gdb/dwarf2/comp-unit.h

   1 /* Low-level DWARF 2 reading 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 #ifndef GDB_DWARF2_COMP_UNIT_H
  28 #define GDB_DWARF2_COMP_UNIT_H
  29
  30 #include "gdbtypes.h"
  31
  32 /* The data in a compilation unit header, after target2host
  33    translation, looks like this.  */
  34 struct comp_unit_head
  35 {
  36   unsigned int length;
  37   short version;
  38   unsigned char addr_size;
  39   unsigned char signed_addr_p;
  40   sect_offset abbrev_sect_off;
  41
  42   /* Size of file offsets; either 4 or 8.  */
  43   unsigned int offset_size;
  44
  45   /* Size of the length field; either 4 or 12.  */
  46   unsigned int initial_length_size;
  47
  48   enum dwarf_unit_type unit_type;
  49
  50   /* Offset to the first byte of this compilation unit header in the
  51      .debug_info section, for resolving relative reference dies.  */
  52   sect_offset sect_off;
  53
  54   /* Offset to first die in this cu from the start of the cu.
  55      This will be the first byte following the compilation unit header.  */
  56   cu_offset first_die_cu_offset;
  57
  58
  59   /* 64-bit signature of this unit. For type units, it denotes the signature of
  60      the type (DW_UT_type in DWARF 4, additionally DW_UT_split_type in DWARF 5).
  61      Also used in DWARF 5, to denote the dwo id when the unit type is
  62      DW_UT_skeleton or DW_UT_split_compile.  */
  63   ULONGEST signature;
  64
  65   /* For types, offset in the type's DIE of the type defined by this TU.  */
  66   cu_offset type_cu_offset_in_tu;
  67
  68   /* Return the total length of the CU described by this header.  */
  69   unsigned int get_length () const
  70   {
  71     return initial_length_size + length;
  72   }
  73
  74   /* Return TRUE if OFF is within this CU.  */
  75   bool offset_in_cu_p (sect_offset off) const
  76   {
  77     sect_offset bottom = sect_off;
  78     sect_offset top = sect_off + get_length ();
  79     return off >= bottom && off < top;
  80   }
  81 };
  82
  83 /* Expected enum dwarf_unit_type for read_comp_unit_head.  */
  84 enum class rcuh_kind { COMPILE, TYPE };
  85
  86 /* Read in the comp unit header information from the debug_info at info_ptr.
  87    Use rcuh_kind::COMPILE as the default type if not known by the caller.
  88    NOTE: This leaves members offset, first_die_offset to be filled in
  89    by the caller.  */
  90 extern const gdb_byte *read_comp_unit_head
  91   (struct comp_unit_head *cu_header,
  92    const gdb_byte *info_ptr,
  93    struct dwarf2_section_info *section,
  94    rcuh_kind section_kind);
  95
  96 /* Read in a CU/TU header and perform some basic error checking.
  97    The contents of the header are stored in HEADER.
  98    The result is a pointer to the start of the first DIE.  */
  99 extern const gdb_byte *read_and_check_comp_unit_head
 100   (struct dwarf2_per_objfile *dwarf2_per_objfile,
 101    struct comp_unit_head *header,
 102    struct dwarf2_section_info *section,
 103    struct dwarf2_section_info *abbrev_section,
 104    const gdb_byte *info_ptr,
 105    rcuh_kind section_kind);
 106
 107 /* Read an offset from the data stream.  The size of the offset is
 108    given by cu_header->offset_size.  */
 109
 110 extern LONGEST read_offset (bfd *abfd, const gdb_byte *buf,
 111                             const struct comp_unit_head *cu_header,
 112                             unsigned int *bytes_read);
 113
 114 #endif /* GDB_DWARF2_COMP_UNIT_H */