| 1 | // fileread.h -- read files for gold -*- C++ -*- |
| 2 | |
| 3 | // Copyright 2006, 2007 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 | // Classes used to read data from binary input files. |
| 24 | |
| 25 | #ifndef GOLD_FILEREAD_H |
| 26 | #define GOLD_FILEREAD_H |
| 27 | |
| 28 | #include <list> |
| 29 | #include <map> |
| 30 | #include <string> |
| 31 | |
| 32 | #include "options.h" |
| 33 | #include "token.h" |
| 34 | |
| 35 | namespace gold |
| 36 | { |
| 37 | |
| 38 | class Dirsearch; |
| 39 | class File_view; |
| 40 | |
| 41 | // File_read manages a file descriptor for a file we are reading. We |
| 42 | // close file descriptors if we run out of them, so this class reopens |
| 43 | // the file as needed. |
| 44 | |
| 45 | class File_read |
| 46 | { |
| 47 | public: |
| 48 | File_read() |
| 49 | : name_(), descriptor_(-1), size_(0), token_(false), views_(), |
| 50 | saved_views_(), contents_(NULL), mapped_bytes_(0), released_(true) |
| 51 | { } |
| 52 | |
| 53 | ~File_read(); |
| 54 | |
| 55 | // Open a file. |
| 56 | bool |
| 57 | open(const Task*, const std::string& name); |
| 58 | |
| 59 | // Pretend to open the file, but provide the file contents. No |
| 60 | // actual file system activity will occur. This is used for |
| 61 | // testing. |
| 62 | bool |
| 63 | open(const Task*, const std::string& name, const unsigned char* contents, |
| 64 | off_t size); |
| 65 | |
| 66 | // Return the file name. |
| 67 | const std::string& |
| 68 | filename() const |
| 69 | { return this->name_; } |
| 70 | |
| 71 | // Lock the file for exclusive access within a particular Task::run |
| 72 | // execution. This means that the descriptor can not be closed. |
| 73 | // This routine may only be called when the workqueue lock is held. |
| 74 | void |
| 75 | lock(const Task* t); |
| 76 | |
| 77 | // Unlock the descriptor, permitting it to be closed if necessary. |
| 78 | void |
| 79 | unlock(const Task* t); |
| 80 | |
| 81 | // Test whether the object is locked. |
| 82 | bool |
| 83 | is_locked() const; |
| 84 | |
| 85 | // Return the token, so that the task can be queued. |
| 86 | Task_token* |
| 87 | token() |
| 88 | { return &this->token_; } |
| 89 | |
| 90 | // Release the file. This indicates that we aren't going to do |
| 91 | // anything further with it until it is unlocked. This is used |
| 92 | // because a Task which locks the file never calls either lock or |
| 93 | // unlock; it just locks the token. The basic rule is that a Task |
| 94 | // which locks a file via the Task::locks interface must explicitly |
| 95 | // call release() when it is done. This is not necessary for code |
| 96 | // which calls unlock() on the file. |
| 97 | void |
| 98 | release(); |
| 99 | |
| 100 | // Return the size of the file. |
| 101 | off_t |
| 102 | filesize() const |
| 103 | { return this->size_; } |
| 104 | |
| 105 | // Return a view into the file starting at file offset START for |
| 106 | // SIZE bytes. The pointer will remain valid until the File_read is |
| 107 | // unlocked. It is an error if we can not read enough data from the |
| 108 | // file. The CACHE parameter is a hint as to whether it will be |
| 109 | // useful to cache this data for later accesses--i.e., later calls |
| 110 | // to get_view, read, or get_lasting_view which retrieve the same |
| 111 | // data. |
| 112 | const unsigned char* |
| 113 | get_view(off_t start, section_size_type size, bool cache); |
| 114 | |
| 115 | // Read data from the file into the buffer P starting at file offset |
| 116 | // START for SIZE bytes. |
| 117 | void |
| 118 | read(off_t start, section_size_type size, void* p) const; |
| 119 | |
| 120 | // Return a lasting view into the file starting at file offset START |
| 121 | // for SIZE bytes. This is allocated with new, and the caller is |
| 122 | // responsible for deleting it when done. The data associated with |
| 123 | // this view will remain valid until the view is deleted. It is an |
| 124 | // error if we can not read enough data from the file. The CACHE |
| 125 | // parameter is as in get_view. |
| 126 | File_view* |
| 127 | get_lasting_view(off_t start, section_size_type size, bool cache); |
| 128 | |
| 129 | // Dump statistical information to stderr. |
| 130 | static void |
| 131 | print_stats(); |
| 132 | |
| 133 | private: |
| 134 | // This class may not be copied. |
| 135 | File_read(const File_read&); |
| 136 | File_read& operator=(const File_read&); |
| 137 | |
| 138 | // Total bytes mapped into memory during the link. This variable |
| 139 | // may not be accurate when running multi-threaded. |
| 140 | static unsigned long long total_mapped_bytes; |
| 141 | |
| 142 | // Current number of bytes mapped into memory during the link. This |
| 143 | // variable may not be accurate when running multi-threaded. |
| 144 | static unsigned long long current_mapped_bytes; |
| 145 | |
| 146 | // High water mark of bytes mapped into memory during the link. |
| 147 | // This variable may not be accurate when running multi-threaded. |
| 148 | static unsigned long long maximum_mapped_bytes; |
| 149 | |
| 150 | // A view into the file. |
| 151 | class View |
| 152 | { |
| 153 | public: |
| 154 | View(off_t start, section_size_type size, const unsigned char* data, |
| 155 | bool cache, bool mapped) |
| 156 | : start_(start), size_(size), data_(data), lock_count_(0), |
| 157 | cache_(cache), mapped_(mapped) |
| 158 | { } |
| 159 | |
| 160 | ~View(); |
| 161 | |
| 162 | off_t |
| 163 | start() const |
| 164 | { return this->start_; } |
| 165 | |
| 166 | section_size_type |
| 167 | size() const |
| 168 | { return this->size_; } |
| 169 | |
| 170 | const unsigned char* |
| 171 | data() const |
| 172 | { return this->data_; } |
| 173 | |
| 174 | void |
| 175 | lock(); |
| 176 | |
| 177 | void |
| 178 | unlock(); |
| 179 | |
| 180 | bool |
| 181 | is_locked(); |
| 182 | |
| 183 | void |
| 184 | set_cache() |
| 185 | { this->cache_ = true; } |
| 186 | |
| 187 | bool |
| 188 | should_cache() const |
| 189 | { return this->cache_; } |
| 190 | |
| 191 | private: |
| 192 | View(const View&); |
| 193 | View& operator=(const View&); |
| 194 | |
| 195 | off_t start_; |
| 196 | section_size_type size_; |
| 197 | const unsigned char* data_; |
| 198 | int lock_count_; |
| 199 | bool cache_; |
| 200 | bool mapped_; |
| 201 | }; |
| 202 | |
| 203 | friend class View; |
| 204 | friend class File_view; |
| 205 | |
| 206 | // Find a view into the file. |
| 207 | View* |
| 208 | find_view(off_t start, section_size_type size) const; |
| 209 | |
| 210 | // Read data from the file into a buffer. |
| 211 | void |
| 212 | do_read(off_t start, section_size_type size, void* p) const; |
| 213 | |
| 214 | // Find or make a view into the file. |
| 215 | View* |
| 216 | find_or_make_view(off_t start, section_size_type size, bool cache); |
| 217 | |
| 218 | // Clear the file views. |
| 219 | void |
| 220 | clear_views(bool); |
| 221 | |
| 222 | // The size of a file page for buffering data. |
| 223 | static const off_t page_size = 8192; |
| 224 | |
| 225 | // Given a file offset, return the page offset. |
| 226 | static off_t |
| 227 | page_offset(off_t file_offset) |
| 228 | { return file_offset & ~ (page_size - 1); } |
| 229 | |
| 230 | // Given a file size, return the size to read integral pages. |
| 231 | static off_t |
| 232 | pages(off_t file_size) |
| 233 | { return (file_size + (page_size - 1)) & ~ (page_size - 1); } |
| 234 | |
| 235 | // The type of a mapping from page start to views. |
| 236 | typedef std::map<off_t, View*> Views; |
| 237 | |
| 238 | // A simple list of Views. |
| 239 | typedef std::list<View*> Saved_views; |
| 240 | |
| 241 | // File name. |
| 242 | std::string name_; |
| 243 | // File descriptor. |
| 244 | int descriptor_; |
| 245 | // File size. |
| 246 | off_t size_; |
| 247 | // A token used to lock the file. |
| 248 | Task_token token_; |
| 249 | // Buffered views into the file. |
| 250 | Views views_; |
| 251 | // List of views which were locked but had to be removed from views_ |
| 252 | // because they were not large enough. |
| 253 | Saved_views saved_views_; |
| 254 | // Specified file contents. Used only for testing purposes. |
| 255 | const unsigned char* contents_; |
| 256 | // Total amount of space mapped into memory. This is only changed |
| 257 | // while the file is locked. When we unlock the file, we transfer |
| 258 | // the total to total_mapped_bytes, and reset this to zero. |
| 259 | size_t mapped_bytes_; |
| 260 | // Whether the file was released. |
| 261 | bool released_; |
| 262 | }; |
| 263 | |
| 264 | // A view of file data that persists even when the file is unlocked. |
| 265 | // Callers should destroy these when no longer required. These are |
| 266 | // obtained form File_read::get_lasting_view. They may only be |
| 267 | // destroyed when the underlying File_read is locked. |
| 268 | |
| 269 | class File_view |
| 270 | { |
| 271 | public: |
| 272 | // This may only be called when the underlying File_read is locked. |
| 273 | ~File_view(); |
| 274 | |
| 275 | // Return a pointer to the data associated with this view. |
| 276 | const unsigned char* |
| 277 | data() const |
| 278 | { return this->data_; } |
| 279 | |
| 280 | private: |
| 281 | File_view(const File_view&); |
| 282 | File_view& operator=(const File_view&); |
| 283 | |
| 284 | friend class File_read; |
| 285 | |
| 286 | // Callers have to get these via File_read::get_lasting_view. |
| 287 | File_view(File_read& file, File_read::View* view, const unsigned char* data) |
| 288 | : file_(file), view_(view), data_(data) |
| 289 | { } |
| 290 | |
| 291 | File_read& file_; |
| 292 | File_read::View* view_; |
| 293 | const unsigned char* data_; |
| 294 | }; |
| 295 | |
| 296 | // All the information we hold for a single input file. This can be |
| 297 | // an object file, a shared library, or an archive. |
| 298 | |
| 299 | class Input_file |
| 300 | { |
| 301 | public: |
| 302 | Input_file(const Input_file_argument* input_argument) |
| 303 | : input_argument_(input_argument), found_name_(), file_(), |
| 304 | is_in_sysroot_(false) |
| 305 | { } |
| 306 | |
| 307 | // Create an input file with the contents already provided. This is |
| 308 | // only used for testing. With this path, don't call the open |
| 309 | // method. |
| 310 | Input_file(const Task*, const char* name, const unsigned char* contents, |
| 311 | off_t size); |
| 312 | |
| 313 | // Open the file. If the open fails, this will report an error and |
| 314 | // return false. |
| 315 | bool |
| 316 | open(const General_options&, const Dirsearch&, const Task*); |
| 317 | |
| 318 | // Return the name given by the user. For -lc this will return "c". |
| 319 | const char* |
| 320 | name() const |
| 321 | { return this->input_argument_->name(); } |
| 322 | |
| 323 | // Return the file name. For -lc this will return something like |
| 324 | // "/usr/lib/libc.so". |
| 325 | const std::string& |
| 326 | filename() const |
| 327 | { return this->file_.filename(); } |
| 328 | |
| 329 | // Return the name under which we found the file, corresponding to |
| 330 | // the command line. For -lc this will return something like |
| 331 | // "libc.so". |
| 332 | const std::string& |
| 333 | found_name() const |
| 334 | { return this->found_name_; } |
| 335 | |
| 336 | // Return the position dependent options. |
| 337 | const Position_dependent_options& |
| 338 | options() const |
| 339 | { return this->input_argument_->options(); } |
| 340 | |
| 341 | // Return the file. |
| 342 | File_read& |
| 343 | file() |
| 344 | { return this->file_; } |
| 345 | |
| 346 | const File_read& |
| 347 | file() const |
| 348 | { return this->file_; } |
| 349 | |
| 350 | // Whether we found the file in a directory in the system root. |
| 351 | bool |
| 352 | is_in_sysroot() const |
| 353 | { return this->is_in_sysroot_; } |
| 354 | |
| 355 | private: |
| 356 | Input_file(const Input_file&); |
| 357 | Input_file& operator=(const Input_file&); |
| 358 | |
| 359 | // The argument from the command line. |
| 360 | const Input_file_argument* input_argument_; |
| 361 | // The name under which we opened the file. This is like the name |
| 362 | // on the command line, but -lc turns into libc.so (or whatever). |
| 363 | // It only includes the full path if the path was on the command |
| 364 | // line. |
| 365 | std::string found_name_; |
| 366 | // The file after we open it. |
| 367 | File_read file_; |
| 368 | // Whether we found the file in a directory in the system root. |
| 369 | bool is_in_sysroot_; |
| 370 | }; |
| 371 | |
| 372 | } // end namespace gold |
| 373 | |
| 374 | #endif // !defined(GOLD_FILEREAD_H) |