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// fileread.cc -- read files for gold

// Copyright 2006, 2007, 2008, 2009 Free Software Foundation, Inc.

// Written by Ian Lance Taylor <iant@google.com>.

// This file is part of gold.

// This program is free software; you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation; either version 3 of the License, or

// (at your option) any later version.

// This program is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License

// along with this program; if not, write to the Free Software

// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,

// MA 02110-1301, USA.

#include "gold.h"

#include <cstring>

#include <cerrno>

#include <fcntl.h>

#include <unistd.h>

#include <sys/mman.h>

#include <sys/uio.h>

#include <sys/stat.h>

#include "filenames.h"

#include "debug.h"

#include "parameters.h"

#include "options.h"

#include "dirsearch.h"

#include "target.h"

#include "binary.h"

#include "descriptors.h"

#include "fileread.h"

#ifndef HAVE_READV

struct iovec { void* iov_base; size_t iov_len };

ssize_t

readv(int, const iovec*, int)

{

  gold_unreachable();

}

#endif

namespace gold

{

// Class File_read::View.

File_read::View::~View()

{

  gold_assert(!this->is_locked());

  if (!this->mapped_)

    delete[] this->data_;

  else

    {

      if (::munmap(const_cast<unsigned char*>(this->data_), this->size_) != 0)

        gold_warning(_("munmap failed: %s"), strerror(errno));

      File_read::current_mapped_bytes -= this->size_;

    }

}

void

File_read::View::lock()

{

  ++this->lock_count_;

}

void

File_read::View::unlock()

{

  gold_assert(this->lock_count_ > 0);

  --this->lock_count_;

}

bool

File_read::View::is_locked()

{

  return this->lock_count_ > 0;

}

// Class File_read.

// The File_read static variables.

unsigned long long File_read::total_mapped_bytes;

unsigned long long File_read::current_mapped_bytes;

unsigned long long File_read::maximum_mapped_bytes;

File_read::~File_read()

{

  gold_assert(this->token_.is_writable());

  if (this->is_descriptor_opened_)

    {

      release_descriptor(this->descriptor_, true);

      this->descriptor_ = -1;

      this->is_descriptor_opened_ = false;

    }

  this->name_.clear();

  this->clear_views(true);

}

// Open the file.

bool

File_read::open(const Task* task, const std::string& name)

{

  gold_assert(this->token_.is_writable()

              && this->descriptor_ < 0

              && !this->is_descriptor_opened_

              && this->name_.empty());

  this->name_ = name;

  this->descriptor_ = open_descriptor(-1, this->name_.c_str(),

                                      O_RDONLY);

  if (this->descriptor_ >= 0)

    {

      this->is_descriptor_opened_ = true;

      struct stat s;

      if (::fstat(this->descriptor_, &s) < 0)

        gold_error(_("%s: fstat failed: %s"),

                   this->name_.c_str(), strerror(errno));

      this->size_ = s.st_size;

      gold_debug(DEBUG_FILES, "Attempt to open %s succeeded",

                 this->name_.c_str());

      this->token_.add_writer(task);

    }

  return this->descriptor_ >= 0;

}

// Open the file with the contents in memory.

bool

File_read::open(const Task* task, const std::string& name,

                const unsigned char* contents, off_t size)

{

  gold_assert(this->token_.is_writable()

              && this->descriptor_ < 0

              && !this->is_descriptor_opened_

              && this->name_.empty());

  this->name_ = name;

  this->contents_ = contents;

  this->size_ = size;

  this->token_.add_writer(task);

  return true;

}

// Reopen a descriptor if necessary.

void

File_read::reopen_descriptor()

{

  if (!this->is_descriptor_opened_)

    {

      this->descriptor_ = open_descriptor(this->descriptor_,

                                          this->name_.c_str(),

                                          O_RDONLY);

      if (this->descriptor_ < 0)

        gold_fatal(_("could not reopen file %s"), this->name_.c_str());

      this->is_descriptor_opened_ = true;

    }

}

// Release the file.  This is called when we are done with the file in

// a Task.

void

File_read::release()

{

  gold_assert(this->is_locked());

  File_read::total_mapped_bytes += this->mapped_bytes_;

  File_read::current_mapped_bytes += this->mapped_bytes_;

  this->mapped_bytes_ = 0;

  if (File_read::current_mapped_bytes > File_read::maximum_mapped_bytes)

    File_read::maximum_mapped_bytes = File_read::current_mapped_bytes;

  // Only clear views if there is only one attached object.  Otherwise

  // we waste time trying to clear cached archive views.  Similarly

  // for releasing the descriptor.

  if (this->object_count_ <= 1)

    {

      this->clear_views(false);

      if (this->is_descriptor_opened_)

        {

          release_descriptor(this->descriptor_, false);

          this->is_descriptor_opened_ = false;

        }

    }

  this->released_ = true;

}

// Lock the file.

void

File_read::lock(const Task* task)

{

  gold_assert(this->released_);

  this->token_.add_writer(task);

  this->released_ = false;

}

// Unlock the file.

void

File_read::unlock(const Task* task)

{

  this->release();

  this->token_.remove_writer(task);

}

// Return whether the file is locked.

bool

File_read::is_locked() const

{

  if (!this->token_.is_writable())

    return true;

  // The file is not locked, so it should have been released.

  gold_assert(this->released_);

  return false;

}

// See if we have a view which covers the file starting at START for

// SIZE bytes.  Return a pointer to the View if found, NULL if not.

// If BYTESHIFT is not -1U, the returned View must have the specified

// byte shift; otherwise, it may have any byte shift.  If VSHIFTED is

// not NULL, this sets *VSHIFTED to a view which would have worked if

// not for the requested BYTESHIFT.

inline File_read::View*

File_read::find_view(off_t start, section_size_type size,

                     unsigned int byteshift, File_read::View** vshifted) const

{

  if (vshifted != NULL)

    *vshifted = NULL;

  off_t page = File_read::page_offset(start);

  unsigned int bszero = 0;

  Views::const_iterator p = this->views_.upper_bound(std::make_pair(page - 1,

                                                                    bszero));

  while (p != this->views_.end() && p->first.first <= page)

    {

      if (p->second->start() <= start

          && (p->second->start() + static_cast<off_t>(p->second->size())

              >= start + static_cast<off_t>(size)))

        {

          if (byteshift == -1U || byteshift == p->second->byteshift())

            {

              p->second->set_accessed();

              return p->second;

            }

          if (vshifted != NULL && *vshifted == NULL)

            *vshifted = p->second;

        }

      ++p;

    }

  return NULL;

}

// Read SIZE bytes from the file starting at offset START.  Read into

// the buffer at P.

void

File_read::do_read(off_t start, section_size_type size, void* p)

{

  ssize_t bytes;

  if (this->contents_ != NULL)

    {

      bytes = this->size_ - start;

      if (static_cast<section_size_type>(bytes) >= size)

        {

          memcpy(p, this->contents_ + start, size);

          return;

        }

    }

  else

    {

      this->reopen_descriptor();

      bytes = ::pread(this->descriptor_, p, size, start);

      if (static_cast<section_size_type>(bytes) == size)

        return;

      if (bytes < 0)

        {

          gold_fatal(_("%s: pread failed: %s"),

                     this->filename().c_str(), strerror(errno));

          return;

        }

    }

  gold_fatal(_("%s: file too short: read only %lld of %lld bytes at %lld"),

             this->filename().c_str(),

             static_cast<long long>(bytes),

             static_cast<long long>(size),

             static_cast<long long>(start));

}

// Read data from the file.

void

File_read::read(off_t start, section_size_type size, void* p)

{

  const File_read::View* pv = this->find_view(start, size, -1U, NULL);

  if (pv != NULL)

    {

      memcpy(p, pv->data() + (start - pv->start() + pv->byteshift()), size);

      return;

    }

  this->do_read(start, size, p);

}

// Add a new view.  There may already be an existing view at this

// offset.  If there is, the new view will be larger, and should

// replace the old view.

void

File_read::add_view(File_read::View* v)

{

  std::pair<Views::iterator, bool> ins =

    this->views_.insert(std::make_pair(std::make_pair(v->start(),

                                                      v->byteshift()),

                                       v));

  if (ins.second)

    return;

  // There was an existing view at this offset.  It must not be large

  // enough.  We can't delete it here, since something might be using

  // it; we put it on a list to be deleted when the file is unlocked.

  File_read::View* vold = ins.first->second;

  gold_assert(vold->size() < v->size());

  if (vold->should_cache())

    {

      v->set_cache();

      vold->clear_cache();

    }

  this->saved_views_.push_back(vold);

  ins.first->second = v;

}

// Make a new view with a specified byteshift, reading the data from

// the file.

File_read::View*

File_read::make_view(off_t start, section_size_type size,

                     unsigned int byteshift, bool cache)

{

  gold_assert(size > 0);

  // Check that start and end of the view are within the file.

  if (start > this->size_

      || (static_cast<unsigned long long>(size)

          > static_cast<unsigned long long>(this->size_ - start)))

    gold_fatal(_("%s: attempt to map %lld bytes at offset %lld exceeds "

                 "size of file; the file may be corrupt"),

                   this->filename().c_str(),

                   static_cast<long long>(size),

                   static_cast<long long>(start));

  off_t poff = File_read::page_offset(start);

  section_size_type psize = File_read::pages(size + (start - poff));

  if (poff + static_cast<off_t>(psize) >= this->size_)

    {

      psize = this->size_ - poff;

      gold_assert(psize >= size);

    }

  File_read::View* v;

  if (this->contents_ != NULL || byteshift != 0)

    {

      unsigned char* p = new unsigned char[psize + byteshift];

      memset(p, 0, byteshift);

      this->do_read(poff, psize, p + byteshift);

      v = new File_read::View(poff, psize, p, byteshift, cache, false);

    }

  else

    {

      this->reopen_descriptor();

      void* p = ::mmap(NULL, psize, PROT_READ, MAP_PRIVATE,

                       this->descriptor_, poff);

      if (p == MAP_FAILED)

        gold_fatal(_("%s: mmap offset %lld size %lld failed: %s"),

                   this->filename().c_str(),

                   static_cast<long long>(poff),

                   static_cast<long long>(psize),

                   strerror(errno));

      this->mapped_bytes_ += psize;

      const unsigned char* pbytes = static_cast<const unsigned char*>(p);

      v = new File_read::View(poff, psize, pbytes, 0, cache, true);

    }

  this->add_view(v);

  return v;

}

// Find a View or make a new one, shifted as required by the file

// offset OFFSET and ALIGNED.

File_read::View*

File_read::find_or_make_view(off_t offset, off_t start,

                             section_size_type size, bool aligned, bool cache)

{

  unsigned int byteshift;

  if (offset == 0)

    byteshift = 0;

  else

    {

      unsigned int target_size = (!parameters->target_valid()

                                  ? 64

                                  : parameters->target().get_size());

      byteshift = offset & ((target_size / 8) - 1);

      // Set BYTESHIFT to the number of dummy bytes which must be

      // inserted before the data in order for this data to be

      // aligned.

      if (byteshift != 0)

        byteshift = (target_size / 8) - byteshift;

    }

  // Try to find a View with the required BYTESHIFT.

  File_read::View* vshifted;

  File_read::View* v = this->find_view(offset + start, size,

                                       aligned ? byteshift : -1U,

                                       &vshifted);

  if (v != NULL)

    {

      if (cache)

        v->set_cache();

      return v;

    }

  // If VSHIFTED is not NULL, then it has the data we need, but with

  // the wrong byteshift.

  v = vshifted;

  if (v != NULL)

    {

      gold_assert(aligned);

      unsigned char* pbytes = new unsigned char[v->size() + byteshift];

      memset(pbytes, 0, byteshift);

      memcpy(pbytes + byteshift, v->data() + v->byteshift(), v->size());

      File_read::View* shifted_view = new File_read::View(v->start(), v->size(),

                                                          pbytes, byteshift,

                                                          cache, false);

      this->add_view(shifted_view);

      return shifted_view;

    }

  // Make a new view.  If we don't need an aligned view, use a

  // byteshift of 0, so that we can use mmap.

  return this->make_view(offset + start, size,

                         aligned ? byteshift : 0,

                         cache);

}

// Get a view into the file.

const unsigned char*

File_read::get_view(off_t offset, off_t start, section_size_type size,

                    bool aligned, bool cache)

{

  File_read::View* pv = this->find_or_make_view(offset, start, size,

                                                aligned, cache);

  return pv->data() + (offset + start - pv->start() + pv->byteshift());

}

File_view*

File_read::get_lasting_view(off_t offset, off_t start, section_size_type size,

                            bool aligned, bool cache)

{

  File_read::View* pv = this->find_or_make_view(offset, start, size,

                                                aligned, cache);

  pv->lock();

  return new File_view(*this, pv,

                       (pv->data()

                        + (offset + start - pv->start() + pv->byteshift())));

}

// Use readv to read COUNT entries from RM starting at START.  BASE

// must be added to all file offsets in RM.

void

File_read::do_readv(off_t base, const Read_multiple& rm, size_t start,

                    size_t count)

{

  unsigned char discard[File_read::page_size];

  iovec iov[File_read::max_readv_entries * 2];

  size_t iov_index = 0;

  off_t first_offset = rm[start].file_offset;

  off_t last_offset = first_offset;

  ssize_t want = 0;

  for (size_t i = 0; i < count; ++i)

    {

      const Read_multiple_entry& i_entry(rm[start + i]);

      if (i_entry.file_offset > last_offset)

        {

          size_t skip = i_entry.file_offset - last_offset;

          gold_assert(skip <= sizeof discard);

          iov[iov_index].iov_base = discard;

          iov[iov_index].iov_len = skip;

          ++iov_index;

          want += skip;

        }

      iov[iov_index].iov_base = i_entry.buffer;

      iov[iov_index].iov_len = i_entry.size;

      ++iov_index;

      want += i_entry.size;

      last_offset = i_entry.file_offset + i_entry.size;

    }

  this->reopen_descriptor();

  gold_assert(iov_index < sizeof iov / sizeof iov[0]);

  if (::lseek(this->descriptor_, base + first_offset, SEEK_SET) < 0)

    gold_fatal(_("%s: lseek failed: %s"),

               this->filename().c_str(), strerror(errno));

  ssize_t got = ::readv(this->descriptor_, iov, iov_index);

  if (got < 0)

    gold_fatal(_("%s: readv failed: %s"),

               this->filename().c_str(), strerror(errno));

  if (got != want)

    gold_fatal(_("%s: file too short: read only %zd of %zd bytes at %lld"),

               this->filename().c_str(),

               got, want, static_cast<long long>(base + first_offset));

}

// Read several pieces of data from the file.

void

File_read::read_multiple(off_t base, const Read_multiple& rm)

{

  size_t count = rm.size();

  size_t i = 0;

  while (i < count)

    {

      // Find up to MAX_READV_ENTRIES consecutive entries which are

      // less than one page apart.

      const Read_multiple_entry& i_entry(rm[i]);

      off_t i_off = i_entry.file_offset;

      off_t end_off = i_off + i_entry.size;

      size_t j;

      for (j = i + 1; j < count; ++j)

        {

          if (j - i >= File_read::max_readv_entries)

            break;

          const Read_multiple_entry& j_entry(rm[j]);

          off_t j_off = j_entry.file_offset;

          gold_assert(j_off >= end_off);

          off_t j_end_off = j_off + j_entry.size;

          if (j_end_off - end_off >= File_read::page_size)

            break;

          end_off = j_end_off;

        }

      if (j == i + 1)

        this->read(base + i_off, i_entry.size, i_entry.buffer);

      else

        {

          File_read::View* view = this->find_view(base + i_off,

                                                  end_off - i_off,

                                                  -1U, NULL);

          if (view == NULL)

            this->do_readv(base, rm, i, j - i);

          else

            {

              const unsigned char* v = (view->data()

                                        + (base + i_off - view->start()

                                           + view->byteshift()));

              for (size_t k = i; k < j; ++k)

                {

                  const Read_multiple_entry& k_entry(rm[k]);

                  gold_assert((convert_to_section_size_type(k_entry.file_offset

                                                           - i_off)

                               + k_entry.size)

                              <= convert_to_section_size_type(end_off

                                                              - i_off));

                  memcpy(k_entry.buffer,

                         v + (k_entry.file_offset - i_off),

                         k_entry.size);

                }

            }

        }

      i = j;

    }

}

// Mark all views as no longer cached.

void

File_read::clear_view_cache_marks()

{

  // Just ignore this if there are multiple objects associated with

  // the file.  Otherwise we will wind up uncaching and freeing some

  // views for other objects.

  if (this->object_count_ > 1)

    return;

  for (Views::iterator p = this->views_.begin();

       p != this->views_.end();

       ++p)

    p->second->clear_cache();