gold/archive.h

   1 // archive.h -- archive support for gold      -*- C++ -*-
   2
   3 // Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@google.com>.
   5
   6 // This file is part of gold.
   7
   8 // This program is free software; you can redistribute it and/or modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3 of the License, or
  11 // (at your option) any later version.
  12
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21 // MA 02110-1301, USA.
  22
  23 #ifndef GOLD_ARCHIVE_H
  24 #define GOLD_ARCHIVE_H
  25
  26 #include <string>
  27 #include <vector>
  28
  29 #include "fileread.h"
  30 #include "workqueue.h"
  31
  32 namespace gold
  33 {
  34
  35 class Task;
  36 class Input_file;
  37 class Input_objects;
  38 class Input_group;
  39 class Layout;
  40 class Symbol_table;
  41 class Object;
  42 class Read_symbols_data;
  43
  44 // This class represents an archive--generally a libNAME.a file.
  45 // Archives have a symbol table and a list of objects.
  46
  47 class Archive
  48 {
  49  public:
  50   Archive(const std::string& name, Input_file* input_file,
  51           bool is_thin_archive, Dirsearch* dirpath, Task* task)
  52     : name_(name), input_file_(input_file), armap_(), armap_names_(),
  53       extended_names_(), armap_checked_(), seen_offsets_(), members_(),
  54       is_thin_archive_(is_thin_archive), nested_archives_(),
  55       dirpath_(dirpath), task_(task), num_members_(0)
  56   { }
  57
  58   // The length of the magic string at the start of an archive.
  59   static const int sarmag = 8;
  60
  61   // The magic string at the start of an archive.
  62   static const char armag[sarmag];
  63   static const char armagt[sarmag];
  64
  65   // The string expected at the end of an archive member header.
  66   static const char arfmag[2];
  67
  68   // The name of the object.  This is the name used on the command
  69   // line; e.g., if "-lgcc" is on the command line, this will be
  70   // "gcc".
  71   const std::string&
  72   name() const
  73   { return this->name_; }
  74
  75   // The file name.
  76   const std::string&
  77   filename() const
  78   { return this->input_file_->filename(); }
  79
  80   // Set up the archive: read the symbol map.
  81   void
  82   setup(Input_objects*);
  83
  84   // Get a reference to the underlying file.
  85   File_read&
  86   file()
  87   { return this->input_file_->file(); }
  88
  89   const File_read&
  90   file() const
  91   { return this->input_file_->file(); }
  92
  93   // Lock the underlying file.
  94   void
  95   lock(const Task* t)
  96   { this->input_file_->file().lock(t); }
  97
  98   // Unlock the underlying file.
  99   void
 100   unlock(const Task* t)
 101   { this->input_file_->file().unlock(t); }
 102
 103   // Return whether the underlying file is locked.
 104   bool
 105   is_locked() const
 106   { return this->input_file_->file().is_locked(); }
 107
 108   // Return the token, so that the task can be queued.
 109   Task_token*
 110   token()
 111   { return this->input_file_->file().token(); }
 112
 113   // Release the underlying file.
 114   void
 115   release()
 116   { this->input_file_->file().release(); }
 117
 118   // Clear uncached views in the underlying file.
 119   void
 120   clear_uncached_views()
 121   { this->input_file_->file().clear_uncached_views(); }
 122
 123   // Whether this is a thin archive.
 124   bool
 125   is_thin_archive() const
 126   { return this->is_thin_archive_; }
 127
 128   // Unlock any nested archives.
 129   void
 130   unlock_nested_archives();
 131
 132   // Select members from the archive as needed and add them to the
 133   // link.
 134   void
 135   add_symbols(Symbol_table*, Layout*, Input_objects*, Mapfile*);
 136
 137   // Dump statistical information to stderr.
 138   static void
 139   print_stats();
 140
 141   // Return the number of members in the archive.
 142   size_t
 143   count_members();
 144
 145  private:
 146   Archive(const Archive&);
 147   Archive& operator=(const Archive&);
 148
 149   struct Archive_header;
 150
 151   // Total number of archives seen.
 152   static unsigned int total_archives;
 153   // Total number of archive members seen.
 154   static unsigned int total_members;
 155   // Number of archive members loaded.
 156   static unsigned int total_members_loaded;
 157
 158   // Get a view into the underlying file.
 159   const unsigned char*
 160   get_view(off_t start, section_size_type size, bool aligned, bool cache)
 161   { return this->input_file_->file().get_view(0, start, size, aligned, cache); }
 162
 163   // Read the archive symbol map.
 164   void
 165   read_armap(off_t start, section_size_type size);
 166
 167   // Read an archive member header at OFF.  CACHE is whether to cache
 168   // the file view.  Return the size of the member, and set *PNAME to
 169   // the name.
 170   off_t
 171   read_header(off_t off, bool cache, std::string* pname, off_t* nested_off);
 172
 173   // Interpret an archive header HDR at OFF.  Return the size of the
 174   // member, and set *PNAME to the name.
 175   off_t
 176   interpret_header(const Archive_header* hdr, off_t off, std::string* pname,
 177                    off_t* nested_off) const;
 178
 179   // Get the file and offset for an archive member, which may be an
 180   // external member of a thin archive.  Set *INPUT_FILE to the
 181   // file containing the actual member, *MEMOFF to the offset
 182   // within that file (0 if not a nested archive), and *MEMBER_NAME
 183   // to the name of the archive member.  Return TRUE on success.
 184   bool
 185   get_file_and_offset(off_t off, Input_objects* input_objects,
 186                       Input_file** input_file, off_t* memoff,
 187                       std::string* member_name);
 188
 189   // Return an ELF object for the member at offset OFF.  Set *MEMBER_NAME to
 190   // the name of the member.
 191   Object*
 192   get_elf_object_for_member(off_t off, Input_objects* input_objects);
 193
 194   // Read the symbols from all the archive members in the link.
 195   void
 196   read_all_symbols(Input_objects* input_objects);
 197
 198   // Read the symbols from an archive member in the link.  OFF is the file
 199   // offset of the member header.
 200   void
 201   read_symbols(Input_objects* input_objects, off_t off);
 202
 203   // Include all the archive members in the link.
 204   void
 205   include_all_members(Symbol_table*, Layout*, Input_objects*, Mapfile*);
 206
 207   // Include an archive member in the link.
 208   void
 209   include_member(Symbol_table*, Layout*, Input_objects*, off_t off,
 210                  Mapfile*, Symbol*, const char* why);
 211
 212   // Iterate over archive members.
 213   class const_iterator;
 214
 215   const_iterator
 216   begin();
 217
 218   const_iterator
 219   end();
 220
 221   friend class const_iterator;
 222
 223   // An entry in the archive map of symbols to object files.
 224   struct Armap_entry
 225   {
 226     // The offset to the symbol name in armap_names_.
 227     off_t name_offset;
 228     // The file offset to the object in the archive.
 229     off_t file_offset;
 230   };
 231
 232   // An entry in the archive map of offsets to members.
 233   struct Archive_member
 234   {
 235     Archive_member()
 236       : obj_(NULL), sd_(NULL)
 237     { }
 238     Archive_member(Object* obj, Read_symbols_data* sd)
 239       : obj_(obj), sd_(sd)
 240     { }
 241     // The object file.
 242     Object* obj_;
 243     // The data to pass from read_symbols() to add_symbols().
 244     Read_symbols_data* sd_;
 245   };
 246
 247   // A simple hash code for off_t values.
 248   class Seen_hash
 249   {
 250    public:
 251     size_t operator()(off_t val) const
 252     { return static_cast<size_t>(val); }
 253   };
 254
 255   // For keeping track of open nested archives in a thin archive file.
 256   typedef Unordered_map<std::string, Archive*> Nested_archive_table;
 257
 258   // Name of object as printed to user.
 259   std::string name_;
 260   // For reading the file.
 261   Input_file* input_file_;
 262   // The archive map.
 263   std::vector<Armap_entry> armap_;
 264   // The names in the archive map.
 265   std::string armap_names_;
 266   // The extended name table.
 267   std::string extended_names_;
 268   // Track which symbols in the archive map are for elements which are
 269   // defined or which have already been included in the link.
 270   std::vector<bool> armap_checked_;
 271   // Track which elements have been included by offset.
 272   Unordered_set<off_t, Seen_hash> seen_offsets_;
 273   // Table of objects whose symbols have been pre-read.
 274   std::map<off_t, Archive_member> members_;
 275   // True if this is a thin archive.
 276   const bool is_thin_archive_;
 277   // Table of nested archives, indexed by filename.
 278   Nested_archive_table nested_archives_;
 279   // The directory search path.
 280   Dirsearch* dirpath_;
 281   // The task reading this archive.
 282   Task *task_;
 283   // Number of members in this archive;
 284   unsigned int num_members_;
 285 };
 286
 287 // This class is used to read an archive and pick out the desired
 288 // elements and add them to the link.
 289
 290 class Add_archive_symbols : public Task
 291 {
 292  public:
 293   Add_archive_symbols(Symbol_table* symtab, Layout* layout,
 294                       Input_objects* input_objects, Mapfile* mapfile,
 295                       Archive* archive, Input_group* input_group,
 296                       Task_token* this_blocker,
 297                       Task_token* next_blocker)
 298     : symtab_(symtab), layout_(layout), input_objects_(input_objects),
 299       mapfile_(mapfile), archive_(archive), input_group_(input_group),
 300       this_blocker_(this_blocker), next_blocker_(next_blocker)
 301   { }
 302
 303   ~Add_archive_symbols();
 304
 305   // The standard Task methods.
 306
 307   Task_token*
 308   is_runnable();
 309
 310   void
 311   locks(Task_locker*);
 312
 313   void
 314   run(Workqueue*);
 315
 316   std::string
 317   get_name() const
 318   {
 319     if (this->archive_ == NULL)
 320       return "Add_archive_symbols";
 321     return "Add_archive_symbols " + this->archive_->file().filename();
 322   }
 323
 324  private:
 325   Symbol_table* symtab_;
 326   Layout* layout_;
 327   Input_objects* input_objects_;
 328   Mapfile* mapfile_;
 329   Archive* archive_;
 330   Input_group* input_group_;
 331   Task_token* this_blocker_;
 332   Task_token* next_blocker_;
 333 };
 334
 335 } // End namespace gold.
 336
 337 #endif // !defined(GOLD_ARCHIVE_H)