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 "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   short 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 the first byte of this compilation unit header in the
  52      .debug_info section, for resolving relative reference dies.  */
  53   sect_offset sect_off;
  54
  55   /* Offset to first die in this cu from the start of the cu.
  56      This will be the first byte following the compilation unit header.  */
  57   cu_offset first_die_cu_offset;
  58
  59
  60   /* 64-bit signature of this unit. For type units, it denotes the signature of
  61      the type (DW_UT_type in DWARF 4, additionally DW_UT_split_type in DWARF 5).
  62      Also used in DWARF 5, to denote the dwo id when the unit type is
  63      DW_UT_skeleton or DW_UT_split_compile.  */
  64   ULONGEST signature;
  65
  66   /* For types, offset in the type's DIE of the type defined by this TU.  */
  67   cu_offset type_cu_offset_in_tu;
  68
  69   /* Return the total length of the CU described by this header.  */
  70   unsigned int get_length () const
  71   {
  72     return initial_length_size + length;
  73   }
  74
  75   /* Return TRUE if OFF is within this CU.  */
  76   bool offset_in_cu_p (sect_offset off) const
  77   {
  78     sect_offset bottom = sect_off;
  79     sect_offset top = sect_off + get_length ();
  80     return off >= bottom && off < top;
  81   }
  82
  83   /* Read an offset from the data stream.  The size of the offset is
  84      given by cu_header->offset_size.  */
  85   LONGEST read_offset (bfd *abfd, const gdb_byte *buf,
  86                        unsigned int *bytes_read) const
  87   {
  88     LONGEST offset = ::read_offset (abfd, buf, offset_size);
  89     *bytes_read = offset_size;
  90     return offset;
  91   }
  92
  93   /* Read an address from BUF.  BYTES_READ is updated.  */
  94   CORE_ADDR read_address (bfd *abfd, const gdb_byte *buf,
  95                           unsigned int *bytes_read) const;
  96 };
  97
  98 /* Expected enum dwarf_unit_type for read_comp_unit_head.  */
  99 enum class rcuh_kind { COMPILE, TYPE };
 100
 101 /* Read in the comp unit header information from the debug_info at info_ptr.
 102    Use rcuh_kind::COMPILE as the default type if not known by the caller.
 103    NOTE: This leaves members offset, first_die_offset to be filled in
 104    by the caller.  */
 105 extern const gdb_byte *read_comp_unit_head
 106   (struct comp_unit_head *cu_header,
 107    const gdb_byte *info_ptr,
 108    struct dwarf2_section_info *section,
 109    rcuh_kind section_kind);
 110
 111 /* Read in a CU/TU header and perform some basic error checking.
 112    The contents of the header are stored in HEADER.
 113    The result is a pointer to the start of the first DIE.  */
 114 extern const gdb_byte *read_and_check_comp_unit_head
 115   (struct dwarf2_per_objfile *dwarf2_per_objfile,
 116    struct comp_unit_head *header,
 117    struct dwarf2_section_info *section,
 118    struct dwarf2_section_info *abbrev_section,
 119    const gdb_byte *info_ptr,
 120    rcuh_kind section_kind);
 121
 122 #endif /* GDB_DWARF2_COMP_UNIT_H */