src/cmd/link/internal/loadpe/ldpe.go

   1 // Copyright 2010 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // Package loadpe implements a PE/COFF file reader.
   6 package loadpe
   7
   8 import (
   9         "bytes"
  10         "cmd/internal/bio"
  11         "cmd/internal/objabi"
  12         "cmd/internal/sys"
  13         "cmd/link/internal/loader"
  14         "cmd/link/internal/sym"
  15         "debug/pe"
  16         "encoding/binary"
  17         "errors"
  18         "fmt"
  19         "io"
  20         "strings"
  21 )
  22
  23 const (
  24         // TODO: the Microsoft doco says IMAGE_SYM_DTYPE_ARRAY is 3 (same with IMAGE_SYM_DTYPE_POINTER and IMAGE_SYM_DTYPE_FUNCTION)
  25         IMAGE_SYM_UNDEFINED              = 0
  26         IMAGE_SYM_ABSOLUTE               = -1
  27         IMAGE_SYM_DEBUG                  = -2
  28         IMAGE_SYM_TYPE_NULL              = 0
  29         IMAGE_SYM_TYPE_VOID              = 1
  30         IMAGE_SYM_TYPE_CHAR              = 2
  31         IMAGE_SYM_TYPE_SHORT             = 3
  32         IMAGE_SYM_TYPE_INT               = 4
  33         IMAGE_SYM_TYPE_LONG              = 5
  34         IMAGE_SYM_TYPE_FLOAT             = 6
  35         IMAGE_SYM_TYPE_DOUBLE            = 7
  36         IMAGE_SYM_TYPE_STRUCT            = 8
  37         IMAGE_SYM_TYPE_UNION             = 9
  38         IMAGE_SYM_TYPE_ENUM              = 10
  39         IMAGE_SYM_TYPE_MOE               = 11
  40         IMAGE_SYM_TYPE_BYTE              = 12
  41         IMAGE_SYM_TYPE_WORD              = 13
  42         IMAGE_SYM_TYPE_UINT              = 14
  43         IMAGE_SYM_TYPE_DWORD             = 15
  44         IMAGE_SYM_TYPE_PCODE             = 32768
  45         IMAGE_SYM_DTYPE_NULL             = 0
  46         IMAGE_SYM_DTYPE_POINTER          = 0x10
  47         IMAGE_SYM_DTYPE_FUNCTION         = 0x20
  48         IMAGE_SYM_DTYPE_ARRAY            = 0x30
  49         IMAGE_SYM_CLASS_END_OF_FUNCTION  = -1
  50         IMAGE_SYM_CLASS_NULL             = 0
  51         IMAGE_SYM_CLASS_AUTOMATIC        = 1
  52         IMAGE_SYM_CLASS_EXTERNAL         = 2
  53         IMAGE_SYM_CLASS_STATIC           = 3
  54         IMAGE_SYM_CLASS_REGISTER         = 4
  55         IMAGE_SYM_CLASS_EXTERNAL_DEF     = 5
  56         IMAGE_SYM_CLASS_LABEL            = 6
  57         IMAGE_SYM_CLASS_UNDEFINED_LABEL  = 7
  58         IMAGE_SYM_CLASS_MEMBER_OF_STRUCT = 8
  59         IMAGE_SYM_CLASS_ARGUMENT         = 9
  60         IMAGE_SYM_CLASS_STRUCT_TAG       = 10
  61         IMAGE_SYM_CLASS_MEMBER_OF_UNION  = 11
  62         IMAGE_SYM_CLASS_UNION_TAG        = 12
  63         IMAGE_SYM_CLASS_TYPE_DEFINITION  = 13
  64         IMAGE_SYM_CLASS_UNDEFINED_STATIC = 14
  65         IMAGE_SYM_CLASS_ENUM_TAG         = 15
  66         IMAGE_SYM_CLASS_MEMBER_OF_ENUM   = 16
  67         IMAGE_SYM_CLASS_REGISTER_PARAM   = 17
  68         IMAGE_SYM_CLASS_BIT_FIELD        = 18
  69         IMAGE_SYM_CLASS_FAR_EXTERNAL     = 68 /* Not in PECOFF v8 spec */
  70         IMAGE_SYM_CLASS_BLOCK            = 100
  71         IMAGE_SYM_CLASS_FUNCTION         = 101
  72         IMAGE_SYM_CLASS_END_OF_STRUCT    = 102
  73         IMAGE_SYM_CLASS_FILE             = 103
  74         IMAGE_SYM_CLASS_SECTION          = 104
  75         IMAGE_SYM_CLASS_WEAK_EXTERNAL    = 105
  76         IMAGE_SYM_CLASS_CLR_TOKEN        = 107
  77         IMAGE_REL_I386_ABSOLUTE          = 0x0000
  78         IMAGE_REL_I386_DIR16             = 0x0001
  79         IMAGE_REL_I386_REL16             = 0x0002
  80         IMAGE_REL_I386_DIR32             = 0x0006
  81         IMAGE_REL_I386_DIR32NB           = 0x0007
  82         IMAGE_REL_I386_SEG12             = 0x0009
  83         IMAGE_REL_I386_SECTION           = 0x000A
  84         IMAGE_REL_I386_SECREL            = 0x000B
  85         IMAGE_REL_I386_TOKEN             = 0x000C
  86         IMAGE_REL_I386_SECREL7           = 0x000D
  87         IMAGE_REL_I386_REL32             = 0x0014
  88         IMAGE_REL_AMD64_ABSOLUTE         = 0x0000
  89         IMAGE_REL_AMD64_ADDR64           = 0x0001
  90         IMAGE_REL_AMD64_ADDR32           = 0x0002
  91         IMAGE_REL_AMD64_ADDR32NB         = 0x0003
  92         IMAGE_REL_AMD64_REL32            = 0x0004
  93         IMAGE_REL_AMD64_REL32_1          = 0x0005
  94         IMAGE_REL_AMD64_REL32_2          = 0x0006
  95         IMAGE_REL_AMD64_REL32_3          = 0x0007
  96         IMAGE_REL_AMD64_REL32_4          = 0x0008
  97         IMAGE_REL_AMD64_REL32_5          = 0x0009
  98         IMAGE_REL_AMD64_SECTION          = 0x000A
  99         IMAGE_REL_AMD64_SECREL           = 0x000B
 100         IMAGE_REL_AMD64_SECREL7          = 0x000C
 101         IMAGE_REL_AMD64_TOKEN            = 0x000D
 102         IMAGE_REL_AMD64_SREL32           = 0x000E
 103         IMAGE_REL_AMD64_PAIR             = 0x000F
 104         IMAGE_REL_AMD64_SSPAN32          = 0x0010
 105         IMAGE_REL_ARM_ABSOLUTE           = 0x0000
 106         IMAGE_REL_ARM_ADDR32             = 0x0001
 107         IMAGE_REL_ARM_ADDR32NB           = 0x0002
 108         IMAGE_REL_ARM_BRANCH24           = 0x0003
 109         IMAGE_REL_ARM_BRANCH11           = 0x0004
 110         IMAGE_REL_ARM_SECTION            = 0x000E
 111         IMAGE_REL_ARM_SECREL             = 0x000F
 112         IMAGE_REL_ARM_MOV32              = 0x0010
 113         IMAGE_REL_THUMB_MOV32            = 0x0011
 114         IMAGE_REL_THUMB_BRANCH20         = 0x0012
 115         IMAGE_REL_THUMB_BRANCH24         = 0x0014
 116         IMAGE_REL_THUMB_BLX23            = 0x0015
 117         IMAGE_REL_ARM_PAIR               = 0x0016
 118         IMAGE_REL_ARM64_ABSOLUTE         = 0x0000
 119         IMAGE_REL_ARM64_ADDR32           = 0x0001
 120         IMAGE_REL_ARM64_ADDR32NB         = 0x0002
 121         IMAGE_REL_ARM64_BRANCH26         = 0x0003
 122         IMAGE_REL_ARM64_PAGEBASE_REL21   = 0x0004
 123         IMAGE_REL_ARM64_REL21            = 0x0005
 124         IMAGE_REL_ARM64_PAGEOFFSET_12A   = 0x0006
 125         IMAGE_REL_ARM64_PAGEOFFSET_12L   = 0x0007
 126         IMAGE_REL_ARM64_SECREL           = 0x0008
 127         IMAGE_REL_ARM64_SECREL_LOW12A    = 0x0009
 128         IMAGE_REL_ARM64_SECREL_HIGH12A   = 0x000A
 129         IMAGE_REL_ARM64_SECREL_LOW12L    = 0x000B
 130         IMAGE_REL_ARM64_TOKEN            = 0x000C
 131         IMAGE_REL_ARM64_SECTION          = 0x000D
 132         IMAGE_REL_ARM64_ADDR64           = 0x000E
 133         IMAGE_REL_ARM64_BRANCH19         = 0x000F
 134         IMAGE_REL_ARM64_BRANCH14         = 0x0010
 135         IMAGE_REL_ARM64_REL32            = 0x0011
 136 )
 137
 138 // TODO(brainman): maybe just add ReadAt method to bio.Reader instead of creating peBiobuf
 139
 140 // peBiobuf makes bio.Reader look like io.ReaderAt.
 141 type peBiobuf bio.Reader
 142
 143 func (f *peBiobuf) ReadAt(p []byte, off int64) (int, error) {
 144         ret := ((*bio.Reader)(f)).MustSeek(off, 0)
 145         if ret < 0 {
 146                 return 0, errors.New("fail to seek")
 147         }
 148         n, err := f.Read(p)
 149         if err != nil {
 150                 return 0, err
 151         }
 152         return n, nil
 153 }
 154
 155 // makeUpdater creates a loader.SymbolBuilder if one hasn't been created previously.
 156 // We use this to lazily make SymbolBuilders as we don't always need a builder, and creating them for all symbols might be an error.
 157 func makeUpdater(l *loader.Loader, bld *loader.SymbolBuilder, s loader.Sym) *loader.SymbolBuilder {
 158         if bld != nil {
 159                 return bld
 160         }
 161         bld = l.MakeSymbolUpdater(s)
 162         return bld
 163 }
 164
 165 // peLoaderState holds various bits of useful state information needed
 166 // while loading a PE object file.
 167 type peLoaderState struct {
 168         l               *loader.Loader
 169         arch            *sys.Arch
 170         f               *pe.File
 171         pn              string
 172         sectsyms        map[*pe.Section]loader.Sym
 173         defWithImp      map[string]struct{}
 174         comdats         map[uint16]int64 // key is section index, val is size
 175         sectdata        map[*pe.Section][]byte
 176         localSymVersion int
 177 }
 178
 179 // comdatDefinitions records the names of symbols for which we've
 180 // previously seen a definition in COMDAT. Key is symbol name, value
 181 // is symbol size (or -1 if we're using the "any" strategy).
 182 var comdatDefinitions = make(map[string]int64)
 183
 184 // Load loads the PE file pn from input.
 185 // Symbols are written into syms, and a slice of the text symbols is returned.
 186 // If an .rsrc section or set of .rsrc$xx sections is found, its symbols are
 187 // returned as rsrc.
 188 func Load(l *loader.Loader, arch *sys.Arch, localSymVersion int, input *bio.Reader, pkg string, length int64, pn string) (textp []loader.Sym, rsrc []loader.Sym, err error) {
 189         state := &peLoaderState{
 190                 l:               l,
 191                 arch:            arch,
 192                 sectsyms:        make(map[*pe.Section]loader.Sym),
 193                 sectdata:        make(map[*pe.Section][]byte),
 194                 localSymVersion: localSymVersion,
 195                 pn:              pn,
 196         }
 197
 198         // Some input files are archives containing multiple of
 199         // object files, and pe.NewFile seeks to the start of
 200         // input file and get confused. Create section reader
 201         // to stop pe.NewFile looking before current position.
 202         sr := io.NewSectionReader((*peBiobuf)(input), input.Offset(), 1<<63-1)
 203
 204         // TODO: replace pe.NewFile with pe.Load (grep for "add Load function" in debug/pe for details)
 205         f, err := pe.NewFile(sr)
 206         if err != nil {
 207                 return nil, nil, err
 208         }
 209         defer f.Close()
 210         state.f = f
 211
 212         // TODO return error if found .cormeta
 213
 214         // create symbols for mapped sections
 215         for _, sect := range f.Sections {
 216                 if sect.Characteristics&pe.IMAGE_SCN_MEM_DISCARDABLE != 0 {
 217                         continue
 218                 }
 219
 220                 if sect.Characteristics&(pe.IMAGE_SCN_CNT_CODE|pe.IMAGE_SCN_CNT_INITIALIZED_DATA|pe.IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0 {
 221                         // This has been seen for .idata sections, which we
 222                         // want to ignore. See issues 5106 and 5273.
 223                         continue
 224                 }
 225
 226                 name := fmt.Sprintf("%s(%s)", pkg, sect.Name)
 227                 s := state.l.LookupOrCreateCgoExport(name, localSymVersion)
 228                 bld := l.MakeSymbolUpdater(s)
 229
 230                 switch sect.Characteristics & (pe.IMAGE_SCN_CNT_UNINITIALIZED_DATA | pe.IMAGE_SCN_CNT_INITIALIZED_DATA | pe.IMAGE_SCN_MEM_READ | pe.IMAGE_SCN_MEM_WRITE | pe.IMAGE_SCN_CNT_CODE | pe.IMAGE_SCN_MEM_EXECUTE) {
 231                 case pe.IMAGE_SCN_CNT_INITIALIZED_DATA | pe.IMAGE_SCN_MEM_READ: //.rdata
 232                         bld.SetType(sym.SRODATA)
 233
 234                 case pe.IMAGE_SCN_CNT_UNINITIALIZED_DATA | pe.IMAGE_SCN_MEM_READ | pe.IMAGE_SCN_MEM_WRITE: //.bss
 235                         bld.SetType(sym.SNOPTRBSS)
 236
 237                 case pe.IMAGE_SCN_CNT_INITIALIZED_DATA | pe.IMAGE_SCN_MEM_READ | pe.IMAGE_SCN_MEM_WRITE: //.data
 238                         bld.SetType(sym.SNOPTRDATA)
 239
 240                 case pe.IMAGE_SCN_CNT_CODE | pe.IMAGE_SCN_MEM_EXECUTE | pe.IMAGE_SCN_MEM_READ: //.text
 241                         bld.SetType(sym.STEXT)
 242
 243                 default:
 244                         return nil, nil, fmt.Errorf("unexpected flags %#06x for PE section %s", sect.Characteristics, sect.Name)
 245                 }
 246
 247                 if bld.Type() != sym.SNOPTRBSS {
 248                         data, err := sect.Data()
 249                         if err != nil {
 250                                 return nil, nil, err
 251                         }
 252                         state.sectdata[sect] = data
 253                         bld.SetData(data)
 254                 }
 255                 bld.SetSize(int64(sect.Size))
 256                 state.sectsyms[sect] = s
 257                 if sect.Name == ".rsrc" || strings.HasPrefix(sect.Name, ".rsrc$") {
 258                         rsrc = append(rsrc, s)
 259                 }
 260         }
 261
 262         // Make a prepass over the symbols to detect situations where
 263         // we have both a defined symbol X and an import symbol __imp_X
 264         // (needed by readpesym()).
 265         if err := state.preprocessSymbols(); err != nil {
 266                 return nil, nil, err
 267         }
 268
 269         // load relocations
 270         for _, rsect := range f.Sections {
 271                 if _, found := state.sectsyms[rsect]; !found {
 272                         continue
 273                 }
 274                 if rsect.NumberOfRelocations == 0 {
 275                         continue
 276                 }
 277                 if rsect.Characteristics&pe.IMAGE_SCN_MEM_DISCARDABLE != 0 {
 278                         continue
 279                 }
 280                 if rsect.Characteristics&(pe.IMAGE_SCN_CNT_CODE|pe.IMAGE_SCN_CNT_INITIALIZED_DATA|pe.IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0 {
 281                         // This has been seen for .idata sections, which we
 282                         // want to ignore. See issues 5106 and 5273.
 283                         continue
 284                 }
 285
 286                 splitResources := strings.HasPrefix(rsect.Name, ".rsrc$")
 287                 sb := l.MakeSymbolUpdater(state.sectsyms[rsect])
 288                 for j, r := range rsect.Relocs {
 289                         if int(r.SymbolTableIndex) >= len(f.COFFSymbols) {
 290                                 return nil, nil, fmt.Errorf("relocation number %d symbol index idx=%d cannot be large then number of symbols %d", j, r.SymbolTableIndex, len(f.COFFSymbols))
 291                         }
 292                         pesym := &f.COFFSymbols[r.SymbolTableIndex]
 293                         _, gosym, err := state.readpesym(pesym)
 294                         if err != nil {
 295                                 return nil, nil, err
 296                         }
 297                         if gosym == 0 {
 298                                 name, err := pesym.FullName(f.StringTable)
 299                                 if err != nil {
 300                                         name = string(pesym.Name[:])
 301                                 }
 302                                 return nil, nil, fmt.Errorf("reloc of invalid sym %s idx=%d type=%d", name, r.SymbolTableIndex, pesym.Type)
 303                         }
 304
 305                         rSym := gosym
 306                         rSize := uint8(4)
 307                         rOff := int32(r.VirtualAddress)
 308                         var rAdd int64
 309                         var rType objabi.RelocType
 310                         switch arch.Family {
 311                         default:
 312                                 return nil, nil, fmt.Errorf("%s: unsupported arch %v", pn, arch.Family)
 313                         case sys.I386, sys.AMD64:
 314                                 switch r.Type {
 315                                 default:
 316                                         return nil, nil, fmt.Errorf("%s: %v: unknown relocation type %v", pn, state.sectsyms[rsect], r.Type)
 317
 318                                 case IMAGE_REL_I386_REL32, IMAGE_REL_AMD64_REL32,
 319                                         IMAGE_REL_AMD64_ADDR32, // R_X86_64_PC32
 320                                         IMAGE_REL_AMD64_ADDR32NB:
 321                                         rType = objabi.R_PCREL
 322
 323                                         rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
 324
 325                                 case IMAGE_REL_I386_DIR32NB, IMAGE_REL_I386_DIR32:
 326                                         rType = objabi.R_ADDR
 327
 328                                         // load addend from image
 329                                         rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
 330
 331                                 case IMAGE_REL_AMD64_ADDR64: // R_X86_64_64
 332                                         rSize = 8
 333
 334                                         rType = objabi.R_ADDR
 335
 336                                         // load addend from image
 337                                         rAdd = int64(binary.LittleEndian.Uint64(state.sectdata[rsect][rOff:]))
 338                                 }
 339
 340                         case sys.ARM:
 341                                 switch r.Type {
 342                                 default:
 343                                         return nil, nil, fmt.Errorf("%s: %v: unknown ARM relocation type %v", pn, state.sectsyms[rsect], r.Type)
 344
 345                                 case IMAGE_REL_ARM_SECREL:
 346                                         rType = objabi.R_PCREL
 347
 348                                         rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
 349
 350                                 case IMAGE_REL_ARM_ADDR32, IMAGE_REL_ARM_ADDR32NB:
 351                                         rType = objabi.R_ADDR
 352
 353                                         rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
 354
 355                                 case IMAGE_REL_ARM_BRANCH24:
 356                                         rType = objabi.R_CALLARM
 357
 358                                         rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
 359                                 }
 360
 361                         case sys.ARM64:
 362                                 switch r.Type {
 363                                 default:
 364                                         return nil, nil, fmt.Errorf("%s: %v: unknown ARM64 relocation type %v", pn, state.sectsyms[rsect], r.Type)
 365
 366                                 case IMAGE_REL_ARM64_ADDR32, IMAGE_REL_ARM64_ADDR32NB:
 367                                         rType = objabi.R_ADDR
 368
 369                                         rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
 370                                 }
 371                         }
 372
 373                         // ld -r could generate multiple section symbols for the
 374                         // same section but with different values, we have to take
 375                         // that into account, or in the case of split resources,
 376                         // the section and its symbols are split into two sections.
 377                         if issect(pesym) || splitResources {
 378                                 rAdd += int64(pesym.Value)
 379                         }
 380
 381                         rel, _ := sb.AddRel(rType)
 382                         rel.SetOff(rOff)
 383                         rel.SetSiz(rSize)
 384                         rel.SetSym(rSym)
 385                         rel.SetAdd(rAdd)
 386                 }
 387
 388                 sb.SortRelocs()
 389         }
 390
 391         // enter sub-symbols into symbol table.
 392         for i, numaux := 0, 0; i < len(f.COFFSymbols); i += numaux + 1 {
 393                 pesym := &f.COFFSymbols[i]
 394
 395                 numaux = int(pesym.NumberOfAuxSymbols)
 396
 397                 name, err := pesym.FullName(f.StringTable)
 398                 if err != nil {
 399                         return nil, nil, err
 400                 }
 401                 if name == "" {
 402                         continue
 403                 }
 404                 if issect(pesym) {
 405                         continue
 406                 }
 407                 if int(pesym.SectionNumber) > len(f.Sections) {
 408                         continue
 409                 }
 410                 if pesym.SectionNumber == IMAGE_SYM_DEBUG {
 411                         continue
 412                 }
 413                 if pesym.SectionNumber == IMAGE_SYM_ABSOLUTE && bytes.Equal(pesym.Name[:], []byte("@feat.00")) {
 414                         // Microsoft's linker looks at whether all input objects have an empty
 415                         // section called @feat.00. If all of them do, then it enables SEH;
 416                         // otherwise it doesn't enable that feature. So, since around the Windows
 417                         // XP SP2 era, most tools that make PE objects just tack on that section,
 418                         // so that it won't gimp Microsoft's linker logic. Go doesn't support SEH,
 419                         // so in theory, none of this really matters to us. But actually, if the
 420                         // linker tries to ingest an object with @feat.00 -- which are produced by
 421                         // LLVM's resource compiler, for example -- it chokes because of the
 422                         // IMAGE_SYM_ABSOLUTE section that it doesn't know how to deal with. Since
 423                         // @feat.00 is just a marking anyway, skip IMAGE_SYM_ABSOLUTE sections that
 424                         // are called @feat.00.
 425                         continue
 426                 }
 427                 var sect *pe.Section
 428                 if pesym.SectionNumber > 0 {
 429                         sect = f.Sections[pesym.SectionNumber-1]
 430                         if _, found := state.sectsyms[sect]; !found {
 431                                 continue
 432                         }
 433                 }
 434
 435                 bld, s, err := state.readpesym(pesym)
 436                 if err != nil {
 437                         return nil, nil, err
 438                 }
 439
 440                 if pesym.SectionNumber == 0 { // extern
 441                         if l.SymType(s) == sym.SDYNIMPORT {
 442                                 bld = makeUpdater(l, bld, s)
 443                                 bld.SetPlt(-2) // flag for dynimport in PE object files.
 444                         }
 445                         if l.SymType(s) == sym.SXREF && pesym.Value > 0 { // global data
 446                                 bld = makeUpdater(l, bld, s)
 447                                 bld.SetType(sym.SNOPTRDATA)
 448                                 bld.SetSize(int64(pesym.Value))
 449                         }
 450
 451                         continue
 452                 } else if pesym.SectionNumber > 0 && int(pesym.SectionNumber) <= len(f.Sections) {
 453                         sect = f.Sections[pesym.SectionNumber-1]
 454                         if _, found := state.sectsyms[sect]; !found {
 455                                 return nil, nil, fmt.Errorf("%s: %v: missing sect.sym", pn, s)
 456                         }
 457                 } else {
 458                         return nil, nil, fmt.Errorf("%s: %v: sectnum < 0!", pn, s)
 459                 }
 460
 461                 if sect == nil {
 462                         return nil, nil, nil
 463                 }
 464
 465                 // Check for COMDAT symbol.
 466                 if sz, ok1 := state.comdats[uint16(pesym.SectionNumber-1)]; ok1 {
 467                         if psz, ok2 := comdatDefinitions[l.SymName(s)]; ok2 {
 468                                 if sz == psz {
 469                                         //  OK to discard, we've seen an instance
 470                                         // already.
 471                                         continue
 472                                 }
 473                         }
 474                 }
 475                 if l.OuterSym(s) != 0 {
 476                         if l.AttrDuplicateOK(s) {
 477                                 continue
 478                         }
 479                         outerName := l.SymName(l.OuterSym(s))
 480                         sectName := l.SymName(state.sectsyms[sect])
 481                         return nil, nil, fmt.Errorf("%s: duplicate symbol reference: %s in both %s and %s", pn, l.SymName(s), outerName, sectName)
 482                 }
 483
 484                 bld = makeUpdater(l, bld, s)
 485                 sectsym := state.sectsyms[sect]
 486                 bld.SetType(l.SymType(sectsym))
 487                 l.AddInteriorSym(sectsym, s)
 488                 bld.SetValue(int64(pesym.Value))
 489                 bld.SetSize(4)
 490                 if l.SymType(sectsym) == sym.STEXT {
 491                         if bld.External() && !bld.DuplicateOK() {
 492                                 return nil, nil, fmt.Errorf("%s: duplicate symbol definition", l.SymName(s))
 493                         }
 494                         bld.SetExternal(true)
 495                 }
 496                 if sz, ok := state.comdats[uint16(pesym.SectionNumber-1)]; ok {
 497                         // This is a COMDAT definition. Record that we're picking
 498                         // this instance so that we can ignore future defs.
 499                         if _, ok := comdatDefinitions[l.SymName(s)]; ok {
 500                                 return nil, nil, fmt.Errorf("internal error: preexisting COMDAT definition for %q", name)
 501                         }
 502                         comdatDefinitions[l.SymName(s)] = sz
 503                 }
 504         }
 505
 506         // Sort outer lists by address, adding to textp.
 507         // This keeps textp in increasing address order.
 508         for _, sect := range f.Sections {
 509                 s := state.sectsyms[sect]
 510                 if s == 0 {
 511                         continue
 512                 }
 513                 l.SortSub(s)
 514                 if l.SymType(s) == sym.STEXT {
 515                         for ; s != 0; s = l.SubSym(s) {
 516                                 if l.AttrOnList(s) {
 517                                         return nil, nil, fmt.Errorf("symbol %s listed multiple times", l.SymName(s))
 518                                 }
 519                                 l.SetAttrOnList(s, true)
 520                                 textp = append(textp, s)
 521                         }
 522                 }
 523         }
 524
 525         return textp, rsrc, nil
 526 }
 527
 528 func issect(s *pe.COFFSymbol) bool {
 529         return s.StorageClass == IMAGE_SYM_CLASS_STATIC && s.Type == 0 && s.Name[0] == '.'
 530 }
 531
 532 func (state *peLoaderState) readpesym(pesym *pe.COFFSymbol) (*loader.SymbolBuilder, loader.Sym, error) {
 533         symname, err := pesym.FullName(state.f.StringTable)
 534         if err != nil {
 535                 return nil, 0, err
 536         }
 537         var name string
 538         if issect(pesym) {
 539                 name = state.l.SymName(state.sectsyms[state.f.Sections[pesym.SectionNumber-1]])
 540         } else {
 541                 name = symname
 542                 if strings.HasPrefix(symname, "__imp_") {
 543                         orig := symname[len("__imp_"):]
 544                         if _, ok := state.defWithImp[orig]; ok {
 545                                 // Don't rename __imp_XXX to XXX, since if we do this
 546                                 // we'll wind up with a duplicate definition. One
 547                                 // example is "__acrt_iob_func"; see commit b295099
 548                                 // from git://git.code.sf.net/p/mingw-w64/mingw-w64
 549                                 // for details.
 550                         } else {
 551                                 name = strings.TrimPrefix(name, "__imp_") // __imp_Name => Name
 552                         }
 553                 }
 554                 if state.arch.Family == sys.I386 && name[0] == '_' {
 555                         name = name[1:] // _Name => Name
 556                 }
 557         }
 558
 559         // remove last @XXX
 560         if i := strings.LastIndex(name, "@"); i >= 0 {
 561                 name = name[:i]
 562         }
 563
 564         var s loader.Sym
 565         var bld *loader.SymbolBuilder
 566         switch pesym.Type {
 567         default:
 568                 return nil, 0, fmt.Errorf("%s: invalid symbol type %d", symname, pesym.Type)
 569
 570         case IMAGE_SYM_DTYPE_FUNCTION, IMAGE_SYM_DTYPE_NULL:
 571                 switch pesym.StorageClass {
 572                 case IMAGE_SYM_CLASS_EXTERNAL: //global
 573                         s = state.l.LookupOrCreateCgoExport(name, 0)
 574
 575                 case IMAGE_SYM_CLASS_NULL, IMAGE_SYM_CLASS_STATIC, IMAGE_SYM_CLASS_LABEL:
 576                         s = state.l.LookupOrCreateCgoExport(name, state.localSymVersion)
 577                         bld = makeUpdater(state.l, bld, s)
 578                         bld.SetDuplicateOK(true)
 579
 580                 default:
 581                         return nil, 0, fmt.Errorf("%s: invalid symbol binding %d", symname, pesym.StorageClass)
 582                 }
 583         }
 584
 585         if s != 0 && state.l.SymType(s) == 0 && (pesym.StorageClass != IMAGE_SYM_CLASS_STATIC || pesym.Value != 0) {
 586                 bld = makeUpdater(state.l, bld, s)
 587                 bld.SetType(sym.SXREF)
 588         }
 589         if strings.HasPrefix(symname, "__imp_") {
 590                 bld = makeUpdater(state.l, bld, s)
 591                 bld.SetGot(-2) // flag for __imp_
 592         }
 593
 594         return bld, s, nil
 595 }
 596
 597 // preprocessSymbols walks the COFF symbols for the PE file we're
 598 // reading and looks for cases where we have both a symbol definition
 599 // for "XXX" and an "__imp_XXX" symbol, recording these cases in a map
 600 // in the state struct. This information will be used in readpesym()
 601 // above to give such symbols special treatment. This function also
 602 // gathers information about COMDAT sections/symbols for later use
 603 // in readpesym().
 604 func (state *peLoaderState) preprocessSymbols() error {
 605
 606         // Locate comdat sections.
 607         state.comdats = make(map[uint16]int64)
 608         for i, s := range state.f.Sections {
 609                 if s.Characteristics&uint32(pe.IMAGE_SCN_LNK_COMDAT) != 0 {
 610                         state.comdats[uint16(i)] = int64(s.Size)
 611                 }
 612         }
 613
 614         // Examine symbol defs.
 615         imp := make(map[string]struct{})
 616         def := make(map[string]struct{})
 617         for i, numaux := 0, 0; i < len(state.f.COFFSymbols); i += numaux + 1 {
 618                 pesym := &state.f.COFFSymbols[i]
 619                 numaux = int(pesym.NumberOfAuxSymbols)
 620                 if pesym.SectionNumber == 0 { // extern
 621                         continue
 622                 }
 623                 symname, err := pesym.FullName(state.f.StringTable)
 624                 if err != nil {
 625                         return err
 626                 }
 627                 def[symname] = struct{}{}
 628                 if strings.HasPrefix(symname, "__imp_") {
 629                         imp[strings.TrimPrefix(symname, "__imp_")] = struct{}{}
 630                 }
 631                 if _, isc := state.comdats[uint16(pesym.SectionNumber-1)]; !isc {
 632                         continue
 633                 }
 634                 if pesym.StorageClass != uint8(IMAGE_SYM_CLASS_STATIC) {
 635                         continue
 636                 }
 637                 // This symbol corresponds to a COMDAT section. Read the
 638                 // aux data for it.
 639                 auxsymp, err := state.f.COFFSymbolReadSectionDefAux(i)
 640                 if err != nil {
 641                         return fmt.Errorf("unable to read aux info for section def symbol %d %s: pe.COFFSymbolReadComdatInfo returns %v", i, symname, err)
 642                 }
 643                 if auxsymp.Selection == pe.IMAGE_COMDAT_SELECT_SAME_SIZE {
 644                         // This is supported.
 645                 } else if auxsymp.Selection == pe.IMAGE_COMDAT_SELECT_ANY {
 646                         // Also supported.
 647                         state.comdats[uint16(pesym.SectionNumber-1)] = int64(-1)
 648                 } else {
 649                         // We don't support any of the other strategies at the
 650                         // moment. I suspect that we may need to also support
 651                         // "associative", we'll see.
 652                         return fmt.Errorf("internal error: unsupported COMDAT selection strategy found in path=%s sec=%d strategy=%d idx=%d, please file a bug", state.pn, auxsymp.SecNum, auxsymp.Selection, i)
 653                 }
 654         }
 655         state.defWithImp = make(map[string]struct{})
 656         for n := range imp {
 657                 if _, ok := def[n]; ok {
 658                         state.defWithImp[n] = struct{}{}
 659                 }
 660         }
 661         return nil
 662 }