gdb/dwarf2/comp-unit-head.h

   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 #ifndef GDB_DWARF2_COMP_UNIT_HEAD_H
  28 #define GDB_DWARF2_COMP_UNIT_HEAD_H
  29
  30 #include "dwarf2.h"
  31 #include "dwarf2/leb.h"
  32 #include "dwarf2/types.h"
  33
  34 struct dwarf2_per_objfile;
  35
  36 /* The data in a compilation unit header, after target2host
  37    translation, looks like this.  */
  38 struct comp_unit_head
  39 {
  40 private:
  41   unsigned int m_length = 0;
  42 public:
  43   unsigned char version = 0;
  44   unsigned char addr_size = 0;
  45   unsigned char signed_addr_p = 0;
  46   sect_offset abbrev_sect_off {};
  47
  48   /* Size of file offsets; either 4 or 8.  */
  49   unsigned int offset_size = 0;
  50
  51   /* Size of the length field; either 4 or 12.  */
  52   unsigned int initial_length_size = 0;
  53
  54   enum dwarf_unit_type unit_type {};
  55
  56   /* Offset to first die in this cu from the start of the cu.
  57      This will be the first byte following the compilation unit header.  */
  58   cu_offset first_die_cu_offset {};
  59
  60   /* Offset to the first byte of this compilation unit header in the
  61      .debug_info section, for resolving relative reference dies.  */
  62   sect_offset sect_off {};
  63
  64   /* For types, offset in the type's DIE of the type defined by this TU.  */
  65   cu_offset type_cu_offset_in_tu {};
  66
  67   /* 64-bit signature of this unit. For type units, it denotes the signature of
  68      the type (DW_UT_type in DWARF 4, additionally DW_UT_split_type in DWARF 5).
  69      Also used in DWARF 5, to denote the dwo id when the unit type is
  70      DW_UT_skeleton or DW_UT_split_compile.  */
  71   ULONGEST signature = 0;
  72
  73   void set_length (unsigned int length)
  74   {
  75     m_length = length;
  76   }
  77
  78   /* Return the total length of the CU described by this header, including the
  79      initial length field.  */
  80   unsigned int get_length_with_initial () const
  81   {
  82     return m_length + initial_length_size;
  83   }
  84
  85   /* Return the total length of the CU described by this header, excluding the
  86      initial length field.  */
  87   unsigned int get_length_without_initial () const
  88   {
  89     return m_length;
  90   }
  91
  92   /* Return TRUE if OFF is within this CU.  */
  93   bool offset_in_cu_p (sect_offset off) const
  94   {
  95     sect_offset bottom = sect_off;
  96     sect_offset top = sect_off + get_length_with_initial ();
  97     return off >= bottom && off < top;
  98   }
  99
 100   /* Read an offset from the data stream.  The size of the offset is
 101      given by cu_header->offset_size.  */
 102   LONGEST read_offset (bfd *abfd, const gdb_byte *buf,
 103                        unsigned int *bytes_read) const
 104   {
 105     LONGEST offset = ::read_offset (abfd, buf, offset_size);
 106     *bytes_read = offset_size;
 107     return offset;
 108   }
 109
 110   /* Read an address from BUF.  BYTES_READ is updated.  */
 111   unrelocated_addr read_address (bfd *abfd, const gdb_byte *buf,
 112                                  unsigned int *bytes_read) const;
 113 };
 114
 115 /* Expected enum dwarf_unit_type for read_comp_unit_head.  */
 116 enum class rcuh_kind { COMPILE, TYPE };
 117
 118 /* Read in the comp unit header information from the debug_info at info_ptr.
 119    Use rcuh_kind::COMPILE as the default type if not known by the caller.
 120    NOTE: This leaves members offset, first_die_offset to be filled in
 121    by the caller.  */
 122 extern const gdb_byte *read_comp_unit_head
 123   (struct comp_unit_head *cu_header,
 124    const gdb_byte *info_ptr,
 125    struct dwarf2_section_info *section,
 126    rcuh_kind section_kind);
 127
 128 /* Read in a CU/TU header and perform some basic error checking.
 129    The contents of the header are stored in HEADER.
 130    The result is a pointer to the start of the first DIE.  */
 131 extern const gdb_byte *read_and_check_comp_unit_head
 132   (dwarf2_per_objfile *per_objfile,
 133    struct comp_unit_head *header,
 134    struct dwarf2_section_info *section,
 135    struct dwarf2_section_info *abbrev_section,
 136    const gdb_byte *info_ptr,
 137    rcuh_kind section_kind);
 138
 139 #endif /* GDB_DWARF2_COMP_UNIT_HEAD_H */