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