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 #include "complaints.h"
  32
  33 void
  34 dwarf2_section_info::overflow_complaint () const
  35 {
  36   complaint (_("debug info runs off end of %s section"
  37                " [in module %s]"),
  38              get_name (), get_file_name ());
  39 }
  40
  41 struct dwarf2_section_info *
  42 dwarf2_section_info::get_containing_section () const
  43 {
  44   gdb_assert (is_virtual);
  45   return s.containing_section;
  46 }
  47
  48 struct bfd *
  49 dwarf2_section_info::get_bfd_owner () const
  50 {
  51   const dwarf2_section_info *section = this;
  52   if (is_virtual)
  53     {
  54       section = get_containing_section ();
  55       gdb_assert (!section->is_virtual);
  56     }
  57   return section->s.section->owner;
  58 }
  59
  60 asection *
  61 dwarf2_section_info::get_bfd_section () const
  62 {
  63   const dwarf2_section_info *section = this;
  64   if (section->is_virtual)
  65     {
  66       section = get_containing_section ();
  67       gdb_assert (!section->is_virtual);
  68     }
  69   return section->s.section;
  70 }
  71
  72 const char *
  73 dwarf2_section_info::get_name () const
  74 {
  75   asection *sectp = get_bfd_section ();
  76
  77   gdb_assert (sectp != NULL);
  78   return bfd_section_name (sectp);
  79 }
  80
  81 const char *
  82 dwarf2_section_info::get_file_name () const
  83 {
  84   bfd *abfd = get_bfd_owner ();
  85
  86   return bfd_get_filename (abfd);
  87 }
  88
  89 int
  90 dwarf2_section_info::get_id () const
  91 {
  92   asection *sectp = get_bfd_section ();
  93
  94   if (sectp == NULL)
  95     return 0;
  96   return sectp->id;
  97 }
  98
  99 int
 100 dwarf2_section_info::get_flags () const
 101 {
 102   asection *sectp = get_bfd_section ();
 103
 104   gdb_assert (sectp != NULL);
 105   return bfd_section_flags (sectp);
 106 }
 107
 108 bool
 109 dwarf2_section_info::empty () const
 110 {
 111   if (is_virtual)
 112     return size == 0;
 113   return s.section == NULL || size == 0;
 114 }
 115
 116 void
 117 dwarf2_section_info::read (struct objfile *objfile)
 118 {
 119   asection *sectp;
 120   bfd *abfd;
 121   gdb_byte *buf, *retbuf;
 122
 123   if (readin)
 124     return;
 125   buffer = NULL;
 126   readin = true;
 127
 128   if (empty ())
 129     return;
 130
 131   sectp = get_bfd_section ();
 132
 133   /* If this is a virtual section we need to read in the real one first.  */
 134   if (is_virtual)
 135     {
 136       struct dwarf2_section_info *containing_section =
 137         get_containing_section ();
 138
 139       gdb_assert (sectp != NULL);
 140       if ((sectp->flags & SEC_RELOC) != 0)
 141         {
 142           error (_("Dwarf Error: DWP format V2 with relocations is not"
 143                    " supported in section %s [in module %s]"),
 144                  get_name (), get_file_name ());
 145         }
 146       containing_section->read (objfile);
 147       /* Other code should have already caught virtual sections that don't
 148          fit.  */
 149       gdb_assert (virtual_offset + size <= containing_section->size);
 150       /* If the real section is empty or there was a problem reading the
 151          section we shouldn't get here.  */
 152       gdb_assert (containing_section->buffer != NULL);
 153       buffer = containing_section->buffer + virtual_offset;
 154       return;
 155     }
 156
 157   /* If the section has relocations, we must read it ourselves.
 158      Otherwise we attach it to the BFD.  */
 159   if ((sectp->flags & SEC_RELOC) == 0)
 160     {
 161       buffer = gdb_bfd_map_section (sectp, &size);
 162       return;
 163     }
 164
 165   buf = (gdb_byte *) obstack_alloc (&objfile->objfile_obstack, size);
 166   buffer = buf;
 167
 168   /* When debugging .o files, we may need to apply relocations; see
 169      http://sourceware.org/ml/gdb-patches/2002-04/msg00136.html .
 170      We never compress sections in .o files, so we only need to
 171      try this when the section is not compressed.  */
 172   retbuf = symfile_relocate_debug_section (objfile, sectp, buf);
 173   if (retbuf != NULL)
 174     {
 175       buffer = retbuf;
 176       return;
 177     }
 178
 179   abfd = get_bfd_owner ();
 180   gdb_assert (abfd != NULL);
 181
 182   if (bfd_seek (abfd, sectp->filepos, SEEK_SET) != 0
 183       || bfd_bread (buf, size, abfd) != size)
 184     {
 185       error (_("Dwarf Error: Can't read DWARF data"
 186                " in section %s [in module %s]"),
 187              bfd_section_name (sectp), bfd_get_filename (abfd));
 188     }
 189 }
 190
 191 const char *
 192 dwarf2_section_info::read_string (struct objfile *objfile, LONGEST str_offset,
 193                                   const char *form_name)
 194 {
 195   read (objfile);
 196   if (buffer == NULL)
 197     error (_("%s used without %s section [in module %s]"),
 198            form_name, get_name (), get_file_name ());
 199   if (str_offset >= size)
 200     error (_("%s pointing outside of %s section [in module %s]"),
 201            form_name, get_name (), get_file_name ());
 202   gdb_assert (HOST_CHAR_BIT == 8);
 203   if (buffer[str_offset] == '\0')
 204     return NULL;
 205   return (const char *) (buffer + str_offset);
 206 }