gold/fileread.cc

   1 // fileread.cc -- read files 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 <cstring>
  26 #include <cerrno>
  27 #include <fcntl.h>
  28 #include <unistd.h>
  29 #include <sys/mman.h>
  30 #include "filenames.h"
  31
  32 #include "options.h"
  33 #include "dirsearch.h"
  34 #include "fileread.h"
  35
  36 namespace gold
  37 {
  38
  39 // Class File_read::View.
  40
  41 File_read::View::~View()
  42 {
  43   gold_assert(!this->is_locked());
  44   if (!this->mapped_)
  45     delete[] this->data_;
  46   else
  47     {
  48       if (::munmap(const_cast<unsigned char*>(this->data_), this->size_) != 0)
  49         fprintf(stderr, _("%s: munmap failed: %s\n"),
  50                 program_name, strerror(errno));
  51     }
  52 }
  53
  54 void
  55 File_read::View::lock()
  56 {
  57   ++this->lock_count_;
  58 }
  59
  60 void
  61 File_read::View::unlock()
  62 {
  63   gold_assert(this->lock_count_ > 0);
  64   --this->lock_count_;
  65 }
  66
  67 bool
  68 File_read::View::is_locked()
  69 {
  70   return this->lock_count_ > 0;
  71 }
  72
  73 // Class File_read.
  74
  75 // The File_read class is designed to support file descriptor caching,
  76 // but this is not currently implemented.
  77
  78 File_read::~File_read()
  79 {
  80   gold_assert(this->lock_count_ == 0);
  81   if (this->descriptor_ >= 0)
  82     {
  83       if (close(this->descriptor_) < 0)
  84         fprintf(stderr, _("%s: warning: close(%s) failed: %s"),
  85                 program_name, this->name_.c_str(), strerror(errno));
  86       this->descriptor_ = -1;
  87     }
  88   this->name_.clear();
  89   this->clear_views(true);
  90 }
  91
  92 // Open the file.
  93
  94 bool
  95 File_read::open(const std::string& name)
  96 {
  97   gold_assert(this->lock_count_ == 0
  98               && this->descriptor_ < 0
  99               && this->name_.empty());
 100   this->name_ = name;
 101
 102   this->descriptor_ = ::open(this->name_.c_str(), O_RDONLY);
 103
 104   if (this->descriptor_ >= 0)
 105     {
 106       struct stat s;
 107       if (::fstat(this->descriptor_, &s) < 0)
 108         {
 109           fprintf(stderr, _("%s: %s: fstat failed: %s"), program_name,
 110                   this->name_.c_str(), strerror(errno));
 111           gold_exit(false);
 112         }
 113       this->size_ = s.st_size;
 114     }
 115
 116   ++this->lock_count_;
 117
 118   return this->descriptor_ >= 0;
 119 }
 120
 121 // Open the file for testing purposes.
 122
 123 bool
 124 File_read::open(const std::string& name, const unsigned char* contents,
 125                 off_t size)
 126 {
 127   gold_assert(this->lock_count_ == 0
 128               && this->descriptor_ < 0
 129               && this->name_.empty());
 130   this->name_ = name;
 131   this->contents_ = contents;
 132   this->size_ = size;
 133   ++this->lock_count_;
 134   return true;
 135 }
 136
 137 void
 138 File_read::lock()
 139 {
 140   ++this->lock_count_;
 141 }
 142
 143 void
 144 File_read::unlock()
 145 {
 146   gold_assert(this->lock_count_ > 0);
 147   --this->lock_count_;
 148   if (this->lock_count_ == 0)
 149     this->clear_views(false);
 150 }
 151
 152 bool
 153 File_read::is_locked()
 154 {
 155   return this->lock_count_ > 0;
 156 }
 157
 158 // See if we have a view which covers the file starting at START for
 159 // SIZE bytes.  Return a pointer to the View if found, NULL if not.
 160
 161 inline File_read::View*
 162 File_read::find_view(off_t start, off_t size)
 163 {
 164   off_t page = File_read::page_offset(start);
 165   Views::iterator p = this->views_.find(page);
 166   if (p == this->views_.end())
 167     return NULL;
 168   if (p->second->size() - (start - page) < size)
 169     return NULL;
 170   return p->second;
 171 }
 172
 173 // Read SIZE bytes from the file starting at offset START.  Read into
 174 // the buffer at P.
 175
 176 void
 177 File_read::do_read(off_t start, off_t size, void* p)
 178 {
 179   gold_assert(this->lock_count_ > 0);
 180
 181   off_t bytes;
 182   if (this->contents_ != NULL)
 183     {
 184       bytes = this->size_ - start;
 185       if (bytes >= size)
 186         {
 187           memcpy(p, this->contents_ + start, size);
 188           return;
 189         }
 190     }
 191   else
 192     {
 193       bytes = ::pread(this->descriptor_, p, size, start);
 194       if (bytes == size)
 195         return;
 196
 197       if (bytes < 0)
 198         {
 199           fprintf(stderr, _("%s: %s: pread failed: %s\n"),
 200                   program_name, this->filename().c_str(), strerror(errno));
 201           gold_exit(false);
 202         }
 203     }
 204
 205   fprintf(stderr,
 206           _("%s: %s: file too short: read only %lld of %lld bytes at %lld\n"),
 207           program_name, this->filename().c_str(),
 208           static_cast<long long>(bytes),
 209           static_cast<long long>(size),
 210           static_cast<long long>(start));
 211   gold_exit(false);
 212 }
 213
 214 // Read data from the file.
 215
 216 void
 217 File_read::read(off_t start, off_t size, void* p)
 218 {
 219   gold_assert(this->lock_count_ > 0);
 220
 221   File_read::View* pv = this->find_view(start, size);
 222   if (pv != NULL)
 223     {
 224       memcpy(p, pv->data() + (start - pv->start()), size);
 225       return;
 226     }
 227
 228   this->do_read(start, size, p);
 229 }
 230
 231 // Find an existing view or make a new one.
 232
 233 File_read::View*
 234 File_read::find_or_make_view(off_t start, off_t size, bool cache)
 235 {
 236   gold_assert(this->lock_count_ > 0);
 237
 238   off_t poff = File_read::page_offset(start);
 239
 240   File_read::View* const vnull = NULL;
 241   std::pair<Views::iterator, bool> ins =
 242     this->views_.insert(std::make_pair(poff, vnull));
 243
 244   if (!ins.second)
 245     {
 246       // There was an existing view at this offset.
 247       File_read::View* v = ins.first->second;
 248       if (v->size() - (start - v->start()) >= size)
 249         {
 250           if (cache)
 251             v->set_cache();
 252           return v;
 253         }
 254
 255       // This view is not large enough.
 256       this->saved_views_.push_back(v);
 257     }
 258
 259   // We need to read data from the file.  We read full pages for
 260   // greater efficiency on small files.
 261
 262   off_t psize = File_read::pages(size + (start - poff));
 263
 264   if (poff + psize >= this->size_)
 265     {
 266       psize = this->size_ - poff;
 267       gold_assert(psize >= size);
 268     }
 269
 270   File_read::View* v;
 271
 272   if (this->contents_ != NULL)
 273     {
 274       unsigned char* p = new unsigned char[psize];
 275       this->do_read(poff, psize, p);
 276       v = new File_read::View(poff, psize, p, cache, false);
 277     }
 278   else
 279     {
 280       void* p = ::mmap(NULL, psize, PROT_READ, MAP_SHARED,
 281                        this->descriptor_, poff);
 282       if (p == MAP_FAILED)
 283         {
 284           fprintf(stderr, _("%s: %s: mmap offset %lld size %lld failed: %s\n"),
 285                   program_name, this->filename().c_str(),
 286                   static_cast<long long>(poff),
 287                   static_cast<long long>(psize),
 288                   strerror(errno));
 289           gold_exit(false);
 290         }
 291
 292       const unsigned char* pbytes = static_cast<const unsigned char*>(p);
 293       v = new File_read::View(poff, psize, pbytes, cache, true);
 294     }
 295
 296   ins.first->second = v;
 297   return v;
 298 }
 299
 300 // This implementation of get_view just reads into a memory buffer,
 301 // which we store on view_list_.  At some point we should support
 302 // mmap.
 303
 304 const unsigned char*
 305 File_read::get_view(off_t start, off_t size, bool cache)
 306 {
 307   gold_assert(this->lock_count_ > 0);
 308   File_read::View* pv = this->find_or_make_view(start, size, cache);
 309   return pv->data() + (start - pv->start());
 310 }
 311
 312 File_view*
 313 File_read::get_lasting_view(off_t start, off_t size, bool cache)
 314 {
 315   gold_assert(this->lock_count_ > 0);
 316   File_read::View* pv = this->find_or_make_view(start, size, cache);
 317   pv->lock();
 318   return new File_view(*this, pv, pv->data() + (start - pv->start()));
 319 }
 320
 321 // Remove all the file views.
 322
 323 void
 324 File_read::clear_views(bool destroying)
 325 {
 326   for (Views::iterator p = this->views_.begin();
 327        p != this->views_.end();
 328        ++p)
 329     {
 330       if (!p->second->is_locked()
 331           && (destroying || !p->second->should_cache()))
 332         delete p->second;
 333       else
 334         {
 335           gold_assert(!destroying);
 336           this->saved_views_.push_back(p->second);
 337         }
 338     }
 339   this->views_.clear();
 340
 341   Saved_views::iterator p = this->saved_views_.begin();
 342   while (p != this->saved_views_.end())
 343     {
 344       if (!(*p)->is_locked()
 345           && (destroying || !(*p)->should_cache()))
 346         {
 347           delete *p;
 348           p = this->saved_views_.erase(p);
 349         }
 350       else
 351         {
 352           gold_assert(!destroying);
 353           ++p;
 354         }
 355     }
 356 }
 357
 358 // Class File_view.
 359
 360 File_view::~File_view()
 361 {
 362   gold_assert(this->file_.is_locked());
 363   this->view_->unlock();
 364 }
 365
 366 // Class Input_file.
 367
 368 // Create a file for testing.
 369
 370 Input_file::Input_file(const char* name, const unsigned char* contents,
 371                        off_t size)
 372   : file_()
 373 {
 374   this->input_argument_ =
 375     new Input_file_argument(name, false, "", Position_dependent_options());
 376   bool ok = file_.open(name, contents, size);
 377   gold_assert(ok);
 378 }
 379
 380 // Open the file.
 381
 382 // If the filename is not absolute, we assume it is in the current
 383 // directory *except* when:
 384 //    A) input_argument_->is_lib() is true; or
 385 //    B) input_argument_->extra_search_path() is not empty.
 386 // In both cases, we look in extra_search_path + library_path to find
 387 // the file location, rather than the current directory.
 388
 389 void
 390 Input_file::open(const General_options& options, const Dirsearch& dirpath)
 391 {
 392   std::string name;
 393
 394   // Case 1: name is an absolute file, just try to open it
 395   // Case 2: name is relative but is_lib is false and extra_search_path
 396   //         is empty
 397   if (IS_ABSOLUTE_PATH (this->input_argument_->name())
 398       || (!this->input_argument_->is_lib()
 399           && this->input_argument_->extra_search_path() == NULL))
 400     {
 401       name = this->input_argument_->name();
 402       this->found_name_ = name;
 403     }
 404   // Case 3: is_lib is true
 405   else if (this->input_argument_->is_lib())
 406     {
 407       // We don't yet support extra_search_path with -l.
 408       gold_assert(this->input_argument_->extra_search_path() == NULL);
 409       std::string n1("lib");
 410       n1 += this->input_argument_->name();
 411       std::string n2;
 412       if (options.is_static())
 413         n1 += ".a";
 414       else
 415         {
 416           n2 = n1 + ".a";
 417           n1 += ".so";
 418         }
 419       name = dirpath.find(n1, n2, &this->is_in_sysroot_);
 420       if (name.empty())
 421         {
 422           fprintf(stderr, _("%s: cannot find -l%s\n"), program_name,
 423                   this->input_argument_->name());
 424           gold_exit(false);
 425         }
 426       if (n2.empty() || name[name.length() - 1] == 'o')
 427         this->found_name_ = n1;
 428       else
 429         this->found_name_ = n2;
 430     }
 431   // Case 4: extra_search_path is not empty
 432   else
 433     {
 434       gold_assert(this->input_argument_->extra_search_path() != NULL);
 435
 436       // First, check extra_search_path.
 437       name = this->input_argument_->extra_search_path();
 438       if (!IS_DIR_SEPARATOR (name[name.length() - 1]))
 439         name += '/';
 440       name += this->input_argument_->name();
 441       struct stat dummy_stat;
 442       if (::stat(name.c_str(), &dummy_stat) < 0)
 443         {
 444           // extra_search_path failed, so check the normal search-path.
 445           name = dirpath.find(this->input_argument_->name(), "",
 446                               &this->is_in_sysroot_);
 447           if (name.empty())
 448             {
 449               fprintf(stderr, _("%s: cannot find %s\n"), program_name,
 450                       this->input_argument_->name());
 451               gold_exit(false);
 452             }
 453         }
 454       this->found_name_ = this->input_argument_->name();
 455     }
 456
 457   // Now that we've figured out where the file lives, try to open it.
 458   if (!this->file_.open(name))
 459     {
 460       fprintf(stderr, _("%s: cannot open %s: %s\n"), program_name,
 461               name.c_str(), strerror(errno));
 462       gold_exit(false);
 463     }
 464 }
 465
 466 } // End namespace gold.