 {
 110   asection *sectp;
 111   bfd *abfd;
 112   gdb_byte *buf, *retbuf;
 113
 114   if (readin)
 115     return;
 116   buffer = NULL;
 117   readin = true;
 118
 119   if (empty ())
 120     return;
 121
 122   sectp = get_bfd_section ();
 123
 124   /* If this is a virtual section we need to read in the real one first.  */
 125   if (is_virtual)
 126     {
 127       struct dwarf2_section_info *containing_section =
 128         get_containing_section ();
 129
 130       gdb_assert (sectp != NULL);
 131       if ((sectp->flags & SEC_RELOC) != 0)
 132         {
 133           error (_("Dwarf Error: DWP format V2 with relocations is not"
 134                    " supported in section %s [in module %s]"),
 135                  get_name (), get_file_name ());
 136         }
 137       containing_section->read (objfile);
 138       /* Other code should have already caught virtual sections that don't
 139          fit.  */
 140       gdb_assert (virtual_offset + size <= containing_section->size);
 141       /* If the real section is empty or there was a problem reading the
 142          section we shouldn't get here.  */
 143       gdb_assert (containing_section->buffer != NULL);
 144       buffer = containing_section->buffer + virtual_offset;
 145       return;
 146     }
 147
 148   /* If the section has relocations, we must read it ourselves.
 149      Otherwise we attach it to the BFD.  */
 150   if ((sectp->flags & SEC_RELOC) == 0)
 151     {
 152       buffer = gdb_bfd_map_section (sectp, &size);
 153       return;
 154     }
 155
 156   buf = (gdb_byte *) obstack_alloc (&objfile->objfile_obstack, size);
 157   buffer = buf;
 158
 159   /* When debugging .o files, we may need to apply relocations; see
 160      http://sourceware.org/ml/gdb-patches/2002-04/msg00136.html .
 161      We never compress sections in .o files, so we only need to
 162      try this when the section is not compressed.  */
 163   retbuf = symfile_relocate_debug_section (objfile, sectp, buf);
 164   if (retbuf != NULL)
 165     {
 166       buffer = retbuf;
 167       return;
 168     }
 169
 170   abfd = get_bfd_owner ();
 171   gdb_assert (abfd != NULL);
 172
 173   if (bfd_seek (abfd, sectp->filepos, SEEK_SET) != 0
 174       || bfd_bread (buf, size, abfd) != size)
 175     {
 176       error (_("Dwarf Error: Can't read DWARF data"
 177                " in section %s [in module %s]"),
 178              bfd_section_name (sectp), bfd_get_filename (abfd));
 179     }
 180 }