gold/archive.cc

   1 // archive.cc -- archive support for gold
   2
   3 // Copyright 2006, 2007 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 #include "gold.h"
  24
  25 #include <cerrno>
  26 #include <cstring>
  27 #include <climits>
  28 #include <vector>
  29
  30 #include "elfcpp.h"
  31 #include "options.h"
  32 #include "fileread.h"
  33 #include "readsyms.h"
  34 #include "symtab.h"
  35 #include "object.h"
  36 #include "archive.h"
  37
  38 namespace gold
  39 {
  40
  41 // The header of an entry in the archive.  This is all readable text,
  42 // padded with spaces where necesary.  If the contents of an archive
  43 // are all text file, the entire archive is readable.
  44
  45 struct Archive::Archive_header
  46 {
  47   // The entry name.
  48   char ar_name[16];
  49   // The file modification time.
  50   char ar_date[12];
  51   // The user's UID in decimal.
  52   char ar_uid[6];
  53   // The user's GID in decimal.
  54   char ar_gid[6];
  55   // The file mode in octal.
  56   char ar_mode[8];
  57   // The file size in decimal.
  58   char ar_size[10];
  59   // The final magic code.
  60   char ar_fmag[2];
  61 };
  62
  63 // Archive methods.
  64
  65 const char Archive::armag[sarmag] =
  66 {
  67   '!', '<', 'a', 'r', 'c', 'h', '>', '\n'
  68 };
  69
  70 const char Archive::arfmag[2] = { '`', '\n' };
  71
  72 // Set up the archive: read the symbol map and the extended name
  73 // table.
  74
  75 void
  76 Archive::setup(Task* task)
  77 {
  78   // We need to ignore empty archives.
  79   if (this->input_file_->file().filesize() == sarmag)
  80     {
  81       this->input_file_->file().unlock(task);
  82       return;
  83     }
  84
  85   // The first member of the archive should be the symbol table.
  86   std::string armap_name;
  87   section_size_type armap_size =
  88     convert_to_section_size_type(this->read_header(sarmag, &armap_name));
  89   off_t off = sarmag;
  90   if (armap_name.empty())
  91     {
  92       this->read_armap(sarmag + sizeof(Archive_header), armap_size);
  93       off = sarmag + sizeof(Archive_header) + armap_size;
  94     }
  95   else if (!this->input_file_->options().include_whole_archive())
  96     gold_error(_("%s: no archive symbol table (run ranlib)"),
  97                this->name().c_str());
  98
  99   // See if there is an extended name table.
 100   if ((off & 1) != 0)
 101     ++off;
 102   std::string xname;
 103   off_t extended_size = this->read_header(off, &xname);
 104   if (xname == "/")
 105     {
 106       const unsigned char* p = this->get_view(off + sizeof(Archive_header),
 107                                               extended_size, false);
 108       const char* px = reinterpret_cast<const char*>(p);
 109       this->extended_names_.assign(px, extended_size);
 110     }
 111
 112   // Opening the file locked it.  Unlock it now.
 113   this->input_file_->file().unlock(task);
 114 }
 115
 116 // Read the archive symbol map.
 117
 118 void
 119 Archive::read_armap(off_t start, section_size_type size)
 120 {
 121   // Read in the entire armap.
 122   const unsigned char* p = this->get_view(start, size, false);
 123
 124   // Numbers in the armap are always big-endian.
 125   const elfcpp::Elf_Word* pword = reinterpret_cast<const elfcpp::Elf_Word*>(p);
 126   unsigned int nsyms = elfcpp::Swap<32, true>::readval(pword);
 127   ++pword;
 128
 129   // Note that the addition is in units of sizeof(elfcpp::Elf_Word).
 130   const char* pnames = reinterpret_cast<const char*>(pword + nsyms);
 131   section_size_type names_size =
 132     reinterpret_cast<const char*>(p) + size - pnames;
 133   this->armap_names_.assign(pnames, names_size);
 134
 135   this->armap_.resize(nsyms);
 136
 137   section_offset_type name_offset = 0;
 138   for (unsigned int i = 0; i < nsyms; ++i)
 139     {
 140       this->armap_[i].name_offset = name_offset;
 141       this->armap_[i].file_offset = elfcpp::Swap<32, true>::readval(pword);
 142       name_offset += strlen(pnames + name_offset) + 1;
 143       ++pword;
 144     }
 145
 146   if (static_cast<section_size_type>(name_offset) > names_size)
 147     gold_error(_("%s: bad archive symbol table names"),
 148                this->name().c_str());
 149
 150   // This array keeps track of which symbols are for archive elements
 151   // which we have already included in the link.
 152   this->armap_checked_.resize(nsyms);
 153 }
 154
 155 // Read the header of an archive member at OFF.  Fail if something
 156 // goes wrong.  Return the size of the member.  Set *PNAME to the name
 157 // of the member.
 158
 159 off_t
 160 Archive::read_header(off_t off, std::string* pname)
 161 {
 162   const unsigned char* p = this->get_view(off, sizeof(Archive_header), false);
 163   const Archive_header* hdr = reinterpret_cast<const Archive_header*>(p);
 164   return this->interpret_header(hdr, off,  pname);
 165 }
 166
 167 // Interpret the header of HDR, the header of the archive member at
 168 // file offset OFF.  Fail if something goes wrong.  Return the size of
 169 // the member.  Set *PNAME to the name of the member.
 170
 171 off_t
 172 Archive::interpret_header(const Archive_header* hdr, off_t off,
 173                           std::string* pname)
 174 {
 175   if (memcmp(hdr->ar_fmag, arfmag, sizeof arfmag) != 0)
 176     {
 177       gold_error(_("%s: malformed archive header at %zu"),
 178                  this->name().c_str(), static_cast<size_t>(off));
 179       return this->input_file_->file().filesize() - off;
 180     }
 181
 182   const int size_string_size = sizeof hdr->ar_size;
 183   char size_string[size_string_size + 1];
 184   memcpy(size_string, hdr->ar_size, size_string_size);
 185   char* ps = size_string + size_string_size;
 186   while (ps[-1] == ' ')
 187     --ps;
 188   *ps = '\0';
 189
 190   errno = 0;
 191   char* end;
 192   off_t member_size = strtol(size_string, &end, 10);
 193   if (*end != '\0'
 194       || member_size < 0
 195       || (member_size == LONG_MAX && errno == ERANGE))
 196     {
 197       gold_error(_("%s: malformed archive header size at %zu"),
 198                  this->name().c_str(), static_cast<size_t>(off));
 199       return this->input_file_->file().filesize() - off;
 200     }
 201
 202   if (hdr->ar_name[0] != '/')
 203     {
 204       const char* name_end = strchr(hdr->ar_name, '/');
 205       if (name_end == NULL
 206           || name_end - hdr->ar_name >= static_cast<int>(sizeof hdr->ar_name))
 207         {
 208           gold_error(_("%s: malformed archive header name at %zu"),
 209                      this->name().c_str(), static_cast<size_t>(off));
 210           return this->input_file_->file().filesize() - off;
 211         }
 212       pname->assign(hdr->ar_name, name_end - hdr->ar_name);
 213     }
 214   else if (hdr->ar_name[1] == ' ')
 215     {
 216       // This is the symbol table.
 217       pname->clear();
 218     }
 219   else if (hdr->ar_name[1] == '/')
 220     {
 221       // This is the extended name table.
 222       pname->assign(1, '/');
 223     }
 224   else
 225     {
 226       errno = 0;
 227       long x = strtol(hdr->ar_name + 1, &end, 10);
 228       if (*end != ' '
 229           || x < 0
 230           || (x == LONG_MAX && errno == ERANGE)
 231           || static_cast<size_t>(x) >= this->extended_names_.size())
 232         {
 233           gold_error(_("%s: bad extended name index at %zu"),
 234                      this->name().c_str(), static_cast<size_t>(off));
 235           return this->input_file_->file().filesize() - off;
 236         }
 237
 238       const char* name = this->extended_names_.data() + x;
 239       const char* name_end = strchr(name, '/');
 240       if (static_cast<size_t>(name_end - name) > this->extended_names_.size()
 241           || name_end[1] != '\n')
 242         {
 243           gold_error(_("%s: bad extended name entry at header %zu"),
 244                      this->name().c_str(), static_cast<size_t>(off));
 245           return this->input_file_->file().filesize() - off;
 246         }
 247       pname->assign(name, name_end - name);
 248     }
 249
 250   return member_size;
 251 }
 252
 253 // Select members from the archive and add them to the link.  We walk
 254 // through the elements in the archive map, and look each one up in
 255 // the symbol table.  If it exists as a strong undefined symbol, we
 256 // pull in the corresponding element.  We have to do this in a loop,
 257 // since pulling in one element may create new undefined symbols which
 258 // may be satisfied by other objects in the archive.
 259
 260 void
 261 Archive::add_symbols(Symbol_table* symtab, Layout* layout,
 262                      Input_objects* input_objects)
 263 {
 264   if (this->input_file_->options().include_whole_archive())
 265     return this->include_all_members(symtab, layout, input_objects);
 266
 267   const size_t armap_size = this->armap_.size();
 268
 269   // This is a quick optimization, since we usually see many symbols
 270   // in a row with the same offset.  last_seen_offset holds the last
 271   // offset we saw that was present in the seen_offsets_ set.
 272   off_t last_seen_offset = -1;
 273
 274   // Track which symbols in the symbol table we've already found to be
 275   // defined.
 276
 277   bool added_new_object;
 278   do
 279     {
 280       added_new_object = false;
 281       for (size_t i = 0; i < armap_size; ++i)
 282         {
 283           if (this->armap_checked_[i])
 284             continue;
 285           if (this->armap_[i].file_offset == last_seen_offset)
 286             {
 287               this->armap_checked_[i] = true;
 288               continue;
 289             }
 290           if (this->seen_offsets_.find(this->armap_[i].file_offset)
 291               != this->seen_offsets_.end())
 292             {
 293               this->armap_checked_[i] = true;
 294               last_seen_offset = this->armap_[i].file_offset;
 295               continue;
 296             }
 297
 298           const char* sym_name = (this->armap_names_.data()
 299                                   + this->armap_[i].name_offset);
 300           Symbol* sym = symtab->lookup(sym_name);
 301           if (sym == NULL)
 302             continue;
 303           else if (!sym->is_undefined())
 304             {
 305               this->armap_checked_[i] = true;
 306               continue;
 307             }
 308           else if (sym->binding() == elfcpp::STB_WEAK)
 309             continue;
 310
 311           // We want to include this object in the link.
 312           last_seen_offset = this->armap_[i].file_offset;
 313           this->seen_offsets_.insert(last_seen_offset);
 314           this->armap_checked_[i] = true;
 315           this->include_member(symtab, layout, input_objects,
 316                                last_seen_offset);
 317           added_new_object = true;
 318         }
 319     }
 320   while (added_new_object);
 321 }
 322
 323 // Include all the archive members in the link.  This is for --whole-archive.
 324
 325 void
 326 Archive::include_all_members(Symbol_table* symtab, Layout* layout,
 327                              Input_objects* input_objects)
 328 {
 329   off_t off = sarmag;
 330   off_t filesize = this->input_file_->file().filesize();
 331   while (true)
 332     {
 333       if (filesize - off < static_cast<off_t>(sizeof(Archive_header)))
 334         {
 335           if (filesize != off)
 336             gold_error(_("%s: short archive header at %zu"),
 337                        this->name().c_str(), static_cast<size_t>(off));
 338           break;
 339         }
 340
 341       unsigned char hdr_buf[sizeof(Archive_header)];
 342       this->input_file_->file().read(off, sizeof(Archive_header), hdr_buf);
 343
 344       const Archive_header* hdr =
 345         reinterpret_cast<const Archive_header*>(hdr_buf);
 346       std::string name;
 347       off_t size = this->interpret_header(hdr, off, &name);
 348       if (name.empty())
 349         {
 350           // Symbol table.
 351         }
 352       else if (name == "/")
 353         {
 354           // Extended name table.
 355         }
 356       else
 357         this->include_member(symtab, layout, input_objects, off);
 358
 359       off += sizeof(Archive_header) + size;
 360       if ((off & 1) != 0)
 361         ++off;
 362     }
 363 }
 364
 365 // Include an archive member in the link.  OFF is the file offset of
 366 // the member header.
 367
 368 void
 369 Archive::include_member(Symbol_table* symtab, Layout* layout,
 370                         Input_objects* input_objects, off_t off)
 371 {
 372   std::string n;
 373   this->read_header(off, &n);
 374
 375   const off_t memoff = off + static_cast<off_t>(sizeof(Archive_header));
 376
 377   // Read enough of the file to pick up the entire ELF header.
 378   unsigned char ehdr_buf[elfcpp::Elf_sizes<64>::ehdr_size];
 379
 380   off_t filesize = this->input_file_->file().filesize();
 381   int read_size = elfcpp::Elf_sizes<64>::ehdr_size;
 382   if (filesize - memoff < read_size)
 383     read_size = filesize - memoff;
 384
 385   if (read_size < 4)
 386     {
 387       gold_error(_("%s: member at %zu is not an ELF object"),
 388                  this->name().c_str(), static_cast<size_t>(off));
 389       return;
 390     }
 391
 392   this->input_file_->file().read(memoff, read_size, ehdr_buf);
 393
 394   static unsigned char elfmagic[4] =
 395     {
 396       elfcpp::ELFMAG0, elfcpp::ELFMAG1,
 397       elfcpp::ELFMAG2, elfcpp::ELFMAG3
 398     };
 399   if (memcmp(ehdr_buf, elfmagic, 4) != 0)
 400     {
 401       gold_error(_("%s: member at %zu is not an ELF object"),
 402                  this->name().c_str(), static_cast<size_t>(off));
 403       return;
 404     }
 405
 406   Object* obj = make_elf_object((std::string(this->input_file_->filename())
 407                                  + "(" + n + ")"),
 408                                 this->input_file_, memoff, ehdr_buf,
 409                                 read_size);
 410
 411   if (input_objects->add_object(obj))
 412     {
 413       Read_symbols_data sd;
 414       obj->read_symbols(&sd);
 415       obj->layout(symtab, layout, &sd);
 416       obj->add_symbols(symtab, &sd);
 417     }
 418   else
 419     {
 420       // FIXME: We need to close the descriptor here.
 421       delete obj;
 422     }
 423
 424 }
 425
 426 // Add_archive_symbols methods.
 427
 428 Add_archive_symbols::~Add_archive_symbols()
 429 {
 430   if (this->this_blocker_ != NULL)
 431     delete this->this_blocker_;
 432   // next_blocker_ is deleted by the task associated with the next
 433   // input file.
 434 }
 435
 436 // Return whether we can add the archive symbols.  We are blocked by
 437 // this_blocker_.  We block next_blocker_.  We also lock the file.
 438
 439 Task_token*
 440 Add_archive_symbols::is_runnable()
 441 {
 442   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 443     return this->this_blocker_;
 444   return NULL;
 445 }
 446
 447 void
 448 Add_archive_symbols::locks(Task_locker* tl)
 449 {
 450   tl->add(this, this->next_blocker_);
 451   tl->add(this, this->archive_->token());
 452 }
 453
 454 void
 455 Add_archive_symbols::run(Workqueue*)
 456 {
 457   this->archive_->add_symbols(this->symtab_, this->layout_,
 458                               this->input_objects_);
 459
 460   this->archive_->release();
 461
 462   if (this->input_group_ != NULL)
 463     this->input_group_->add_archive(this->archive_);
 464   else
 465     {
 466       // We no longer need to know about this archive.
 467       delete this->archive_;
 468       this->archive_ = NULL;
 469     }
 470 }
 471
 472 } // End namespace gold.