gdb/dwarf2/leb.c

   1 /* Low-level DWARF 2 reading code
   2
   3    Copyright (C) 1994-2024 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 "dwarf2/leb.h"
  28
  29 ULONGEST
  30 read_unsigned_leb128 (bfd *abfd, const gdb_byte *buf,
  31                           unsigned int *bytes_read_ptr)
  32 {
  33   ULONGEST result;
  34   unsigned int num_read;
  35   int shift;
  36   unsigned char byte;
  37
  38   result = 0;
  39   shift = 0;
  40   num_read = 0;
  41   while (1)
  42     {
  43       byte = bfd_get_8 (abfd, buf);
  44       buf++;
  45       num_read++;
  46       result |= ((ULONGEST) (byte & 127) << shift);
  47       if ((byte & 128) == 0)
  48         {
  49           break;
  50         }
  51       shift += 7;
  52     }
  53   *bytes_read_ptr = num_read;
  54   return result;
  55 }
  56
  57 LONGEST
  58 read_signed_leb128 (bfd *abfd, const gdb_byte *buf,
  59                     unsigned int *bytes_read_ptr)
  60 {
  61   ULONGEST result;
  62   int shift, num_read;
  63   unsigned char byte;
  64
  65   result = 0;
  66   shift = 0;
  67   num_read = 0;
  68   while (1)
  69     {
  70       byte = bfd_get_8 (abfd, buf);
  71       buf++;
  72       num_read++;
  73       result |= ((ULONGEST) (byte & 127) << shift);
  74       shift += 7;
  75       if ((byte & 128) == 0)
  76         {
  77           break;
  78         }
  79     }
  80   if ((shift < 8 * sizeof (result)) && (byte & 0x40))
  81     result |= -(((ULONGEST) 1) << shift);
  82   *bytes_read_ptr = num_read;
  83   return result;
  84 }
  85
  86 /* See leb.h.  */
  87
  88 LONGEST
  89 read_initial_length (bfd *abfd, const gdb_byte *buf, unsigned int *bytes_read,
  90                      bool handle_nonstd)
  91 {
  92   LONGEST length = bfd_get_32 (abfd, buf);
  93
  94   if (length == 0xffffffff)
  95     {
  96       length = bfd_get_64 (abfd, buf + 4);
  97       *bytes_read = 12;
  98     }
  99   else if (handle_nonstd && length == 0)
 100     {
 101       /* Handle the (non-standard) 64-bit DWARF2 format used by IRIX.  */
 102       length = bfd_get_64 (abfd, buf);
 103       *bytes_read = 8;
 104     }
 105   else
 106     {
 107       *bytes_read = 4;
 108     }
 109
 110   return length;
 111 }
 112
 113 /* See leb.h.  */
 114
 115 LONGEST
 116 read_offset (bfd *abfd, const gdb_byte *buf, unsigned int offset_size)
 117 {
 118   LONGEST retval = 0;
 119
 120   switch (offset_size)
 121     {
 122     case 4:
 123       retval = bfd_get_32 (abfd, buf);
 124       break;
 125     case 8:
 126       retval = bfd_get_64 (abfd, buf);
 127       break;
 128     default:
 129       internal_error (_("read_offset_1: bad switch [in module %s]"),
 130                       bfd_get_filename (abfd));
 131     }
 132
 133   return retval;
 134 }