2008-06-25 Cary Coutant <ccoutant@google.com>
[external/binutils.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.