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