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 }
 140
 141 bool
 142 File_read::is_locked()
 143 {
 144   return this->lock_count_ > 0;
 145 }
 146
 147 // See if we have a view which covers the file starting at START for
 148 // SIZE bytes.  Return a pointer to the View if found, NULL if not.
 149
 150 inline File_read::View*
 151 File_read::find_view(off_t start, off_t size)
 152 {
 153   off_t page = File_read::page_offset(start);
 154   Views::iterator p = this->views_.find(page);
 155   if (p == this->views_.end())
 156     return NULL;
 157   if (p->second->size() - (start - page) < size)
 158     return NULL;
 159   return p->second;
 160 }
 161
 162 // Read SIZE bytes from the file starting at offset START.  Read into
 163 // the buffer at P.  Return the number of bytes read, which should
 164 // always be at least SIZE except at the end of the file.
 165
 166 off_t
 167 File_read::do_read(off_t start, off_t size, void* p)
 168 {
 169   gold_assert(this->lock_count_ > 0);
 170
 171   if (this->contents_ != NULL)
 172     {
 173       off_t bytes = this->size_ - start;
 174       if (bytes < 0)
 175         bytes = 0;
 176       else if (bytes > size)
 177         bytes = size;
 178       memcpy(p, this->contents_ + start, bytes);
 179       return bytes;
 180     }
 181
 182   off_t bytes = ::pread(this->descriptor_, p, size, start);
 183   if (bytes < 0)
 184     {
 185       fprintf(stderr, _("%s: %s: pread failed: %s\n"),
 186               program_name, this->filename().c_str(), strerror(errno));
 187       gold_exit(false);
 188     }
 189
 190   return bytes;
 191 }
 192
 193 // Read exactly SIZE bytes from the file starting at offset START.
 194 // Read into the buffer at P.
 195
 196 void
 197 File_read::do_read_exact(off_t start, off_t size, void* p)
 198 {
 199   off_t bytes = this->do_read(start, size, p);
 200   if (bytes != size)
 201     {
 202       fprintf(stderr,
 203               _("%s: %s: file too short: read only %lld of %lld "
 204                 "bytes at %lld\n"),
 205               program_name, this->filename().c_str(),
 206               static_cast<long long>(bytes),
 207               static_cast<long long>(size),
 208               static_cast<long long>(start));
 209       gold_exit(false);
 210     }
 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_exact(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)
 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         return v;
 249
 250       // This view is not large enough.
 251       this->saved_views_.push_back(v);
 252     }
 253
 254   // We need to read data from the file.  We read full pages for
 255   // greater efficiency on small files.
 256
 257   off_t psize = File_read::pages(size + (start - poff));
 258
 259   if (poff + psize >= this->size_)
 260     {
 261       psize = this->size_ - poff;
 262       gold_assert(psize >= size);
 263     }
 264
 265   unsigned char* p = new unsigned char[psize];
 266
 267   this->do_read_exact(poff, psize, p);
 268
 269   File_read::View* v = new File_read::View(poff, psize, p);
 270   ins.first->second = v;
 271   return v;
 272 }
 273
 274 // This implementation of get_view just reads into a memory buffer,
 275 // which we store on view_list_.  At some point we should support
 276 // mmap.
 277
 278 const unsigned char*
 279 File_read::get_view(off_t start, off_t size)
 280 {
 281   gold_assert(this->lock_count_ > 0);
 282   File_read::View* pv = this->find_or_make_view(start, size);
 283   return pv->data() + (start - pv->start());
 284 }
 285
 286 File_view*
 287 File_read::get_lasting_view(off_t start, off_t size)
 288 {
 289   gold_assert(this->lock_count_ > 0);
 290   File_read::View* pv = this->find_or_make_view(start, size);
 291   pv->lock();
 292   return new File_view(*this, pv, pv->data() + (start - pv->start()));
 293 }
 294
 295 // Remove all the file views.
 296
 297 void
 298 File_read::clear_views(bool destroying)
 299 {
 300   for (Views::iterator p = this->views_.begin();
 301        p != this->views_.end();
 302        ++p)
 303     {
 304       if (!p->second->is_locked())
 305         delete p->second;
 306       else
 307         {
 308           gold_assert(!destroying);
 309           this->saved_views_.push_back(p->second);
 310         }
 311     }
 312   this->views_.clear();
 313
 314   Saved_views::iterator p = this->saved_views_.begin();
 315   while (p != this->saved_views_.end())
 316     {
 317       if (!(*p)->is_locked())
 318         {
 319           delete *p;
 320           p = this->saved_views_.erase(p);
 321         }
 322       else
 323         {
 324           gold_assert(!destroying);
 325           ++p;
 326         }
 327     }
 328 }
 329
 330 // Class File_view.
 331
 332 File_view::~File_view()
 333 {
 334   gold_assert(this->file_.is_locked());
 335   this->view_->unlock();
 336 }
 337
 338 // Class Input_file.
 339
 340 // Create a file for testing.
 341
 342 Input_file::Input_file(const char* name, const unsigned char* contents,
 343                        off_t size)
 344   : file_()
 345 {
 346   this->input_argument_ =
 347     new Input_file_argument(name, false, Position_dependent_options());
 348   bool ok = file_.open(name, contents, size);
 349   gold_assert(ok);
 350 }
 351
 352 // Open the file.
 353
 354 void
 355 Input_file::open(const General_options& options, const Dirsearch& dirpath)
 356 {
 357   std::string name;
 358   if (!this->input_argument_->is_lib())
 359     name = this->input_argument_->name();
 360   else
 361     {
 362       std::string n1("lib");
 363       n1 += this->input_argument_->name();
 364       std::string n2;
 365       if (options.is_static())
 366         n1 += ".a";
 367       else
 368         {
 369           n2 = n1 + ".a";
 370           n1 += ".so";
 371         }
 372       name = dirpath.find(n1, n2);
 373       if (name.empty())
 374         {
 375           fprintf(stderr, _("%s: cannot find %s\n"), program_name,
 376                   this->input_argument_->name());
 377           gold_exit(false);
 378         }
 379     }
 380
 381   if (!this->file_.open(name))
 382     {
 383       fprintf(stderr, _("%s: cannot open %s: %s\n"), program_name,
 384               name.c_str(), strerror(errno));
 385       gold_exit(false);
 386     }
 387 }
 388
 389 } // End namespace gold.