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