2008-06-25 Cary Coutant <ccoutant@google.com>
[deliverable/binutils-gdb.git] / gold / fileread.cc
1 // fileread.cc -- read files for gold
2
3 // Copyright 2006, 2007, 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 <cstring>
26 #include <cerrno>
27 #include <fcntl.h>
28 #include <unistd.h>
29 #include <sys/mman.h>
30 #include <sys/uio.h>
31 #include "filenames.h"
32
33 #include "debug.h"
34 #include "parameters.h"
35 #include "options.h"
36 #include "dirsearch.h"
37 #include "target.h"
38 #include "binary.h"
39 #include "fileread.h"
40
41 namespace gold
42 {
43
44 // Class File_read::View.
45
46 File_read::View::~View()
47 {
48 gold_assert(!this->is_locked());
49 if (!this->mapped_)
50 delete[] this->data_;
51 else
52 {
53 if (::munmap(const_cast<unsigned char*>(this->data_), this->size_) != 0)
54 gold_warning(_("munmap failed: %s"), strerror(errno));
55
56 File_read::current_mapped_bytes -= this->size_;
57 }
58 }
59
60 void
61 File_read::View::lock()
62 {
63 ++this->lock_count_;
64 }
65
66 void
67 File_read::View::unlock()
68 {
69 gold_assert(this->lock_count_ > 0);
70 --this->lock_count_;
71 }
72
73 bool
74 File_read::View::is_locked()
75 {
76 return this->lock_count_ > 0;
77 }
78
79 // Class File_read.
80
81 // The File_read static variables.
82 unsigned long long File_read::total_mapped_bytes;
83 unsigned long long File_read::current_mapped_bytes;
84 unsigned long long File_read::maximum_mapped_bytes;
85
86 // The File_read class is designed to support file descriptor caching,
87 // but this is not currently implemented.
88
89 File_read::~File_read()
90 {
91 gold_assert(this->token_.is_writable());
92 if (this->descriptor_ >= 0)
93 {
94 if (close(this->descriptor_) < 0)
95 gold_warning(_("close of %s failed: %s"),
96 this->name_.c_str(), strerror(errno));
97 this->descriptor_ = -1;
98 }
99 this->name_.clear();
100 this->clear_views(true);
101 }
102
103 // Open the file.
104
105 bool
106 File_read::open(const Task* task, const std::string& name)
107 {
108 gold_assert(this->token_.is_writable()
109 && this->descriptor_ < 0
110 && this->name_.empty());
111 this->name_ = name;
112
113 this->descriptor_ = ::open(this->name_.c_str(), O_RDONLY);
114
115 if (this->descriptor_ >= 0)
116 {
117 struct stat s;
118 if (::fstat(this->descriptor_, &s) < 0)
119 gold_error(_("%s: fstat failed: %s"),
120 this->name_.c_str(), strerror(errno));
121 this->size_ = s.st_size;
122 gold_debug(DEBUG_FILES, "Attempt to open %s succeeded",
123 this->name_.c_str());
124 }
125
126 this->token_.add_writer(task);
127
128 return this->descriptor_ >= 0;
129 }
130
131 // Open the file with the contents in memory.
132
133 bool
134 File_read::open(const Task* task, const std::string& name,
135 const unsigned char* contents, off_t size)
136 {
137 gold_assert(this->token_.is_writable()
138 && this->descriptor_ < 0
139 && this->name_.empty());
140 this->name_ = name;
141 this->contents_ = contents;
142 this->size_ = size;
143 this->token_.add_writer(task);
144 return true;
145 }
146
147 // Release the file. This is called when we are done with the file in
148 // a Task.
149
150 void
151 File_read::release()
152 {
153 gold_assert(this->is_locked());
154
155 File_read::total_mapped_bytes += this->mapped_bytes_;
156 File_read::current_mapped_bytes += this->mapped_bytes_;
157 this->mapped_bytes_ = 0;
158 if (File_read::current_mapped_bytes > File_read::maximum_mapped_bytes)
159 File_read::maximum_mapped_bytes = File_read::current_mapped_bytes;
160
161 // Only clear views if there is only one attached object. Otherwise
162 // we waste time trying to clear cached archive views.
163 if (this->object_count_ <= 1)
164 this->clear_views(false);
165
166 this->released_ = true;
167 }
168
169 // Lock the file.
170
171 void
172 File_read::lock(const Task* task)
173 {
174 gold_assert(this->released_);
175 this->token_.add_writer(task);
176 this->released_ = false;
177 }
178
179 // Unlock the file.
180
181 void
182 File_read::unlock(const Task* task)
183 {
184 this->release();
185 this->token_.remove_writer(task);
186 }
187
188 // Return whether the file is locked.
189
190 bool
191 File_read::is_locked() const
192 {
193 if (!this->token_.is_writable())
194 return true;
195 // The file is not locked, so it should have been released.
196 gold_assert(this->released_);
197 return false;
198 }
199
200 // See if we have a view which covers the file starting at START for
201 // SIZE bytes. Return a pointer to the View if found, NULL if not.
202 // If BYTESHIFT is not -1U, the returned View must have the specified
203 // byte shift; otherwise, it may have any byte shift. If VSHIFTED is
204 // not NULL, this sets *VSHIFTED to a view which would have worked if
205 // not for the requested BYTESHIFT.
206
207 inline File_read::View*
208 File_read::find_view(off_t start, section_size_type size,
209 unsigned int byteshift, File_read::View** vshifted) const
210 {
211 if (vshifted != NULL)
212 *vshifted = NULL;
213
214 off_t page = File_read::page_offset(start);
215
216 unsigned int bszero = 0;
217 Views::const_iterator p = this->views_.upper_bound(std::make_pair(page - 1,
218 bszero));
219
220 while (p != this->views_.end() && p->first.first <= page)
221 {
222 if (p->second->start() <= start
223 && (p->second->start() + static_cast<off_t>(p->second->size())
224 >= start + static_cast<off_t>(size)))
225 {
226 if (byteshift == -1U || byteshift == p->second->byteshift())
227 {
228 p->second->set_accessed();
229 return p->second;
230 }
231
232 if (vshifted != NULL && *vshifted == NULL)
233 *vshifted = p->second;
234 }
235
236 ++p;
237 }
238
239 return NULL;
240 }
241
242 // Read SIZE bytes from the file starting at offset START. Read into
243 // the buffer at P.
244
245 void
246 File_read::do_read(off_t start, section_size_type size, void* p) const
247 {
248 ssize_t bytes;
249 if (this->contents_ != NULL)
250 {
251 bytes = this->size_ - start;
252 if (static_cast<section_size_type>(bytes) >= size)
253 {
254 memcpy(p, this->contents_ + start, size);
255 return;
256 }
257 }
258 else
259 {
260 bytes = ::pread(this->descriptor_, p, size, start);
261 if (static_cast<section_size_type>(bytes) == size)
262 return;
263
264 if (bytes < 0)
265 {
266 gold_fatal(_("%s: pread failed: %s"),
267 this->filename().c_str(), strerror(errno));
268 return;
269 }
270 }
271
272 gold_fatal(_("%s: file too short: read only %lld of %lld bytes at %lld"),
273 this->filename().c_str(),
274 static_cast<long long>(bytes),
275 static_cast<long long>(size),
276 static_cast<long long>(start));
277 }
278
279 // Read data from the file.
280
281 void
282 File_read::read(off_t start, section_size_type size, void* p) const
283 {
284 const File_read::View* pv = this->find_view(start, size, -1U, NULL);
285 if (pv != NULL)
286 {
287 memcpy(p, pv->data() + (start - pv->start() + pv->byteshift()), size);
288 return;
289 }
290
291 this->do_read(start, size, p);
292 }
293
294 // Add a new view. There may already be an existing view at this
295 // offset. If there is, the new view will be larger, and should
296 // replace the old view.
297
298 void
299 File_read::add_view(File_read::View* v)
300 {
301 std::pair<Views::iterator, bool> ins =
302 this->views_.insert(std::make_pair(std::make_pair(v->start(),
303 v->byteshift()),
304 v));
305 if (ins.second)
306 return;
307
308 // There was an existing view at this offset. It must not be large
309 // enough. We can't delete it here, since something might be using
310 // it; we put it on a list to be deleted when the file is unlocked.
311 File_read::View* vold = ins.first->second;
312 gold_assert(vold->size() < v->size());
313 if (vold->should_cache())
314 {
315 v->set_cache();
316 vold->clear_cache();
317 }
318 this->saved_views_.push_back(vold);
319
320 ins.first->second = v;
321 }
322
323 // Make a new view with a specified byteshift, reading the data from
324 // the file.
325
326 File_read::View*
327 File_read::make_view(off_t start, section_size_type size,
328 unsigned int byteshift, bool cache)
329 {
330 gold_assert(size > 0);
331
332 off_t poff = File_read::page_offset(start);
333
334 section_size_type psize = File_read::pages(size + (start - poff));
335
336 if (poff + static_cast<off_t>(psize) >= this->size_)
337 {
338 psize = this->size_ - poff;
339 gold_assert(psize >= size);
340 }
341
342 File_read::View* v;
343 if (this->contents_ != NULL || byteshift != 0)
344 {
345 unsigned char* p = new unsigned char[psize + byteshift];
346 memset(p, 0, byteshift);
347 this->do_read(poff, psize, p + byteshift);
348 v = new File_read::View(poff, psize, p, byteshift, cache, false);
349 }
350 else
351 {
352 void* p = ::mmap(NULL, psize, PROT_READ, MAP_PRIVATE,
353 this->descriptor_, poff);
354 if (p == MAP_FAILED)
355 gold_fatal(_("%s: mmap offset %lld size %lld failed: %s"),
356 this->filename().c_str(),
357 static_cast<long long>(poff),
358 static_cast<long long>(psize),
359 strerror(errno));
360
361 this->mapped_bytes_ += psize;
362
363 const unsigned char* pbytes = static_cast<const unsigned char*>(p);
364 v = new File_read::View(poff, psize, pbytes, 0, cache, true);
365 }
366
367 this->add_view(v);
368
369 return v;
370 }
371
372 // Find a View or make a new one, shifted as required by the file
373 // offset OFFSET and ALIGNED.
374
375 File_read::View*
376 File_read::find_or_make_view(off_t offset, off_t start,
377 section_size_type size, bool aligned, bool cache)
378 {
379 unsigned int byteshift;
380 if (offset == 0)
381 byteshift = 0;
382 else
383 {
384 unsigned int target_size = (!parameters->target_valid()
385 ? 64
386 : parameters->target().get_size());
387 byteshift = offset & ((target_size / 8) - 1);
388
389 // Set BYTESHIFT to the number of dummy bytes which must be
390 // inserted before the data in order for this data to be
391 // aligned.
392 if (byteshift != 0)
393 byteshift = (target_size / 8) - byteshift;
394 }
395
396 // Try to find a View with the required BYTESHIFT.
397 File_read::View* vshifted;
398 File_read::View* v = this->find_view(offset + start, size,
399 aligned ? byteshift : -1U,
400 &vshifted);
401 if (v != NULL)
402 {
403 if (cache)
404 v->set_cache();
405 return v;
406 }
407
408 // If VSHIFTED is not NULL, then it has the data we need, but with
409 // the wrong byteshift.
410 v = vshifted;
411 if (v != NULL)
412 {
413 gold_assert(aligned);
414
415 unsigned char* pbytes = new unsigned char[v->size() + byteshift];
416 memset(pbytes, 0, byteshift);
417 memcpy(pbytes + byteshift, v->data() + v->byteshift(), v->size());
418
419 File_read::View* shifted_view = new File_read::View(v->start(), v->size(),
420 pbytes, byteshift,
421 cache, false);
422
423 this->add_view(shifted_view);
424 return shifted_view;
425 }
426
427 // Make a new view. If we don't need an aligned view, use a
428 // byteshift of 0, so that we can use mmap.
429 return this->make_view(offset + start, size,
430 aligned ? byteshift : 0,
431 cache);
432 }
433
434 // Get a view into the file.
435
436 const unsigned char*
437 File_read::get_view(off_t offset, off_t start, section_size_type size,
438 bool aligned, bool cache)
439 {
440 File_read::View* pv = this->find_or_make_view(offset, start, size,
441 aligned, cache);
442 return pv->data() + (offset + start - pv->start() + pv->byteshift());
443 }
444
445 File_view*
446 File_read::get_lasting_view(off_t offset, off_t start, section_size_type size,
447 bool aligned, bool cache)
448 {
449 File_read::View* pv = this->find_or_make_view(offset, start, size,
450 aligned, cache);
451 pv->lock();
452 return new File_view(*this, pv,
453 (pv->data()
454 + (offset + start - pv->start() + pv->byteshift())));
455 }
456
457 // Use readv to read COUNT entries from RM starting at START. BASE
458 // must be added to all file offsets in RM.
459
460 void
461 File_read::do_readv(off_t base, const Read_multiple& rm, size_t start,
462 size_t count)
463 {
464 unsigned char discard[File_read::page_size];
465 iovec iov[File_read::max_readv_entries * 2];
466 size_t iov_index = 0;
467
468 off_t first_offset = rm[start].file_offset;
469 off_t last_offset = first_offset;
470 ssize_t want = 0;
471 for (size_t i = 0; i < count; ++i)
472 {
473 const Read_multiple_entry& i_entry(rm[start + i]);
474
475 if (i_entry.file_offset > last_offset)
476 {
477 size_t skip = i_entry.file_offset - last_offset;
478 gold_assert(skip <= sizeof discard);
479
480 iov[iov_index].iov_base = discard;
481 iov[iov_index].iov_len = skip;
482 ++iov_index;
483
484 want += skip;
485 }
486
487 iov[iov_index].iov_base = i_entry.buffer;
488 iov[iov_index].iov_len = i_entry.size;
489 ++iov_index;
490
491 want += i_entry.size;
492
493 last_offset = i_entry.file_offset + i_entry.size;
494 }
495
496 gold_assert(iov_index < sizeof iov / sizeof iov[0]);
497
498 if (::lseek(this->descriptor_, base + first_offset, SEEK_SET) < 0)
499 gold_fatal(_("%s: lseek failed: %s"),
500 this->filename().c_str(), strerror(errno));
501
502 ssize_t got = ::readv(this->descriptor_, iov, iov_index);
503
504 if (got < 0)
505 gold_fatal(_("%s: readv failed: %s"),
506 this->filename().c_str(), strerror(errno));
507 if (got != want)
508 gold_fatal(_("%s: file too short: read only %zd of %zd bytes at %lld"),
509 this->filename().c_str(),
510 got, want, static_cast<long long>(base + first_offset));
511 }
512
513 // Read several pieces of data from the file.
514
515 void
516 File_read::read_multiple(off_t base, const Read_multiple& rm)
517 {
518 size_t count = rm.size();
519 size_t i = 0;
520 while (i < count)
521 {
522 // Find up to MAX_READV_ENTRIES consecutive entries which are
523 // less than one page apart.
524 const Read_multiple_entry& i_entry(rm[i]);
525 off_t i_off = i_entry.file_offset;
526 off_t end_off = i_off + i_entry.size;
527 size_t j;
528 for (j = i + 1; j < count; ++j)
529 {
530 if (j - i >= File_read::max_readv_entries)
531 break;
532 const Read_multiple_entry& j_entry(rm[j]);
533 off_t j_off = j_entry.file_offset;
534 gold_assert(j_off >= end_off);
535 off_t j_end_off = j_off + j_entry.size;
536 if (j_end_off - end_off >= File_read::page_size)
537 break;
538 end_off = j_end_off;
539 }
540
541 if (j == i + 1)
542 this->read(base + i_off, i_entry.size, i_entry.buffer);
543 else
544 {
545 File_read::View* view = this->find_view(base + i_off,
546 end_off - i_off,
547 -1U, NULL);
548 if (view == NULL)
549 this->do_readv(base, rm, i, j - i);
550 else
551 {
552 const unsigned char* v = (view->data()
553 + (base + i_off - view->start()
554 + view->byteshift()));
555 for (size_t k = i; k < j; ++k)
556 {
557 const Read_multiple_entry& k_entry(rm[k]);
558 gold_assert((convert_to_section_size_type(k_entry.file_offset
559 - i_off)
560 + k_entry.size)
561 <= convert_to_section_size_type(end_off
562 - i_off));
563 memcpy(k_entry.buffer,
564 v + (k_entry.file_offset - i_off),
565 k_entry.size);
566 }
567 }
568 }
569
570 i = j;
571 }
572 }
573
574 // Mark all views as no longer cached.
575
576 void
577 File_read::clear_view_cache_marks()
578 {
579 // Just ignore this if there are multiple objects associated with
580 // the file. Otherwise we will wind up uncaching and freeing some
581 // views for other objects.
582 if (this->object_count_ > 1)
583 return;
584
585 for (Views::iterator p = this->views_.begin();
586 p != this->views_.end();
587 ++p)
588 p->second->clear_cache();
589 for (Saved_views::iterator p = this->saved_views_.begin();
590 p != this->saved_views_.end();
591 ++p)
592 (*p)->clear_cache();
593 }
594
595 // Remove all the file views. For a file which has multiple
596 // associated objects (i.e., an archive), we keep accessed views
597 // around until next time, in the hopes that they will be useful for
598 // the next object.
599
600 void
601 File_read::clear_views(bool destroying)
602 {
603 Views::iterator p = this->views_.begin();
604 while (p != this->views_.end())
605 {
606 bool should_delete;
607 if (p->second->is_locked())
608 should_delete = false;
609 else if (destroying)
610 should_delete = true;
611 else if (p->second->should_cache())
612 should_delete = false;
613 else if (this->object_count_ > 1 && p->second->accessed())
614 should_delete = false;
615 else
616 should_delete = true;
617
618 if (should_delete)
619 {
620 delete p->second;
621
622 // map::erase invalidates only the iterator to the deleted
623 // element.
624 Views::iterator pe = p;
625 ++p;
626 this->views_.erase(pe);
627 }
628 else
629 {
630 gold_assert(!destroying);
631 p->second->clear_accessed();
632 ++p;
633 }
634 }
635
636 Saved_views::iterator q = this->saved_views_.begin();
637 while (q != this->saved_views_.end())
638 {
639 if (!(*q)->is_locked())
640 {
641 delete *q;
642 q = this->saved_views_.erase(q);
643 }
644 else
645 {
646 gold_assert(!destroying);
647 ++q;
648 }
649 }
650 }
651
652 // Print statistical information to stderr. This is used for --stats.
653
654 void
655 File_read::print_stats()
656 {
657 fprintf(stderr, _("%s: total bytes mapped for read: %llu\n"),
658 program_name, File_read::total_mapped_bytes);
659 fprintf(stderr, _("%s: maximum bytes mapped for read at one time: %llu\n"),
660 program_name, File_read::maximum_mapped_bytes);
661 }
662
663 // Class File_view.
664
665 File_view::~File_view()
666 {
667 gold_assert(this->file_.is_locked());
668 this->view_->unlock();
669 }
670
671 // Class Input_file.
672
673 // Create a file for testing.
674
675 Input_file::Input_file(const Task* task, const char* name,
676 const unsigned char* contents, off_t size)
677 : file_()
678 {
679 this->input_argument_ =
680 new Input_file_argument(name, false, "", false,
681 Position_dependent_options());
682 bool ok = file_.open(task, name, contents, size);
683 gold_assert(ok);
684 }
685
686 // Return the position dependent options in force for this file.
687
688 const Position_dependent_options&
689 Input_file::options() const
690 {
691 return this->input_argument_->options();
692 }
693
694 // Return the name given by the user. For -lc this will return "c".
695
696 const char*
697 Input_file::name() const
698 {
699 return this->input_argument_->name();
700 }
701
702 // Return whether we are only reading symbols.
703
704 bool
705 Input_file::just_symbols() const
706 {
707 return this->input_argument_->just_symbols();
708 }
709
710 // Open the file.
711
712 // If the filename is not absolute, we assume it is in the current
713 // directory *except* when:
714 // A) input_argument_->is_lib() is true; or
715 // B) input_argument_->extra_search_path() is not empty.
716 // In both cases, we look in extra_search_path + library_path to find
717 // the file location, rather than the current directory.
718
719 bool
720 Input_file::open(const General_options& options, const Dirsearch& dirpath,
721 const Task* task)
722 {
723 std::string name;
724
725 // Case 1: name is an absolute file, just try to open it
726 // Case 2: name is relative but is_lib is false and extra_search_path
727 // is empty
728 if (IS_ABSOLUTE_PATH (this->input_argument_->name())
729 || (!this->input_argument_->is_lib()
730 && this->input_argument_->extra_search_path() == NULL))
731 {
732 name = this->input_argument_->name();
733 this->found_name_ = name;
734 }
735 // Case 3: is_lib is true
736 else if (this->input_argument_->is_lib())
737 {
738 // We don't yet support extra_search_path with -l.
739 gold_assert(this->input_argument_->extra_search_path() == NULL);
740 std::string n1("lib");
741 n1 += this->input_argument_->name();
742 std::string n2;
743 if (options.is_static()
744 || !this->input_argument_->options().Bdynamic())
745 n1 += ".a";
746 else
747 {
748 n2 = n1 + ".a";
749 n1 += ".so";
750 }
751 name = dirpath.find(n1, n2, &this->is_in_sysroot_);
752 if (name.empty())
753 {
754 gold_error(_("cannot find -l%s"),
755 this->input_argument_->name());
756 return false;
757 }
758 if (n2.empty() || name[name.length() - 1] == 'o')
759 this->found_name_ = n1;
760 else
761 this->found_name_ = n2;
762 }
763 // Case 4: extra_search_path is not empty
764 else
765 {
766 gold_assert(this->input_argument_->extra_search_path() != NULL);
767
768 // First, check extra_search_path.
769 name = this->input_argument_->extra_search_path();
770 if (!IS_DIR_SEPARATOR (name[name.length() - 1]))
771 name += '/';
772 name += this->input_argument_->name();
773 struct stat dummy_stat;
774 if (::stat(name.c_str(), &dummy_stat) < 0)
775 {
776 // extra_search_path failed, so check the normal search-path.
777 name = dirpath.find(this->input_argument_->name(), "",
778 &this->is_in_sysroot_);
779 if (name.empty())
780 {
781 gold_error(_("cannot find %s"),
782 this->input_argument_->name());
783 return false;
784 }
785 }
786 this->found_name_ = this->input_argument_->name();
787 }
788
789 // Now that we've figured out where the file lives, try to open it.
790
791 General_options::Object_format format =
792 this->input_argument_->options().format_enum();
793 bool ok;
794 if (format == General_options::OBJECT_FORMAT_ELF)
795 ok = this->file_.open(task, name);
796 else
797 {
798 gold_assert(format == General_options::OBJECT_FORMAT_BINARY);
799 ok = this->open_binary(options, task, name);
800 }
801
802 if (!ok)
803 {
804 gold_error(_("cannot open %s: %s"),
805 name.c_str(), strerror(errno));
806 return false;
807 }
808
809 return true;
810 }
811
812 // Open a file for --format binary.
813
814 bool
815 Input_file::open_binary(const General_options&,
816 const Task* task, const std::string& name)
817 {
818 // In order to open a binary file, we need machine code, size, and
819 // endianness. We may not have a valid target at this point, in
820 // which case we use the default target.
821 const Target* target;
822 if (parameters->target_valid())
823 target = &parameters->target();
824 else
825 target = &parameters->default_target();
826
827 Binary_to_elf binary_to_elf(target->machine_code(),
828 target->get_size(),
829 target->is_big_endian(),
830 name);
831 if (!binary_to_elf.convert(task))
832 return false;
833 return this->file_.open(task, name, binary_to_elf.converted_data_leak(),
834 binary_to_elf.converted_size());
835 }
836
837 } // End namespace gold.
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