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// descriptors.cc -- manage file descriptors for gold
// Copyright 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 <cerrno>
#include <cstring>
#include <fcntl.h>
#include <unistd.h>
#include "parameters.h"
#include "gold-threads.h"
#include "descriptors.h"
namespace gold
{
// Class Descriptors.
// The default for limit_ is meant to simply be large. It gets
// adjusted downward if we run out of file descriptors.
Descriptors::Descriptors()
: lock_(NULL), open_descriptors_(), stack_top_(-1), current_(0),
limit_(8192 - 16)
{
this->open_descriptors_.reserve(128);
}
// Open a file.
int
Descriptors::open(int descriptor, const char* name, int flags, int mode)
{
// We don't initialize this until we are called, because we can't
// initialize a Lock until we have parsed the options to find out
// whether we are running with threads. We can be called before
// options are valid when reading a linker script.
if (this->lock_ == NULL)
{
if (parameters->options_valid())
this->lock_ = new Lock();
else
gold_assert(descriptor < 0);
}
if (descriptor >= 0)
{
Hold_lock hl(*this->lock_);
gold_assert(static_cast<size_t>(descriptor)
< this->open_descriptors_.size());
Open_descriptor* pod = &this->open_descriptors_[descriptor];
if (pod->name == name
|| (pod->name != NULL && strcmp(pod->name, name) == 0))
{
gold_assert(!pod->inuse);
pod->inuse = true;
if (descriptor == this->stack_top_)
{
this->stack_top_ = pod->stack_next;
pod->stack_next = -1;
pod->is_on_stack = false;
}
return descriptor;
}
}
while (true)
{
int new_descriptor = ::open(name, flags, mode);
if (new_descriptor < 0
&& errno != ENFILE
&& errno != EMFILE)
{
if (descriptor >= 0 && errno == ENOENT)
{
{
Hold_lock hl(*this->lock_);
gold_error(_("file %s was removed during the link"),
this->open_descriptors_[descriptor].name);
}
errno = ENOENT;
}
return new_descriptor;
}
if (new_descriptor >= 0)
{
Hold_optional_lock hl(this->lock_);
if (static_cast<size_t>(new_descriptor)
>= this->open_descriptors_.size())
this->open_descriptors_.resize(new_descriptor + 64);
Open_descriptor* pod = &this->open_descriptors_[new_descriptor];
pod->name = name;
pod->stack_next = -1;
pod->inuse = true;
pod->is_write = (flags & O_ACCMODE) != O_RDONLY;
pod->is_on_stack = false;
++this->current_;
if (this->current_ >= this->limit_)
this->close_some_descriptor();
return new_descriptor;
}
// We ran out of file descriptors.
{
Hold_optional_lock hl(this->lock_);
this->limit_ = this->current_ - 16;
if (this->limit_ < 8)
this->limit_ = 8;
if (!this->close_some_descriptor())
gold_fatal(_("out of file descriptors and couldn't close any"));
}
}
}
// Release a descriptor.
void
Descriptors::release(int descriptor, bool permanent)
{
Hold_optional_lock hl(this->lock_);
gold_assert(descriptor >= 0
&& (static_cast<size_t>(descriptor)
< this->open_descriptors_.size()));
Open_descriptor* pod = &this->open_descriptors_[descriptor];
if (permanent
|| (this->current_ > this->limit_ && !pod->is_write))
{
if (::close(descriptor) < 0)
gold_warning(_("while closing %s: %s"), pod->name, strerror(errno));
pod->name = NULL;
--this->current_;
}
else
{
pod->inuse = false;
if (!pod->is_write && !pod->is_on_stack)
{
pod->stack_next = this->stack_top_;
this->stack_top_ = descriptor;
pod->is_on_stack = true;
}
}
}
// Close some descriptor. The lock is held when this is called. We
// close the descriptor on the top of the free stack. Note that this
// is the opposite of an LRU algorithm--we close the most recently
// used descriptor. That is because the linker tends to cycle through
// all the files; after we release a file, we are unlikely to need it
// again until we have looked at all the other files. Return true if
// we closed a descriptor.
bool
Descriptors::close_some_descriptor()
{
int last = -1;
int i = this->stack_top_;
while (i >= 0)
{
gold_assert(static_cast<size_t>(i) < this->open_descriptors_.size());
Open_descriptor* pod = &this->open_descriptors_[i];
if (!pod->inuse && !pod->is_write)
{
if (::close(i) < 0)
gold_warning(_("while closing %s: %s"), pod->name, strerror(errno));
--this->current_;
pod->name = NULL;
if (last < 0)
this->stack_top_ = pod->stack_next;
else
this->open_descriptors_[last].stack_next = pod->stack_next;
pod->stack_next = -1;
pod->is_on_stack = false;
return true;
}
last = i;
i = pod->stack_next;
}
// We couldn't find any descriptors to close. This is weird but not
// necessarily an error.
return false;
}
// The single global variable which manages descriptors.
Descriptors descriptors;
} // End namespace gold.
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