aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/go/_std_1.21/src/internal/xcoff/file.go
blob: 9135822f22704431cebdd9866d353f86ddf7704d (plain) (blame)
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
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package xcoff implements access to XCOFF (Extended Common Object File Format) files.
package xcoff

import (
	"debug/dwarf"
	"encoding/binary"
	"fmt"
	"internal/saferio"
	"io"
	"os"
	"strings"
)

// SectionHeader holds information about an XCOFF section header.
type SectionHeader struct {
	Name           string
	VirtualAddress uint64
	Size           uint64
	Type           uint32
	Relptr         uint64
	Nreloc         uint32
}

type Section struct {
	SectionHeader
	Relocs []Reloc
	io.ReaderAt
	sr *io.SectionReader
}

// AuxiliaryCSect holds information about an XCOFF symbol in an AUX_CSECT entry.
type AuxiliaryCSect struct {
	Length              int64
	StorageMappingClass int
	SymbolType          int
}

// AuxiliaryFcn holds information about an XCOFF symbol in an AUX_FCN entry.
type AuxiliaryFcn struct {
	Size int64
}

type Symbol struct {
	Name          string
	Value         uint64
	SectionNumber int
	StorageClass  int
	AuxFcn        AuxiliaryFcn
	AuxCSect      AuxiliaryCSect
}

type Reloc struct {
	VirtualAddress   uint64
	Symbol           *Symbol
	Signed           bool
	InstructionFixed bool
	Length           uint8
	Type             uint8
}

// ImportedSymbol holds information about an imported XCOFF symbol.
type ImportedSymbol struct {
	Name    string
	Library string
}

// FileHeader holds information about an XCOFF file header.
type FileHeader struct {
	TargetMachine uint16
}

// A File represents an open XCOFF file.
type File struct {
	FileHeader
	Sections     []*Section
	Symbols      []*Symbol
	StringTable  []byte
	LibraryPaths []string

	closer io.Closer
}

// Open opens the named file using os.Open and prepares it for use as an XCOFF binary.
func Open(name string) (*File, error) {
	f, err := os.Open(name)
	if err != nil {
		return nil, err
	}
	ff, err := NewFile(f)
	if err != nil {
		f.Close()
		return nil, err
	}
	ff.closer = f
	return ff, nil
}

// Close closes the File.
// If the File was created using NewFile directly instead of Open,
// Close has no effect.
func (f *File) Close() error {
	var err error
	if f.closer != nil {
		err = f.closer.Close()
		f.closer = nil
	}
	return err
}

// Section returns the first section with the given name, or nil if no such
// section exists.
// Xcoff have section's name limited to 8 bytes. Some sections like .gosymtab
// can be trunked but this method will still find them.
func (f *File) Section(name string) *Section {
	for _, s := range f.Sections {
		if s.Name == name || (len(name) > 8 && s.Name == name[:8]) {
			return s
		}
	}
	return nil
}

// SectionByType returns the first section in f with the
// given type, or nil if there is no such section.
func (f *File) SectionByType(typ uint32) *Section {
	for _, s := range f.Sections {
		if s.Type == typ {
			return s
		}
	}
	return nil
}

// cstring converts ASCII byte sequence b to string.
// It stops once it finds 0 or reaches end of b.
func cstring(b []byte) string {
	var i int
	for i = 0; i < len(b) && b[i] != 0; i++ {
	}
	return string(b[:i])
}

// getString extracts a string from an XCOFF string table.
func getString(st []byte, offset uint32) (string, bool) {
	if offset < 4 || int(offset) >= len(st) {
		return "", false
	}
	return cstring(st[offset:]), true
}

// NewFile creates a new File for accessing an XCOFF binary in an underlying reader.
func NewFile(r io.ReaderAt) (*File, error) {
	sr := io.NewSectionReader(r, 0, 1<<63-1)
	// Read XCOFF target machine
	var magic uint16
	if err := binary.Read(sr, binary.BigEndian, &magic); err != nil {
		return nil, err
	}
	if magic != U802TOCMAGIC && magic != U64_TOCMAGIC {
		return nil, fmt.Errorf("unrecognised XCOFF magic: 0x%x", magic)
	}

	f := new(File)
	f.TargetMachine = magic

	// Read XCOFF file header
	if _, err := sr.Seek(0, io.SeekStart); err != nil {
		return nil, err
	}
	var nscns uint16
	var symptr uint64
	var nsyms uint32
	var opthdr uint16
	var hdrsz int
	switch f.TargetMachine {
	case U802TOCMAGIC:
		fhdr := new(FileHeader32)
		if err := binary.Read(sr, binary.BigEndian, fhdr); err != nil {
			return nil, err
		}
		nscns = fhdr.Fnscns
		symptr = uint64(fhdr.Fsymptr)
		nsyms = fhdr.Fnsyms
		opthdr = fhdr.Fopthdr
		hdrsz = FILHSZ_32
	case U64_TOCMAGIC:
		fhdr := new(FileHeader64)
		if err := binary.Read(sr, binary.BigEndian, fhdr); err != nil {
			return nil, err
		}
		nscns = fhdr.Fnscns
		symptr = fhdr.Fsymptr
		nsyms = fhdr.Fnsyms
		opthdr = fhdr.Fopthdr
		hdrsz = FILHSZ_64
	}

	if symptr == 0 || nsyms <= 0 {
		return nil, fmt.Errorf("no symbol table")
	}

	// Read string table (located right after symbol table).
	offset := symptr + uint64(nsyms)*SYMESZ
	if _, err := sr.Seek(int64(offset), io.SeekStart); err != nil {
		return nil, err
	}
	// The first 4 bytes contain the length (in bytes).
	var l uint32
	if err := binary.Read(sr, binary.BigEndian, &l); err != nil {
		return nil, err
	}
	if l > 4 {
		st, err := saferio.ReadDataAt(sr, uint64(l), int64(offset))
		if err != nil {
			return nil, err
		}
		f.StringTable = st
	}

	// Read section headers
	if _, err := sr.Seek(int64(hdrsz)+int64(opthdr), io.SeekStart); err != nil {
		return nil, err
	}
	c := saferio.SliceCap((**Section)(nil), uint64(nscns))
	if c < 0 {
		return nil, fmt.Errorf("too many XCOFF sections (%d)", nscns)
	}
	f.Sections = make([]*Section, 0, c)
	for i := 0; i < int(nscns); i++ {
		var scnptr uint64
		s := new(Section)
		switch f.TargetMachine {
		case U802TOCMAGIC:
			shdr := new(SectionHeader32)
			if err := binary.Read(sr, binary.BigEndian, shdr); err != nil {
				return nil, err
			}
			s.Name = cstring(shdr.Sname[:])
			s.VirtualAddress = uint64(shdr.Svaddr)
			s.Size = uint64(shdr.Ssize)
			scnptr = uint64(shdr.Sscnptr)
			s.Type = shdr.Sflags
			s.Relptr = uint64(shdr.Srelptr)
			s.Nreloc = uint32(shdr.Snreloc)
		case U64_TOCMAGIC:
			shdr := new(SectionHeader64)
			if err := binary.Read(sr, binary.BigEndian, shdr); err != nil {
				return nil, err
			}
			s.Name = cstring(shdr.Sname[:])
			s.VirtualAddress = shdr.Svaddr
			s.Size = shdr.Ssize
			scnptr = shdr.Sscnptr
			s.Type = shdr.Sflags
			s.Relptr = shdr.Srelptr
			s.Nreloc = shdr.Snreloc
		}
		r2 := r
		if scnptr == 0 { // .bss must have all 0s
			r2 = zeroReaderAt{}
		}
		s.sr = io.NewSectionReader(r2, int64(scnptr), int64(s.Size))
		s.ReaderAt = s.sr
		f.Sections = append(f.Sections, s)
	}

	// Symbol map needed by relocation
	var idxToSym = make(map[int]*Symbol)

	// Read symbol table
	if _, err := sr.Seek(int64(symptr), io.SeekStart); err != nil {
		return nil, err
	}
	f.Symbols = make([]*Symbol, 0)
	for i := 0; i < int(nsyms); i++ {
		var numaux int
		var ok, needAuxFcn bool
		sym := new(Symbol)
		switch f.TargetMachine {
		case U802TOCMAGIC:
			se := new(SymEnt32)
			if err := binary.Read(sr, binary.BigEndian, se); err != nil {
				return nil, err
			}
			numaux = int(se.Nnumaux)
			sym.SectionNumber = int(se.Nscnum)
			sym.StorageClass = int(se.Nsclass)
			sym.Value = uint64(se.Nvalue)
			needAuxFcn = se.Ntype&SYM_TYPE_FUNC != 0 && numaux > 1
			zeroes := binary.BigEndian.Uint32(se.Nname[:4])
			if zeroes != 0 {
				sym.Name = cstring(se.Nname[:])
			} else {
				offset := binary.BigEndian.Uint32(se.Nname[4:])
				sym.Name, ok = getString(f.StringTable, offset)
				if !ok {
					goto skip
				}
			}
		case U64_TOCMAGIC:
			se := new(SymEnt64)
			if err := binary.Read(sr, binary.BigEndian, se); err != nil {
				return nil, err
			}
			numaux = int(se.Nnumaux)
			sym.SectionNumber = int(se.Nscnum)
			sym.StorageClass = int(se.Nsclass)
			sym.Value = se.Nvalue
			needAuxFcn = se.Ntype&SYM_TYPE_FUNC != 0 && numaux > 1
			sym.Name, ok = getString(f.StringTable, se.Noffset)
			if !ok {
				goto skip
			}
		}
		if sym.StorageClass != C_EXT && sym.StorageClass != C_WEAKEXT && sym.StorageClass != C_HIDEXT {
			goto skip
		}
		// Must have at least one csect auxiliary entry.
		if numaux < 1 || i+numaux >= int(nsyms) {
			goto skip
		}

		if sym.SectionNumber > int(nscns) {
			goto skip
		}
		if sym.SectionNumber == 0 {
			sym.Value = 0
		} else {
			sym.Value -= f.Sections[sym.SectionNumber-1].VirtualAddress
		}

		idxToSym[i] = sym

		// If this symbol is a function, it must retrieve its size from
		// its AUX_FCN entry.
		// It can happen that a function symbol doesn't have any AUX_FCN.
		// In this case, needAuxFcn is false and their size will be set to 0.
		if needAuxFcn {
			switch f.TargetMachine {
			case U802TOCMAGIC:
				aux := new(AuxFcn32)
				if err := binary.Read(sr, binary.BigEndian, aux); err != nil {
					return nil, err
				}
				sym.AuxFcn.Size = int64(aux.Xfsize)
			case U64_TOCMAGIC:
				aux := new(AuxFcn64)
				if err := binary.Read(sr, binary.BigEndian, aux); err != nil {
					return nil, err
				}
				sym.AuxFcn.Size = int64(aux.Xfsize)
			}
		}

		// Read csect auxiliary entry (by convention, it is the last).
		if !needAuxFcn {
			if _, err := sr.Seek(int64(numaux-1)*SYMESZ, io.SeekCurrent); err != nil {
				return nil, err
			}
		}
		i += numaux
		numaux = 0
		switch f.TargetMachine {
		case U802TOCMAGIC:
			aux := new(AuxCSect32)
			if err := binary.Read(sr, binary.BigEndian, aux); err != nil {
				return nil, err
			}
			sym.AuxCSect.SymbolType = int(aux.Xsmtyp & 0x7)
			sym.AuxCSect.StorageMappingClass = int(aux.Xsmclas)
			sym.AuxCSect.Length = int64(aux.Xscnlen)
		case U64_TOCMAGIC:
			aux := new(AuxCSect64)
			if err := binary.Read(sr, binary.BigEndian, aux); err != nil {
				return nil, err
			}
			sym.AuxCSect.SymbolType = int(aux.Xsmtyp & 0x7)
			sym.AuxCSect.StorageMappingClass = int(aux.Xsmclas)
			sym.AuxCSect.Length = int64(aux.Xscnlenhi)<<32 | int64(aux.Xscnlenlo)
		}
		f.Symbols = append(f.Symbols, sym)
	skip:
		i += numaux // Skip auxiliary entries
		if _, err := sr.Seek(int64(numaux)*SYMESZ, io.SeekCurrent); err != nil {
			return nil, err
		}
	}

	// Read relocations
	// Only for .data or .text section
	for sectNum, sect := range f.Sections {
		if sect.Type != STYP_TEXT && sect.Type != STYP_DATA {
			continue
		}
		if sect.Relptr == 0 {
			continue
		}
		c := saferio.SliceCap((*Reloc)(nil), uint64(sect.Nreloc))
		if c < 0 {
			return nil, fmt.Errorf("too many relocs (%d) for section %d", sect.Nreloc, sectNum)
		}
		sect.Relocs = make([]Reloc, 0, c)
		if _, err := sr.Seek(int64(sect.Relptr), io.SeekStart); err != nil {
			return nil, err
		}
		for i := uint32(0); i < sect.Nreloc; i++ {
			var reloc Reloc
			switch f.TargetMachine {
			case U802TOCMAGIC:
				rel := new(Reloc32)
				if err := binary.Read(sr, binary.BigEndian, rel); err != nil {
					return nil, err
				}
				reloc.VirtualAddress = uint64(rel.Rvaddr)
				reloc.Symbol = idxToSym[int(rel.Rsymndx)]
				reloc.Type = rel.Rtype
				reloc.Length = rel.Rsize&0x3F + 1

				if rel.Rsize&0x80 != 0 {
					reloc.Signed = true
				}
				if rel.Rsize&0x40 != 0 {
					reloc.InstructionFixed = true
				}

			case U64_TOCMAGIC:
				rel := new(Reloc64)
				if err := binary.Read(sr, binary.BigEndian, rel); err != nil {
					return nil, err
				}
				reloc.VirtualAddress = rel.Rvaddr
				reloc.Symbol = idxToSym[int(rel.Rsymndx)]
				reloc.Type = rel.Rtype
				reloc.Length = rel.Rsize&0x3F + 1
				if rel.Rsize&0x80 != 0 {
					reloc.Signed = true
				}
				if rel.Rsize&0x40 != 0 {
					reloc.InstructionFixed = true
				}
			}

			sect.Relocs = append(sect.Relocs, reloc)
		}
	}

	return f, nil
}

// zeroReaderAt is ReaderAt that reads 0s.
type zeroReaderAt struct{}

// ReadAt writes len(p) 0s into p.
func (w zeroReaderAt) ReadAt(p []byte, off int64) (n int, err error) {
	for i := range p {
		p[i] = 0
	}
	return len(p), nil
}

// Data reads and returns the contents of the XCOFF section s.
func (s *Section) Data() ([]byte, error) {
	dat := make([]byte, s.sr.Size())
	n, err := s.sr.ReadAt(dat, 0)
	if n == len(dat) {
		err = nil
	}
	return dat[:n], err
}

// CSect reads and returns the contents of a csect.
func (f *File) CSect(name string) []byte {
	for _, sym := range f.Symbols {
		if sym.Name == name && sym.AuxCSect.SymbolType == XTY_SD {
			if i := sym.SectionNumber - 1; 0 <= i && i < len(f.Sections) {
				s := f.Sections[i]
				if sym.Value+uint64(sym.AuxCSect.Length) <= s.Size {
					dat := make([]byte, sym.AuxCSect.Length)
					_, err := s.sr.ReadAt(dat, int64(sym.Value))
					if err != nil {
						return nil
					}
					return dat
				}
			}
			break
		}
	}
	return nil
}

func (f *File) DWARF() (*dwarf.Data, error) {
	// There are many other DWARF sections, but these
	// are the ones the debug/dwarf package uses.
	// Don't bother loading others.
	var subtypes = [...]uint32{SSUBTYP_DWABREV, SSUBTYP_DWINFO, SSUBTYP_DWLINE, SSUBTYP_DWRNGES, SSUBTYP_DWSTR}
	var dat [len(subtypes)][]byte
	for i, subtype := range subtypes {
		s := f.SectionByType(STYP_DWARF | subtype)
		if s != nil {
			b, err := s.Data()
			if err != nil && uint64(len(b)) < s.Size {
				return nil, err
			}
			dat[i] = b
		}
	}

	abbrev, info, line, ranges, str := dat[0], dat[1], dat[2], dat[3], dat[4]
	return dwarf.New(abbrev, nil, nil, info, line, nil, ranges, str)
}

// readImportID returns the import file IDs stored inside the .loader section.
// Library name pattern is either path/base/member or base/member
func (f *File) readImportIDs(s *Section) ([]string, error) {
	// Read loader header
	if _, err := s.sr.Seek(0, io.SeekStart); err != nil {
		return nil, err
	}
	var istlen uint32
	var nimpid uint32
	var impoff uint64
	switch f.TargetMachine {
	case U802TOCMAGIC:
		lhdr := new(LoaderHeader32)
		if err := binary.Read(s.sr, binary.BigEndian, lhdr); err != nil {
			return nil, err
		}
		istlen = lhdr.Listlen
		nimpid = lhdr.Lnimpid
		impoff = uint64(lhdr.Limpoff)
	case U64_TOCMAGIC:
		lhdr := new(LoaderHeader64)
		if err := binary.Read(s.sr, binary.BigEndian, lhdr); err != nil {
			return nil, err
		}
		istlen = lhdr.Listlen
		nimpid = lhdr.Lnimpid
		impoff = lhdr.Limpoff
	}

	// Read loader import file ID table
	if _, err := s.sr.Seek(int64(impoff), io.SeekStart); err != nil {
		return nil, err
	}
	table := make([]byte, istlen)
	if _, err := io.ReadFull(s.sr, table); err != nil {
		return nil, err
	}

	offset := 0
	// First import file ID is the default LIBPATH value
	libpath := cstring(table[offset:])
	f.LibraryPaths = strings.Split(libpath, ":")
	offset += len(libpath) + 3 // 3 null bytes
	all := make([]string, 0)
	for i := 1; i < int(nimpid); i++ {
		impidpath := cstring(table[offset:])
		offset += len(impidpath) + 1
		impidbase := cstring(table[offset:])
		offset += len(impidbase) + 1
		impidmem := cstring(table[offset:])
		offset += len(impidmem) + 1
		var path string
		if len(impidpath) > 0 {
			path = impidpath + "/" + impidbase + "/" + impidmem
		} else {
			path = impidbase + "/" + impidmem
		}
		all = append(all, path)
	}

	return all, nil
}

// ImportedSymbols returns the names of all symbols
// referred to by the binary f that are expected to be
// satisfied by other libraries at dynamic load time.
// It does not return weak symbols.
func (f *File) ImportedSymbols() ([]ImportedSymbol, error) {
	s := f.SectionByType(STYP_LOADER)
	if s == nil {
		return nil, nil
	}
	// Read loader header
	if _, err := s.sr.Seek(0, io.SeekStart); err != nil {
		return nil, err
	}
	var stlen uint32
	var stoff uint64
	var nsyms uint32
	var symoff uint64
	switch f.TargetMachine {
	case U802TOCMAGIC:
		lhdr := new(LoaderHeader32)
		if err := binary.Read(s.sr, binary.BigEndian, lhdr); err != nil {
			return nil, err
		}
		stlen = lhdr.Lstlen
		stoff = uint64(lhdr.Lstoff)
		nsyms = lhdr.Lnsyms
		symoff = LDHDRSZ_32
	case U64_TOCMAGIC:
		lhdr := new(LoaderHeader64)
		if err := binary.Read(s.sr, binary.BigEndian, lhdr); err != nil {
			return nil, err
		}
		stlen = lhdr.Lstlen
		stoff = lhdr.Lstoff
		nsyms = lhdr.Lnsyms
		symoff = lhdr.Lsymoff
	}

	// Read loader section string table
	if _, err := s.sr.Seek(int64(stoff), io.SeekStart); err != nil {
		return nil, err
	}
	st := make([]byte, stlen)
	if _, err := io.ReadFull(s.sr, st); err != nil {
		return nil, err
	}

	// Read imported libraries
	libs, err := f.readImportIDs(s)
	if err != nil {
		return nil, err
	}

	// Read loader symbol table
	if _, err := s.sr.Seek(int64(symoff), io.SeekStart); err != nil {
		return nil, err
	}
	all := make([]ImportedSymbol, 0)
	for i := 0; i < int(nsyms); i++ {
		var name string
		var ifile uint32
		var ok bool
		switch f.TargetMachine {
		case U802TOCMAGIC:
			ldsym := new(LoaderSymbol32)
			if err := binary.Read(s.sr, binary.BigEndian, ldsym); err != nil {
				return nil, err
			}
			if ldsym.Lsmtype&0x40 == 0 {
				continue // Imported symbols only
			}
			zeroes := binary.BigEndian.Uint32(ldsym.Lname[:4])
			if zeroes != 0 {
				name = cstring(ldsym.Lname[:])
			} else {
				offset := binary.BigEndian.Uint32(ldsym.Lname[4:])
				name, ok = getString(st, offset)
				if !ok {
					continue
				}
			}
			ifile = ldsym.Lifile
		case U64_TOCMAGIC:
			ldsym := new(LoaderSymbol64)
			if err := binary.Read(s.sr, binary.BigEndian, ldsym); err != nil {
				return nil, err
			}
			if ldsym.Lsmtype&0x40 == 0 {
				continue // Imported symbols only
			}
			name, ok = getString(st, ldsym.Loffset)
			if !ok {
				continue
			}
			ifile = ldsym.Lifile
		}
		var sym ImportedSymbol
		sym.Name = name
		if ifile >= 1 && int(ifile) <= len(libs) {
			sym.Library = libs[ifile-1]
		}
		all = append(all, sym)
	}

	return all, nil
}

// ImportedLibraries returns the names of all libraries
// referred to by the binary f that are expected to be
// linked with the binary at dynamic link time.
func (f *File) ImportedLibraries() ([]string, error) {
	s := f.SectionByType(STYP_LOADER)
	if s == nil {
		return nil, nil
	}
	all, err := f.readImportIDs(s)
	return all, err
}