gdb/dwarf2/line-header.h

   1 /* DWARF 2 debugging format support for GDB.
   2
   3    Copyright (C) 1994-2020 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef DWARF2_LINE_HEADER_H
  21 #define DWARF2_LINE_HEADER_H
  22
  23 #include "gdbtypes.h"
  24
  25 /* dir_index is 1-based in DWARF 4 and before, and is 0-based in DWARF 5 and
  26    later.  */
  27 typedef int dir_index;
  28
  29 /* file_name_index is 1-based in DWARF 4 and before, and is 0-based in DWARF 5
  30    and later.  */
  31 typedef int file_name_index;
  32
  33 struct line_header;
  34
  35 struct file_entry
  36 {
  37   file_entry () = default;
  38
  39   file_entry (const char *name_, dir_index d_index_,
  40               unsigned int mod_time_, unsigned int length_)
  41     : name (name_),
  42       d_index (d_index_),
  43       mod_time (mod_time_),
  44       length (length_)
  45   {}
  46
  47   /* Return the include directory at D_INDEX stored in LH.  Returns
  48      NULL if D_INDEX is out of bounds.  */
  49   const char *include_dir (const line_header *lh) const;
  50
  51   /* The file name.  Note this is an observing pointer.  The memory is
  52      owned by debug_line_buffer.  */
  53   const char *name {};
  54
  55   /* The directory index (1-based).  */
  56   dir_index d_index {};
  57
  58   unsigned int mod_time {};
  59
  60   unsigned int length {};
  61
  62   /* True if referenced by the Line Number Program.  */
  63   bool included_p {};
  64
  65   /* The associated symbol table, if any.  */
  66   struct symtab *symtab {};
  67 };
  68
  69 /* The line number information for a compilation unit (found in the
  70    .debug_line section) begins with a "statement program header",
  71    which contains the following information.  */
  72 struct line_header
  73 {
  74   line_header ()
  75     : offset_in_dwz {}
  76   {}
  77
  78   /* Add an entry to the include directory table.  */
  79   void add_include_dir (const char *include_dir);
  80
  81   /* Add an entry to the file name table.  */
  82   void add_file_name (const char *name, dir_index d_index,
  83                       unsigned int mod_time, unsigned int length);
  84
  85   /* Return the include dir at INDEX (0-based in DWARF 5 and 1-based before).
  86      Returns NULL if INDEX is out of bounds.  */
  87   const char *include_dir_at (dir_index index) const
  88   {
  89     int vec_index;
  90     if (version >= 5)
  91       vec_index = index;
  92     else
  93       vec_index = index - 1;
  94     if (vec_index < 0 || vec_index >= m_include_dirs.size ())
  95       return NULL;
  96     return m_include_dirs[vec_index];
  97   }
  98
  99   bool is_valid_file_index (int file_index) const
 100   {
 101     if (version >= 5)
 102       return 0 <= file_index && file_index < file_names_size ();
 103     return 1 <= file_index && file_index <= file_names_size ();
 104   }
 105
 106   /* Return the file name at INDEX (0-based in DWARF 5 and 1-based before).
 107      Returns NULL if INDEX is out of bounds.  */
 108   file_entry *file_name_at (file_name_index index)
 109   {
 110     int vec_index;
 111     if (version >= 5)
 112       vec_index = index;
 113     else
 114       vec_index = index - 1;
 115     if (vec_index < 0 || vec_index >= m_file_names.size ())
 116       return NULL;
 117     return &m_file_names[vec_index];
 118   }
 119
 120   /* A const overload of the same.  */
 121   const file_entry *file_name_at (file_name_index index) const
 122   {
 123     line_header *lh = const_cast<line_header *> (this);
 124     return lh->file_name_at (index);
 125   }
 126
 127   /* The indexes are 0-based in DWARF 5 and 1-based in DWARF 4. Therefore,
 128      this method should only be used to iterate through all file entries in an
 129      index-agnostic manner.  */
 130   std::vector<file_entry> &file_names ()
 131   { return m_file_names; }
 132   /* A const overload of the same.  */
 133   const std::vector<file_entry> &file_names () const
 134   { return m_file_names; }
 135
 136   /* Offset of line number information in .debug_line section.  */
 137   sect_offset sect_off {};
 138
 139   /* OFFSET is for struct dwz_file associated with dwarf2_per_objfile.  */
 140   unsigned offset_in_dwz : 1; /* Can't initialize bitfields in-class.  */
 141
 142   unsigned int total_length {};
 143   unsigned short version {};
 144   unsigned int header_length {};
 145   unsigned char minimum_instruction_length {};
 146   unsigned char maximum_ops_per_instruction {};
 147   unsigned char default_is_stmt {};
 148   int line_base {};
 149   unsigned char line_range {};
 150   unsigned char opcode_base {};
 151
 152   /* standard_opcode_lengths[i] is the number of operands for the
 153      standard opcode whose value is i.  This means that
 154      standard_opcode_lengths[0] is unused, and the last meaningful
 155      element is standard_opcode_lengths[opcode_base - 1].  */
 156   std::unique_ptr<unsigned char[]> standard_opcode_lengths;
 157
 158   int file_names_size () const
 159   { return m_file_names.size(); }
 160
 161   /* The start and end of the statement program following this
 162      header.  These point into dwarf2_per_objfile->line_buffer.  */
 163   const gdb_byte *statement_program_start {}, *statement_program_end {};
 164
 165   /* Return the full name of file number I in this object's file name
 166      table.  Use COMP_DIR as the name of the current directory of the
 167      compilation.  The result is allocated using xmalloc; the caller
 168      is responsible for freeing it.  */
 169   gdb::unique_xmalloc_ptr<char> file_full_name (int file,
 170                                                 const char *comp_dir) const;
 171
 172   /* Return file name relative to the compilation directory of file
 173      number I in this object's file name table.  The result is
 174      allocated using xmalloc; the caller is responsible for freeing
 175      it.  */
 176   gdb::unique_xmalloc_ptr<char> file_file_name (int file) const;
 177
 178  private:
 179   /* The include_directories table.  Note these are observing
 180      pointers.  The memory is owned by debug_line_buffer.  */
 181   std::vector<const char *> m_include_dirs;
 182
 183   /* The file_names table. This is private because the meaning of indexes
 184      differs among DWARF versions (The first valid index is 1 in DWARF 4 and
 185      before, and is 0 in DWARF 5 and later).  So the client should use
 186      file_name_at method for access.  */
 187   std::vector<file_entry> m_file_names;
 188 };
 189
 190 typedef std::unique_ptr<line_header> line_header_up;
 191
 192 inline const char *
 193 file_entry::include_dir (const line_header *lh) const
 194 {
 195   return lh->include_dir_at (d_index);
 196 }
 197
 198 /* Read the statement program header starting at SECT_OFF in SECTION.
 199    Return line_header.  Returns nullptr if there is a problem reading
 200    the header, e.g., if it has a version we don't understand.
 201
 202    NOTE: the strings in the include directory and file name tables of
 203    the returned object point into the dwarf line section buffer,
 204    and must not be freed.  */
 205
 206 extern line_header_up dwarf_decode_line_header
 207   (sect_offset sect_off, bool is_dwz, dwarf2_per_objfile *per_objfile,
 208    struct dwarf2_section_info *section, const struct comp_unit_head *cu_header);
 209
 210 #endif /* DWARF2_LINE_HEADER_H */