1 files changed, 136 insertions, 0 deletions
diff --git a/gdb/dwarf2/unit-head.h b/gdb/dwarf2/unit-head.h
new file mode 100644
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+++ b/gdb/dwarf2/unit-head.h
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+/* Low-level DWARF 2 reading code
+
+   Copyright (C) 1994-2025 Free Software Foundation, Inc.
+
+   Adapted by Gary Funck (gary@intrepid.com), Intrepid Technology,
+   Inc.  with support from Florida State University (under contract
+   with the Ada Joint Program Office), and Silicon Graphics, Inc.
+   Initial contribution by Brent Benson, Harris Computer Systems, Inc.,
+   based on Fred Fish's (Cygnus Support) implementation of DWARF 1
+   support.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef GDB_DWARF2_UNIT_HEAD_H
+#define GDB_DWARF2_UNIT_HEAD_H
+
+#include "dwarf2.h"
+#include "dwarf2/leb.h"
+#include "dwarf2/types.h"
+
+struct dwarf2_per_objfile;
+struct dwarf2_section_info;
+
+/* The data in a unit header, after target2host translation, looks like
+   this.  */
+struct unit_head
+{
+private:
+  unsigned int m_length = 0;
+public:
+  unsigned char version = 0;
+  unsigned char addr_size = 0;
+  unsigned char signed_addr_p = 0;
+  sect_offset abbrev_sect_off {};
+
+  /* Size of file offsets; either 4 or 8.  */
+  unsigned int offset_size = 0;
+
+  /* Size of the length field; either 4 or 12.  */
+  unsigned int initial_length_size = 0;
+
+  enum dwarf_unit_type unit_type {};
+
+  /* Offset to first die in this unit from the start of the unit.
+     This will be the first byte following the unit header.  */
+  cu_offset first_die_offset_in_unit {};
+
+  /* Offset to the first byte of this unit header in the containing section,
+     for resolving relative reference dies.  */
+  sect_offset sect_off {};
+
+  /* For types, offset in the type's DIE of the type defined by this TU.  */
+  cu_offset type_offset_in_tu {};
+
+  /* 64-bit signature of this unit. For type units, it denotes the signature of
+     the type (DW_UT_type in DWARF 4, additionally DW_UT_split_type in DWARF 5).
+     Also used in DWARF 5, to denote the dwo id when the unit type is
+     DW_UT_skeleton or DW_UT_split_compile.  */
+  ULONGEST signature = 0;
+
+  void set_length (unsigned int length)
+  {
+    m_length = length;
+  }
+
+  /* Return the total length of the unit described by this header, including the
+     initial length field.  */
+  unsigned int get_length_with_initial () const
+  {
+    return m_length + initial_length_size;
+  }
+
+  /* Return the total length of the unit described by this header, excluding the
+     initial length field.  */
+  unsigned int get_length_without_initial () const
+  {
+    return m_length;
+  }
+
+  /* Return TRUE if OFF is within this unit.  */
+  bool offset_in_unit_p (sect_offset off) const
+  {
+    sect_offset bottom = sect_off;
+    sect_offset top = sect_off + get_length_with_initial ();
+    return off >= bottom && off < top;
+  }
+
+  /* Read an offset from the data stream.  The size of the offset is
+     given by unit_head::offset_size.  */
+  LONGEST read_offset (bfd *abfd, const gdb_byte *buf,
+		       unsigned int *bytes_read) const
+  {
+    LONGEST offset = ::read_offset (abfd, buf, offset_size);
+    *bytes_read = offset_size;
+    return offset;
+  }
+
+  /* Read an address from BUF.  BYTES_READ is updated.  */
+  unrelocated_addr read_address (bfd *abfd, const gdb_byte *buf,
+				 unsigned int *bytes_read) const;
+};
+
+/* Expected enum dwarf_unit_type for read_unit_head.  */
+enum class ruh_kind { COMPILE, TYPE };
+
+/* Read in the unit header information from the debug_info at info_ptr.
+   Use ruh_kind::COMPILE as the default type if not known by the caller.
+   NOTE: This leaves members sect_off, first_die_unit_offset to be filled in
+   by the caller.  */
+extern const gdb_byte *read_unit_head (unit_head *header,
+				       const gdb_byte *info_ptr,
+				       dwarf2_section_info *section,
+				       ruh_kind section_kind);
+
+/* Read in a unit header and perform some basic error checking.
+   The contents of the header are stored in HEADER.
+   The result is a pointer to the start of the first DIE.  */
+extern const gdb_byte *read_and_check_unit_head
+  (unit_head *header, dwarf2_section_info *section,
+   dwarf2_section_info *abbrev_section, const gdb_byte *info_ptr,
+   ruh_kind section_kind);
+
+#endif /* GDB_DWARF2_UNIT_HEAD_H */