gold/archive.cc

   1 // archive.cc -- archive support for gold
   2
   3 #include "gold.h"
   4
   5 #include <cerrno>
   6 #include <cstring>
   7 #include <climits>
   8 #include <vector>
   9
  10 #include "elfcpp.h"
  11 #include "options.h"
  12 #include "fileread.h"
  13 #include "readsyms.h"
  14 #include "symtab.h"
  15 #include "object.h"
  16 #include "archive.h"
  17
  18 namespace gold
  19 {
  20
  21 // The header of an entry in the archive.  This is all readable text,
  22 // padded with spaces where necesary.  If the contents of an archive
  23 // are all text file, the entire archive is readable.
  24
  25 struct Archive::Archive_header
  26 {
  27   // The entry name.
  28   char ar_name[16];
  29   // The file modification time.
  30   char ar_date[12];
  31   // The user's UID in decimal.
  32   char ar_uid[6];
  33   // The user's GID in decimal.
  34   char ar_gid[6];
  35   // The file mode in octal.
  36   char ar_mode[8];
  37   // The file size in decimal.
  38   char ar_size[10];
  39   // The final magic code.
  40   char ar_fmag[2];
  41 };
  42
  43 // Archive methods.
  44
  45 const char Archive::armag[sarmag] =
  46 {
  47   '!', '<', 'a', 'r', 'c', 'h', '>', '\n'
  48 };
  49
  50 const char Archive::arfmag[2] = { '`', '\n' };
  51
  52 // Set up the archive: read the symbol map and the extended name
  53 // table.
  54
  55 void
  56 Archive::setup()
  57 {
  58   // The first member of the archive should be the symbol table.
  59   std::string armap_name;
  60   off_t armap_size = this->read_header(sarmag, &armap_name);
  61   off_t off;
  62   if (armap_name.empty())
  63     {
  64       this->read_armap(sarmag + sizeof(Archive_header), armap_size);
  65       off = sarmag + sizeof(Archive_header) + armap_size;
  66     }
  67   else if (!this->input_file_->options().include_whole_archive())
  68     {
  69       fprintf(stderr, _("%s: %s: no archive symbol table (run ranlib)\n"),
  70               program_name, this->name().c_str());
  71       gold_exit(false);
  72     }
  73   else
  74     off = sarmag;
  75
  76   // See if there is an extended name table.
  77   if ((off & 1) != 0)
  78     ++off;
  79   std::string xname;
  80   off_t extended_size = this->read_header(off, &xname);
  81   if (xname == "/")
  82     {
  83       const unsigned char* p = this->get_view(off + sizeof(Archive_header),
  84                                               extended_size);
  85       const char* px = reinterpret_cast<const char*>(p);
  86       this->extended_names_.assign(px, extended_size);
  87     }
  88
  89   // Opening the file locked it.  Unlock it now.
  90   this->input_file_->file().unlock();
  91 }
  92
  93 // Read the archive symbol map.
  94
  95 void
  96 Archive::read_armap(off_t start, off_t size)
  97 {
  98   // Read in the entire armap.
  99   const unsigned char* p = this->get_view(start, size);
 100
 101   // Numbers in the armap are always big-endian.
 102   const elfcpp::Elf_Word* pword = reinterpret_cast<const elfcpp::Elf_Word*>(p);
 103   unsigned int nsyms = elfcpp::Swap<32, true>::readval(pword);
 104   ++pword;
 105
 106   // Note that the addition is in units of sizeof(elfcpp::Elf_Word).
 107   const char* pnames = reinterpret_cast<const char*>(pword + nsyms);
 108
 109   this->armap_.resize(nsyms);
 110
 111   for (unsigned int i = 0; i < nsyms; ++i)
 112     {
 113       this->armap_[i].name = pnames;
 114       this->armap_[i].offset = elfcpp::Swap<32, true>::readval(pword);
 115       pnames += strlen(pnames) + 1;
 116       ++pword;
 117     }
 118
 119   if (reinterpret_cast<const unsigned char*>(pnames) - p > size)
 120     {
 121       fprintf(stderr, _("%s: %s: bad archive symbol table names\n"),
 122               program_name, this->name().c_str());
 123       gold_exit(false);
 124     }
 125
 126   // This array keeps track of which symbols are for archive elements
 127   // which we have already included in the link.
 128   this->armap_checked_.resize(nsyms);
 129 }
 130
 131 // Read the header of an archive member at OFF.  Fail if something
 132 // goes wrong.  Return the size of the member.  Set *PNAME to the name
 133 // of the member.
 134
 135 off_t
 136 Archive::read_header(off_t off, std::string* pname)
 137 {
 138   const unsigned char* p = this->get_view(off, sizeof(Archive_header));
 139   const Archive_header* hdr = reinterpret_cast<const Archive_header*>(p);
 140   return this->interpret_header(hdr, off,  pname);
 141 }
 142
 143 // Interpret the header of HDR, the header of the archive member at
 144 // file offset OFF.  Fail if something goes wrong.  Return the size of
 145 // the member.  Set *PNAME to the name of the member.
 146
 147 off_t
 148 Archive::interpret_header(const Archive_header* hdr, off_t off,
 149                           std::string* pname)
 150 {
 151   if (memcmp(hdr->ar_fmag, arfmag, sizeof arfmag) != 0)
 152     {
 153       fprintf(stderr, _("%s; %s: malformed archive header at %ld\n"),
 154               program_name, this->name().c_str(),
 155               static_cast<long>(off));
 156       gold_exit(false);
 157     }
 158
 159   const int size_string_size = sizeof hdr->ar_size;
 160   char size_string[size_string_size + 1];
 161   memcpy(size_string, hdr->ar_size, size_string_size);
 162   char* ps = size_string + size_string_size;
 163   while (ps[-1] == ' ')
 164     --ps;
 165   *ps = '\0';
 166
 167   errno = 0;
 168   char* end;
 169   off_t member_size = strtol(size_string, &end, 10);
 170   if (*end != '\0'
 171       || member_size < 0
 172       || (member_size == LONG_MAX && errno == ERANGE))
 173     {
 174       fprintf(stderr, _("%s: %s: malformed archive header size at %ld\n"),
 175               program_name, this->name().c_str(),
 176               static_cast<long>(off));
 177       gold_exit(false);
 178     }
 179
 180   if (hdr->ar_name[0] != '/')
 181     {
 182       const char* name_end = strchr(hdr->ar_name, '/');
 183       if (name_end == NULL
 184           || name_end - hdr->ar_name >= static_cast<int>(sizeof hdr->ar_name))
 185         {
 186           fprintf(stderr, _("%s: %s: malformed archive header name at %ld\n"),
 187                   program_name, this->name().c_str(),
 188                   static_cast<long>(off));
 189           gold_exit(false);
 190         }
 191       pname->assign(hdr->ar_name, name_end - hdr->ar_name);
 192     }
 193   else if (hdr->ar_name[1] == ' ')
 194     {
 195       // This is the symbol table.
 196       pname->clear();
 197     }
 198   else if (hdr->ar_name[1] == '/')
 199     {
 200       // This is the extended name table.
 201       pname->assign(1, '/');
 202     }
 203   else
 204     {
 205       errno = 0;
 206       long x = strtol(hdr->ar_name + 1, &end, 10);
 207       if (*end != ' '
 208           || x < 0
 209           || (x == LONG_MAX && errno == ERANGE)
 210           || static_cast<size_t>(x) >= this->extended_names_.size())
 211         {
 212           fprintf(stderr, _("%s: %s: bad extended name index at %ld\n"),
 213                   program_name, this->name().c_str(),
 214                   static_cast<long>(off));
 215           gold_exit(false);
 216         }
 217
 218       const char* name = this->extended_names_.data() + x;
 219       const char* name_end = strchr(name, '/');
 220       if (static_cast<size_t>(name_end - name) > this->extended_names_.size()
 221           || name_end[1] != '\n')
 222         {
 223           fprintf(stderr, _("%s: %s: bad extended name entry at header %ld\n"),
 224                   program_name, this->name().c_str(),
 225                   static_cast<long>(off));
 226           gold_exit(false);
 227         }
 228       pname->assign(name, name_end - name);
 229     }
 230
 231   return member_size;
 232 }
 233
 234 // Select members from the archive and add them to the link.  We walk
 235 // through the elements in the archive map, and look each one up in
 236 // the symbol table.  If it exists as a strong undefined symbol, we
 237 // pull in the corresponding element.  We have to do this in a loop,
 238 // since pulling in one element may create new undefined symbols which
 239 // may be satisfied by other objects in the archive.
 240
 241 void
 242 Archive::add_symbols(Symbol_table* symtab, Layout* layout,
 243                      Input_objects* input_objects)
 244 {
 245   if (this->input_file_->options().include_whole_archive())
 246     return this->include_all_members(symtab, layout, input_objects);
 247
 248   const size_t armap_size = this->armap_.size();
 249
 250   // This is a quick optimization, since we usually see many symbols
 251   // in a row with the same offset.  last_seen_offset holds the last
 252   // offset we saw that was present in the seen_offsets_ set.
 253   off_t last_seen_offset = -1;
 254
 255   // Track which symbols in the symbol table we've already found to be
 256   // defined.
 257
 258   bool added_new_object;
 259   do
 260     {
 261       added_new_object = false;
 262       for (size_t i = 0; i < armap_size; ++i)
 263         {
 264           if (this->armap_checked_[i])
 265             continue;
 266           if (this->armap_[i].offset == last_seen_offset)
 267             {
 268               this->armap_checked_[i] = true;
 269               continue;
 270             }
 271           if (this->seen_offsets_.find(this->armap_[i].offset)
 272               != this->seen_offsets_.end())
 273             {
 274               this->armap_checked_[i] = true;
 275               last_seen_offset = this->armap_[i].offset;
 276               continue;
 277             }
 278
 279           Symbol* sym = symtab->lookup(this->armap_[i].name);
 280           if (sym == NULL)
 281             continue;
 282           else if (!sym->is_undefined())
 283             {
 284               this->armap_checked_[i] = true;
 285               continue;
 286             }
 287           else if (sym->binding() == elfcpp::STB_WEAK)
 288             continue;
 289
 290           // We want to include this object in the link.
 291           last_seen_offset = this->armap_[i].offset;
 292           this->seen_offsets_.insert(last_seen_offset);
 293           this->armap_checked_[i] = true;
 294           this->include_member(symtab, layout, input_objects,
 295                                last_seen_offset);
 296           added_new_object = true;
 297         }
 298     }
 299   while (added_new_object);
 300 }
 301
 302 // Include all the archive members in the link.  This is for --whole-archive.
 303
 304 void
 305 Archive::include_all_members(Symbol_table* symtab, Layout* layout,
 306                              Input_objects* input_objects)
 307 {
 308   off_t off = sarmag;
 309   while (true)
 310     {
 311       off_t bytes;
 312       const unsigned char* p = this->get_view(off, sizeof(Archive_header),
 313                                               &bytes);
 314       if (bytes < sizeof(Archive_header))
 315         {
 316           if (bytes != 0)
 317             {
 318               fprintf(stderr, _("%s: %s: short archive header at %ld\n"),
 319                       program_name, this->name().c_str(),
 320                       static_cast<long>(off));
 321               gold_exit(false);
 322             }
 323
 324           break;
 325         }
 326
 327       const Archive_header* hdr = reinterpret_cast<const Archive_header*>(p);
 328       std::string name;
 329       off_t size = this->interpret_header(hdr, off, &name);
 330       if (name.empty())
 331         {
 332           // Symbol table.
 333         }
 334       else if (name == "/")
 335         {
 336           // Extended name table.
 337         }
 338       else
 339         this->include_member(symtab, layout, input_objects, off);
 340
 341       off += sizeof(Archive_header) + size;
 342       if ((off & 1) != 0)
 343         ++off;
 344     }
 345 }
 346
 347 // Include an archive member in the link.  OFF is the file offset of
 348 // the member header.
 349
 350 void
 351 Archive::include_member(Symbol_table* symtab, Layout* layout,
 352                         Input_objects* input_objects, off_t off)
 353 {
 354   std::string n;
 355   this->read_header(off, &n);
 356
 357   size_t memoff = off + sizeof(Archive_header);
 358
 359   // Read enough of the file to pick up the entire ELF header.
 360   int ehdr_size = elfcpp::Elf_sizes<64>::ehdr_size;
 361   off_t bytes;
 362   const unsigned char* p = this->input_file_->file().get_view(memoff,
 363                                                               ehdr_size,
 364                                                               &bytes);
 365   if (bytes < 4)
 366     {
 367       fprintf(stderr, _("%s: %s: member at %ld is not an ELF object"),
 368               program_name, this->name().c_str(),
 369               static_cast<long>(off));
 370       gold_exit(false);
 371     }
 372
 373   static unsigned char elfmagic[4] =
 374     {
 375       elfcpp::ELFMAG0, elfcpp::ELFMAG1,
 376       elfcpp::ELFMAG2, elfcpp::ELFMAG3
 377     };
 378   if (memcmp(p, elfmagic, 4) != 0)
 379     {
 380       fprintf(stderr, _("%s: %s: member at %ld is not an ELF object"),
 381               program_name, this->name().c_str(),
 382               static_cast<long>(off));
 383       gold_exit(false);
 384     }
 385
 386   Object* obj = make_elf_object((std::string(this->input_file_->filename())
 387                                  + "(" + n + ")"),
 388                                 this->input_file_, memoff, p, bytes);
 389
 390   input_objects->add_object(obj);
 391
 392   Read_symbols_data sd;
 393   obj->read_symbols(&sd);
 394   obj->layout(symtab, layout, &sd);
 395   obj->add_symbols(symtab, &sd);
 396 }
 397
 398 // Add_archive_symbols methods.
 399
 400 Add_archive_symbols::~Add_archive_symbols()
 401 {
 402   if (this->this_blocker_ != NULL)
 403     delete this->this_blocker_;
 404   // next_blocker_ is deleted by the task associated with the next
 405   // input file.
 406 }
 407
 408 // Return whether we can add the archive symbols.  We are blocked by
 409 // this_blocker_.  We block next_blocker_.  We also lock the file.
 410
 411 Task::Is_runnable_type
 412 Add_archive_symbols::is_runnable(Workqueue*)
 413 {
 414   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 415     return IS_BLOCKED;
 416   return IS_RUNNABLE;
 417 }
 418
 419 class Add_archive_symbols::Add_archive_symbols_locker : public Task_locker
 420 {
 421  public:
 422   Add_archive_symbols_locker(Task_token& token, Workqueue* workqueue,
 423                              File_read& file)
 424     : blocker_(token, workqueue), filelock_(file)
 425   { }
 426
 427  private:
 428   Task_locker_block blocker_;
 429   Task_locker_obj<File_read> filelock_;
 430 };
 431
 432 Task_locker*
 433 Add_archive_symbols::locks(Workqueue* workqueue)
 434 {
 435   return new Add_archive_symbols_locker(*this->next_blocker_,
 436                                         workqueue,
 437                                         this->archive_->file());
 438 }
 439
 440 void
 441 Add_archive_symbols::run(Workqueue*)
 442 {
 443   this->archive_->add_symbols(this->symtab_, this->layout_,
 444                               this->input_objects_);
 445
 446   if (this->input_group_ != NULL)
 447     this->input_group_->add_archive(this->archive_);
 448   else
 449     {
 450       // We no longer need to know about this archive.
 451       delete this->archive_;
 452     }
 453 }
 454
 455 } // End namespace gold.