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 get_containing_section (const struct dwarf2_section_info *section)
  34 {
  35   gdb_assert (section->is_virtual);
  36   return section->s.containing_section;
  37 }
  38
  39 struct bfd *
  40 get_section_bfd_owner (const struct dwarf2_section_info *section)
  41 {
  42   if (section->is_virtual)
  43     {
  44       section = get_containing_section (section);
  45       gdb_assert (!section->is_virtual);
  46     }
  47   return section->s.section->owner;
  48 }
  49
  50 asection *
  51 get_section_bfd_section (const struct dwarf2_section_info *section)
  52 {
  53   if (section->is_virtual)
  54     {
  55       section = get_containing_section (section);
  56       gdb_assert (!section->is_virtual);
  57     }
  58   return section->s.section;
  59 }
  60
  61 const char *
  62 get_section_name (const struct dwarf2_section_info *section)
  63 {
  64   asection *sectp = get_section_bfd_section (section);
  65
  66   gdb_assert (sectp != NULL);
  67   return bfd_section_name (sectp);
  68 }
  69
  70 const char *
  71 get_section_file_name (const struct dwarf2_section_info *section)
  72 {
  73   bfd *abfd = get_section_bfd_owner (section);
  74
  75   return bfd_get_filename (abfd);
  76 }
  77
  78 int
  79 get_section_id (const struct dwarf2_section_info *section)
  80 {
  81   asection *sectp = get_section_bfd_section (section);
  82
  83   if (sectp == NULL)
  84     return 0;
  85   return sectp->id;
  86 }
  87
  88 int
  89 get_section_flags (const struct dwarf2_section_info *section)
  90 {
  91   asection *sectp = get_section_bfd_section (section);
  92
  93   gdb_assert (sectp != NULL);
  94   return bfd_section_flags (sectp);
  95 }
  96
  97 int
  98 dwarf2_section_empty_p (const struct dwarf2_section_info *section)
  99 {
 100   if (section->is_virtual)
 101     return section->size == 0;
 102   return section->s.section == NULL || section->size == 0;
 103 }
 104
 105 void
 106 dwarf2_read_section (struct objfile *objfile, dwarf2_section_info *info)
 107 {
 108   asection *sectp;
 109   bfd *abfd;
 110   gdb_byte *buf, *retbuf;
 111
 112   if (info->readin)
 113     return;
 114   info->buffer = NULL;
 115   info->readin = true;
 116
 117   if (dwarf2_section_empty_p (info))
 118     return;
 119
 120   sectp = get_section_bfd_section (info);
 121
 122   /* If this is a virtual section we need to read in the real one first.  */
 123   if (info->is_virtual)
 124     {
 125       struct dwarf2_section_info *containing_section =
 126         get_containing_section (info);
 127
 128       gdb_assert (sectp != NULL);
 129       if ((sectp->flags & SEC_RELOC) != 0)
 130         {
 131           error (_("Dwarf Error: DWP format V2 with relocations is not"
 132                    " supported in section %s [in module %s]"),
 133                  get_section_name (info), get_section_file_name (info));
 134         }
 135       dwarf2_read_section (objfile, containing_section);
 136       /* Other code should have already caught virtual sections that don't
 137          fit.  */
 138       gdb_assert (info->virtual_offset + info->size
 139                   <= containing_section->size);
 140       /* If the real section is empty or there was a problem reading the
 141          section we shouldn't get here.  */
 142       gdb_assert (containing_section->buffer != NULL);
 143       info->buffer = containing_section->buffer + info->virtual_offset;
 144       return;
 145     }
 146
 147   /* If the section has relocations, we must read it ourselves.
 148      Otherwise we attach it to the BFD.  */
 149   if ((sectp->flags & SEC_RELOC) == 0)
 150     {
 151       info->buffer = gdb_bfd_map_section (sectp, &info->size);
 152       return;
 153     }
 154
 155   buf = (gdb_byte *) obstack_alloc (&objfile->objfile_obstack, info->size);
 156   info->buffer = buf;
 157
 158   /* When debugging .o files, we may need to apply relocations; see
 159      http://sourceware.org/ml/gdb-patches/2002-04/msg00136.html .
 160      We never compress sections in .o files, so we only need to
 161      try this when the section is not compressed.  */
 162   retbuf = symfile_relocate_debug_section (objfile, sectp, buf);
 163   if (retbuf != NULL)
 164     {
 165       info->buffer = retbuf;
 166       return;
 167     }
 168
 169   abfd = get_section_bfd_owner (info);
 170   gdb_assert (abfd != NULL);
 171
 172   if (bfd_seek (abfd, sectp->filepos, SEEK_SET) != 0
 173       || bfd_bread (buf, info->size, abfd) != info->size)
 174     {
 175       error (_("Dwarf Error: Can't read DWARF data"
 176                " in section %s [in module %s]"),
 177              bfd_section_name (sectp), bfd_get_filename (abfd));
 178     }
 179 }