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/sym"
  13         "debug/pe"
  14         "encoding/binary"
  15         "errors"
  16         "fmt"
  17         "io"
  18         "sort"
  19         "strings"
  20 )
  21
  22 const (
  23         // TODO: the Microsoft doco says IMAGE_SYM_DTYPE_ARRAY is 3 (same with IMAGE_SYM_DTYPE_POINTER and IMAGE_SYM_DTYPE_FUNCTION)
  24         IMAGE_SYM_UNDEFINED              = 0
  25         IMAGE_SYM_ABSOLUTE               = -1
  26         IMAGE_SYM_DEBUG                  = -2
  27         IMAGE_SYM_TYPE_NULL              = 0
  28         IMAGE_SYM_TYPE_VOID              = 1
  29         IMAGE_SYM_TYPE_CHAR              = 2
  30         IMAGE_SYM_TYPE_SHORT             = 3
  31         IMAGE_SYM_TYPE_INT               = 4
  32         IMAGE_SYM_TYPE_LONG              = 5
  33         IMAGE_SYM_TYPE_FLOAT             = 6
  34         IMAGE_SYM_TYPE_DOUBLE            = 7
  35         IMAGE_SYM_TYPE_STRUCT            = 8
  36         IMAGE_SYM_TYPE_UNION             = 9
  37         IMAGE_SYM_TYPE_ENUM              = 10
  38         IMAGE_SYM_TYPE_MOE               = 11
  39         IMAGE_SYM_TYPE_BYTE              = 12
  40         IMAGE_SYM_TYPE_WORD              = 13
  41         IMAGE_SYM_TYPE_UINT              = 14
  42         IMAGE_SYM_TYPE_DWORD             = 15
  43         IMAGE_SYM_TYPE_PCODE             = 32768
  44         IMAGE_SYM_DTYPE_NULL             = 0
  45         IMAGE_SYM_DTYPE_POINTER          = 0x10
  46         IMAGE_SYM_DTYPE_FUNCTION         = 0x20
  47         IMAGE_SYM_DTYPE_ARRAY            = 0x30
  48         IMAGE_SYM_CLASS_END_OF_FUNCTION  = -1
  49         IMAGE_SYM_CLASS_NULL             = 0
  50         IMAGE_SYM_CLASS_AUTOMATIC        = 1
  51         IMAGE_SYM_CLASS_EXTERNAL         = 2
  52         IMAGE_SYM_CLASS_STATIC           = 3
  53         IMAGE_SYM_CLASS_REGISTER         = 4
  54         IMAGE_SYM_CLASS_EXTERNAL_DEF     = 5
  55         IMAGE_SYM_CLASS_LABEL            = 6
  56         IMAGE_SYM_CLASS_UNDEFINED_LABEL  = 7
  57         IMAGE_SYM_CLASS_MEMBER_OF_STRUCT = 8
  58         IMAGE_SYM_CLASS_ARGUMENT         = 9
  59         IMAGE_SYM_CLASS_STRUCT_TAG       = 10
  60         IMAGE_SYM_CLASS_MEMBER_OF_UNION  = 11
  61         IMAGE_SYM_CLASS_UNION_TAG        = 12
  62         IMAGE_SYM_CLASS_TYPE_DEFINITION  = 13
  63         IMAGE_SYM_CLASS_UNDEFINED_STATIC = 14
  64         IMAGE_SYM_CLASS_ENUM_TAG         = 15
  65         IMAGE_SYM_CLASS_MEMBER_OF_ENUM   = 16
  66         IMAGE_SYM_CLASS_REGISTER_PARAM   = 17
  67         IMAGE_SYM_CLASS_BIT_FIELD        = 18
  68         IMAGE_SYM_CLASS_FAR_EXTERNAL     = 68 /* Not in PECOFF v8 spec */
  69         IMAGE_SYM_CLASS_BLOCK            = 100
  70         IMAGE_SYM_CLASS_FUNCTION         = 101
  71         IMAGE_SYM_CLASS_END_OF_STRUCT    = 102
  72         IMAGE_SYM_CLASS_FILE             = 103
  73         IMAGE_SYM_CLASS_SECTION          = 104
  74         IMAGE_SYM_CLASS_WEAK_EXTERNAL    = 105
  75         IMAGE_SYM_CLASS_CLR_TOKEN        = 107
  76         IMAGE_REL_I386_ABSOLUTE          = 0x0000
  77         IMAGE_REL_I386_DIR16             = 0x0001
  78         IMAGE_REL_I386_REL16             = 0x0002
  79         IMAGE_REL_I386_DIR32             = 0x0006
  80         IMAGE_REL_I386_DIR32NB           = 0x0007
  81         IMAGE_REL_I386_SEG12             = 0x0009
  82         IMAGE_REL_I386_SECTION           = 0x000A
  83         IMAGE_REL_I386_SECREL            = 0x000B
  84         IMAGE_REL_I386_TOKEN             = 0x000C
  85         IMAGE_REL_I386_SECREL7           = 0x000D
  86         IMAGE_REL_I386_REL32             = 0x0014
  87         IMAGE_REL_AMD64_ABSOLUTE         = 0x0000
  88         IMAGE_REL_AMD64_ADDR64           = 0x0001
  89         IMAGE_REL_AMD64_ADDR32           = 0x0002
  90         IMAGE_REL_AMD64_ADDR32NB         = 0x0003
  91         IMAGE_REL_AMD64_REL32            = 0x0004
  92         IMAGE_REL_AMD64_REL32_1          = 0x0005
  93         IMAGE_REL_AMD64_REL32_2          = 0x0006
  94         IMAGE_REL_AMD64_REL32_3          = 0x0007
  95         IMAGE_REL_AMD64_REL32_4          = 0x0008
  96         IMAGE_REL_AMD64_REL32_5          = 0x0009
  97         IMAGE_REL_AMD64_SECTION          = 0x000A
  98         IMAGE_REL_AMD64_SECREL           = 0x000B
  99         IMAGE_REL_AMD64_SECREL7          = 0x000C
 100         IMAGE_REL_AMD64_TOKEN            = 0x000D
 101         IMAGE_REL_AMD64_SREL32           = 0x000E
 102         IMAGE_REL_AMD64_PAIR             = 0x000F
 103         IMAGE_REL_AMD64_SSPAN32          = 0x0010
 104 )
 105
 106 // TODO(crawshaw): de-duplicate these symbols with cmd/internal/ld, ideally in debug/pe.
 107 const (
 108         IMAGE_SCN_CNT_CODE               = 0x00000020
 109         IMAGE_SCN_CNT_INITIALIZED_DATA   = 0x00000040
 110         IMAGE_SCN_CNT_UNINITIALIZED_DATA = 0x00000080
 111         IMAGE_SCN_MEM_DISCARDABLE        = 0x02000000
 112         IMAGE_SCN_MEM_EXECUTE            = 0x20000000
 113         IMAGE_SCN_MEM_READ               = 0x40000000
 114         IMAGE_SCN_MEM_WRITE              = 0x80000000
 115 )
 116
 117 // TODO(brainman): maybe just add ReadAt method to bio.Reader instead of creating peBiobuf
 118
 119 // peBiobuf makes bio.Reader look like io.ReaderAt.
 120 type peBiobuf bio.Reader
 121
 122 func (f *peBiobuf) ReadAt(p []byte, off int64) (int, error) {
 123         ret := ((*bio.Reader)(f)).Seek(off, 0)
 124         if ret < 0 {
 125                 return 0, errors.New("fail to seek")
 126         }
 127         n, err := f.Read(p)
 128         if err != nil {
 129                 return 0, err
 130         }
 131         return n, nil
 132 }
 133
 134 // Load loads the PE file pn from input.
 135 // Symbols are written into syms, and a slice of the text symbols is returned.
 136 // If an .rsrc section is found, its symbol is returned as rsrc.
 137 func Load(arch *sys.Arch, syms *sym.Symbols, input *bio.Reader, pkg string, length int64, pn string) (textp []*sym.Symbol, rsrc *sym.Symbol, err error) {
 138         localSymVersion := syms.IncVersion()
 139
 140         sectsyms := make(map[*pe.Section]*sym.Symbol)
 141         sectdata := make(map[*pe.Section][]byte)
 142
 143         // Some input files are archives containing multiple of
 144         // object files, and pe.NewFile seeks to the start of
 145         // input file and get confused. Create section reader
 146         // to stop pe.NewFile looking before current position.
 147         sr := io.NewSectionReader((*peBiobuf)(input), input.Offset(), 1<<63-1)
 148
 149         // TODO: replace pe.NewFile with pe.Load (grep for "add Load function" in debug/pe for details)
 150         f, err := pe.NewFile(sr)
 151         if err != nil {
 152                 return nil, nil, err
 153         }
 154         defer f.Close()
 155
 156         // TODO return error if found .cormeta
 157
 158         // create symbols for mapped sections
 159         for _, sect := range f.Sections {
 160                 if sect.Characteristics&IMAGE_SCN_MEM_DISCARDABLE != 0 {
 161                         continue
 162                 }
 163
 164                 if sect.Characteristics&(IMAGE_SCN_CNT_CODE|IMAGE_SCN_CNT_INITIALIZED_DATA|IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0 {
 165                         // This has been seen for .idata sections, which we
 166                         // want to ignore. See issues 5106 and 5273.
 167                         continue
 168                 }
 169
 170                 name := fmt.Sprintf("%s(%s)", pkg, sect.Name)
 171                 s := syms.Lookup(name, localSymVersion)
 172
 173                 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) {
 174                 case IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ: //.rdata
 175                         s.Type = sym.SRODATA
 176
 177                 case IMAGE_SCN_CNT_UNINITIALIZED_DATA | IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE: //.bss
 178                         s.Type = sym.SNOPTRBSS
 179
 180                 case IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE: //.data
 181                         s.Type = sym.SNOPTRDATA
 182
 183                 case IMAGE_SCN_CNT_CODE | IMAGE_SCN_MEM_EXECUTE | IMAGE_SCN_MEM_READ: //.text
 184                         s.Type = sym.STEXT
 185
 186                 default:
 187                         return nil, nil, fmt.Errorf("unexpected flags %#06x for PE section %s", sect.Characteristics, sect.Name)
 188                 }
 189
 190                 if s.Type != sym.SNOPTRBSS {
 191                         data, err := sect.Data()
 192                         if err != nil {
 193                                 return nil, nil, err
 194                         }
 195                         sectdata[sect] = data
 196                         s.P = data
 197                 }
 198                 s.Size = int64(sect.Size)
 199                 sectsyms[sect] = s
 200                 if sect.Name == ".rsrc" {
 201                         rsrc = s
 202                 }
 203         }
 204
 205         // load relocations
 206         for _, rsect := range f.Sections {
 207                 if _, found := sectsyms[rsect]; !found {
 208                         continue
 209                 }
 210                 if rsect.NumberOfRelocations == 0 {
 211                         continue
 212                 }
 213                 if rsect.Characteristics&IMAGE_SCN_MEM_DISCARDABLE != 0 {
 214                         continue
 215                 }
 216                 if rsect.Characteristics&(IMAGE_SCN_CNT_CODE|IMAGE_SCN_CNT_INITIALIZED_DATA|IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0 {
 217                         // This has been seen for .idata sections, which we
 218                         // want to ignore. See issues 5106 and 5273.
 219                         continue
 220                 }
 221
 222                 rs := make([]sym.Reloc, rsect.NumberOfRelocations)
 223                 for j, r := range rsect.Relocs {
 224                         rp := &rs[j]
 225                         if int(r.SymbolTableIndex) >= len(f.COFFSymbols) {
 226                                 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))
 227                         }
 228                         pesym := &f.COFFSymbols[r.SymbolTableIndex]
 229                         gosym, err := readpesym(arch, syms, f, pesym, sectsyms, localSymVersion)
 230                         if err != nil {
 231                                 return nil, nil, err
 232                         }
 233                         if gosym == nil {
 234                                 name, err := pesym.FullName(f.StringTable)
 235                                 if err != nil {
 236                                         name = string(pesym.Name[:])
 237                                 }
 238                                 return nil, nil, fmt.Errorf("reloc of invalid sym %s idx=%d type=%d", name, r.SymbolTableIndex, pesym.Type)
 239                         }
 240
 241                         rp.Sym = gosym
 242                         rp.Siz = 4
 243                         rp.Off = int32(r.VirtualAddress)
 244                         switch r.Type {
 245                         default:
 246                                 return nil, nil, fmt.Errorf("%s: %v: unknown relocation type %v", pn, sectsyms[rsect], r.Type)
 247
 248                         case IMAGE_REL_I386_REL32, IMAGE_REL_AMD64_REL32,
 249                                 IMAGE_REL_AMD64_ADDR32, // R_X86_64_PC32
 250                                 IMAGE_REL_AMD64_ADDR32NB:
 251                                 rp.Type = objabi.R_PCREL
 252
 253                                 rp.Add = int64(int32(binary.LittleEndian.Uint32(sectdata[rsect][rp.Off:])))
 254
 255                         case IMAGE_REL_I386_DIR32NB, IMAGE_REL_I386_DIR32:
 256                                 rp.Type = objabi.R_ADDR
 257
 258                                 // load addend from image
 259                                 rp.Add = int64(int32(binary.LittleEndian.Uint32(sectdata[rsect][rp.Off:])))
 260
 261                         case IMAGE_REL_AMD64_ADDR64: // R_X86_64_64
 262                                 rp.Siz = 8
 263
 264                                 rp.Type = objabi.R_ADDR
 265
 266                                 // load addend from image
 267                                 rp.Add = int64(binary.LittleEndian.Uint64(sectdata[rsect][rp.Off:]))
 268                         }
 269
 270                         // ld -r could generate multiple section symbols for the
 271                         // same section but with different values, we have to take
 272                         // that into account
 273                         if issect(pesym) {
 274                                 rp.Add += int64(pesym.Value)
 275                         }
 276                 }
 277
 278                 sort.Sort(sym.RelocByOff(rs[:rsect.NumberOfRelocations]))
 279
 280                 s := sectsyms[rsect]
 281                 s.R = rs
 282                 s.R = s.R[:rsect.NumberOfRelocations]
 283         }
 284
 285         // enter sub-symbols into symbol table.
 286         for i, numaux := 0, 0; i < len(f.COFFSymbols); i += numaux + 1 {
 287                 pesym := &f.COFFSymbols[i]
 288
 289                 numaux = int(pesym.NumberOfAuxSymbols)
 290
 291                 name, err := pesym.FullName(f.StringTable)
 292                 if err != nil {
 293                         return nil, nil, err
 294                 }
 295                 if name == "" {
 296                         continue
 297                 }
 298                 if issect(pesym) {
 299                         continue
 300                 }
 301                 if int(pesym.SectionNumber) > len(f.Sections) {
 302                         continue
 303                 }
 304                 if pesym.SectionNumber == IMAGE_SYM_DEBUG {
 305                         continue
 306                 }
 307                 var sect *pe.Section
 308                 if pesym.SectionNumber > 0 {
 309                         sect = f.Sections[pesym.SectionNumber-1]
 310                         if _, found := sectsyms[sect]; !found {
 311                                 continue
 312                         }
 313                 }
 314
 315                 s, err := readpesym(arch, syms, f, pesym, sectsyms, localSymVersion)
 316                 if err != nil {
 317                         return nil, nil, err
 318                 }
 319
 320                 if pesym.SectionNumber == 0 { // extern
 321                         if s.Type == sym.SDYNIMPORT {
 322                                 s.Plt = -2 // flag for dynimport in PE object files.
 323                         }
 324                         if s.Type == sym.SXREF && pesym.Value > 0 { // global data
 325                                 s.Type = sym.SNOPTRDATA
 326                                 s.Size = int64(pesym.Value)
 327                         }
 328
 329                         continue
 330                 } else if pesym.SectionNumber > 0 && int(pesym.SectionNumber) <= len(f.Sections) {
 331                         sect = f.Sections[pesym.SectionNumber-1]
 332                         if _, found := sectsyms[sect]; !found {
 333                                 return nil, nil, fmt.Errorf("%s: %v: missing sect.sym", pn, s)
 334                         }
 335                 } else {
 336                         return nil, nil, fmt.Errorf("%s: %v: sectnum < 0!", pn, s)
 337                 }
 338
 339                 if sect == nil {
 340                         return nil, rsrc, nil
 341                 }
 342
 343                 if s.Outer != nil {
 344                         if s.Attr.DuplicateOK() {
 345                                 continue
 346                         }
 347                         return nil, nil, fmt.Errorf("%s: duplicate symbol reference: %s in both %s and %s", pn, s.Name, s.Outer.Name, sectsyms[sect].Name)
 348                 }
 349
 350                 sectsym := sectsyms[sect]
 351                 s.Sub = sectsym.Sub
 352                 sectsym.Sub = s
 353                 s.Type = sectsym.Type
 354                 s.Attr |= sym.AttrSubSymbol
 355                 s.Value = int64(pesym.Value)
 356                 s.Size = 4
 357                 s.Outer = sectsym
 358                 if sectsym.Type == sym.STEXT {
 359                         if s.Attr.External() && !s.Attr.DuplicateOK() {
 360                                 return nil, nil, fmt.Errorf("%s: duplicate symbol definition", s.Name)
 361                         }
 362                         s.Attr |= sym.AttrExternal
 363                 }
 364         }
 365
 366         // Sort outer lists by address, adding to textp.
 367         // This keeps textp in increasing address order.
 368         for _, sect := range f.Sections {
 369                 s := sectsyms[sect]
 370                 if s == nil {
 371                         continue
 372                 }
 373                 if s.Sub != nil {
 374                         s.Sub = sym.SortSub(s.Sub)
 375                 }
 376                 if s.Type == sym.STEXT {
 377                         if s.Attr.OnList() {
 378                                 return nil, nil, fmt.Errorf("symbol %s listed multiple times", s.Name)
 379                         }
 380                         s.Attr |= sym.AttrOnList
 381                         textp = append(textp, s)
 382                         for s = s.Sub; s != nil; s = s.Sub {
 383                                 if s.Attr.OnList() {
 384                                         return nil, nil, fmt.Errorf("symbol %s listed multiple times", s.Name)
 385                                 }
 386                                 s.Attr |= sym.AttrOnList
 387                                 textp = append(textp, s)
 388                         }
 389                 }
 390         }
 391
 392         return textp, rsrc, nil
 393 }
 394
 395 func issect(s *pe.COFFSymbol) bool {
 396         return s.StorageClass == IMAGE_SYM_CLASS_STATIC && s.Type == 0 && s.Name[0] == '.'
 397 }
 398
 399 func readpesym(arch *sys.Arch, syms *sym.Symbols, f *pe.File, pesym *pe.COFFSymbol, sectsyms map[*pe.Section]*sym.Symbol, localSymVersion int) (*sym.Symbol, error) {
 400         symname, err := pesym.FullName(f.StringTable)
 401         if err != nil {
 402                 return nil, err
 403         }
 404         var name string
 405         if issect(pesym) {
 406                 name = sectsyms[f.Sections[pesym.SectionNumber-1]].Name
 407         } else {
 408                 name = symname
 409                 if strings.HasPrefix(name, "__imp_") {
 410                         name = name[6:] // __imp_Name => Name
 411                 }
 412                 if arch.Family == sys.I386 && name[0] == '_' {
 413                         name = name[1:] // _Name => Name
 414                 }
 415         }
 416
 417         // remove last @XXX
 418         if i := strings.LastIndex(name, "@"); i >= 0 {
 419                 name = name[:i]
 420         }
 421
 422         var s *sym.Symbol
 423         switch pesym.Type {
 424         default:
 425                 return nil, fmt.Errorf("%s: invalid symbol type %d", symname, pesym.Type)
 426
 427         case IMAGE_SYM_DTYPE_FUNCTION, IMAGE_SYM_DTYPE_NULL:
 428                 switch pesym.StorageClass {
 429                 case IMAGE_SYM_CLASS_EXTERNAL: //global
 430                         s = syms.Lookup(name, 0)
 431
 432                 case IMAGE_SYM_CLASS_NULL, IMAGE_SYM_CLASS_STATIC, IMAGE_SYM_CLASS_LABEL:
 433                         s = syms.Lookup(name, localSymVersion)
 434                         s.Attr |= sym.AttrDuplicateOK
 435
 436                 default:
 437                         return nil, fmt.Errorf("%s: invalid symbol binding %d", symname, pesym.StorageClass)
 438                 }
 439         }
 440
 441         if s != nil && s.Type == 0 && (pesym.StorageClass != IMAGE_SYM_CLASS_STATIC || pesym.Value != 0) {
 442                 s.Type = sym.SXREF
 443         }
 444         if strings.HasPrefix(symname, "__imp_") {
 445                 s.Got = -2 // flag for __imp_
 446         }
 447
 448         return s, nil
 449 }