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+// descriptors.h -- manage file descriptors for gold -*- C++ -*-
+
+// Copyright 2008 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)