1 // descriptors.h -- manage file descriptors for gold -*- C++ -*-
2
3 // Copyright (C) 2008-2016 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
5
6 // This file is part of gold.
7
8 // This program is free software; you can redistribute it and/or modify
9 // it under the terms of the GNU General Public License as published by
10 // the Free Software Foundation; either version 3 of the License, or
11 // (at your option) any later version.
12
13 // This program is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
17
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
21 // MA 02110-1301, USA.
22
23 #ifndef GOLD_DESCRIPTORS_H
24 #define GOLD_DESCRIPTORS_H
25
26 #include <vector>
27
28 #include "gold-threads.h"
29
30 namespace gold
31 {
32
33 // This class manages file descriptors for gold.
34
35 class Descriptors
36 {
37 public:
38 Descriptors();
39
40 // Get a file descriptor for a file. The DESCRIPTOR parameter is
41 // the descriptor the last time the file was used; this will be -1
42 // if this is the first time the file is being opened. The NAME,
43 // FLAGS, and MODE parameters are as for ::open. NAME must be in
44 // permanent storage. This returns the descriptor to use, which may
45 // or may not be the same as DESCRIPTOR. If there is an error
46 // opening the file, this will return -1 with errno set
47 // appropriately.
48 int
49 open(int descriptor, const char* name, int flags, int mode = 0);
50
51 // Release the file descriptor DESCRIPTOR. If PERMANENT is true, it
52 // will be closed, and the caller may not reopen it. If PERMANENT
53 // is false this doesn't necessarily close the descriptor, but it
54 // makes it available to be closed; the descriptor must not be used
55 // again except as an argument to Descriptor::open.
56 void
57 release(int descriptor, bool permanent);
58
59 // Close all the descriptors open for reading.
60 void
61 close_all();
62
63 private:
64 // Information kept for a descriptor.
65 struct Open_descriptor
66 {
67 // File name currently associated with descriptor. This is empty
68 // if none.
69 const char* name;
70 // Index of next descriptor on stack of released descriptors.
71 int stack_next;
72 // Whether the descriptor is currently in use.
73 bool inuse;
74 // Whether this is a write descriptor.
75 bool is_write;
76 // Whether the descriptor is on the stack.
77 bool is_on_stack;
78 };
79
80 bool
81 close_some_descriptor();
82
83 // We need to lock before accessing any fields.
84 Lock* lock_;
85 // Used to initialize the lock_ field exactly once.
86 Initialize_lock initialize_lock_;
87 // Information for descriptors.
88 std::vector<Open_descriptor> open_descriptors_;
89 // Top of stack.
90 int stack_top_;
91 // The current number of file descriptors open.
92 int current_;
93 // The maximum number of file descriptors we open.
94 int limit_;
95 };
96
97 // File descriptors are a centralized data structure, and we use a
98 // global variable rather than passing the data structure into every
99 // routine that does file I/O.
100
101 extern Descriptors descriptors;
102
103 inline int
104 open_descriptor(int descriptor, const char* name, int flags, int mode = 0)
105 { return descriptors.open(descriptor, name, flags, mode); }
106
107 inline void
release_descriptor(int descriptor,bool permanent)108 release_descriptor(int descriptor, bool permanent)
109 { descriptors.release(descriptor, permanent); }
110
111 inline void
close_all_descriptors()112 close_all_descriptors()
113 { descriptors.close_all(); }
114
115 } // End namespace gold.
116
117 #endif // !defined(GOLD_DESCRIPTORS_H)
118