gdb/dwarf2/comp-unit.h

   1 /* Low-level DWARF 2 reading code
   2
   3    Copyright (C) 1994-2021 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 "dwarf2/leb.h"
  31 #include "gdbtypes.h"
  32
  33 /* The data in a compilation unit header, after target2host
  34    translation, looks like this.  */
  35 struct comp_unit_head
  36 {
  37   unsigned int length;
  38   unsigned char version;
  39   unsigned char addr_size;
  40   unsigned char signed_addr_p;
  41   sect_offset abbrev_sect_off;
  42
  43   /* Size of file offsets; either 4 or 8.  */
  44   unsigned int offset_size;
  45
  46   /* Size of the length field; either 4 or 12.  */
  47   unsigned int initial_length_size;
  48
  49   enum dwarf_unit_type unit_type;
  50
  51   /* Offset to first die in this cu from the start of the cu.
  52      This will be the first byte following the compilation unit header.  */
  53   cu_offset first_die_cu_offset;
  54
  55   /* Offset to the first byte of this compilation unit header in the
  56      .debug_info section, for resolving relative reference dies.  */
  57   sect_offset sect_off;
  58
  59   /* For types, offset in the type's DIE of the type defined by this TU.  */
  60   cu_offset type_cu_offset_in_tu;
  61
  62   /* 64-bit signature of this unit. For type units, it denotes the signature of
  63      the type (DW_UT_type in DWARF 4, additionally DW_UT_split_type in DWARF 5).
  64      Also used in DWARF 5, to denote the dwo id when the unit type is
  65      DW_UT_skeleton or DW_UT_split_compile.  */
  66   ULONGEST signature;
  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   /* Read an offset from the data stream.  The size of the offset is
  83      given by cu_header->offset_size.  */
  84   LONGEST read_offset (bfd *abfd, const gdb_byte *buf,
  85                        unsigned int *bytes_read) const
  86   {
  87     LONGEST offset = ::read_offset (abfd, buf, offset_size);
  88     *bytes_read = offset_size;
  89     return offset;
  90   }
  91
  92   /* Read an address from BUF.  BYTES_READ is updated.  */
  93   CORE_ADDR read_address (bfd *abfd, const gdb_byte *buf,
  94                           unsigned int *bytes_read) const;
  95 };
  96
  97 /* Expected enum dwarf_unit_type for read_comp_unit_head.  */
  98 enum class rcuh_kind { COMPILE, TYPE };
  99
 100 /* Read in the comp unit header information from the debug_info at info_ptr.
 101    Use rcuh_kind::COMPILE as the default type if not known by the caller.
 102    NOTE: This leaves members offset, first_die_offset to be filled in
 103    by the caller.  */
 104 extern const gdb_byte *read_comp_unit_head
 105   (struct comp_unit_head *cu_header,
 106    const gdb_byte *info_ptr,
 107    struct dwarf2_section_info *section,
 108    rcuh_kind section_kind);
 109
 110 /* Read in a CU/TU header and perform some basic error checking.
 111    The contents of the header are stored in HEADER.
 112    The result is a pointer to the start of the first DIE.  */
 113 extern const gdb_byte *read_and_check_comp_unit_head
 114   (dwarf2_per_objfile *per_objfile,
 115    struct comp_unit_head *header,
 116    struct dwarf2_section_info *section,
 117    struct dwarf2_section_info *abbrev_section,
 118    const gdb_byte *info_ptr,
 119    rcuh_kind section_kind);
 120
 121 #endif /* GDB_DWARF2_COMP_UNIT_H */