aboutsummaryrefslogtreecommitdiff
path: root/libbuild2/bin/def-rule.cxx
blob: 032d521209435c1e365bc76d4a576e6e7c3b9684 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
// file      : libbuild2/bin/def-rule.cxx -*- C++ -*-
// license   : MIT; see accompanying LICENSE file

#include <libbuild2/bin/def-rule.hxx>

#include <libbuild2/depdb.hxx>
#include <libbuild2/scope.hxx>
#include <libbuild2/target.hxx>
#include <libbuild2/algorithm.hxx>
#include <libbuild2/diagnostics.hxx>

#include <libbuild2/bin/target.hxx>
#include <libbuild2/bin/utility.hxx>

namespace build2
{
  namespace bin
  {
    // In C global uninitialized data becomes a "common symbol" (an equivalent
    // definition compiled as C++ results in a BSS symbol) which allows some
    // archaic merging of multiple such definitions during linking (see GNU ld
    // --warn-common for background). Note that this merging may happen with
    // other data symbol types, not just common.
    //
    struct symbols
    {
      set<string> d; // data
      set<string> r; // read-only data
      set<string> b; // uninitialized data (BSS)
      set<string> c; // common uninitialized data
      set<string> t; // text (code)
    };

    static void
    read_dumpbin (istream& is, symbols& syms)
    {
      // Lines that describe symbols look like:
      //
      // 0   1        2      3          4            5 6
      // IDX OFFSET   SECT   SYMTYPE    VISIBILITY     SYMNAME
      // ----------------------------------------------------------------------
      // 02E 00000130 SECTA  notype     External     | _standbyState
      // 02F 00000009 SECT9  notype     Static       | _LocalRecoveryInProgress
      // 064 00000020 SECTC  notype ()  Static       | _XLogCheckBuffer
      // 065 00000000 UNDEF  notype ()  External     | _BufferGetTag
      //
      // IDX is the symbol index and OFFSET is its offset.
      //
      // SECT[ION] is the name of the section where the symbol is defined. If
      // UNDEF, then it's a symbol to be resolved at link time from another
      // object file.
      //
      // SYMTYPE is always notype for C/C++ symbols as there's no typeinfo and
      // no way to get the symbol type from name (de)mangling. However, we
      // care if "notype" is suffixed by "()" or not. The presence of () means
      // the symbol is a function, the absence means it isn't.
      //
      // VISIBILITY indicates whether it's a compilation-unit local static
      // symbol ("Static"), or whether it's available for use from other
      // compilation units ("External"). Note that there are other values,
      // such as "WeakExternal", and "Label".
      //
      // SYMNAME is the symbol name.
      //
      // The first symbol in each section appears to specify the section type,
      // for example:
      //
      // 006 00000000 SECT3  notype    Static       | .rdata
      // B44 00000000 SECT4  notype    Static       | .rdata$r
      // AA2 00000000 SECT5  notype    Static       | .bss
      //
      // Note that an UNDEF data symbol with non-zero OFFSET is a "common
      // symbol", equivalent to the nm `C` type.

      // Map of read-only (.rdata, .xdata) and uninitialized (.bss) sections
      // to their types (R and B, respectively). If a section is not found in
      // this map, then it's assumed to be normal data (.data).
      //
      map<string, char> sections;

      string l;
      while (!eof (getline (is, l)))
      {
        size_t b (0), e (0), n;

        // IDX (note that it can be more than 3 characters).
        //
        if (next_word (l, b, e) == 0)
          continue;

        // OFFSET (always 8 characters).
        //
        n = next_word (l, b, e);

        if (n != 8)
          continue;

        string off (l, b, n);

        // SECT
        //
        n = next_word (l, b, e);

        if (n == 0)
          continue;

        string sec (l, b, n);

        // TYPE
        //
        n = next_word (l, b, e);

        if (l.compare (b, n, "notype") != 0)
          continue;

        bool dat;
        if (l[e] == ' ' && l[e + 1] == '(' && l[e + 2] == ')')
        {
          e += 3;
          dat = false;
        }
        else
          dat = true;

        // VISIBILITY
        //
        n = next_word (l, b, e);

        if (n == 0)
          continue;

        string vis (l, b, n);

        // |
        //
        n = next_word (l, b, e);

        if (n != 1 || l[b] != '|')
          continue;

        // SYMNAME
        //
        n = next_word (l, b, e);

        if (n == 0)
          continue;

        string s (l, b, n);

        // See if this is the section type symbol.
        //
        if (dat &&
            off == "00000000" &&
            sec != "UNDEF"    &&
            vis == "Static"   &&
            s[0] == '.')
        {
          auto cmp = [&s] (const char* n, size_t l)
          {
            return s.compare (0, l, n) == 0 && (s[l] == '\0' || s[l] == '$');
          };

          if      (cmp (".rdata", 6) ||
                   cmp (".xdata", 6))    sections.emplace (move (sec), 'R');
          else if (cmp (".bss",   4))    sections.emplace (move (sec), 'B');

          continue;
        }

        // We can only export extern symbols.
        //
        if (vis != "External")
          continue;

        if (dat)
        {
          if (sec != "UNDEF")
          {
            auto i (sections.find (sec));
            switch (i == sections.end () ? 'D' : i->second)
            {
            case 'D': syms.d.insert (move (s)); break;
            case 'R': syms.r.insert (move (s)); break;
            case 'B': syms.b.insert (move (s)); break;
            }
          }
          else
          {
            if (off != "00000000")
              syms.c.insert (move (s));
          }
        }
        else
        {
          if (sec != "UNDEF")
            syms.t.insert (move (s));
        }
      }
    }

    static void
    read_posix_nm (istream& is, symbols& syms)
    {
      // Lines that describe symbols look like:
      //
      // <NAME> <TYPE> <VALUE> <SIZE>
      //
      // The types that we are interested in are T, D, R, and B.
      //
      string l;
      while (!eof (getline (is, l)))
      {
        size_t b (0), e (0), n;

        // NAME
        //
        n = next_word (l, b, e);

        if (n == 0)
          continue;

        string s (l, b, n);

        // TYPE
        //
        n = next_word (l, b, e);

        if (n != 1)
          continue;

        switch (l[b])
        {
        case 'D': syms.d.insert (move (s)); break;
        case 'R': syms.r.insert (move (s)); break;
        case 'B': syms.b.insert (move (s)); break;
        case 'c':
        case 'C': syms.c.insert (move (s)); break;
        case 'T': syms.t.insert (move (s)); break;
        }
      }
    }

    static void
    write_win32_msvc (ostream& os, const symbols& syms, bool i386)
    {
      // Our goal here is to export the same types of symbols as what gets
      // exported by MSVC with __declspec(dllexport) (can be viewed with
      // dumpbin /EXPORTS).
      //
      // Some special C++ symbol patterns:
      //
      // Data symbols:
      //
      // ??_C* -- string literal                      (R,   not exported)
      // ??_7* -- vtable                              (R,   exported)
      // ??_R* -- rtti, can be prefixed with _CT/__CT (D/R, not exported)
      //
      // Text symbols:
      //
      // ??_G* -- scalar deleting destructor (not exported)
      // ??_E* -- vector deleting destructor (not exported)
      //
      // The following two symbols seem to be related to exception
      // throwing and most likely should not be exported.
      //
      // R _CTA3?AVinvalid_argument@std@@
      // R _TI3?AVinvalid_argument@std@@
      //
      // There are also what appears to be floating point literals:
      //
      // R __real@3f80000
      //
      // For some reason i386 object files have extern "C" symbols (both
      // data and text) prefixed with an underscore which must be stripped
      // in the .def file.
      //
      // Note that the extra prefix seems to be also added to special
      // symbols so something like _CT??... becomes __CT??... on i386.
      // However, for such symbols the underscore shall not be removed.
      // Which means an extern "C" _CT becomes __CT on i383 and hard to
      // distinguish from the special symbols. We deal with this by only
      // stripping the underscore if the symbols doesn't contain any
      // special characters (?@).
      //
      auto extern_c = [] (const string& s)
      {
        return s.find_first_of ("?@") == string::npos;
      };

      auto strip = [i386, &extern_c] (const string& s) -> const char*
      {
        const char* r (s.c_str ());

        if (i386 && s[0] == '_' && extern_c (s))
          r++;

        return r;
      };

      // Code.
      //
      for (const string& s: syms.t)
      {
        auto filter = [&strip] (const string& s) -> const char*
        {
          if (s.compare (0, 4, "??_G") == 0 ||
              s.compare (0, 4, "??_E") == 0)
            return nullptr;

          return strip (s);
        };

        if (const char* v = filter (s))
          os << "  " << v << '\n';
      }

      // Data.
      //
      // Note that it's not easy to import data without a dllimport
      // declaration.
      //
      {
        auto filter = [&strip] (const string& s) -> const char*
        {
          if (s.compare (0, 4, "??_R") == 0 ||
              s.compare (0, 4, "??_C") == 0)
            return nullptr;

          return strip (s);
        };

        for (const string& s: syms.d)
          if (const char* v = filter (s))
            os << "  " << v << " DATA\n";

        for (const string& s: syms.b)
          if (const char* v = filter (s))
            os << "  " << v << " DATA\n";

        // For common symbols, only write extern C.
        //
        for (const string& s: syms.c)
          if (extern_c (s))
            if (const char* v = filter (s))
              os << "  " << v << " DATA\n";

        // Read-only data contains an especially large number of various
        // special symbols. Instead of trying to filter them out case by case,
        // we will try to recognize C/C++ identifiers plus the special symbols
        // that we need to export (e.g., vtable).
        //
        //
        for (const string& s: syms.r)
        {
          if (extern_c (s)                 || // C
              (s[0] == '?' && s[1] != '?') || // C++
              s.compare (0, 4, "??_7") == 0)  // vtable
          {
            os << "  " << strip (s) << " DATA\n";
          }
        }
      }
    }

    static void
    write_mingw32 (ostream& os, const symbols& syms, bool i386)
    {
      // Our goal here is to export the same types of symbols as what gets
      // exported by GCC with __declspec(dllexport) (can be viewed with
      // dumpbin /EXPORTS).
      //
      // Some special C++ symbol patterns (Itanium C++ ABI):
      //
      // Data symbols:
      //
      // _ZTVN* -- vtable          (R,   exported)
      // _ZTIN* -- typeinfo        (R,   exported)
      // _ZTSN* -- typeinfo name   (R, not exported)
      //
      // There are also some special R symbols which start with .refptr.
      // that are not exported.
      //
      // Normal symbols (both text and data) appear to start with _ZN.
      //
      // Note that we have the same extra underscore for i386 as in the
      // win32-msvc case above but here even for mangled symbols (e.g., __Z*).
      //
      auto skip = [i386] (const string& s) -> size_t
      {
        return i386 && s[0] == '_' ? 1 : 0;
      };

      // Code.
      //
      for (const string& s: syms.t)
      {
        auto filter = [&skip] (const string& s) -> const char*
        {
          return s.c_str () + skip (s);
        };

        if (const char* v = filter (s))
          os << "  " << v << '\n';
      }

      // Data.
      //
      {
        auto filter = [&skip] (const string& s) -> const char*
        {
          return s.c_str () + skip (s);
        };

        for (const string& s: syms.d)
          if (const char* v = filter (s))
            os << "  " << v << " DATA\n";

        for (const string& s: syms.b)
          if (const char* v = filter (s))
            os << "  " << v << " DATA\n";

        for (const string& s: syms.c)
          if (const char* v = filter (s))
            os << "  " << v << " DATA\n";

        // Read-only data contains an especially large number of various
        // special symbols. Instead of trying to filter them out case by case,
        // we will try to recognize C/C++ identifiers plus the special symbols
        // that we need to export (e.g., vtable and typeinfo).
        //
        for (const string& s: syms.r)
        {
          if (s.find_first_of (".") != string::npos) // Special (.refptr.*)
            continue;

          size_t p (skip (s)), n (s.size () - p);

          if ((n < 2 || s[p] != '_' || s[p + 1] != 'Z') ||  // C
              (s[p + 2] == 'N'                        ) ||  // C++ (normal)
              (s[p + 2] == 'T' && (s[p + 3] == 'V' ||       // vtable
                                   s[p + 3] == 'I') &&      // typeinfo
               s[p + 4] == 'N'))
          {
            os << "  " << s.c_str () + p << " DATA\n";
          }
        }
      }
    }

    bool def_rule::
    match (action a, target& t, const string&) const
    {
      tracer trace ("bin::def_rule::match");

      // See if we have an object file or a utility library.
      //
      for (prerequisite_member p: reverse_group_prerequisite_members (a, t))
      {
        // If excluded or ad hoc, then don't factor it into our tests.
        //
        if (include (a, t, p) != include_type::normal)
          continue;

        if (p.is_a<obj> ()   || p.is_a<objs> () ||
            p.is_a<bmi> ()   || p.is_a<bmis> () ||
            p.is_a<libul> () || p.is_a<libus> ())
          return true;
      }

      l4 ([&]{trace << "no object or utility library prerequisite for target "
                    << t;});
      return false;
    }

    recipe def_rule::
    apply (action a, target& xt) const
    {
      def& t (xt.as<def> ());

      t.derive_path ();

      // Inject dependency on the output directory.
      //
      inject_fsdir (a, t);

      // Match prerequisites only picking object files and utility libraries.
      //
      match_prerequisite_members (
        a,
        t,
        [] (action a,
            const target& t,
            const prerequisite_member& p,
            include_type i) -> prerequisite_target
        {
          return
            i == include_type::adhoc ? nullptr :
            //
            // If this is a target group, then pick the appropriate member
            // (the same semantics as what we have in link-rule).
            //
            p.is_a<obj> ()   ? &search (t, objs::static_type, p.key ()) :
            p.is_a<bmi> ()   ? &search (t, bmis::static_type, p.key ()) :
            p.is_a<libul> () ? link_member (p.search (t).as<libul> (),
                                            a,
                                            linfo {otype::s, lorder::s}) :
            p.is_a<objs> () ||
            p.is_a<bmis> () ||
            p.is_a<libus> () ? &p.search (t) : nullptr;
        });

      switch (a)
      {
      case perform_update_id: return &perform_update;
      case perform_clean_id:  return &perform_clean_depdb; // Standard clean.
      default:                return noop_recipe;          // Configure update.
      }
    }

    target_state def_rule::
    perform_update (action a, const target& xt)
    {
      tracer trace ("bin::def_rule::perform_update");

      const def& t (xt.as<def> ());
      const path& tp (t.path ());

      context& ctx (t.ctx);

      const scope& bs (t.base_scope ());
      const scope& rs (*bs.root_scope ());

      // For link.exe we use its /DUMP option to access dumpbin.exe. Otherwise
      // (lld-link, MinGW), we use nm (llvm-nm, MinGW nm). For good measure
      // (e.g., the bin.def module is loaded without bin.ld), we also handle
      // the direct dumpbin.exe usage.
      //
      const string& lid (cast_empty<string> (rs["bin.ld.id"]));

      // Update prerequisites and determine if anything changed.
      //
      timestamp mt (t.load_mtime ());
      optional<target_state> ts (execute_prerequisites (a, t, mt));

      bool update (!ts);

      // We use depdb to track changes to the input set, etc.
      //
      depdb dd (tp + ".d");

      // First should come the rule name/version.
      //
      if (dd.expect (rule_id_) != nullptr)
        l4 ([&]{trace << "rule mismatch forcing update of " << t;});

      // Then the nm checksum.
      //
      if (dd.expect (lid == "msvc"
                     ? cast<string> (rs["bin.ld.checksum"])
                     : cast<string> (rs["bin.nm.checksum"])) != nullptr)
        l4 ([&]{trace << "linker mismatch forcing update of " << t;});

      // @@ TODO: track in depdb if making symbol filtering configurable.

      // Collect and hash the list of object files seeing through libus{}.
      //
      vector<reference_wrapper<const objs>> os;
      {
        sha256 cs;

        auto collect = [a, &rs, &os, &cs] (const file& t,
                                           const auto& collect) -> void
        {
          for (const target* pt: t.prerequisite_targets[a])
          {
            if (pt == nullptr)
              continue;

            const objs* o;
            if ((o = pt->is_a<objs> ()) != nullptr)
              ;
            else if (pt->is_a<hbmi> ())
              o = find_adhoc_member<objs> (*pt);
            //
            // Note that in prerequisite targets we will have the libux{}
            // members, not the group.
            //
            else if (const libus* l = pt->is_a<libus> ())
            {
              collect (*l, collect);
              continue;
            }
            else
              continue;

            hash_path (cs, o->path (), rs.out_path ());
            os.push_back (*o);
          }
        };

        collect (t, collect);

        if (dd.expect (cs.string ()) != nullptr)
          l4 ([&]{trace << "file set mismatch forcing update of " << t;});
      }

      // Update if any mismatch or depdb is newer that the output.
      //
      if (dd.writing () || dd.mtime > mt)
        update = true;

      dd.close ();

      // If nothing changed, then we are done.
      //
      if (!update)
        return *ts;

      const process_path& nm (lid == "msvc"
                              ? cast<process_path> (rs["bin.ld.path"])
                              : cast<process_path> (rs["bin.nm.path"]));

      cstrings args {nm.recall_string ()};

      string nid;
      if (lid == "msvc")
      {
        args.push_back ("/DUMP"); // Must come first.
        args.push_back ("/NOLOGO");
        args.push_back ("/SYMBOLS");
      }
      else
      {
        nid = cast<string> (rs["bin.nm.id"]);

        if (nid == "msvc")
        {
          args.push_back ("/NOLOGO");
          args.push_back ("/SYMBOLS");
        }
        else
        {
          // Note that llvm-nm's --no-weak is only available since LLVM 7.
          //
          args.push_back ("--extern-only");
          args.push_back ("--format=posix");
        }
      }

      args.push_back (nullptr); // Argument placeholder.
      args.push_back (nullptr);

      const char*& arg (*(args.end () - 2));

      if (verb == 1)
        text << "def " << t;

      // Extract symbols from each object file.
      //
      symbols syms;
      for (const objs& o: os)
      {
        // Use a relative path for nicer diagnostics.
        //
        path rp (relative (o.path ()));
        arg = rp.string ().c_str ();

        if (verb >= 2)
          print_process (args);

        if (ctx.dry_run)
          continue;

        // Both dumpbin.exe and nm send their output to stdout. While nm sends
        // diagnostics to stderr, dumpbin sends it to stdout together with the
        // output.
        //
        process pr (run_start (nm,
                               args,
                               0     /* stdin */,
                               -1    /* stdout */));
        bool io (false);
        try
        {
          ifdstream is (
            move (pr.in_ofd), fdstream_mode::skip, ifdstream::badbit);

          if (lid == "msvc" || nid == "msvc")
            read_dumpbin (is, syms);
          else
            read_posix_nm (is, syms);

          is.close ();
        }
        catch (const io_error&)
        {
          // Presumably the child process failed so let run_finish() deal with
          // that first.
          //
          io = true;
        }

        if (!run_finish_code (args.data (), pr) || io)
          fail << "unable to extract symbols from " << arg;
      }

#if 0
      for (const string& s: syms.d) text << "D " << s;
      for (const string& s: syms.r) text << "R " << s;
      for (const string& s: syms.b) text << "B " << s;
      for (const string& s: syms.c) text << "C " << s;
      for (const string& s: syms.t) text << "T " << s;
#endif

      if (verb >= 3)
        text << "cat >" << tp;

      if (!ctx.dry_run)
      {
        const auto& tgt (cast<target_triplet> (rs["bin.target"]));

        bool i386 (tgt.cpu.size () == 4 &&
                   tgt.cpu[0] == 'i' && tgt.cpu[2] == '8' && tgt.cpu[3] == '6');

        auto_rmfile rm (tp);
        try
        {
          ofdstream os (tp);

          os << "; Auto-generated, do not edit.\n"
             << "EXPORTS\n";

          if (tgt.system == "mingw32")
            write_mingw32 (os, syms, i386);
          else
            write_win32_msvc (os, syms, i386);

          os.close ();
          rm.cancel ();
        }
        catch (const io_error& e)
        {
          fail << "unable to write to " << tp << ": " << e;
        }

        dd.check_mtime (tp);
      }

      t.mtime (system_clock::now ());
      return target_state::changed;
    }

    const string def_rule::rule_id_ {"bin.def 2"};
  }
}