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.
30 #include "parameters.h"
32 #include "gold-threads.h"
33 #include "descriptors.h"
35 // Very old systems may not define FD_CLOEXEC.
40 // O_CLOEXEC is only available on newer systems.
50 // The default for limit_ is meant to simply be large. It gets
51 // adjusted downward if we run out of file descriptors.
53 Descriptors::Descriptors()
54 : lock_(NULL), initialize_lock_(&this->lock_), open_descriptors_(),
55 stack_top_(-1), current_(0), limit_(8192 - 16)
57 this->open_descriptors_.reserve(128);
63 Descriptors::open(int descriptor, const char* name, int flags, int mode)
65 // We don't initialize this until we are called, because we can't
66 // initialize a Lock until we have parsed the options to find out
67 // whether we are running with threads. We can be called before
68 // options are valid when reading a linker script.
69 bool lock_initialized = this->initialize_lock_.initialize();
71 gold_assert(lock_initialized || descriptor < 0);
75 Hold_lock hl(*this->lock_);
77 gold_assert(static_cast<size_t>(descriptor)
78 < this->open_descriptors_.size());
79 Open_descriptor* pod = &this->open_descriptors_[descriptor];
81 || (pod->name != NULL && strcmp(pod->name, name) == 0))
83 gold_assert(!pod->inuse);
85 if (descriptor == this->stack_top_)
87 this->stack_top_ = pod->stack_next;
89 pod->is_on_stack = false;
97 // We always want to set the close-on-exec flag; we don't
98 // require callers to pass it.
101 int new_descriptor = ::open(name, flags, mode);
102 if (new_descriptor < 0
106 if (descriptor >= 0 && errno == ENOENT)
109 Hold_lock hl(*this->lock_);
111 gold_error(_("file %s was removed during the link"),
112 this->open_descriptors_[descriptor].name);
118 return new_descriptor;
121 if (new_descriptor >= 0)
123 // If we have any plugins, we really do need to set the
124 // close-on-exec flag, even if O_CLOEXEC is not defined.
125 // FIXME: In some cases O_CLOEXEC may be defined in the
126 // header file but not supported by the kernel.
127 // Unfortunately there doesn't seem to be any obvious way to
128 // detect that, as unknown flags passed to open are ignored.
130 && parameters->options_valid()
131 && parameters->options().has_plugins())
132 fcntl(new_descriptor, F_SETFD, FD_CLOEXEC);
135 Hold_optional_lock hl(this->lock_);
137 if (static_cast<size_t>(new_descriptor)
138 >= this->open_descriptors_.size())
139 this->open_descriptors_.resize(new_descriptor + 64);
141 Open_descriptor* pod = &this->open_descriptors_[new_descriptor];
143 pod->stack_next = -1;
145 pod->is_write = (flags & O_ACCMODE) != O_RDONLY;
146 pod->is_on_stack = false;
149 if (this->current_ >= this->limit_)
150 this->close_some_descriptor();
152 return new_descriptor;
156 // We ran out of file descriptors.
158 Hold_optional_lock hl(this->lock_);
160 this->limit_ = this->current_ - 16;
161 if (this->limit_ < 8)
163 if (!this->close_some_descriptor())
164 gold_fatal(_("out of file descriptors and couldn't close any"));
169 // Release a descriptor.
172 Descriptors::release(int descriptor, bool permanent)
174 Hold_optional_lock hl(this->lock_);
176 gold_assert(descriptor >= 0
177 && (static_cast<size_t>(descriptor)
178 < this->open_descriptors_.size()));
179 Open_descriptor* pod = &this->open_descriptors_[descriptor];
182 || (this->current_ > this->limit_ && !pod->is_write))
184 if (::close(descriptor) < 0)
185 gold_warning(_("while closing %s: %s"), pod->name, strerror(errno));
192 if (!pod->is_write && !pod->is_on_stack)
194 pod->stack_next = this->stack_top_;
195 this->stack_top_ = descriptor;
196 pod->is_on_stack = true;
201 // Close some descriptor. The lock is held when this is called. We
202 // close the descriptor on the top of the free stack. Note that this
203 // is the opposite of an LRU algorithm--we close the most recently
204 // used descriptor. That is because the linker tends to cycle through
205 // all the files; after we release a file, we are unlikely to need it
206 // again until we have looked at all the other files. Return true if
207 // we closed a descriptor.
210 Descriptors::close_some_descriptor()
213 int i = this->stack_top_;
216 gold_assert(static_cast<size_t>(i) < this->open_descriptors_.size());
217 Open_descriptor* pod = &this->open_descriptors_[i];
218 if (!pod->inuse && !pod->is_write)
221 gold_warning(_("while closing %s: %s"), pod->name, strerror(errno));
225 this->stack_top_ = pod->stack_next;
227 this->open_descriptors_[last].stack_next = pod->stack_next;
228 pod->stack_next = -1;
229 pod->is_on_stack = false;
236 // We couldn't find any descriptors to close. This is weird but not
237 // necessarily an error.
241 // The single global variable which manages descriptors.
243 Descriptors descriptors;
245 } // End namespace gold.