mirror of
https://github.com/autc04/Retro68.git
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251 lines
6.7 KiB
C++
251 lines
6.7 KiB
C++
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// descriptors.cc -- manage file descriptors for gold
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// Copyright 2008, 2009 Free Software Foundation, Inc.
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// Written by Ian Lance Taylor <iant@google.com>.
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// This file is part of gold.
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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// MA 02110-1301, USA.
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#include "gold.h"
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#include <cerrno>
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#include <cstdio>
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#include <cstring>
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#include <fcntl.h>
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#include <unistd.h>
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#include "parameters.h"
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#include "options.h"
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#include "gold-threads.h"
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#include "descriptors.h"
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#include "binary-io.h"
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// Very old systems may not define FD_CLOEXEC.
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#ifndef FD_CLOEXEC
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#define FD_CLOEXEC 1
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#endif
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// O_CLOEXEC is only available on newer systems.
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#ifndef O_CLOEXEC
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#define O_CLOEXEC 0
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#endif
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namespace gold
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{
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// Class Descriptors.
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// The default for limit_ is meant to simply be large. It gets
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// adjusted downward if we run out of file descriptors.
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Descriptors::Descriptors()
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: lock_(NULL), initialize_lock_(&this->lock_), open_descriptors_(),
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stack_top_(-1), current_(0), limit_(8192 - 16)
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{
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this->open_descriptors_.reserve(128);
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}
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// Open a file.
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int
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Descriptors::open(int descriptor, const char* name, int flags, int mode)
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{
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// We don't initialize this until we are called, because we can't
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// initialize a Lock until we have parsed the options to find out
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// whether we are running with threads. We can be called before
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// options are valid when reading a linker script.
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bool lock_initialized = this->initialize_lock_.initialize();
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gold_assert(lock_initialized || descriptor < 0);
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if (descriptor >= 0)
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{
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Hold_lock hl(*this->lock_);
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gold_assert(static_cast<size_t>(descriptor)
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< this->open_descriptors_.size());
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Open_descriptor* pod = &this->open_descriptors_[descriptor];
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if (pod->name == name
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|| (pod->name != NULL && strcmp(pod->name, name) == 0))
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{
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gold_assert(!pod->inuse);
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pod->inuse = true;
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if (descriptor == this->stack_top_)
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{
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this->stack_top_ = pod->stack_next;
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pod->stack_next = -1;
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pod->is_on_stack = false;
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}
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return descriptor;
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}
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}
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while (true)
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{
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// We always want to set the close-on-exec flag; we don't
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// require callers to pass it.
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flags |= O_CLOEXEC;
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// Always open the file as a binary file.
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flags |= O_BINARY;
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int new_descriptor = ::open(name, flags, mode);
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if (new_descriptor < 0
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&& errno != ENFILE
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&& errno != EMFILE)
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{
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if (descriptor >= 0 && errno == ENOENT)
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{
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{
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Hold_lock hl(*this->lock_);
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gold_error(_("file %s was removed during the link"),
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this->open_descriptors_[descriptor].name);
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}
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errno = ENOENT;
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}
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return new_descriptor;
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}
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if (new_descriptor >= 0)
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{
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// If we have any plugins, we really do need to set the
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// close-on-exec flag, even if O_CLOEXEC is not defined.
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// FIXME: In some cases O_CLOEXEC may be defined in the
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// header file but not supported by the kernel.
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// Unfortunately there doesn't seem to be any obvious way to
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// detect that, as unknown flags passed to open are ignored.
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if (O_CLOEXEC == 0
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&& parameters->options_valid()
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&& parameters->options().has_plugins())
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fcntl(new_descriptor, F_SETFD, FD_CLOEXEC);
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{
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Hold_optional_lock hl(this->lock_);
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if (static_cast<size_t>(new_descriptor)
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>= this->open_descriptors_.size())
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this->open_descriptors_.resize(new_descriptor + 64);
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Open_descriptor* pod = &this->open_descriptors_[new_descriptor];
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pod->name = name;
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pod->stack_next = -1;
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pod->inuse = true;
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pod->is_write = (flags & O_ACCMODE) != O_RDONLY;
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pod->is_on_stack = false;
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++this->current_;
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if (this->current_ >= this->limit_)
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this->close_some_descriptor();
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return new_descriptor;
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}
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}
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// We ran out of file descriptors.
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{
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Hold_optional_lock hl(this->lock_);
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this->limit_ = this->current_ - 16;
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if (this->limit_ < 8)
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this->limit_ = 8;
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if (!this->close_some_descriptor())
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gold_fatal(_("out of file descriptors and couldn't close any"));
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}
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}
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}
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// Release a descriptor.
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void
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Descriptors::release(int descriptor, bool permanent)
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{
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Hold_optional_lock hl(this->lock_);
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gold_assert(descriptor >= 0
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&& (static_cast<size_t>(descriptor)
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< this->open_descriptors_.size()));
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Open_descriptor* pod = &this->open_descriptors_[descriptor];
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if (permanent
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|| (this->current_ > this->limit_ && !pod->is_write))
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{
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if (::close(descriptor) < 0)
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gold_warning(_("while closing %s: %s"), pod->name, strerror(errno));
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pod->name = NULL;
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--this->current_;
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}
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else
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{
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pod->inuse = false;
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if (!pod->is_write && !pod->is_on_stack)
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{
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pod->stack_next = this->stack_top_;
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this->stack_top_ = descriptor;
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pod->is_on_stack = true;
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}
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}
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}
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// Close some descriptor. The lock is held when this is called. We
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// close the descriptor on the top of the free stack. Note that this
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// is the opposite of an LRU algorithm--we close the most recently
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// used descriptor. That is because the linker tends to cycle through
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// all the files; after we release a file, we are unlikely to need it
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// again until we have looked at all the other files. Return true if
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// we closed a descriptor.
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bool
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Descriptors::close_some_descriptor()
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{
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int last = -1;
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int i = this->stack_top_;
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while (i >= 0)
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{
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gold_assert(static_cast<size_t>(i) < this->open_descriptors_.size());
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Open_descriptor* pod = &this->open_descriptors_[i];
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if (!pod->inuse && !pod->is_write)
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{
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if (::close(i) < 0)
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gold_warning(_("while closing %s: %s"), pod->name, strerror(errno));
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--this->current_;
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pod->name = NULL;
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if (last < 0)
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this->stack_top_ = pod->stack_next;
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else
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this->open_descriptors_[last].stack_next = pod->stack_next;
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pod->stack_next = -1;
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pod->is_on_stack = false;
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return true;
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}
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last = i;
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i = pod->stack_next;
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}
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// We couldn't find any descriptors to close. This is weird but not
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// necessarily an error.
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return false;
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}
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// The single global variable which manages descriptors.
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Descriptors descriptors;
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} // End namespace gold.
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