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   // This array keeps track of which symbols are for archive elements
 126   // which we have already included in the link.
 127   this->armap_checked_.resize(nsyms);
 128 }
 129
 130 // Read the header of an archive member at OFF.  Fail if something
 131 // goes wrong.  Return the size of the member.  Set *PNAME to the name
 132 // of the member.
 133
 134 off_t
 135 Archive::read_header(off_t off, std::string* pname)
 136 {
 137   const unsigned char* p = this->get_view(off, sizeof(Archive_header));
 138   const Archive_header* hdr = reinterpret_cast<const Archive_header*>(p);
 139   return this->interpret_header(hdr, off,  pname);
 140 }
 141
 142 // Interpret the header of HDR, the header of the archive member at
 143 // file offset OFF.  Fail if something goes wrong.  Return the size of
 144 // the member.  Set *PNAME to the name of the member.
 145
 146 off_t
 147 Archive::interpret_header(const Archive_header* hdr, off_t off,
 148                           std::string* pname)
 149 {
 150   if (memcmp(hdr->ar_fmag, arfmag, sizeof arfmag) != 0)
 151     {
 152       fprintf(stderr, _("%s; %s: malformed archive header at %ld\n"),
 153               program_name, this->name().c_str(),
 154               static_cast<long>(off));
 155       gold_exit(false);
 156     }
 157
 158   const int size_string_size = sizeof hdr->ar_size;
 159   char size_string[size_string_size + 1];
 160   memcpy(size_string, hdr->ar_size, size_string_size);
 161   char* ps = size_string + size_string_size;
 162   while (ps[-1] == ' ')
 163     --ps;
 164   *ps = '\0';
 165
 166   errno = 0;
 167   char* end;
 168   off_t member_size = strtol(size_string, &end, 10);
 169   if (*end != '\0'
 170       || member_size < 0
 171       || (member_size == LONG_MAX && errno == ERANGE))
 172     {
 173       fprintf(stderr, _("%s: %s: malformed archive header size at %ld\n"),
 174               program_name, this->name().c_str(),
 175               static_cast<long>(off));
 176       gold_exit(false);
 177     }
 178
 179   if (hdr->ar_name[0] != '/')
 180     {
 181       const char* name_end = strchr(hdr->ar_name, '/');
 182       if (name_end == NULL
 183           || name_end - hdr->ar_name >= static_cast<int>(sizeof hdr->ar_name))
 184         {
 185           fprintf(stderr, _("%s: %s: malformed archive header name at %ld\n"),
 186                   program_name, this->name().c_str(),
 187                   static_cast<long>(off));
 188           gold_exit(false);
 189         }
 190       pname->assign(hdr->ar_name, name_end - hdr->ar_name);
 191     }
 192   else if (hdr->ar_name[1] == ' ')
 193     {
 194       // This is the symbol table.
 195       pname->clear();
 196     }
 197   else if (hdr->ar_name[1] == '/')
 198     {
 199       // This is the extended name table.
 200       pname->assign(1, '/');
 201     }
 202   else
 203     {
 204       errno = 0;
 205       long x = strtol(hdr->ar_name + 1, &end, 10);
 206       if (*end != ' '
 207           || x < 0
 208           || (x == LONG_MAX && errno == ERANGE)
 209           || static_cast<size_t>(x) >= this->extended_names_.size())
 210         {
 211           fprintf(stderr, _("%s: %s: bad extended name index at %ld\n"),
 212                   program_name, this->name().c_str(),
 213                   static_cast<long>(off));
 214           gold_exit(false);
 215         }
 216
 217       const char* name = this->extended_names_.data() + x;
 218       const char* name_end = strchr(name, '/');
 219       if (static_cast<size_t>(name_end - name) > this->extended_names_.size()
 220           || name_end[1] != '\n')
 221         {
 222           fprintf(stderr, _("%s: %s: bad extended name entry at header %ld\n"),
 223                   program_name, this->name().c_str(),
 224                   static_cast<long>(off));
 225           gold_exit(false);
 226         }
 227       pname->assign(name, name_end - name);
 228     }
 229
 230   return member_size;
 231 }
 232
 233 // Select members from the archive and add them to the link.  We walk
 234 // through the elements in the archive map, and look each one up in
 235 // the symbol table.  If it exists as a strong undefined symbol, we
 236 // pull in the corresponding element.  We have to do this in a loop,
 237 // since pulling in one element may create new undefined symbols which
 238 // may be satisfied by other objects in the archive.
 239
 240 void
 241 Archive::add_symbols(const General_options& options, Symbol_table* symtab,
 242                      Layout* layout, Input_objects* input_objects)
 243 {
 244   if (this->input_file_->options().include_whole_archive())
 245     return this->include_all_members(options, symtab, layout, input_objects);
 246
 247   const size_t armap_size = this->armap_.size();
 248
 249   // This is a quick optimization, since we usually see many symbols
 250   // in a row with the same offset.  last_seen_offset holds the last
 251   // offset we saw that was present in the seen_offsets_ set.
 252   off_t last_seen_offset = -1;
 253
 254   // Track which symbols in the symbol table we've already found to be
 255   // defined.
 256
 257   bool added_new_object;
 258   do
 259     {
 260       added_new_object = false;
 261       for (size_t i = 0; i < armap_size; ++i)
 262         {
 263           if (this->armap_checked_[i])
 264             continue;
 265           if (this->armap_[i].offset == last_seen_offset)
 266             {
 267               this->armap_checked_[i] = true;
 268               continue;
 269             }
 270           if (this->seen_offsets_.find(this->armap_[i].offset)
 271               != this->seen_offsets_.end())
 272             {
 273               this->armap_checked_[i] = true;
 274               last_seen_offset = this->armap_[i].offset;
 275               continue;
 276             }
 277
 278           Symbol* sym = symtab->lookup(this->armap_[i].name);
 279           if (sym == NULL)
 280             continue;
 281           else if (!sym->is_undefined())
 282             {
 283               this->armap_checked_[i] = true;
 284               continue;
 285             }
 286           else if (sym->binding() == elfcpp::STB_WEAK)
 287             continue;
 288
 289           // We want to include this object in the link.
 290           last_seen_offset = this->armap_[i].offset;
 291           this->seen_offsets_.insert(last_seen_offset);
 292           this->armap_checked_[i] = true;
 293           this->include_member(options, symtab, layout, input_objects,
 294                                last_seen_offset);
 295           added_new_object = true;
 296         }
 297     }
 298   while (added_new_object);
 299 }
 300
 301 // Include all the archive members in the link.  This is for --whole-archive.
 302
 303 void
 304 Archive::include_all_members(const General_options& options,
 305                              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(options, 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(const General_options& options, Symbol_table* symtab,
 352                         Layout* layout, Input_objects* input_objects,
 353                         off_t off)
 354 {
 355   std::string n;
 356   this->read_header(off, &n);
 357
 358   size_t memoff = off + sizeof(Archive_header);
 359
 360   // Read enough of the file to pick up the entire ELF header.
 361   int ehdr_size = elfcpp::Elf_sizes<64>::ehdr_size;
 362   off_t bytes;
 363   const unsigned char* p = this->input_file_->file().get_view(memoff,
 364                                                               ehdr_size,
 365                                                               &bytes);
 366   if (bytes < 4)
 367     {
 368       fprintf(stderr, _("%s: %s: member at %ld is not an ELF object"),
 369               program_name, this->name().c_str(),
 370               static_cast<long>(off));
 371       gold_exit(false);
 372     }
 373
 374   static unsigned char elfmagic[4] =
 375     {
 376       elfcpp::ELFMAG0, elfcpp::ELFMAG1,
 377       elfcpp::ELFMAG2, elfcpp::ELFMAG3
 378     };
 379   if (memcmp(p, elfmagic, 4) != 0)
 380     {
 381       fprintf(stderr, _("%s: %s: member at %ld is not an ELF object"),
 382               program_name, this->name().c_str(),
 383               static_cast<long>(off));
 384       gold_exit(false);
 385     }
 386
 387   Object* obj = make_elf_object((std::string(this->input_file_->filename())
 388                                  + "(" + n + ")"),
 389                                 this->input_file_, memoff, p, bytes);
 390
 391   input_objects->add_object(obj);
 392
 393   Read_symbols_data sd;
 394   obj->read_symbols(&sd);
 395   obj->layout(options, symtab, layout, &sd);
 396   obj->add_symbols(symtab, &sd);
 397 }
 398
 399 // Add_archive_symbols methods.
 400
 401 Add_archive_symbols::~Add_archive_symbols()
 402 {
 403   if (this->this_blocker_ != NULL)
 404     delete this->this_blocker_;
 405   // next_blocker_ is deleted by the task associated with the next
 406   // input file.
 407 }
 408
 409 // Return whether we can add the archive symbols.  We are blocked by
 410 // this_blocker_.  We block next_blocker_.  We also lock the file.
 411
 412 Task::Is_runnable_type
 413 Add_archive_symbols::is_runnable(Workqueue*)
 414 {
 415   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 416     return IS_BLOCKED;
 417   return IS_RUNNABLE;
 418 }
 419
 420 class Add_archive_symbols::Add_archive_symbols_locker : public Task_locker
 421 {
 422  public:
 423   Add_archive_symbols_locker(Task_token& token, Workqueue* workqueue,
 424                              File_read& file)
 425     : blocker_(token, workqueue), filelock_(file)
 426   { }
 427
 428  private:
 429   Task_locker_block blocker_;
 430   Task_locker_obj<File_read> filelock_;
 431 };
 432
 433 Task_locker*
 434 Add_archive_symbols::locks(Workqueue* workqueue)
 435 {
 436   return new Add_archive_symbols_locker(*this->next_blocker_,
 437                                         workqueue,
 438                                         this->archive_->file());
 439 }
 440
 441 void
 442 Add_archive_symbols::run(Workqueue*)
 443 {
 444   this->archive_->add_symbols(this->options_, this->symtab_, this->layout_,
 445                               this->input_objects_);
 446
 447   if (this->input_group_ != NULL)
 448     this->input_group_->add_archive(this->archive_);
 449   else
 450     {
 451       // We no longer need to know about this archive.
 452       delete this->archive_;
 453     }
 454 }
 455
 456 } // End namespace gold.