| 1 | // descriptors.h -- manage file descriptors for gold -*- C++ -*- |
| 2 | |
| 3 | // Copyright 2008, 2009 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 | private: |
| 60 | // Information kept for a descriptor. |
| 61 | struct Open_descriptor |
| 62 | { |
| 63 | // File name currently associated with descriptor. This is empty |
| 64 | // if none. |
| 65 | const char* name; |
| 66 | // Index of next descriptor on stack of released descriptors. |
| 67 | int stack_next; |
| 68 | // Whether the descriptor is currently in use. |
| 69 | bool inuse; |
| 70 | // Whether this is a write descriptor. |
| 71 | bool is_write; |
| 72 | // Whether the descriptor is on the stack. |
| 73 | bool is_on_stack; |
| 74 | }; |
| 75 | |
| 76 | bool |
| 77 | close_some_descriptor(); |
| 78 | |
| 79 | // We need to lock before accessing any fields. |
| 80 | Lock* lock_; |
| 81 | // Used to initialize the lock_ field exactly once. |
| 82 | Initialize_lock initialize_lock_; |
| 83 | // Information for descriptors. |
| 84 | std::vector<Open_descriptor> open_descriptors_; |
| 85 | // Top of stack. |
| 86 | int stack_top_; |
| 87 | // The current number of file descriptors open. |
| 88 | int current_; |
| 89 | // The maximum number of file descriptors we open. |
| 90 | int limit_; |
| 91 | }; |
| 92 | |
| 93 | // File descriptors are a centralized data structure, and we use a |
| 94 | // global variable rather than passing the data structure into every |
| 95 | // routine that does file I/O. |
| 96 | |
| 97 | extern Descriptors descriptors; |
| 98 | |
| 99 | inline int |
| 100 | open_descriptor(int descriptor, const char* name, int flags, int mode = 0) |
| 101 | { return descriptors.open(descriptor, name, flags, mode); } |
| 102 | |
| 103 | inline void |
| 104 | release_descriptor(int descriptor, bool permanent) |
| 105 | { descriptors.release(descriptor, permanent); } |
| 106 | |
| 107 | } // End namespace gold. |
| 108 | |
| 109 | #endif // !defined(GOLD_DESCRIPTORS_H) |