1 // descriptors.cc -- manage file descriptors for gold
3 // Copyright 2008, 2009 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
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.
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.
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.
31 #include "parameters.h"
33 #include "gold-threads.h"
34 #include "descriptors.h"
35 #include "binary-io.h"
37 // Very old systems may not define FD_CLOEXEC.
42 // O_CLOEXEC is only available on newer systems.
52 // The default for limit_ is meant to simply be large. It gets
53 // adjusted downward if we run out of file descriptors.
55 Descriptors::Descriptors()
56 : lock_(NULL), initialize_lock_(&this->lock_), open_descriptors_(),
57 stack_top_(-1), current_(0), limit_(8192 - 16)
59 this->open_descriptors_.reserve(128);
65 Descriptors::open(int descriptor, const char* name, int flags, int mode)
67 // We don't initialize this until we are called, because we can't
68 // initialize a Lock until we have parsed the options to find out
69 // whether we are running with threads. We can be called before
70 // options are valid when reading a linker script.
71 bool lock_initialized = this->initialize_lock_.initialize();
73 gold_assert(lock_initialized || descriptor < 0);
77 Hold_lock hl(*this->lock_);
79 gold_assert(static_cast<size_t>(descriptor)
80 < this->open_descriptors_.size());
81 Open_descriptor* pod = &this->open_descriptors_[descriptor];
83 || (pod->name != NULL && strcmp(pod->name, name) == 0))
85 gold_assert(!pod->inuse);
87 if (descriptor == this->stack_top_)
89 this->stack_top_ = pod->stack_next;
91 pod->is_on_stack = false;
99 // We always want to set the close-on-exec flag; we don't
100 // require callers to pass it.
103 // Always open the file as a binary file.
106 int new_descriptor = ::open(name, flags, mode);
107 if (new_descriptor < 0
111 if (descriptor >= 0 && errno == ENOENT)
114 Hold_lock hl(*this->lock_);
116 gold_error(_("file %s was removed during the link"), name);
122 return new_descriptor;
125 if (new_descriptor >= 0)
127 // If we have any plugins, we really do need to set the
128 // close-on-exec flag, even if O_CLOEXEC is not defined.
129 // FIXME: In some cases O_CLOEXEC may be defined in the
130 // header file but not supported by the kernel.
131 // Unfortunately there doesn't seem to be any obvious way to
132 // detect that, as unknown flags passed to open are ignored.
134 && parameters->options_valid()
135 && parameters->options().has_plugins())
136 fcntl(new_descriptor, F_SETFD, FD_CLOEXEC);
139 Hold_optional_lock hl(this->lock_);
141 if (static_cast<size_t>(new_descriptor)
142 >= this->open_descriptors_.size())
143 this->open_descriptors_.resize(new_descriptor + 64);
145 Open_descriptor* pod = &this->open_descriptors_[new_descriptor];
147 pod->stack_next = -1;
149 pod->is_write = (flags & O_ACCMODE) != O_RDONLY;
150 pod->is_on_stack = false;
153 if (this->current_ >= this->limit_)
154 this->close_some_descriptor();
156 return new_descriptor;
160 // We ran out of file descriptors.
162 Hold_optional_lock hl(this->lock_);
164 this->limit_ = this->current_ - 16;
165 if (this->limit_ < 8)
167 if (!this->close_some_descriptor())
168 gold_fatal(_("out of file descriptors and couldn't close any"));
173 // Release a descriptor.
176 Descriptors::release(int descriptor, bool permanent)
178 Hold_optional_lock hl(this->lock_);
180 gold_assert(descriptor >= 0
181 && (static_cast<size_t>(descriptor)
182 < this->open_descriptors_.size()));
183 Open_descriptor* pod = &this->open_descriptors_[descriptor];
186 || (this->current_ > this->limit_ && !pod->is_write))
188 if (::close(descriptor) < 0)
189 gold_warning(_("while closing %s: %s"), pod->name, strerror(errno));
196 if (!pod->is_write && !pod->is_on_stack)
198 pod->stack_next = this->stack_top_;
199 this->stack_top_ = descriptor;
200 pod->is_on_stack = true;
205 // Close some descriptor. The lock is held when this is called. We
206 // close the descriptor on the top of the free stack. Note that this
207 // is the opposite of an LRU algorithm--we close the most recently
208 // used descriptor. That is because the linker tends to cycle through
209 // all the files; after we release a file, we are unlikely to need it
210 // again until we have looked at all the other files. Return true if
211 // we closed a descriptor.
214 Descriptors::close_some_descriptor()
217 int i = this->stack_top_;
220 gold_assert(static_cast<size_t>(i) < this->open_descriptors_.size());
221 Open_descriptor* pod = &this->open_descriptors_[i];
222 if (!pod->inuse && !pod->is_write)
225 gold_warning(_("while closing %s: %s"), pod->name, strerror(errno));
229 this->stack_top_ = pod->stack_next;
231 this->open_descriptors_[last].stack_next = pod->stack_next;
232 pod->stack_next = -1;
233 pod->is_on_stack = false;
240 // We couldn't find any descriptors to close. This is weird but not
241 // necessarily an error.
245 // The single global variable which manages descriptors.
247 Descriptors descriptors;
249 } // End namespace gold.