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, false,
  89                                                    &armap_name));
  90   off_t off = sarmag;
  91   if (armap_name.empty())
  92     {
  93       this->read_armap(sarmag + sizeof(Archive_header), armap_size);
  94       off = sarmag + sizeof(Archive_header) + armap_size;
  95     }
  96   else if (!this->input_file_->options().include_whole_archive())
  97     gold_error(_("%s: no archive symbol table (run ranlib)"),
  98                this->name().c_str());
  99
 100   // See if there is an extended name table.  We cache these views
 101   // because it is likely that we will want to read the following
 102   // header in the add_symbols routine.
 103   if ((off & 1) != 0)
 104     ++off;
 105   std::string xname;
 106   section_size_type extended_size =
 107     convert_to_section_size_type(this->read_header(off, true, &xname));
 108   if (xname == "/")
 109     {
 110       const unsigned char* p = this->get_view(off + sizeof(Archive_header),
 111                                               extended_size, true);
 112       const char* px = reinterpret_cast<const char*>(p);
 113       this->extended_names_.assign(px, extended_size);
 114     }
 115
 116   // Opening the file locked it.  Unlock it now.
 117   this->input_file_->file().unlock(task);
 118 }
 119
 120 // Read the archive symbol map.
 121
 122 void
 123 Archive::read_armap(off_t start, section_size_type size)
 124 {
 125   // Read in the entire armap.
 126   const unsigned char* p = this->get_view(start, size, false);
 127
 128   // Numbers in the armap are always big-endian.
 129   const elfcpp::Elf_Word* pword = reinterpret_cast<const elfcpp::Elf_Word*>(p);
 130   unsigned int nsyms = elfcpp::Swap<32, true>::readval(pword);
 131   ++pword;
 132
 133   // Note that the addition is in units of sizeof(elfcpp::Elf_Word).
 134   const char* pnames = reinterpret_cast<const char*>(pword + nsyms);
 135   section_size_type names_size =
 136     reinterpret_cast<const char*>(p) + size - pnames;
 137   this->armap_names_.assign(pnames, names_size);
 138
 139   this->armap_.resize(nsyms);
 140
 141   section_offset_type name_offset = 0;
 142   for (unsigned int i = 0; i < nsyms; ++i)
 143     {
 144       this->armap_[i].name_offset = name_offset;
 145       this->armap_[i].file_offset = elfcpp::Swap<32, true>::readval(pword);
 146       name_offset += strlen(pnames + name_offset) + 1;
 147       ++pword;
 148     }
 149
 150   if (static_cast<section_size_type>(name_offset) > names_size)
 151     gold_error(_("%s: bad archive symbol table names"),
 152                this->name().c_str());
 153
 154   // This array keeps track of which symbols are for archive elements
 155   // which we have already included in the link.
 156   this->armap_checked_.resize(nsyms);
 157 }
 158
 159 // Read the header of an archive member at OFF.  Fail if something
 160 // goes wrong.  Return the size of the member.  Set *PNAME to the name
 161 // of the member.
 162
 163 off_t
 164 Archive::read_header(off_t off, bool cache, std::string* pname)
 165 {
 166   const unsigned char* p = this->get_view(off, sizeof(Archive_header), cache);
 167   const Archive_header* hdr = reinterpret_cast<const Archive_header*>(p);
 168   return this->interpret_header(hdr, off,  pname);
 169 }
 170
 171 // Interpret the header of HDR, the header of the archive member at
 172 // file offset OFF.  Fail if something goes wrong.  Return the size of
 173 // the member.  Set *PNAME to the name of the member.
 174
 175 off_t
 176 Archive::interpret_header(const Archive_header* hdr, off_t off,
 177                           std::string* pname)
 178 {
 179   if (memcmp(hdr->ar_fmag, arfmag, sizeof arfmag) != 0)
 180     {
 181       gold_error(_("%s: malformed archive header at %zu"),
 182                  this->name().c_str(), static_cast<size_t>(off));
 183       return this->input_file_->file().filesize() - off;
 184     }
 185
 186   const int size_string_size = sizeof hdr->ar_size;
 187   char size_string[size_string_size + 1];
 188   memcpy(size_string, hdr->ar_size, size_string_size);
 189   char* ps = size_string + size_string_size;
 190   while (ps[-1] == ' ')
 191     --ps;
 192   *ps = '\0';
 193
 194   errno = 0;
 195   char* end;
 196   off_t member_size = strtol(size_string, &end, 10);
 197   if (*end != '\0'
 198       || member_size < 0
 199       || (member_size == LONG_MAX && errno == ERANGE))
 200     {
 201       gold_error(_("%s: malformed archive header size at %zu"),
 202                  this->name().c_str(), static_cast<size_t>(off));
 203       return this->input_file_->file().filesize() - off;
 204     }
 205
 206   if (hdr->ar_name[0] != '/')
 207     {
 208       const char* name_end = strchr(hdr->ar_name, '/');
 209       if (name_end == NULL
 210           || name_end - hdr->ar_name >= static_cast<int>(sizeof hdr->ar_name))
 211         {
 212           gold_error(_("%s: malformed archive header name at %zu"),
 213                      this->name().c_str(), static_cast<size_t>(off));
 214           return this->input_file_->file().filesize() - off;
 215         }
 216       pname->assign(hdr->ar_name, name_end - hdr->ar_name);
 217     }
 218   else if (hdr->ar_name[1] == ' ')
 219     {
 220       // This is the symbol table.
 221       pname->clear();
 222     }
 223   else if (hdr->ar_name[1] == '/')
 224     {
 225       // This is the extended name table.
 226       pname->assign(1, '/');
 227     }
 228   else
 229     {
 230       errno = 0;
 231       long x = strtol(hdr->ar_name + 1, &end, 10);
 232       if (*end != ' '
 233           || x < 0
 234           || (x == LONG_MAX && errno == ERANGE)
 235           || static_cast<size_t>(x) >= this->extended_names_.size())
 236         {
 237           gold_error(_("%s: bad extended name index at %zu"),
 238                      this->name().c_str(), static_cast<size_t>(off));
 239           return this->input_file_->file().filesize() - off;
 240         }
 241
 242       const char* name = this->extended_names_.data() + x;
 243       const char* name_end = strchr(name, '/');
 244       if (static_cast<size_t>(name_end - name) > this->extended_names_.size()
 245           || name_end[1] != '\n')
 246         {
 247           gold_error(_("%s: bad extended name entry at header %zu"),
 248                      this->name().c_str(), static_cast<size_t>(off));
 249           return this->input_file_->file().filesize() - off;
 250         }
 251       pname->assign(name, name_end - name);
 252     }
 253
 254   return member_size;
 255 }
 256
 257 // Select members from the archive and add them to the link.  We walk
 258 // through the elements in the archive map, and look each one up in
 259 // the symbol table.  If it exists as a strong undefined symbol, we
 260 // pull in the corresponding element.  We have to do this in a loop,
 261 // since pulling in one element may create new undefined symbols which
 262 // may be satisfied by other objects in the archive.
 263
 264 void
 265 Archive::add_symbols(Symbol_table* symtab, Layout* layout,
 266                      Input_objects* input_objects)
 267 {
 268   if (this->input_file_->options().include_whole_archive())
 269     return this->include_all_members(symtab, layout, input_objects);
 270
 271   const size_t armap_size = this->armap_.size();
 272
 273   // This is a quick optimization, since we usually see many symbols
 274   // in a row with the same offset.  last_seen_offset holds the last
 275   // offset we saw that was present in the seen_offsets_ set.
 276   off_t last_seen_offset = -1;
 277
 278   // Track which symbols in the symbol table we've already found to be
 279   // defined.
 280
 281   bool added_new_object;
 282   do
 283     {
 284       added_new_object = false;
 285       for (size_t i = 0; i < armap_size; ++i)
 286         {
 287           if (this->armap_checked_[i])
 288             continue;
 289           if (this->armap_[i].file_offset == last_seen_offset)
 290             {
 291               this->armap_checked_[i] = true;
 292               continue;
 293             }
 294           if (this->seen_offsets_.find(this->armap_[i].file_offset)
 295               != this->seen_offsets_.end())
 296             {
 297               this->armap_checked_[i] = true;
 298               last_seen_offset = this->armap_[i].file_offset;
 299               continue;
 300             }
 301
 302           const char* sym_name = (this->armap_names_.data()
 303                                   + this->armap_[i].name_offset);
 304           Symbol* sym = symtab->lookup(sym_name);
 305           if (sym == NULL)
 306             continue;
 307           else if (!sym->is_undefined())
 308             {
 309               this->armap_checked_[i] = true;
 310               continue;
 311             }
 312           else if (sym->binding() == elfcpp::STB_WEAK)
 313             continue;
 314
 315           // We want to include this object in the link.
 316           last_seen_offset = this->armap_[i].file_offset;
 317           this->seen_offsets_.insert(last_seen_offset);
 318           this->armap_checked_[i] = true;
 319           this->include_member(symtab, layout, input_objects,
 320                                last_seen_offset);
 321           added_new_object = true;
 322         }
 323     }
 324   while (added_new_object);
 325 }
 326
 327 // Include all the archive members in the link.  This is for --whole-archive.
 328
 329 void
 330 Archive::include_all_members(Symbol_table* symtab, Layout* layout,
 331                              Input_objects* input_objects)
 332 {
 333   off_t off = sarmag;
 334   off_t filesize = this->input_file_->file().filesize();
 335   while (true)
 336     {
 337       if (filesize - off < static_cast<off_t>(sizeof(Archive_header)))
 338         {
 339           if (filesize != off)
 340             gold_error(_("%s: short archive header at %zu"),
 341                        this->name().c_str(), static_cast<size_t>(off));
 342           break;
 343         }
 344
 345       unsigned char hdr_buf[sizeof(Archive_header)];
 346       this->input_file_->file().read(off, sizeof(Archive_header), hdr_buf);
 347
 348       const Archive_header* hdr =
 349         reinterpret_cast<const Archive_header*>(hdr_buf);
 350       std::string name;
 351       off_t size = this->interpret_header(hdr, off, &name);
 352       if (name.empty())
 353         {
 354           // Symbol table.
 355         }
 356       else if (name == "/")
 357         {
 358           // Extended name table.
 359         }
 360       else
 361         this->include_member(symtab, layout, input_objects, off);
 362
 363       off += sizeof(Archive_header) + size;
 364       if ((off & 1) != 0)
 365         ++off;
 366     }
 367 }
 368
 369 // Include an archive member in the link.  OFF is the file offset of
 370 // the member header.
 371
 372 void
 373 Archive::include_member(Symbol_table* symtab, Layout* layout,
 374                         Input_objects* input_objects, off_t off)
 375 {
 376   std::string n;
 377   this->read_header(off, false, &n);
 378
 379   const off_t memoff = off + static_cast<off_t>(sizeof(Archive_header));
 380
 381   // Read enough of the file to pick up the entire ELF header.
 382   unsigned char ehdr_buf[elfcpp::Elf_sizes<64>::ehdr_size];
 383
 384   off_t filesize = this->input_file_->file().filesize();
 385   int read_size = elfcpp::Elf_sizes<64>::ehdr_size;
 386   if (filesize - memoff < read_size)
 387     read_size = filesize - memoff;
 388
 389   if (read_size < 4)
 390     {
 391       gold_error(_("%s: member at %zu is not an ELF object"),
 392                  this->name().c_str(), static_cast<size_t>(off));
 393       return;
 394     }
 395
 396   this->input_file_->file().read(memoff, read_size, ehdr_buf);
 397
 398   static unsigned char elfmagic[4] =
 399     {
 400       elfcpp::ELFMAG0, elfcpp::ELFMAG1,
 401       elfcpp::ELFMAG2, elfcpp::ELFMAG3
 402     };
 403   if (memcmp(ehdr_buf, elfmagic, 4) != 0)
 404     {
 405       gold_error(_("%s: member at %zu is not an ELF object"),
 406                  this->name().c_str(), static_cast<size_t>(off));
 407       return;
 408     }
 409
 410   Object* obj = make_elf_object((std::string(this->input_file_->filename())
 411                                  + "(" + n + ")"),
 412                                 this->input_file_, memoff, ehdr_buf,
 413                                 read_size);
 414
 415   if (input_objects->add_object(obj))
 416     {
 417       Read_symbols_data sd;
 418       obj->read_symbols(&sd);
 419       obj->layout(symtab, layout, &sd);
 420       obj->add_symbols(symtab, &sd);
 421     }
 422   else
 423     {
 424       // FIXME: We need to close the descriptor here.
 425       delete obj;
 426     }
 427
 428 }
 429
 430 // Add_archive_symbols methods.
 431
 432 Add_archive_symbols::~Add_archive_symbols()
 433 {
 434   if (this->this_blocker_ != NULL)
 435     delete this->this_blocker_;
 436   // next_blocker_ is deleted by the task associated with the next
 437   // input file.
 438 }
 439
 440 // Return whether we can add the archive symbols.  We are blocked by
 441 // this_blocker_.  We block next_blocker_.  We also lock the file.
 442
 443 Task_token*
 444 Add_archive_symbols::is_runnable()
 445 {
 446   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 447     return this->this_blocker_;
 448   return NULL;
 449 }
 450
 451 void
 452 Add_archive_symbols::locks(Task_locker* tl)
 453 {
 454   tl->add(this, this->next_blocker_);
 455   tl->add(this, this->archive_->token());
 456 }
 457
 458 void
 459 Add_archive_symbols::run(Workqueue*)
 460 {
 461   this->archive_->add_symbols(this->symtab_, this->layout_,
 462                               this->input_objects_);
 463
 464   this->archive_->release();
 465
 466   if (this->input_group_ != NULL)
 467     this->input_group_->add_archive(this->archive_);
 468   else
 469     {
 470       // We no longer need to know about this archive.
 471       delete this->archive_;
 472       this->archive_ = NULL;
 473     }
 474 }
 475
 476 } // End namespace gold.