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.
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