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// descriptors.h -- manage file descriptors for gold -*- C++ -*-
// 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.
#ifndef GOLD_DESCRIPTORS_H
#define GOLD_DESCRIPTORS_H
#include <vector>
namespace gold
{
class Lock;
// This class manages file descriptors for gold.
class Descriptors
{
public:
Descriptors();
// Get a file descriptor for a file. The DESCRIPTOR parameter is
// the descriptor the last time the file was used; this will be -1
// if this is the first time the file is being opened. The NAME,
// FLAGS, and MODE parameters are as for ::open. NAME must be in
// permanent storage. This returns the descriptor to use, which may
// or may not be the same as DESCRIPTOR. If there is an error
// opening the file, this will return -1 with errno set
// appropriately.
int
open(int descriptor, const char* name, int flags, int mode = 0);
// Release the file descriptor DESCRIPTOR. If PERMANENT is true, it
// will be closed, and the caller may not reopen it. If PERMANENT
// is false this doesn't necessarily close the descriptor, but it
// makes it available to be closed; the descriptor must not be used
// again except as an argument to Descriptor::open.
void
release(int descriptor, bool permanent);
private:
// Information kept for a descriptor.
struct Open_descriptor
{
// File name currently associated with descriptor. This is empty
// if none.
const char* name;
// Index of next descriptor on stack of released descriptors.
int stack_next;
// Whether the descriptor is currently in use.
bool inuse;
// Whether this is a write descriptor.
bool is_write;
};
bool
close_some_descriptor();
// We need to lock before accessing any fields.
Lock* lock_;
// Information for descriptors.
std::vector<Open_descriptor> open_descriptors_;
// Top of stack.
int stack_top_;
// The current number of file descriptors open.
int current_;
// The maximum number of file descriptors we open.
int limit_;
};
// File descriptors are a centralized data structure, and we use a
// global variable rather than passing the data structure into every
// routine that does file I/O.
extern Descriptors descriptors;
inline int
open_descriptor(int descriptor, const char* name, int flags, int mode = 0)
{ return descriptors.open(descriptor, name, flags, mode); }
inline void
release_descriptor(int descriptor, bool permanent)
{ descriptors.release(descriptor, permanent); }
} // End namespace gold.
#endif // !defined(GOLD_DESCRIPTORS_H)
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