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         "cmd/internal/bio"
  10         "cmd/internal/objabi"
  11         "cmd/internal/sys"
  12         "cmd/link/internal/loader"
  13         "cmd/link/internal/sym"
  14         "debug/pe"
  15         "encoding/binary"
  16         "errors"
  17         "fmt"
  18         "io"
  19         "sort"
  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 )
 119
 120 // TODO(crawshaw): de-duplicate these symbols with cmd/internal/ld, ideally in debug/pe.
 121 const (
 122         IMAGE_SCN_CNT_CODE               = 0x00000020
 123         IMAGE_SCN_CNT_INITIALIZED_DATA   = 0x00000040
 124         IMAGE_SCN_CNT_UNINITIALIZED_DATA = 0x00000080
 125         IMAGE_SCN_MEM_DISCARDABLE        = 0x02000000
 126         IMAGE_SCN_MEM_EXECUTE            = 0x20000000
 127         IMAGE_SCN_MEM_READ               = 0x40000000
 128         IMAGE_SCN_MEM_WRITE              = 0x80000000
 129 )
 130
 131 // TODO(brainman): maybe just add ReadAt method to bio.Reader instead of creating peBiobuf
 132
 133 // peBiobuf makes bio.Reader look like io.ReaderAt.
 134 type peBiobuf bio.Reader
 135
 136 func (f *peBiobuf) ReadAt(p []byte, off int64) (int, error) {
 137         ret := ((*bio.Reader)(f)).MustSeek(off, 0)
 138         if ret < 0 {
 139                 return 0, errors.New("fail to seek")
 140         }
 141         n, err := f.Read(p)
 142         if err != nil {
 143                 return 0, err
 144         }
 145         return n, nil
 146 }
 147
 148 // Load loads the PE file pn from input.
 149 // Symbols are written into syms, and a slice of the text symbols is returned.
 150 // If an .rsrc section is found, its symbol is returned as rsrc.
 151 func Load(l *loader.Loader, arch *sys.Arch, localSymVersion int, input *bio.Reader, pkg string, length int64, pn string) (textp []*sym.Symbol, rsrc *sym.Symbol, err error) {
 152         lookup := func(name string, version int) *sym.Symbol {
 153                 return l.LookupOrCreate(name, version)
 154         }
 155         sectsyms := make(map[*pe.Section]*sym.Symbol)
 156         sectdata := make(map[*pe.Section][]byte)
 157
 158         // Some input files are archives containing multiple of
 159         // object files, and pe.NewFile seeks to the start of
 160         // input file and get confused. Create section reader
 161         // to stop pe.NewFile looking before current position.
 162         sr := io.NewSectionReader((*peBiobuf)(input), input.Offset(), 1<<63-1)
 163
 164         // TODO: replace pe.NewFile with pe.Load (grep for "add Load function" in debug/pe for details)
 165         f, err := pe.NewFile(sr)
 166         if err != nil {
 167                 return nil, nil, err
 168         }
 169         defer f.Close()
 170
 171         // TODO return error if found .cormeta
 172
 173         // create symbols for mapped sections
 174         for _, sect := range f.Sections {
 175                 if sect.Characteristics&IMAGE_SCN_MEM_DISCARDABLE != 0 {
 176                         continue
 177                 }
 178
 179                 if sect.Characteristics&(IMAGE_SCN_CNT_CODE|IMAGE_SCN_CNT_INITIALIZED_DATA|IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0 {
 180                         // This has been seen for .idata sections, which we
 181                         // want to ignore. See issues 5106 and 5273.
 182                         continue
 183                 }
 184
 185                 name := fmt.Sprintf("%s(%s)", pkg, sect.Name)
 186                 s := lookup(name, localSymVersion)
 187
 188                 switch sect.Characteristics & (IMAGE_SCN_CNT_UNINITIALIZED_DATA | IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE | IMAGE_SCN_CNT_CODE | IMAGE_SCN_MEM_EXECUTE) {
 189                 case IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ: //.rdata
 190                         s.Type = sym.SRODATA
 191
 192                 case IMAGE_SCN_CNT_UNINITIALIZED_DATA | IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE: //.bss
 193                         s.Type = sym.SNOPTRBSS
 194
 195                 case IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE: //.data
 196                         s.Type = sym.SNOPTRDATA
 197
 198                 case IMAGE_SCN_CNT_CODE | IMAGE_SCN_MEM_EXECUTE | IMAGE_SCN_MEM_READ: //.text
 199                         s.Type = sym.STEXT
 200
 201                 default:
 202                         return nil, nil, fmt.Errorf("unexpected flags %#06x for PE section %s", sect.Characteristics, sect.Name)
 203                 }
 204
 205                 if s.Type != sym.SNOPTRBSS {
 206                         data, err := sect.Data()
 207                         if err != nil {
 208                                 return nil, nil, err
 209                         }
 210                         sectdata[sect] = data
 211                         s.P = data
 212                 }
 213                 s.Size = int64(sect.Size)
 214                 sectsyms[sect] = s
 215                 if sect.Name == ".rsrc" {
 216                         rsrc = s
 217                 }
 218         }
 219
 220         // load relocations
 221         for _, rsect := range f.Sections {
 222                 if _, found := sectsyms[rsect]; !found {
 223                         continue
 224                 }
 225                 if rsect.NumberOfRelocations == 0 {
 226                         continue
 227                 }
 228                 if rsect.Characteristics&IMAGE_SCN_MEM_DISCARDABLE != 0 {
 229                         continue
 230                 }
 231                 if rsect.Characteristics&(IMAGE_SCN_CNT_CODE|IMAGE_SCN_CNT_INITIALIZED_DATA|IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0 {
 232                         // This has been seen for .idata sections, which we
 233                         // want to ignore. See issues 5106 and 5273.
 234                         continue
 235                 }
 236
 237                 rs := make([]sym.Reloc, rsect.NumberOfRelocations)
 238                 for j, r := range rsect.Relocs {
 239                         rp := &rs[j]
 240                         if int(r.SymbolTableIndex) >= len(f.COFFSymbols) {
 241                                 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))
 242                         }
 243                         pesym := &f.COFFSymbols[r.SymbolTableIndex]
 244                         gosym, err := readpesym(arch, lookup, f, pesym, sectsyms, localSymVersion)
 245                         if err != nil {
 246                                 return nil, nil, err
 247                         }
 248                         if gosym == nil {
 249                                 name, err := pesym.FullName(f.StringTable)
 250                                 if err != nil {
 251                                         name = string(pesym.Name[:])
 252                                 }
 253                                 return nil, nil, fmt.Errorf("reloc of invalid sym %s idx=%d type=%d", name, r.SymbolTableIndex, pesym.Type)
 254                         }
 255
 256                         rp.Sym = gosym
 257                         rp.Siz = 4
 258                         rp.Off = int32(r.VirtualAddress)
 259                         switch arch.Family {
 260                         default:
 261                                 return nil, nil, fmt.Errorf("%s: unsupported arch %v", pn, arch.Family)
 262                         case sys.I386, sys.AMD64:
 263                                 switch r.Type {
 264                                 default:
 265                                         return nil, nil, fmt.Errorf("%s: %v: unknown relocation type %v", pn, sectsyms[rsect], r.Type)
 266
 267                                 case IMAGE_REL_I386_REL32, IMAGE_REL_AMD64_REL32,
 268                                         IMAGE_REL_AMD64_ADDR32, // R_X86_64_PC32
 269                                         IMAGE_REL_AMD64_ADDR32NB:
 270                                         rp.Type = objabi.R_PCREL
 271
 272                                         rp.Add = int64(int32(binary.LittleEndian.Uint32(sectdata[rsect][rp.Off:])))
 273
 274                                 case IMAGE_REL_I386_DIR32NB, IMAGE_REL_I386_DIR32:
 275                                         rp.Type = objabi.R_ADDR
 276
 277                                         // load addend from image
 278                                         rp.Add = int64(int32(binary.LittleEndian.Uint32(sectdata[rsect][rp.Off:])))
 279
 280                                 case IMAGE_REL_AMD64_ADDR64: // R_X86_64_64
 281                                         rp.Siz = 8
 282
 283                                         rp.Type = objabi.R_ADDR
 284
 285                                         // load addend from image
 286                                         rp.Add = int64(binary.LittleEndian.Uint64(sectdata[rsect][rp.Off:]))
 287                                 }
 288
 289                         case sys.ARM:
 290                                 switch r.Type {
 291                                 default:
 292                                         return nil, nil, fmt.Errorf("%s: %v: unknown ARM relocation type %v", pn, sectsyms[rsect], r.Type)
 293
 294                                 case IMAGE_REL_ARM_SECREL:
 295                                         rp.Type = objabi.R_PCREL
 296
 297                                         rp.Add = int64(int32(binary.LittleEndian.Uint32(sectdata[rsect][rp.Off:])))
 298
 299                                 case IMAGE_REL_ARM_ADDR32:
 300                                         rp.Type = objabi.R_ADDR
 301
 302                                         rp.Add = int64(int32(binary.LittleEndian.Uint32(sectdata[rsect][rp.Off:])))
 303
 304                                 case IMAGE_REL_ARM_BRANCH24:
 305                                         rp.Type = objabi.R_CALLARM
 306
 307                                         rp.Add = int64(int32(binary.LittleEndian.Uint32(sectdata[rsect][rp.Off:])))
 308                                 }
 309                         }
 310
 311                         // ld -r could generate multiple section symbols for the
 312                         // same section but with different values, we have to take
 313                         // that into account
 314                         if issect(pesym) {
 315                                 rp.Add += int64(pesym.Value)
 316                         }
 317                 }
 318
 319                 sort.Sort(sym.RelocByOff(rs[:rsect.NumberOfRelocations]))
 320
 321                 s := sectsyms[rsect]
 322                 s.R = rs
 323                 s.R = s.R[:rsect.NumberOfRelocations]
 324         }
 325
 326         // enter sub-symbols into symbol table.
 327         for i, numaux := 0, 0; i < len(f.COFFSymbols); i += numaux + 1 {
 328                 pesym := &f.COFFSymbols[i]
 329
 330                 numaux = int(pesym.NumberOfAuxSymbols)
 331
 332                 name, err := pesym.FullName(f.StringTable)
 333                 if err != nil {
 334                         return nil, nil, err
 335                 }
 336                 if name == "" {
 337                         continue
 338                 }
 339                 if issect(pesym) {
 340                         continue
 341                 }
 342                 if int(pesym.SectionNumber) > len(f.Sections) {
 343                         continue
 344                 }
 345                 if pesym.SectionNumber == IMAGE_SYM_DEBUG {
 346                         continue
 347                 }
 348                 var sect *pe.Section
 349                 if pesym.SectionNumber > 0 {
 350                         sect = f.Sections[pesym.SectionNumber-1]
 351                         if _, found := sectsyms[sect]; !found {
 352                                 continue
 353                         }
 354                 }
 355
 356                 s, err := readpesym(arch, lookup, f, pesym, sectsyms, localSymVersion)
 357                 if err != nil {
 358                         return nil, nil, err
 359                 }
 360
 361                 if pesym.SectionNumber == 0 { // extern
 362                         if s.Type == sym.SDYNIMPORT {
 363                                 s.SetPlt(-2) // flag for dynimport in PE object files.
 364                         }
 365                         if s.Type == sym.SXREF && pesym.Value > 0 { // global data
 366                                 s.Type = sym.SNOPTRDATA
 367                                 s.Size = int64(pesym.Value)
 368                         }
 369
 370                         continue
 371                 } else if pesym.SectionNumber > 0 && int(pesym.SectionNumber) <= len(f.Sections) {
 372                         sect = f.Sections[pesym.SectionNumber-1]
 373                         if _, found := sectsyms[sect]; !found {
 374                                 return nil, nil, fmt.Errorf("%s: %v: missing sect.sym", pn, s)
 375                         }
 376                 } else {
 377                         return nil, nil, fmt.Errorf("%s: %v: sectnum < 0!", pn, s)
 378                 }
 379
 380                 if sect == nil {
 381                         return nil, rsrc, nil
 382                 }
 383
 384                 if s.Outer != nil {
 385                         if s.Attr.DuplicateOK() {
 386                                 continue
 387                         }
 388                         return nil, nil, fmt.Errorf("%s: duplicate symbol reference: %s in both %s and %s", pn, s.Name, s.Outer.Name, sectsyms[sect].Name)
 389                 }
 390
 391                 sectsym := sectsyms[sect]
 392                 s.Sub = sectsym.Sub
 393                 sectsym.Sub = s
 394                 s.Type = sectsym.Type
 395                 s.Attr |= sym.AttrSubSymbol
 396                 s.Value = int64(pesym.Value)
 397                 s.Size = 4
 398                 s.Outer = sectsym
 399                 if sectsym.Type == sym.STEXT {
 400                         if s.Attr.External() && !s.Attr.DuplicateOK() {
 401                                 return nil, nil, fmt.Errorf("%s: duplicate symbol definition", s.Name)
 402                         }
 403                         s.Attr |= sym.AttrExternal
 404                 }
 405         }
 406
 407         // Sort outer lists by address, adding to textp.
 408         // This keeps textp in increasing address order.
 409         for _, sect := range f.Sections {
 410                 s := sectsyms[sect]
 411                 if s == nil {
 412                         continue
 413                 }
 414                 if s.Sub != nil {
 415                         s.Sub = sym.SortSub(s.Sub)
 416                 }
 417                 if s.Type == sym.STEXT {
 418                         if s.Attr.OnList() {
 419                                 return nil, nil, fmt.Errorf("symbol %s listed multiple times", s.Name)
 420                         }
 421                         s.Attr |= sym.AttrOnList
 422                         textp = append(textp, s)
 423                         for s = s.Sub; s != nil; s = s.Sub {
 424                                 if s.Attr.OnList() {
 425                                         return nil, nil, fmt.Errorf("symbol %s listed multiple times", s.Name)
 426                                 }
 427                                 s.Attr |= sym.AttrOnList
 428                                 textp = append(textp, s)
 429                         }
 430                 }
 431         }
 432
 433         return textp, rsrc, nil
 434 }
 435
 436 func issect(s *pe.COFFSymbol) bool {
 437         return s.StorageClass == IMAGE_SYM_CLASS_STATIC && s.Type == 0 && s.Name[0] == '.'
 438 }
 439
 440 func readpesym(arch *sys.Arch, lookup func(string, int) *sym.Symbol, f *pe.File, pesym *pe.COFFSymbol, sectsyms map[*pe.Section]*sym.Symbol, localSymVersion int) (*sym.Symbol, error) {
 441         symname, err := pesym.FullName(f.StringTable)
 442         if err != nil {
 443                 return nil, err
 444         }
 445         var name string
 446         if issect(pesym) {
 447                 name = sectsyms[f.Sections[pesym.SectionNumber-1]].Name
 448         } else {
 449                 name = symname
 450                 switch arch.Family {
 451                 case sys.AMD64:
 452                         if name == "__imp___acrt_iob_func" {
 453                                 // Do not rename __imp___acrt_iob_func into __acrt_iob_func,
 454                                 // because __imp___acrt_iob_func symbol is real
 455                                 // (see commit b295099 from git://git.code.sf.net/p/mingw-w64/mingw-w64 for details).
 456                         } else {
 457                                 name = strings.TrimPrefix(name, "__imp_") // __imp_Name => Name
 458                         }
 459                 case sys.I386:
 460                         if name == "__imp____acrt_iob_func" {
 461                                 // Do not rename __imp____acrt_iob_func into ___acrt_iob_func,
 462                                 // because __imp____acrt_iob_func symbol is real
 463                                 // (see commit b295099 from git://git.code.sf.net/p/mingw-w64/mingw-w64 for details).
 464                         } else {
 465                                 name = strings.TrimPrefix(name, "__imp_") // __imp_Name => Name
 466                         }
 467                         if name[0] == '_' {
 468                                 name = name[1:] // _Name => Name
 469                         }
 470                 }
 471         }
 472
 473         // remove last @XXX
 474         if i := strings.LastIndex(name, "@"); i >= 0 {
 475                 name = name[:i]
 476         }
 477
 478         var s *sym.Symbol
 479         switch pesym.Type {
 480         default:
 481                 return nil, fmt.Errorf("%s: invalid symbol type %d", symname, pesym.Type)
 482
 483         case IMAGE_SYM_DTYPE_FUNCTION, IMAGE_SYM_DTYPE_NULL:
 484                 switch pesym.StorageClass {
 485                 case IMAGE_SYM_CLASS_EXTERNAL: //global
 486                         s = lookup(name, 0)
 487
 488                 case IMAGE_SYM_CLASS_NULL, IMAGE_SYM_CLASS_STATIC, IMAGE_SYM_CLASS_LABEL:
 489                         s = lookup(name, localSymVersion)
 490                         s.Attr |= sym.AttrDuplicateOK
 491
 492                 default:
 493                         return nil, fmt.Errorf("%s: invalid symbol binding %d", symname, pesym.StorageClass)
 494                 }
 495         }
 496
 497         if s != nil && s.Type == 0 && (pesym.StorageClass != IMAGE_SYM_CLASS_STATIC || pesym.Value != 0) {
 498                 s.Type = sym.SXREF
 499         }
 500         if strings.HasPrefix(symname, "__imp_") {
 501                 s.SetGot(-2) // flag for __imp_
 502         }
 503
 504         return s, nil
 505 }