xref: /netbsd-src/external/gpl3/binutils/dist/gold/descriptors.cc (revision 288bb96063654ec504ca8732afc683d3ebc514b5)
1 // descriptors.cc -- manage file descriptors for gold
2 
3 // Copyright 2008 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
5 
6 // This file is part of gold.
7 
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.
12 
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.
17 
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.
22 
23 #include "gold.h"
24 
25 #include <cerrno>
26 #include <cstring>
27 #include <fcntl.h>
28 #include <unistd.h>
29 
30 #include "parameters.h"
31 #include "gold-threads.h"
32 #include "descriptors.h"
33 
34 namespace gold
35 {
36 
37 // Class Descriptors.
38 
39 // The default for limit_ is meant to simply be large.  It gets
40 // adjusted downward if we run out of file descriptors.
41 
42 Descriptors::Descriptors()
43   : lock_(NULL), open_descriptors_(), stack_top_(-1), current_(0),
44     limit_(8192 - 16)
45 {
46   this->open_descriptors_.reserve(128);
47 }
48 
49 // Open a file.
50 
51 int
52 Descriptors::open(int descriptor, const char* name, int flags, int mode)
53 {
54   // We don't initialize this until we are called, because we can't
55   // initialize a Lock until we have parsed the options to find out
56   // whether we are running with threads.  We can be called before
57   // options are valid when reading a linker script.
58   if (this->lock_ == NULL)
59     {
60       if (parameters->options_valid())
61 	this->lock_ = new Lock();
62       else
63 	gold_assert(descriptor < 0);
64     }
65 
66   if (descriptor >= 0)
67     {
68       Hold_lock hl(*this->lock_);
69 
70       gold_assert(static_cast<size_t>(descriptor)
71 		  < this->open_descriptors_.size());
72       Open_descriptor* pod = &this->open_descriptors_[descriptor];
73       if (pod->name == name
74 	  || (pod->name != NULL && strcmp(pod->name, name) == 0))
75 	{
76 	  gold_assert(!pod->inuse);
77 	  pod->inuse = true;
78 	  return descriptor;
79 	}
80     }
81 
82   while (true)
83     {
84       int new_descriptor = ::open(name, flags, mode);
85       if (new_descriptor < 0
86 	  && errno != ENFILE
87 	  && errno != EMFILE)
88 	{
89 	  if (descriptor >= 0 && errno == ENOENT)
90 	    {
91 	      {
92 		Hold_lock hl(*this->lock_);
93 
94 		gold_error(_("file %s was removed during the link"),
95 			   this->open_descriptors_[descriptor].name);
96 	      }
97 
98 	      errno = ENOENT;
99 	    }
100 
101 	  return new_descriptor;
102 	}
103 
104       if (new_descriptor >= 0)
105 	{
106 	  Hold_optional_lock hl(this->lock_);
107 
108 	  if (static_cast<size_t>(new_descriptor)
109 	      >= this->open_descriptors_.size())
110 	    this->open_descriptors_.resize(new_descriptor + 64);
111 
112 	  Open_descriptor* pod = &this->open_descriptors_[new_descriptor];
113 	  pod->name = name;
114 	  pod->stack_next = -1;
115 	  pod->inuse = true;
116 	  pod->is_write = (flags & O_ACCMODE) != O_RDONLY;
117 
118 	  ++this->current_;
119 	  if (this->current_ >= this->limit_)
120 	    this->close_some_descriptor();
121 
122 	  return new_descriptor;
123 	}
124 
125       // We ran out of file descriptors.
126       {
127 	Hold_optional_lock hl(this->lock_);
128 
129 	this->limit_ = this->current_ - 16;
130 	if (this->limit_ < 8)
131 	  this->limit_ = 8;
132 	if (!this->close_some_descriptor())
133 	  gold_fatal(_("out of file descriptors and couldn't close any"));
134       }
135     }
136 }
137 
138 // Release a descriptor.
139 
140 void
141 Descriptors::release(int descriptor, bool permanent)
142 {
143   Hold_optional_lock hl(this->lock_);
144 
145   gold_assert(descriptor >= 0
146 	      && (static_cast<size_t>(descriptor)
147 		  < this->open_descriptors_.size()));
148   Open_descriptor* pod = &this->open_descriptors_[descriptor];
149 
150   if (permanent
151       || (this->current_ > this->limit_ && !pod->is_write))
152     {
153       if (::close(descriptor) < 0)
154 	gold_warning(_("while closing %s: %s"), pod->name, strerror(errno));
155       pod->name = NULL;
156       --this->current_;
157     }
158   else
159     {
160       pod->inuse = false;
161       if (!pod->is_write)
162 	{
163 	  pod->stack_next = this->stack_top_;
164 	  this->stack_top_ = descriptor;
165 	}
166     }
167 }
168 
169 // Close some descriptor.  The lock is held when this is called.  We
170 // close the descriptor on the top of the free stack.  Note that this
171 // is the opposite of an LRU algorithm--we close the most recently
172 // used descriptor.  That is because the linker tends to cycle through
173 // all the files; after we release a file, we are unlikely to need it
174 // again until we have looked at all the other files.  Return true if
175 // we closed a descriptor.
176 
177 bool
178 Descriptors::close_some_descriptor()
179 {
180   int last = -1;
181   int i = this->stack_top_;
182   while (i >= 0)
183     {
184       gold_assert(static_cast<size_t>(i) < this->open_descriptors_.size());
185       Open_descriptor* pod = &this->open_descriptors_[i];
186       if (!pod->inuse && !pod->is_write)
187 	{
188 	  if (::close(i) < 0)
189 	    gold_warning(_("while closing %s: %s"), pod->name, strerror(errno));
190 	  --this->current_;
191 	  pod->name = NULL;
192 	  if (last < 0)
193 	    this->stack_top_ = pod->stack_next;
194 	  else
195 	    this->open_descriptors_[last].stack_next = pod->stack_next;
196 	  return true;
197 	}
198       last = i;
199       i = pod->stack_next;
200     }
201 
202   // We couldn't find any descriptors to close.  This is weird but not
203   // necessarily an error.
204   return false;
205 }
206 
207 // The single global variable which manages descriptors.
208 
209 Descriptors descriptors;
210 
211 } // End namespace gold.
212