gas/
[binutils.git] / gold / descriptors.cc
blob2ab0d5c8816306dd58d561bf69a08e47d0f6ef57
1 // descriptors.cc -- manage file descriptors for gold
3 // Copyright 2008, 2009, 2010, 2011 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.
23 #include "gold.h"
25 #include <cerrno>
26 #include <cstdio>
27 #include <cstring>
28 #include <fcntl.h>
29 #include <unistd.h>
31 #include "parameters.h"
32 #include "options.h"
33 #include "gold-threads.h"
34 #include "descriptors.h"
35 #include "binary-io.h"
37 // O_CLOEXEC is only available on newer systems.
38 #ifndef O_CLOEXEC
39 #define O_CLOEXEC 0
40 #endif
42 // Very old systems may not define FD_CLOEXEC.
43 #ifndef FD_CLOEXEC
44 #define FD_CLOEXEC 1
45 #endif
47 static inline void
48 set_close_on_exec(int fd)
50 // Mingw does not define F_SETFD.
51 #ifdef F_SETFD
52 fcntl(fd, F_SETFD, FD_CLOEXEC);
53 #endif
56 namespace gold
59 // Class Descriptors.
61 // The default for limit_ is meant to simply be large. It gets
62 // adjusted downward if we run out of file descriptors.
64 Descriptors::Descriptors()
65 : lock_(NULL), initialize_lock_(&this->lock_), open_descriptors_(),
66 stack_top_(-1), current_(0), limit_(8192 - 16)
68 this->open_descriptors_.reserve(128);
71 // Open a file.
73 int
74 Descriptors::open(int descriptor, const char* name, int flags, int mode)
76 // We don't initialize this until we are called, because we can't
77 // initialize a Lock until we have parsed the options to find out
78 // whether we are running with threads. We can be called before
79 // options are valid when reading a linker script.
80 bool lock_initialized = this->initialize_lock_.initialize();
82 gold_assert(lock_initialized || descriptor < 0);
84 if (descriptor >= 0)
86 Hold_lock hl(*this->lock_);
88 gold_assert(static_cast<size_t>(descriptor)
89 < this->open_descriptors_.size());
90 Open_descriptor* pod = &this->open_descriptors_[descriptor];
91 if (pod->name == name
92 || (pod->name != NULL && strcmp(pod->name, name) == 0))
94 gold_assert(!pod->inuse);
95 pod->inuse = true;
96 if (descriptor == this->stack_top_)
98 this->stack_top_ = pod->stack_next;
99 pod->stack_next = -1;
100 pod->is_on_stack = false;
102 return descriptor;
106 while (true)
108 // We always want to set the close-on-exec flag; we don't
109 // require callers to pass it.
110 flags |= O_CLOEXEC;
112 // Always open the file as a binary file.
113 flags |= O_BINARY;
115 int new_descriptor = ::open(name, flags, mode);
116 if (new_descriptor < 0
117 && errno != ENFILE
118 && errno != EMFILE)
120 if (descriptor >= 0 && errno == ENOENT)
123 Hold_lock hl(*this->lock_);
125 gold_error(_("file %s was removed during the link"), name);
128 errno = ENOENT;
131 return new_descriptor;
134 if (new_descriptor >= 0)
136 // If we have any plugins, we really do need to set the
137 // close-on-exec flag, even if O_CLOEXEC is not defined.
138 // FIXME: In some cases O_CLOEXEC may be defined in the
139 // header file but not supported by the kernel.
140 // Unfortunately there doesn't seem to be any obvious way to
141 // detect that, as unknown flags passed to open are ignored.
142 if (O_CLOEXEC == 0
143 && parameters->options_valid()
144 && parameters->options().has_plugins())
145 set_close_on_exec(new_descriptor);
148 Hold_optional_lock hl(this->lock_);
150 if (static_cast<size_t>(new_descriptor)
151 >= this->open_descriptors_.size())
152 this->open_descriptors_.resize(new_descriptor + 64);
154 Open_descriptor* pod = &this->open_descriptors_[new_descriptor];
155 pod->name = name;
156 pod->stack_next = -1;
157 pod->inuse = true;
158 pod->is_write = (flags & O_ACCMODE) != O_RDONLY;
159 pod->is_on_stack = false;
161 ++this->current_;
162 if (this->current_ >= this->limit_)
163 this->close_some_descriptor();
165 return new_descriptor;
169 // We ran out of file descriptors.
171 Hold_optional_lock hl(this->lock_);
173 this->limit_ = this->current_ - 16;
174 if (this->limit_ < 8)
175 this->limit_ = 8;
176 if (!this->close_some_descriptor())
177 gold_fatal(_("out of file descriptors and couldn't close any"));
182 // Release a descriptor.
184 void
185 Descriptors::release(int descriptor, bool permanent)
187 Hold_optional_lock hl(this->lock_);
189 gold_assert(descriptor >= 0
190 && (static_cast<size_t>(descriptor)
191 < this->open_descriptors_.size()));
192 Open_descriptor* pod = &this->open_descriptors_[descriptor];
194 if (permanent
195 || (this->current_ > this->limit_ && !pod->is_write))
197 if (::close(descriptor) < 0)
198 gold_warning(_("while closing %s: %s"), pod->name, strerror(errno));
199 pod->name = NULL;
200 --this->current_;
202 else
204 pod->inuse = false;
205 if (!pod->is_write && !pod->is_on_stack)
207 pod->stack_next = this->stack_top_;
208 this->stack_top_ = descriptor;
209 pod->is_on_stack = true;
214 // Close some descriptor. The lock is held when this is called. We
215 // close the descriptor on the top of the free stack. Note that this
216 // is the opposite of an LRU algorithm--we close the most recently
217 // used descriptor. That is because the linker tends to cycle through
218 // all the files; after we release a file, we are unlikely to need it
219 // again until we have looked at all the other files. Return true if
220 // we closed a descriptor.
222 bool
223 Descriptors::close_some_descriptor()
225 int last = -1;
226 int i = this->stack_top_;
227 while (i >= 0)
229 gold_assert(static_cast<size_t>(i) < this->open_descriptors_.size());
230 Open_descriptor* pod = &this->open_descriptors_[i];
231 if (!pod->inuse && !pod->is_write)
233 if (::close(i) < 0)
234 gold_warning(_("while closing %s: %s"), pod->name, strerror(errno));
235 --this->current_;
236 pod->name = NULL;
237 if (last < 0)
238 this->stack_top_ = pod->stack_next;
239 else
240 this->open_descriptors_[last].stack_next = pod->stack_next;
241 pod->stack_next = -1;
242 pod->is_on_stack = false;
243 return true;
245 last = i;
246 i = pod->stack_next;
249 // We couldn't find any descriptors to close. This is weird but not
250 // necessarily an error.
251 return false;
254 // The single global variable which manages descriptors.
256 Descriptors descriptors;
258 } // End namespace gold.