1 // descriptors.cc -- manage file descriptors for gold
3 // Copyright (C) 2008-2017 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.
32 #include "parameters.h"
34 #include "gold-threads.h"
35 #include "descriptors.h"
36 #include "binary-io.h"
38 // O_CLOEXEC is only available on newer systems.
43 // Very old systems may not define FD_CLOEXEC.
49 set_close_on_exec(int fd ATTRIBUTE_UNUSED
)
51 // Mingw does not define F_SETFD.
53 fcntl(fd
, F_SETFD
, FD_CLOEXEC
);
62 // The default for limit_ is meant to simply be large. It gets
63 // adjusted downward if we run out of file descriptors.
65 Descriptors::Descriptors()
66 : lock_(NULL
), initialize_lock_(&this->lock_
), open_descriptors_(),
67 stack_top_(-1), current_(0), limit_(8192 - 16)
69 this->open_descriptors_
.reserve(128);
75 Descriptors::open(int descriptor
, const char* name
, int flags
, int mode
)
77 // We don't initialize this until we are called, because we can't
78 // initialize a Lock until we have parsed the options to find out
79 // whether we are running with threads. We can be called before
80 // options are valid when reading a linker script.
81 bool lock_initialized
= this->initialize_lock_
.initialize();
83 gold_assert(lock_initialized
|| descriptor
< 0);
85 if (is_debugging_enabled(DEBUG_FILES
))
90 Hold_lock
hl(*this->lock_
);
92 gold_assert(static_cast<size_t>(descriptor
)
93 < this->open_descriptors_
.size());
94 Open_descriptor
* pod
= &this->open_descriptors_
[descriptor
];
96 || (pod
->name
!= NULL
&& strcmp(pod
->name
, name
) == 0))
98 gold_assert(!pod
->inuse
);
100 if (descriptor
== this->stack_top_
)
102 this->stack_top_
= pod
->stack_next
;
103 pod
->stack_next
= -1;
104 pod
->is_on_stack
= false;
106 gold_debug(DEBUG_FILES
, "Reused existing descriptor %d for \"%s\"",
114 // We always want to set the close-on-exec flag; we don't
115 // require callers to pass it.
118 // Always open the file as a binary file.
121 int new_descriptor
= ::open(name
, flags
, mode
);
122 if (new_descriptor
< 0
126 if (descriptor
>= 0 && errno
== ENOENT
)
129 Hold_lock
hl(*this->lock_
);
131 gold_error(_("file %s was removed during the link"), name
);
137 gold_debug(DEBUG_FILES
, "Opened new descriptor %d for \"%s\"",
138 new_descriptor
, name
);
139 return new_descriptor
;
142 if (new_descriptor
>= 0)
144 // If we have any plugins, we really do need to set the
145 // close-on-exec flag, even if O_CLOEXEC is not defined.
146 // FIXME: In some cases O_CLOEXEC may be defined in the
147 // header file but not supported by the kernel.
148 // Unfortunately there doesn't seem to be any obvious way to
149 // detect that, as unknown flags passed to open are ignored.
151 && parameters
->options_valid()
152 && parameters
->options().has_plugins())
153 set_close_on_exec(new_descriptor
);
156 Hold_optional_lock
hl(this->lock_
);
158 if (static_cast<size_t>(new_descriptor
)
159 >= this->open_descriptors_
.size())
160 this->open_descriptors_
.resize(new_descriptor
+ 64);
162 Open_descriptor
* pod
= &this->open_descriptors_
[new_descriptor
];
164 pod
->stack_next
= -1;
166 pod
->is_write
= (flags
& O_ACCMODE
) != O_RDONLY
;
167 pod
->is_on_stack
= false;
170 if (this->current_
>= this->limit_
)
171 this->close_some_descriptor();
173 gold_debug(DEBUG_FILES
, "Opened new descriptor %d for \"%s\"",
174 new_descriptor
, name
);
175 return new_descriptor
;
179 // We ran out of file descriptors.
181 Hold_optional_lock
hl(this->lock_
);
183 this->limit_
= this->current_
- 16;
184 if (this->limit_
< 8)
186 if (!this->close_some_descriptor())
187 gold_fatal(_("out of file descriptors and couldn't close any"));
192 // Release a descriptor.
195 Descriptors::release(int descriptor
, bool permanent
)
197 Hold_optional_lock
hl(this->lock_
);
199 gold_assert(descriptor
>= 0
200 && (static_cast<size_t>(descriptor
)
201 < this->open_descriptors_
.size()));
202 Open_descriptor
* pod
= &this->open_descriptors_
[descriptor
];
205 || (this->current_
> this->limit_
&& !pod
->is_write
))
207 if (::close(descriptor
) < 0)
208 gold_warning(_("while closing %s: %s"), pod
->name
, strerror(errno
));
215 if (!pod
->is_write
&& !pod
->is_on_stack
)
217 pod
->stack_next
= this->stack_top_
;
218 this->stack_top_
= descriptor
;
219 pod
->is_on_stack
= true;
223 gold_debug(DEBUG_FILES
, "Released descriptor %d for \"%s\"",
224 descriptor
, pod
->name
);
227 // Close some descriptor. The lock is held when this is called. We
228 // close the descriptor on the top of the free stack. Note that this
229 // is the opposite of an LRU algorithm--we close the most recently
230 // used descriptor. That is because the linker tends to cycle through
231 // all the files; after we release a file, we are unlikely to need it
232 // again until we have looked at all the other files. Return true if
233 // we closed a descriptor.
236 Descriptors::close_some_descriptor()
239 int i
= this->stack_top_
;
242 gold_assert(static_cast<size_t>(i
) < this->open_descriptors_
.size());
243 Open_descriptor
* pod
= &this->open_descriptors_
[i
];
244 if (!pod
->inuse
&& !pod
->is_write
)
247 gold_warning(_("while closing %s: %s"), pod
->name
, strerror(errno
));
249 gold_debug(DEBUG_FILES
, "Closed descriptor %d for \"%s\"",
253 this->stack_top_
= pod
->stack_next
;
255 this->open_descriptors_
[last
].stack_next
= pod
->stack_next
;
256 pod
->stack_next
= -1;
257 pod
->is_on_stack
= false;
264 // We couldn't find any descriptors to close. This is weird but not
265 // necessarily an error.
269 // Close all the descriptors open for reading.
272 Descriptors::close_all()
274 Hold_optional_lock
hl(this->lock_
);
276 for (size_t i
= 0; i
< this->open_descriptors_
.size(); i
++)
278 Open_descriptor
* pod
= &this->open_descriptors_
[i
];
279 if (pod
->name
!= NULL
&& !pod
->inuse
&& !pod
->is_write
)
282 gold_warning(_("while closing %s: %s"), pod
->name
, strerror(errno
));
283 gold_debug(DEBUG_FILES
, "Closed descriptor %d for \"%s\" (close_all)",
284 static_cast<int>(i
), pod
->name
);
286 pod
->stack_next
= -1;
287 pod
->is_on_stack
= false;
290 this->stack_top_
= -1;
293 // The single global variable which manages descriptors.
295 Descriptors descriptors
;
297 } // End namespace gold.
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