binutils-gdb/gold/fileread.cc

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// fileread.cc -- read files for gold
// Copyright 2006, 2007 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.
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#include "gold.h"
#include <cstring>
#include <cerrno>
#include <fcntl.h>
#include <unistd.h>
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#include <sys/mman.h>
#include "filenames.h"
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#include "options.h"
#include "dirsearch.h"
#include "fileread.h"
namespace gold
{
// Class File_read::View.
File_read::View::~View()
{
gold_assert(!this->is_locked());
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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_;
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}
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}
void
File_read::View::lock()
{
++this->lock_count_;
}
void
File_read::View::unlock()
{
gold_assert(this->lock_count_ > 0);
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--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;
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// The File_read class is designed to support file descriptor caching,
// but this is not currently implemented.
File_read::~File_read()
{
gold_assert(this->lock_count_ == 0);
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if (this->descriptor_ >= 0)
{
if (close(this->descriptor_) < 0)
gold_warning(_("close of %s failed: %s"),
this->name_.c_str(), strerror(errno));
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this->descriptor_ = -1;
}
this->name_.clear();
this->clear_views(true);
}
// Open the file.
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bool
File_read::open(const std::string& name)
{
gold_assert(this->lock_count_ == 0
&& this->descriptor_ < 0
&& this->name_.empty());
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this->name_ = name;
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this->descriptor_ = ::open(this->name_.c_str(), O_RDONLY);
if (this->descriptor_ >= 0)
{
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;
}
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++this->lock_count_;
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return this->descriptor_ >= 0;
}
// Open the file for testing purposes.
bool
File_read::open(const std::string& name, const unsigned char* contents,
off_t size)
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{
gold_assert(this->lock_count_ == 0
&& this->descriptor_ < 0
&& this->name_.empty());
this->name_ = name;
this->contents_ = contents;
this->size_ = size;
++this->lock_count_;
return true;
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}
void
File_read::lock()
{
++this->lock_count_;
}
void
File_read::unlock()
{
gold_assert(this->lock_count_ > 0);
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--this->lock_count_;
if (this->lock_count_ == 0)
{
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;
this->clear_views(false);
}
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}
bool
File_read::is_locked()
{
return this->lock_count_ > 0;
}
// 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.
inline File_read::View*
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File_read::find_view(off_t start, off_t size)
{
off_t page = File_read::page_offset(start);
Views::iterator p = this->views_.find(page);
if (p == this->views_.end())
return NULL;
if (p->second->size() - (start - page) < size)
return NULL;
return p->second;
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}
// Read SIZE bytes from the file starting at offset START. Read into
// the buffer at P.
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void
File_read::do_read(off_t start, off_t size, void* p)
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{
gold_assert(this->lock_count_ > 0);
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off_t bytes;
if (this->contents_ != NULL)
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{
bytes = this->size_ - start;
if (bytes >= size)
{
memcpy(p, this->contents_ + start, size);
return;
}
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}
else
{
bytes = ::pread(this->descriptor_, p, size, start);
if (bytes == size)
return;
if (bytes < 0)
{
gold_fatal(_("%s: pread failed: %s"),
this->filename().c_str(), strerror(errno));
return;
}
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}
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));
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}
// Read data from the file.
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void
File_read::read(off_t start, off_t size, void* p)
{
gold_assert(this->lock_count_ > 0);
File_read::View* pv = this->find_view(start, size);
if (pv != NULL)
{
memcpy(p, pv->data() + (start - pv->start()), size);
return;
}
this->do_read(start, size, p);
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}
// Find an existing view or make a new one.
File_read::View*
File_read::find_or_make_view(off_t start, off_t size, bool cache)
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{
gold_assert(this->lock_count_ > 0);
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off_t poff = File_read::page_offset(start);
File_read::View* const vnull = NULL;
std::pair<Views::iterator, bool> ins =
this->views_.insert(std::make_pair(poff, vnull));
if (!ins.second)
{
// There was an existing view at this offset.
File_read::View* v = ins.first->second;
if (v->size() - (start - v->start()) >= size)
{
if (cache)
v->set_cache();
return v;
}
// This view is not large enough.
this->saved_views_.push_back(v);
}
// We need to read data from the file. We read full pages for
// greater efficiency on small files.
off_t psize = File_read::pages(size + (start - poff));
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if (poff + psize >= this->size_)
{
psize = this->size_ - poff;
gold_assert(psize >= size);
}
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File_read::View* v;
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if (this->contents_ != NULL)
{
unsigned char* p = new unsigned char[psize];
this->do_read(poff, psize, p);
v = new File_read::View(poff, psize, p, cache, false);
}
else
{
void* p = ::mmap(NULL, psize, PROT_READ, MAP_SHARED,
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));
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this->mapped_bytes_ += psize;
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const unsigned char* pbytes = static_cast<const unsigned char*>(p);
v = new File_read::View(poff, psize, pbytes, cache, true);
}
ins.first->second = v;
return v;
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}
// This implementation of get_view just reads into a memory buffer,
// which we store on view_list_. At some point we should support
// mmap.
const unsigned char*
File_read::get_view(off_t start, off_t size, bool cache)
{
gold_assert(this->lock_count_ > 0);
File_read::View* pv = this->find_or_make_view(start, size, cache);
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return pv->data() + (start - pv->start());
}
File_view*
File_read::get_lasting_view(off_t start, off_t size, bool cache)
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{
gold_assert(this->lock_count_ > 0);
File_read::View* pv = this->find_or_make_view(start, size, cache);
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pv->lock();
return new File_view(*this, pv, pv->data() + (start - pv->start()));
}
// Remove all the file views.
void
File_read::clear_views(bool destroying)
{
for (Views::iterator p = this->views_.begin();
p != this->views_.end();
++p)
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{
if (!p->second->is_locked()
&& (destroying || !p->second->should_cache()))
delete p->second;
else
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{
gold_assert(!destroying);
this->saved_views_.push_back(p->second);
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}
}
this->views_.clear();
Saved_views::iterator p = this->saved_views_.begin();
while (p != this->saved_views_.end())
{
if (!(*p)->is_locked()
&& (destroying || !(*p)->should_cache()))
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{
delete *p;
p = this->saved_views_.erase(p);
}
else
{
gold_assert(!destroying);
++p;
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}
}
}
// Print statistical information to stderr. This is used for --stats.
void
File_read::print_stats()
{
fprintf(stderr, _("%s: total bytes mapped for read: %llu\n"),
program_name, File_read::total_mapped_bytes);
fprintf(stderr, _("%s: maximum bytes mapped for read at one time: %llu\n"),
program_name, File_read::maximum_mapped_bytes);
}
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// Class File_view.
File_view::~File_view()
{
gold_assert(this->file_.is_locked());
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this->view_->unlock();
}
// Class Input_file.
// Create a file for testing.
Input_file::Input_file(const char* name, const unsigned char* contents,
off_t size)
: file_()
{
this->input_argument_ =
new Input_file_argument(name, false, "", Position_dependent_options());
bool ok = file_.open(name, contents, size);
gold_assert(ok);
}
// Open the file.
// If the filename is not absolute, we assume it is in the current
// directory *except* when:
// A) input_argument_->is_lib() is true; or
// B) input_argument_->extra_search_path() is not empty.
// In both cases, we look in extra_search_path + library_path to find
// the file location, rather than the current directory.
bool
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Input_file::open(const General_options& options, const Dirsearch& dirpath)
{
std::string name;
// Case 1: name is an absolute file, just try to open it
// Case 2: name is relative but is_lib is false and extra_search_path
// is empty
if (IS_ABSOLUTE_PATH (this->input_argument_->name())
|| (!this->input_argument_->is_lib()
&& this->input_argument_->extra_search_path() == NULL))
{
name = this->input_argument_->name();
this->found_name_ = name;
}
// Case 3: is_lib is true
else if (this->input_argument_->is_lib())
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{
// We don't yet support extra_search_path with -l.
gold_assert(this->input_argument_->extra_search_path() == NULL);
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std::string n1("lib");
n1 += this->input_argument_->name();
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std::string n2;
if (options.is_static())
n1 += ".a";
else
{
n2 = n1 + ".a";
n1 += ".so";
}
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name = dirpath.find(n1, n2, &this->is_in_sysroot_);
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if (name.empty())
{
gold_error(_("cannot find -l%s\n"),
this->input_argument_->name());
return false;
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}
if (n2.empty() || name[name.length() - 1] == 'o')
this->found_name_ = n1;
else
this->found_name_ = n2;
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}
// Case 4: extra_search_path is not empty
else
{
gold_assert(this->input_argument_->extra_search_path() != NULL);
// First, check extra_search_path.
name = this->input_argument_->extra_search_path();
if (!IS_DIR_SEPARATOR (name[name.length() - 1]))
name += '/';
name += this->input_argument_->name();
struct stat dummy_stat;
if (::stat(name.c_str(), &dummy_stat) < 0)
{
// extra_search_path failed, so check the normal search-path.
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name = dirpath.find(this->input_argument_->name(), "",
&this->is_in_sysroot_);
if (name.empty())
{
gold_error(_("cannot find %s\n"),
this->input_argument_->name());
return false;
}
}
this->found_name_ = this->input_argument_->name();
}
// Now that we've figured out where the file lives, try to open it.
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if (!this->file_.open(name))
{
gold_error(_("cannot open %s: %s\n"),
name.c_str(), strerror(errno));
return false;
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}
return true;
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}
} // End namespace gold.