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_argument;
  37 class Input_file;
  38 class Input_objects;
  39 class Input_group;
  40 class Layout;
  41 class Symbol_table;
  42 class Object;
  43 class Read_symbols_data;
  44
  45 // This class represents an archive--generally a libNAME.a file.
  46 // Archives have a symbol table and a list of objects.
  47
  48 class Archive
  49 {
  50  public:
  51   Archive(const std::string& name, Input_file* input_file,
  52           bool is_thin_archive, Dirsearch* dirpath, Task* task)
  53     : name_(name), input_file_(input_file), armap_(), armap_names_(),
  54       extended_names_(), armap_checked_(), seen_offsets_(), members_(),
  55       is_thin_archive_(is_thin_archive), included_member_(false),
  56       nested_archives_(), dirpath_(dirpath), task_(task), num_members_(0)
  57   { }
  58
  59   // The length of the magic string at the start of an archive.
  60   static const int sarmag = 8;
  61
  62   // The magic string at the start of an archive.
  63   static const char armag[sarmag];
  64   static const char armagt[sarmag];
  65
  66   // The string expected at the end of an archive member header.
  67   static const char arfmag[2];
  68
  69   // The name of the object.  This is the name used on the command
  70   // line; e.g., if "-lgcc" is on the command line, this will be
  71   // "gcc".
  72   const std::string&
  73   name() const
  74   { return this->name_; }
  75
  76   // The input file.
  77   const Input_file*
  78   input_file() const
  79   { return this->input_file_; }
  80
  81   // The file name.
  82   const std::string&
  83   filename() const
  84   { return this->input_file_->filename(); }
  85
  86   // Set up the archive: read the symbol map.
  87   void
  88   setup();
  89
  90   // Get a reference to the underlying file.
  91   File_read&
  92   file()
  93   { return this->input_file_->file(); }
  94
  95   const File_read&
  96   file() const
  97   { return this->input_file_->file(); }
  98
  99   // Lock the underlying file.
 100   void
 101   lock(const Task* t)
 102   { this->input_file_->file().lock(t); }
 103
 104   // Unlock the underlying file.
 105   void
 106   unlock(const Task* t)
 107   { this->input_file_->file().unlock(t); }
 108
 109   // Return whether the underlying file is locked.
 110   bool
 111   is_locked() const
 112   { return this->input_file_->file().is_locked(); }
 113
 114   // Return the token, so that the task can be queued.
 115   Task_token*
 116   token()
 117   { return this->input_file_->file().token(); }
 118
 119   // Release the underlying file.
 120   void
 121   release()
 122   { this->input_file_->file().release(); }
 123
 124   // Clear uncached views in the underlying file.
 125   void
 126   clear_uncached_views()
 127   { this->input_file_->file().clear_uncached_views(); }
 128
 129   // Whether this is a thin archive.
 130   bool
 131   is_thin_archive() const
 132   { return this->is_thin_archive_; }
 133
 134   // Unlock any nested archives.
 135   void
 136   unlock_nested_archives();
 137
 138   // Select members from the archive as needed and add them to the
 139   // link.
 140   bool
 141   add_symbols(Symbol_table*, Layout*, Input_objects*, Mapfile*);
 142
 143   // Dump statistical information to stderr.
 144   static void
 145   print_stats();
 146
 147   // Return the number of members in the archive.
 148   size_t
 149   count_members();
 150
 151  private:
 152   Archive(const Archive&);
 153   Archive& operator=(const Archive&);
 154
 155   struct Archive_header;
 156
 157   // Total number of archives seen.
 158   static unsigned int total_archives;
 159   // Total number of archive members seen.
 160   static unsigned int total_members;
 161   // Number of archive members loaded.
 162   static unsigned int total_members_loaded;
 163
 164   // Get a view into the underlying file.
 165   const unsigned char*
 166   get_view(off_t start, section_size_type size, bool aligned, bool cache)
 167   { return this->input_file_->file().get_view(0, start, size, aligned, cache); }
 168
 169   // Read the archive symbol map.
 170   void
 171   read_armap(off_t start, section_size_type size);
 172
 173   // Read an archive member header at OFF.  CACHE is whether to cache
 174   // the file view.  Return the size of the member, and set *PNAME to
 175   // the name.
 176   off_t
 177   read_header(off_t off, bool cache, std::string* pname, off_t* nested_off);
 178
 179   // Interpret an archive header HDR at OFF.  Return the size of the
 180   // member, and set *PNAME to the name.
 181   off_t
 182   interpret_header(const Archive_header* hdr, off_t off, std::string* pname,
 183                    off_t* nested_off) const;
 184
 185   // Get the file and offset for an archive member, which may be an
 186   // external member of a thin archive.  Set *INPUT_FILE to the
 187   // file containing the actual member, *MEMOFF to the offset
 188   // within that file (0 if not a nested archive), and *MEMBER_NAME
 189   // to the name of the archive member.  Return TRUE on success.
 190   bool
 191   get_file_and_offset(off_t off, Input_file** input_file, off_t* memoff,
 192                       off_t* memsize, std::string* member_name);
 193
 194   // Return an ELF object for the member at offset OFF.
 195   Object*
 196   get_elf_object_for_member(off_t off, bool*);
 197
 198   // Read the symbols from all the archive members in the link.
 199   void
 200   read_all_symbols();
 201
 202   // Read the symbols from an archive member in the link.  OFF is the file
 203   // offset of the member header.
 204   void
 205   read_symbols(off_t off);
 206
 207   // Include all the archive members in the link.
 208   bool
 209   include_all_members(Symbol_table*, Layout*, Input_objects*, Mapfile*);
 210
 211   // Include an archive member in the link.
 212   bool
 213   include_member(Symbol_table*, Layout*, Input_objects*, off_t off,
 214                  Mapfile*, Symbol*, const char* why);
 215
 216   // Return whether we found this archive by searching a directory.
 217   bool
 218   searched_for() const
 219   { return this->input_file_->will_search_for(); }
 220
 221   // Iterate over archive members.
 222   class const_iterator;
 223
 224   const_iterator
 225   begin();
 226
 227   const_iterator
 228   end();
 229
 230   friend class const_iterator;
 231
 232   // An entry in the archive map of symbols to object files.
 233   struct Armap_entry
 234   {
 235     // The offset to the symbol name in armap_names_.
 236     off_t name_offset;
 237     // The file offset to the object in the archive.
 238     off_t file_offset;
 239   };
 240
 241   // An entry in the archive map of offsets to members.
 242   struct Archive_member
 243   {
 244     Archive_member()
 245       : obj_(NULL), sd_(NULL)
 246     { }
 247     Archive_member(Object* obj, Read_symbols_data* sd)
 248       : obj_(obj), sd_(sd)
 249     { }
 250     // The object file.
 251     Object* obj_;
 252     // The data to pass from read_symbols() to add_symbols().
 253     Read_symbols_data* sd_;
 254   };
 255
 256   // A simple hash code for off_t values.
 257   class Seen_hash
 258   {
 259    public:
 260     size_t operator()(off_t val) const
 261     { return static_cast<size_t>(val); }
 262   };
 263
 264   // For keeping track of open nested archives in a thin archive file.
 265   typedef Unordered_map<std::string, Archive*> Nested_archive_table;
 266
 267   // Name of object as printed to user.
 268   std::string name_;
 269   // For reading the file.
 270   Input_file* input_file_;
 271   // The archive map.
 272   std::vector<Armap_entry> armap_;
 273   // The names in the archive map.
 274   std::string armap_names_;
 275   // The extended name table.
 276   std::string extended_names_;
 277   // Track which symbols in the archive map are for elements which are
 278   // defined or which have already been included in the link.
 279   std::vector<bool> armap_checked_;
 280   // Track which elements have been included by offset.
 281   Unordered_set<off_t, Seen_hash> seen_offsets_;
 282   // Table of objects whose symbols have been pre-read.
 283   std::map<off_t, Archive_member> members_;
 284   // True if this is a thin archive.
 285   const bool is_thin_archive_;
 286   // True if we have included at least one object from this archive.
 287   bool included_member_;
 288   // Table of nested archives, indexed by filename.
 289   Nested_archive_table nested_archives_;
 290   // The directory search path.
 291   Dirsearch* dirpath_;
 292   // The task reading this archive.
 293   Task *task_;
 294   // Number of members in this archive;
 295   unsigned int num_members_;
 296 };
 297
 298 // This class is used to read an archive and pick out the desired
 299 // elements and add them to the link.
 300
 301 class Add_archive_symbols : public Task
 302 {
 303  public:
 304   Add_archive_symbols(Symbol_table* symtab, Layout* layout,
 305                       Input_objects* input_objects, Dirsearch* dirpath,
 306                       int dirindex, Mapfile* mapfile,
 307                       const Input_argument* input_argument,
 308                       Archive* archive, Input_group* input_group,
 309                       Task_token* this_blocker,
 310                       Task_token* next_blocker)
 311     : symtab_(symtab), layout_(layout), input_objects_(input_objects),
 312       dirpath_(dirpath), dirindex_(dirindex), mapfile_(mapfile),
 313       input_argument_(input_argument), archive_(archive),
 314       input_group_(input_group), this_blocker_(this_blocker),
 315       next_blocker_(next_blocker)
 316   { }
 317
 318   ~Add_archive_symbols();
 319
 320   // The standard Task methods.
 321
 322   Task_token*
 323   is_runnable();
 324
 325   void
 326   locks(Task_locker*);
 327
 328   void
 329   run(Workqueue*);
 330
 331   std::string
 332   get_name() const
 333   {
 334     if (this->archive_ == NULL)
 335       return "Add_archive_symbols";
 336     return "Add_archive_symbols " + this->archive_->file().filename();
 337   }
 338
 339  private:
 340   Symbol_table* symtab_;
 341   Layout* layout_;
 342   Input_objects* input_objects_;
 343   Dirsearch* dirpath_;
 344   int dirindex_;
 345   Mapfile* mapfile_;
 346   const Input_argument* input_argument_;
 347   Archive* archive_;
 348   Input_group* input_group_;
 349   Task_token* this_blocker_;
 350   Task_token* next_blocker_;
 351 };
 352
 353 } // End namespace gold.
 354
 355 #endif // !defined(GOLD_ARCHIVE_H)