1 // fileread.h -- read files for gold -*- C++ -*-
3 // Copyright 2006, 2007 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 // Classes used to read data from binary input files.
25 #ifndef GOLD_FILEREAD_H
26 #define GOLD_FILEREAD_H
38 class Position_dependent_options;
39 class Input_file_argument;
43 // File_read manages a file descriptor for a file we are reading. We
44 // close file descriptors if we run out of them, so this class reopens
45 // the file as needed.
51 : name_(), descriptor_(-1), object_count_(0), size_(0), token_(false),
52 views_(), saved_views_(), contents_(NULL), mapped_bytes_(0),
60 open(const Task*, const std::string& name);
62 // Pretend to open the file, but provide the file contents. No
63 // actual file system activity will occur. This is used for
66 open(const Task*, const std::string& name, const unsigned char* contents,
69 // Return the file name.
72 { return this->name_; }
74 // Add an object associated with a file.
77 { ++this->object_count_; }
79 // Remove an object associated with a file.
82 { --this->object_count_; }
84 // Lock the file for exclusive access within a particular Task::run
85 // execution. This means that the descriptor can not be closed.
86 // This routine may only be called when the workqueue lock is held.
90 // Unlock the descriptor, permitting it to be closed if necessary.
92 unlock(const Task* t);
94 // Test whether the object is locked.
98 // Return the token, so that the task can be queued.
101 { return &this->token_; }
103 // Release the file. This indicates that we aren't going to do
104 // anything further with it until it is unlocked. This is used
105 // because a Task which locks the file never calls either lock or
106 // unlock; it just locks the token. The basic rule is that a Task
107 // which locks a file via the Task::locks interface must explicitly
108 // call release() when it is done. This is not necessary for code
109 // which calls unlock() on the file.
113 // Return the size of the file.
116 { return this->size_; }
118 // Return a view into the file starting at file offset START for
119 // SIZE bytes. The pointer will remain valid until the File_read is
120 // unlocked. It is an error if we can not read enough data from the
121 // file. The CACHE parameter is a hint as to whether it will be
122 // useful to cache this data for later accesses--i.e., later calls
123 // to get_view, read, or get_lasting_view which retrieve the same
126 get_view(off_t start, section_size_type size, bool cache);
128 // Read data from the file into the buffer P starting at file offset
129 // START for SIZE bytes.
131 read(off_t start, section_size_type size, void* p) const;
133 // Return a lasting view into the file starting at file offset START
134 // for SIZE bytes. This is allocated with new, and the caller is
135 // responsible for deleting it when done. The data associated with
136 // this view will remain valid until the view is deleted. It is an
137 // error if we can not read enough data from the file. The CACHE
138 // parameter is as in get_view.
140 get_lasting_view(off_t start, section_size_type size, bool cache);
142 // Mark all views as no longer cached.
144 clear_view_cache_marks();
146 // A struct used to do a multiple read.
147 struct Read_multiple_entry
149 // The file offset of the data to read.
151 // The amount of data to read.
152 section_size_type size;
153 // The buffer where the data should be placed.
154 unsigned char* buffer;
156 Read_multiple_entry(off_t o, section_size_type s, unsigned char* b)
157 : file_offset(o), size(s), buffer(b)
161 typedef std::vector<Read_multiple_entry> Read_multiple;
163 // Read a bunch of data from the file into various different
164 // locations. The vector must be sorted by ascending file_offset.
165 // BASE is a base offset to be added to all the offsets in the
168 read_multiple(off_t base, const Read_multiple&);
170 // Dump statistical information to stderr.
175 // This class may not be copied.
176 File_read(const File_read&);
177 File_read& operator=(const File_read&);
179 // Total bytes mapped into memory during the link. This variable
180 // may not be accurate when running multi-threaded.
181 static unsigned long long total_mapped_bytes;
183 // Current number of bytes mapped into memory during the link. This
184 // variable may not be accurate when running multi-threaded.
185 static unsigned long long current_mapped_bytes;
187 // High water mark of bytes mapped into memory during the link.
188 // This variable may not be accurate when running multi-threaded.
189 static unsigned long long maximum_mapped_bytes;
191 // A view into the file.
195 View(off_t start, section_size_type size, const unsigned char* data,
196 bool cache, bool mapped)
197 : start_(start), size_(size), data_(data), lock_count_(0),
198 cache_(cache), mapped_(mapped), accessed_(true)
205 { return this->start_; }
209 { return this->size_; }
213 { return this->data_; }
226 { this->cache_ = true; }
230 { this->cache_ = false; }
234 { return this->cache_; }
238 { this->accessed_ = true; }
242 { this->accessed_= false; }
246 { return this->accessed_; }
250 View& operator=(const View&);
253 section_size_type size_;
254 const unsigned char* data_;
262 friend class File_view;
264 // Find a view into the file.
266 find_view(off_t start, section_size_type size) const;
268 // Read data from the file into a buffer.
270 do_read(off_t start, section_size_type size, void* p) const;
272 // Find or make a view into the file.
274 find_or_make_view(off_t start, section_size_type size, bool cache);
276 // Clear the file views.
280 // The size of a file page for buffering data.
281 static const off_t page_size = 8192;
283 // Given a file offset, return the page offset.
285 page_offset(off_t file_offset)
286 { return file_offset & ~ (page_size - 1); }
288 // Given a file size, return the size to read integral pages.
290 pages(off_t file_size)
291 { return (file_size + (page_size - 1)) & ~ (page_size - 1); }
293 // The type of a mapping from page start to views.
294 typedef std::map<off_t, View*> Views;
296 // A simple list of Views.
297 typedef std::list<View*> Saved_views;
299 // The maximum number of entries we will pass to ::readv.
300 static const size_t max_readv_entries = 128;
302 // Use readv to read data.
304 do_readv(off_t base, const Read_multiple&, size_t start, size_t count);
310 // The number of objects associated with this file. This will be
311 // more than 1 in the case of an archive.
315 // A token used to lock the file.
317 // Buffered views into the file.
319 // List of views which were locked but had to be removed from views_
320 // because they were not large enough.
321 Saved_views saved_views_;
322 // Specified file contents. Used only for testing purposes.
323 const unsigned char* contents_;
324 // Total amount of space mapped into memory. This is only changed
325 // while the file is locked. When we unlock the file, we transfer
326 // the total to total_mapped_bytes, and reset this to zero.
327 size_t mapped_bytes_;
328 // Whether the file was released.
332 // A view of file data that persists even when the file is unlocked.
333 // Callers should destroy these when no longer required. These are
334 // obtained form File_read::get_lasting_view. They may only be
335 // destroyed when the underlying File_read is locked.
340 // This may only be called when the underlying File_read is locked.
343 // Return a pointer to the data associated with this view.
346 { return this->data_; }
349 File_view(const File_view&);
350 File_view& operator=(const File_view&);
352 friend class File_read;
354 // Callers have to get these via File_read::get_lasting_view.
355 File_view(File_read& file, File_read::View* view, const unsigned char* data)
356 : file_(file), view_(view), data_(data)
360 File_read::View* view_;
361 const unsigned char* data_;
364 // All the information we hold for a single input file. This can be
365 // an object file, a shared library, or an archive.
370 Input_file(const Input_file_argument* input_argument)
371 : input_argument_(input_argument), found_name_(), file_(),
372 is_in_sysroot_(false)
375 // Create an input file with the contents already provided. This is
376 // only used for testing. With this path, don't call the open
378 Input_file(const Task*, const char* name, const unsigned char* contents,
381 // Open the file. If the open fails, this will report an error and
384 open(const General_options&, const Dirsearch&, const Task*);
386 // Return the name given by the user. For -lc this will return "c".
390 // Return the file name. For -lc this will return something like
391 // "/usr/lib/libc.so".
394 { return this->file_.filename(); }
396 // Return the name under which we found the file, corresponding to
397 // the command line. For -lc this will return something like
401 { return this->found_name_; }
403 // Return the position dependent options.
404 const Position_dependent_options&
410 { return this->file_; }
414 { return this->file_; }
416 // Whether we found the file in a directory in the system root.
418 is_in_sysroot() const
419 { return this->is_in_sysroot_; }
421 // Return whether this file is to be read only for its symbols.
423 just_symbols() const;
426 Input_file(const Input_file&);
427 Input_file& operator=(const Input_file&);
429 // Open a binary file.
431 open_binary(const General_options&, const Task* task,
432 const std::string& name);
434 // The argument from the command line.
435 const Input_file_argument* input_argument_;
436 // The name under which we opened the file. This is like the name
437 // on the command line, but -lc turns into libc.so (or whatever).
438 // It only includes the full path if the path was on the command
440 std::string found_name_;
441 // The file after we open it.
443 // Whether we found the file in a directory in the system root.
447 } // end namespace gold
449 #endif // !defined(GOLD_FILEREAD_H)