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 (at) 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 108 release_descriptor(int descriptor, bool permanent) 109 { descriptors.release(descriptor, permanent); } 110 111 inline void 112 close_all_descriptors() 113 { descriptors.close_all(); } 114 115 } // End namespace gold. 116 117 #endif // !defined(GOLD_DESCRIPTORS_H) 118
