mirror of https://github.com/golang/go.git
780 lines
26 KiB
Go
780 lines
26 KiB
Go
// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package loadpe implements a PE/COFF file reader.
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package loadpe
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import (
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"bytes"
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"cmd/internal/bio"
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"cmd/internal/objabi"
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"cmd/internal/sys"
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"cmd/link/internal/loader"
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"cmd/link/internal/sym"
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"debug/pe"
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"encoding/binary"
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"errors"
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"fmt"
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"io"
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"strings"
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)
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const (
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IMAGE_SYM_UNDEFINED = 0
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IMAGE_SYM_ABSOLUTE = -1
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IMAGE_SYM_DEBUG = -2
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IMAGE_SYM_TYPE_NULL = 0
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IMAGE_SYM_TYPE_VOID = 1
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IMAGE_SYM_TYPE_CHAR = 2
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IMAGE_SYM_TYPE_SHORT = 3
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IMAGE_SYM_TYPE_INT = 4
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IMAGE_SYM_TYPE_LONG = 5
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IMAGE_SYM_TYPE_FLOAT = 6
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IMAGE_SYM_TYPE_DOUBLE = 7
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IMAGE_SYM_TYPE_STRUCT = 8
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IMAGE_SYM_TYPE_UNION = 9
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IMAGE_SYM_TYPE_ENUM = 10
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IMAGE_SYM_TYPE_MOE = 11
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IMAGE_SYM_TYPE_BYTE = 12
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IMAGE_SYM_TYPE_WORD = 13
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IMAGE_SYM_TYPE_UINT = 14
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IMAGE_SYM_TYPE_DWORD = 15
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IMAGE_SYM_TYPE_PCODE = 32768
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IMAGE_SYM_DTYPE_NULL = 0
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IMAGE_SYM_DTYPE_POINTER = 1
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IMAGE_SYM_DTYPE_FUNCTION = 2
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IMAGE_SYM_DTYPE_ARRAY = 3
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IMAGE_SYM_CLASS_END_OF_FUNCTION = -1
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IMAGE_SYM_CLASS_NULL = 0
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IMAGE_SYM_CLASS_AUTOMATIC = 1
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IMAGE_SYM_CLASS_EXTERNAL = 2
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IMAGE_SYM_CLASS_STATIC = 3
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IMAGE_SYM_CLASS_REGISTER = 4
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IMAGE_SYM_CLASS_EXTERNAL_DEF = 5
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IMAGE_SYM_CLASS_LABEL = 6
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IMAGE_SYM_CLASS_UNDEFINED_LABEL = 7
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IMAGE_SYM_CLASS_MEMBER_OF_STRUCT = 8
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IMAGE_SYM_CLASS_ARGUMENT = 9
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IMAGE_SYM_CLASS_STRUCT_TAG = 10
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IMAGE_SYM_CLASS_MEMBER_OF_UNION = 11
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IMAGE_SYM_CLASS_UNION_TAG = 12
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IMAGE_SYM_CLASS_TYPE_DEFINITION = 13
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IMAGE_SYM_CLASS_UNDEFINED_STATIC = 14
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IMAGE_SYM_CLASS_ENUM_TAG = 15
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IMAGE_SYM_CLASS_MEMBER_OF_ENUM = 16
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IMAGE_SYM_CLASS_REGISTER_PARAM = 17
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IMAGE_SYM_CLASS_BIT_FIELD = 18
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IMAGE_SYM_CLASS_FAR_EXTERNAL = 68 /* Not in PECOFF v8 spec */
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IMAGE_SYM_CLASS_BLOCK = 100
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IMAGE_SYM_CLASS_FUNCTION = 101
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IMAGE_SYM_CLASS_END_OF_STRUCT = 102
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IMAGE_SYM_CLASS_FILE = 103
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IMAGE_SYM_CLASS_SECTION = 104
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IMAGE_SYM_CLASS_WEAK_EXTERNAL = 105
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IMAGE_SYM_CLASS_CLR_TOKEN = 107
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IMAGE_REL_I386_ABSOLUTE = 0x0000
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IMAGE_REL_I386_DIR16 = 0x0001
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IMAGE_REL_I386_REL16 = 0x0002
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IMAGE_REL_I386_DIR32 = 0x0006
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IMAGE_REL_I386_DIR32NB = 0x0007
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IMAGE_REL_I386_SEG12 = 0x0009
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IMAGE_REL_I386_SECTION = 0x000A
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IMAGE_REL_I386_SECREL = 0x000B
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IMAGE_REL_I386_TOKEN = 0x000C
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IMAGE_REL_I386_SECREL7 = 0x000D
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IMAGE_REL_I386_REL32 = 0x0014
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IMAGE_REL_AMD64_ABSOLUTE = 0x0000
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IMAGE_REL_AMD64_ADDR64 = 0x0001
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IMAGE_REL_AMD64_ADDR32 = 0x0002
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IMAGE_REL_AMD64_ADDR32NB = 0x0003
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IMAGE_REL_AMD64_REL32 = 0x0004
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IMAGE_REL_AMD64_REL32_1 = 0x0005
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IMAGE_REL_AMD64_REL32_2 = 0x0006
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IMAGE_REL_AMD64_REL32_3 = 0x0007
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IMAGE_REL_AMD64_REL32_4 = 0x0008
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IMAGE_REL_AMD64_REL32_5 = 0x0009
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IMAGE_REL_AMD64_SECTION = 0x000A
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IMAGE_REL_AMD64_SECREL = 0x000B
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IMAGE_REL_AMD64_SECREL7 = 0x000C
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IMAGE_REL_AMD64_TOKEN = 0x000D
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IMAGE_REL_AMD64_SREL32 = 0x000E
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IMAGE_REL_AMD64_PAIR = 0x000F
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IMAGE_REL_AMD64_SSPAN32 = 0x0010
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IMAGE_REL_ARM_ABSOLUTE = 0x0000
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IMAGE_REL_ARM_ADDR32 = 0x0001
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IMAGE_REL_ARM_ADDR32NB = 0x0002
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IMAGE_REL_ARM_BRANCH24 = 0x0003
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IMAGE_REL_ARM_BRANCH11 = 0x0004
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IMAGE_REL_ARM_SECTION = 0x000E
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IMAGE_REL_ARM_SECREL = 0x000F
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IMAGE_REL_ARM_MOV32 = 0x0010
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IMAGE_REL_THUMB_MOV32 = 0x0011
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IMAGE_REL_THUMB_BRANCH20 = 0x0012
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IMAGE_REL_THUMB_BRANCH24 = 0x0014
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IMAGE_REL_THUMB_BLX23 = 0x0015
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IMAGE_REL_ARM_PAIR = 0x0016
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IMAGE_REL_ARM64_ABSOLUTE = 0x0000
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IMAGE_REL_ARM64_ADDR32 = 0x0001
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IMAGE_REL_ARM64_ADDR32NB = 0x0002
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IMAGE_REL_ARM64_BRANCH26 = 0x0003
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IMAGE_REL_ARM64_PAGEBASE_REL21 = 0x0004
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IMAGE_REL_ARM64_REL21 = 0x0005
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IMAGE_REL_ARM64_PAGEOFFSET_12A = 0x0006
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IMAGE_REL_ARM64_PAGEOFFSET_12L = 0x0007
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IMAGE_REL_ARM64_SECREL = 0x0008
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IMAGE_REL_ARM64_SECREL_LOW12A = 0x0009
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IMAGE_REL_ARM64_SECREL_HIGH12A = 0x000A
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IMAGE_REL_ARM64_SECREL_LOW12L = 0x000B
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IMAGE_REL_ARM64_TOKEN = 0x000C
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IMAGE_REL_ARM64_SECTION = 0x000D
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IMAGE_REL_ARM64_ADDR64 = 0x000E
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IMAGE_REL_ARM64_BRANCH19 = 0x000F
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IMAGE_REL_ARM64_BRANCH14 = 0x0010
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IMAGE_REL_ARM64_REL32 = 0x0011
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)
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const (
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// When stored into the PLT value for a symbol, this token tells
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// windynrelocsym to redirect direct references to this symbol to a stub
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// that loads from the corresponding import symbol and then does
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// a jump to the loaded value.
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CreateImportStubPltToken = -2
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// When stored into the GOT value for an import symbol __imp_X this
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// token tells windynrelocsym to redirect references to the
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// underlying DYNIMPORT symbol X.
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RedirectToDynImportGotToken = -2
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)
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// TODO(brainman): maybe just add ReadAt method to bio.Reader instead of creating peBiobuf
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// peBiobuf makes bio.Reader look like io.ReaderAt.
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type peBiobuf bio.Reader
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func (f *peBiobuf) ReadAt(p []byte, off int64) (int, error) {
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ret := ((*bio.Reader)(f)).MustSeek(off, 0)
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if ret < 0 {
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return 0, errors.New("fail to seek")
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}
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n, err := f.Read(p)
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if err != nil {
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return 0, err
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}
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return n, nil
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}
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// makeUpdater creates a loader.SymbolBuilder if one hasn't been created previously.
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// 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.
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func makeUpdater(l *loader.Loader, bld *loader.SymbolBuilder, s loader.Sym) *loader.SymbolBuilder {
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if bld != nil {
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return bld
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}
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bld = l.MakeSymbolUpdater(s)
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return bld
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}
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// peImportSymsState tracks the set of DLL import symbols we've seen
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// while reading host objects. We create a singleton instance of this
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// type, which will persist across multiple host objects.
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type peImportSymsState struct {
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// Text and non-text sections read in by the host object loader.
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secSyms []loader.Sym
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// SDYNIMPORT symbols encountered along the way
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dynimports map[loader.Sym]struct{}
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// Loader and arch, for use in postprocessing.
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l *loader.Loader
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arch *sys.Arch
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}
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var importSymsState *peImportSymsState
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func createImportSymsState(l *loader.Loader, arch *sys.Arch) {
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if importSymsState != nil {
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return
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}
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importSymsState = &peImportSymsState{
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dynimports: make(map[loader.Sym]struct{}),
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l: l,
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arch: arch,
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}
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}
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// peLoaderState holds various bits of useful state information needed
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// while loading a single PE object file.
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type peLoaderState struct {
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l *loader.Loader
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arch *sys.Arch
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f *pe.File
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pn string
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sectsyms map[*pe.Section]loader.Sym
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comdats map[uint16]int64 // key is section index, val is size
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sectdata map[*pe.Section][]byte
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localSymVersion int
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}
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// comdatDefinitions records the names of symbols for which we've
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// previously seen a definition in COMDAT. Key is symbol name, value
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// is symbol size (or -1 if we're using the "any" strategy).
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var comdatDefinitions = make(map[string]int64)
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// Load loads the PE file pn from input.
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// Symbols from the object file are created via the loader 'l', and
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// and a slice of the text symbols is returned.
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// If an .rsrc section or set of .rsrc$xx sections is found, its symbols are
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// returned as rsrc.
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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) {
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state := &peLoaderState{
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l: l,
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arch: arch,
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sectsyms: make(map[*pe.Section]loader.Sym),
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sectdata: make(map[*pe.Section][]byte),
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localSymVersion: localSymVersion,
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pn: pn,
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}
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createImportSymsState(state.l, state.arch)
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// Some input files are archives containing multiple of
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// object files, and pe.NewFile seeks to the start of
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// input file and get confused. Create section reader
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// to stop pe.NewFile looking before current position.
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sr := io.NewSectionReader((*peBiobuf)(input), input.Offset(), 1<<63-1)
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// TODO: replace pe.NewFile with pe.Load (grep for "add Load function" in debug/pe for details)
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f, err := pe.NewFile(sr)
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if err != nil {
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return nil, nil, err
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}
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defer f.Close()
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state.f = f
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// TODO return error if found .cormeta
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// create symbols for mapped sections
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for _, sect := range f.Sections {
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if sect.Characteristics&pe.IMAGE_SCN_MEM_DISCARDABLE != 0 {
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continue
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}
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if sect.Characteristics&(pe.IMAGE_SCN_CNT_CODE|pe.IMAGE_SCN_CNT_INITIALIZED_DATA|pe.IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0 {
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// This has been seen for .idata sections, which we
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// want to ignore. See issues 5106 and 5273.
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continue
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}
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name := fmt.Sprintf("%s(%s)", pkg, sect.Name)
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s := state.l.LookupOrCreateCgoExport(name, localSymVersion)
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bld := l.MakeSymbolUpdater(s)
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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) {
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case pe.IMAGE_SCN_CNT_INITIALIZED_DATA | pe.IMAGE_SCN_MEM_READ: //.rdata
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bld.SetType(sym.SRODATA)
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case pe.IMAGE_SCN_CNT_UNINITIALIZED_DATA | pe.IMAGE_SCN_MEM_READ | pe.IMAGE_SCN_MEM_WRITE: //.bss
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bld.SetType(sym.SNOPTRBSS)
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case pe.IMAGE_SCN_CNT_INITIALIZED_DATA | pe.IMAGE_SCN_MEM_READ | pe.IMAGE_SCN_MEM_WRITE: //.data
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bld.SetType(sym.SNOPTRDATA)
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case pe.IMAGE_SCN_CNT_CODE | pe.IMAGE_SCN_MEM_EXECUTE | pe.IMAGE_SCN_MEM_READ: //.text
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bld.SetType(sym.STEXT)
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default:
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return nil, nil, fmt.Errorf("unexpected flags %#06x for PE section %s", sect.Characteristics, sect.Name)
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}
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if bld.Type() != sym.SNOPTRBSS {
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data, err := sect.Data()
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if err != nil {
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return nil, nil, err
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}
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state.sectdata[sect] = data
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bld.SetData(data)
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}
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bld.SetSize(int64(sect.Size))
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state.sectsyms[sect] = s
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if sect.Name == ".rsrc" || strings.HasPrefix(sect.Name, ".rsrc$") {
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rsrc = append(rsrc, s)
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}
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}
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// Make a prepass over the symbols to collect info about COMDAT symbols.
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if err := state.preprocessSymbols(); err != nil {
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return nil, nil, err
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}
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// load relocations
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for _, rsect := range f.Sections {
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if _, found := state.sectsyms[rsect]; !found {
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continue
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}
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if rsect.NumberOfRelocations == 0 {
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continue
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}
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if rsect.Characteristics&pe.IMAGE_SCN_MEM_DISCARDABLE != 0 {
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continue
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}
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if rsect.Characteristics&(pe.IMAGE_SCN_CNT_CODE|pe.IMAGE_SCN_CNT_INITIALIZED_DATA|pe.IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0 {
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// This has been seen for .idata sections, which we
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// want to ignore. See issues 5106 and 5273.
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continue
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}
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splitResources := strings.HasPrefix(rsect.Name, ".rsrc$")
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sb := l.MakeSymbolUpdater(state.sectsyms[rsect])
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for j, r := range rsect.Relocs {
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if int(r.SymbolTableIndex) >= len(f.COFFSymbols) {
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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))
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}
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pesym := &f.COFFSymbols[r.SymbolTableIndex]
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_, gosym, err := state.readpesym(pesym)
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if err != nil {
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return nil, nil, err
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}
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if gosym == 0 {
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name, err := pesym.FullName(f.StringTable)
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if err != nil {
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name = string(pesym.Name[:])
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}
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return nil, nil, fmt.Errorf("reloc of invalid sym %s idx=%d type=%d", name, r.SymbolTableIndex, pesym.Type)
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}
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rSym := gosym
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rSize := uint8(4)
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rOff := int32(r.VirtualAddress)
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var rAdd int64
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var rType objabi.RelocType
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switch arch.Family {
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default:
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return nil, nil, fmt.Errorf("%s: unsupported arch %v", pn, arch.Family)
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case sys.I386, sys.AMD64:
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switch r.Type {
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default:
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return nil, nil, fmt.Errorf("%s: %v: unknown relocation type %v", pn, state.sectsyms[rsect], r.Type)
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case IMAGE_REL_I386_REL32, IMAGE_REL_AMD64_REL32,
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IMAGE_REL_AMD64_ADDR32, // R_X86_64_PC32
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IMAGE_REL_AMD64_ADDR32NB:
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rType = objabi.R_PCREL
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rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
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case IMAGE_REL_I386_DIR32NB, IMAGE_REL_I386_DIR32:
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rType = objabi.R_ADDR
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// load addend from image
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rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
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case IMAGE_REL_AMD64_ADDR64: // R_X86_64_64
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rSize = 8
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rType = objabi.R_ADDR
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// load addend from image
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rAdd = int64(binary.LittleEndian.Uint64(state.sectdata[rsect][rOff:]))
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}
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case sys.ARM:
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switch r.Type {
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default:
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return nil, nil, fmt.Errorf("%s: %v: unknown ARM relocation type %v", pn, state.sectsyms[rsect], r.Type)
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case IMAGE_REL_ARM_SECREL:
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rType = objabi.R_PCREL
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rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
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case IMAGE_REL_ARM_ADDR32, IMAGE_REL_ARM_ADDR32NB:
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rType = objabi.R_ADDR
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rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
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case IMAGE_REL_ARM_BRANCH24:
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rType = objabi.R_CALLARM
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rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
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}
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case sys.ARM64:
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switch r.Type {
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default:
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return nil, nil, fmt.Errorf("%s: %v: unknown ARM64 relocation type %v", pn, state.sectsyms[rsect], r.Type)
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case IMAGE_REL_ARM64_ADDR32, IMAGE_REL_ARM64_ADDR32NB:
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rType = objabi.R_ADDR
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rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
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}
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}
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// ld -r could generate multiple section symbols for the
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// same section but with different values, we have to take
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// that into account, or in the case of split resources,
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// the section and its symbols are split into two sections.
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if issect(pesym) || splitResources {
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rAdd += int64(pesym.Value)
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}
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rel, _ := sb.AddRel(rType)
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rel.SetOff(rOff)
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rel.SetSiz(rSize)
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rel.SetSym(rSym)
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rel.SetAdd(rAdd)
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}
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sb.SortRelocs()
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}
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// enter sub-symbols into symbol table.
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for i, numaux := 0, 0; i < len(f.COFFSymbols); i += numaux + 1 {
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pesym := &f.COFFSymbols[i]
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numaux = int(pesym.NumberOfAuxSymbols)
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name, err := pesym.FullName(f.StringTable)
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if err != nil {
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return nil, nil, err
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}
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if name == "" {
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continue
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}
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if issect(pesym) {
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continue
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}
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if int(pesym.SectionNumber) > len(f.Sections) {
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continue
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}
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if pesym.SectionNumber == IMAGE_SYM_DEBUG {
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continue
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}
|
|
if pesym.SectionNumber == IMAGE_SYM_ABSOLUTE && bytes.Equal(pesym.Name[:], []byte("@feat.00")) {
|
|
// Microsoft's linker looks at whether all input objects have an empty
|
|
// section called @feat.00. If all of them do, then it enables SEH;
|
|
// otherwise it doesn't enable that feature. So, since around the Windows
|
|
// XP SP2 era, most tools that make PE objects just tack on that section,
|
|
// so that it won't gimp Microsoft's linker logic. Go doesn't support SEH,
|
|
// so in theory, none of this really matters to us. But actually, if the
|
|
// linker tries to ingest an object with @feat.00 -- which are produced by
|
|
// LLVM's resource compiler, for example -- it chokes because of the
|
|
// IMAGE_SYM_ABSOLUTE section that it doesn't know how to deal with. Since
|
|
// @feat.00 is just a marking anyway, skip IMAGE_SYM_ABSOLUTE sections that
|
|
// are called @feat.00.
|
|
continue
|
|
}
|
|
var sect *pe.Section
|
|
if pesym.SectionNumber > 0 {
|
|
sect = f.Sections[pesym.SectionNumber-1]
|
|
if _, found := state.sectsyms[sect]; !found {
|
|
continue
|
|
}
|
|
}
|
|
|
|
bld, s, err := state.readpesym(pesym)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
|
|
if pesym.SectionNumber == 0 { // extern
|
|
if l.SymType(s) == sym.SXREF && pesym.Value > 0 { // global data
|
|
bld = makeUpdater(l, bld, s)
|
|
bld.SetType(sym.SNOPTRDATA)
|
|
bld.SetSize(int64(pesym.Value))
|
|
}
|
|
|
|
continue
|
|
} else if pesym.SectionNumber > 0 && int(pesym.SectionNumber) <= len(f.Sections) {
|
|
sect = f.Sections[pesym.SectionNumber-1]
|
|
if _, found := state.sectsyms[sect]; !found {
|
|
return nil, nil, fmt.Errorf("%s: %v: missing sect.sym", pn, s)
|
|
}
|
|
} else {
|
|
return nil, nil, fmt.Errorf("%s: %v: sectnum < 0!", pn, s)
|
|
}
|
|
|
|
if sect == nil {
|
|
return nil, nil, nil
|
|
}
|
|
|
|
// Check for COMDAT symbol.
|
|
if sz, ok1 := state.comdats[uint16(pesym.SectionNumber-1)]; ok1 {
|
|
if psz, ok2 := comdatDefinitions[l.SymName(s)]; ok2 {
|
|
if sz == psz {
|
|
// OK to discard, we've seen an instance
|
|
// already.
|
|
continue
|
|
}
|
|
}
|
|
}
|
|
if l.OuterSym(s) != 0 {
|
|
if l.AttrDuplicateOK(s) {
|
|
continue
|
|
}
|
|
outerName := l.SymName(l.OuterSym(s))
|
|
sectName := l.SymName(state.sectsyms[sect])
|
|
return nil, nil, fmt.Errorf("%s: duplicate symbol reference: %s in both %s and %s", pn, l.SymName(s), outerName, sectName)
|
|
}
|
|
|
|
bld = makeUpdater(l, bld, s)
|
|
sectsym := state.sectsyms[sect]
|
|
bld.SetType(l.SymType(sectsym))
|
|
l.AddInteriorSym(sectsym, s)
|
|
bld.SetValue(int64(pesym.Value))
|
|
bld.SetSize(4)
|
|
if l.SymType(sectsym) == sym.STEXT {
|
|
if bld.External() && !bld.DuplicateOK() {
|
|
return nil, nil, fmt.Errorf("%s: duplicate symbol definition", l.SymName(s))
|
|
}
|
|
bld.SetExternal(true)
|
|
}
|
|
if sz, ok := state.comdats[uint16(pesym.SectionNumber-1)]; ok {
|
|
// This is a COMDAT definition. Record that we're picking
|
|
// this instance so that we can ignore future defs.
|
|
if _, ok := comdatDefinitions[l.SymName(s)]; ok {
|
|
return nil, nil, fmt.Errorf("internal error: preexisting COMDAT definition for %q", name)
|
|
}
|
|
comdatDefinitions[l.SymName(s)] = sz
|
|
}
|
|
}
|
|
|
|
// Sort outer lists by address, adding to textp.
|
|
// This keeps textp in increasing address order.
|
|
for _, sect := range f.Sections {
|
|
s := state.sectsyms[sect]
|
|
if s == 0 {
|
|
continue
|
|
}
|
|
l.SortSub(s)
|
|
importSymsState.secSyms = append(importSymsState.secSyms, s)
|
|
if l.SymType(s) == sym.STEXT {
|
|
for ; s != 0; s = l.SubSym(s) {
|
|
if l.AttrOnList(s) {
|
|
return nil, nil, fmt.Errorf("symbol %s listed multiple times", l.SymName(s))
|
|
}
|
|
l.SetAttrOnList(s, true)
|
|
textp = append(textp, s)
|
|
}
|
|
}
|
|
}
|
|
|
|
return textp, rsrc, nil
|
|
}
|
|
|
|
// PostProcessImports works to resolve inconsistencies with DLL import
|
|
// symbols; it is needed when building with more "modern" C compilers
|
|
// with internal linkage.
|
|
//
|
|
// Background: DLL import symbols are data (SNOPTRDATA) symbols whose
|
|
// name is of the form "__imp_XXX", which contain a pointer/reference
|
|
// to symbol XXX. It's possible to have import symbols for both data
|
|
// symbols ("__imp__fmode") and text symbols ("__imp_CreateEventA").
|
|
// In some case import symbols are just references to some external
|
|
// thing, and in other cases we see actual definitions of import
|
|
// symbols when reading host objects.
|
|
//
|
|
// Previous versions of the linker would in most cases immediately
|
|
// "forward" import symbol references, e.g. treat a references to
|
|
// "__imp_XXX" a references to "XXX", however this doesn't work well
|
|
// with more modern compilers, where you can sometimes see import
|
|
// symbols that are defs (as opposed to external refs).
|
|
//
|
|
// The main actions taken below are to search for references to
|
|
// SDYNIMPORT symbols in host object text/data sections and flag the
|
|
// symbols for later fixup. When we see a reference to an import
|
|
// symbol __imp_XYZ where XYZ corresponds to some SDYNIMPORT symbol,
|
|
// we flag the symbol (via GOT setting) so that it can be redirected
|
|
// to XYZ later in windynrelocsym. When we see a direct reference to
|
|
// an SDYNIMPORT symbol XYZ, we also flag the symbol (via PLT setting)
|
|
// to indicated that the reference will need to be redirected to a
|
|
// stub.
|
|
func PostProcessImports() error {
|
|
ldr := importSymsState.l
|
|
arch := importSymsState.arch
|
|
keeprelocneeded := make(map[loader.Sym]loader.Sym)
|
|
for _, s := range importSymsState.secSyms {
|
|
isText := ldr.SymType(s) == sym.STEXT
|
|
relocs := ldr.Relocs(s)
|
|
for i := 0; i < relocs.Count(); i++ {
|
|
r := relocs.At(i)
|
|
rs := r.Sym()
|
|
if ldr.SymType(rs) == sym.SDYNIMPORT {
|
|
// Tag the symbol for later stub generation.
|
|
ldr.SetPlt(rs, CreateImportStubPltToken)
|
|
continue
|
|
}
|
|
isym, err := LookupBaseFromImport(rs, ldr, arch)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if isym == 0 {
|
|
continue
|
|
}
|
|
if ldr.SymType(isym) != sym.SDYNIMPORT {
|
|
continue
|
|
}
|
|
// For non-text symbols, forward the reference from __imp_X to
|
|
// X immediately.
|
|
if !isText {
|
|
r.SetSym(isym)
|
|
continue
|
|
}
|
|
// Flag this imp symbol to be processed later in windynrelocsym.
|
|
ldr.SetGot(rs, RedirectToDynImportGotToken)
|
|
// Consistency check: should be no PLT token here.
|
|
splt := ldr.SymPlt(rs)
|
|
if splt != -1 {
|
|
return fmt.Errorf("internal error: import symbol %q has invalid PLT setting %d", ldr.SymName(rs), splt)
|
|
}
|
|
// Flag for dummy relocation.
|
|
keeprelocneeded[rs] = isym
|
|
}
|
|
}
|
|
for k, v := range keeprelocneeded {
|
|
sb := ldr.MakeSymbolUpdater(k)
|
|
r, _ := sb.AddRel(objabi.R_KEEP)
|
|
r.SetSym(v)
|
|
}
|
|
importSymsState = nil
|
|
return nil
|
|
}
|
|
|
|
func issect(s *pe.COFFSymbol) bool {
|
|
return s.StorageClass == IMAGE_SYM_CLASS_STATIC && s.Type == 0 && s.Name[0] == '.'
|
|
}
|
|
|
|
func (state *peLoaderState) readpesym(pesym *pe.COFFSymbol) (*loader.SymbolBuilder, loader.Sym, error) {
|
|
symname, err := pesym.FullName(state.f.StringTable)
|
|
if err != nil {
|
|
return nil, 0, err
|
|
}
|
|
var name string
|
|
if issect(pesym) {
|
|
name = state.l.SymName(state.sectsyms[state.f.Sections[pesym.SectionNumber-1]])
|
|
} else {
|
|
name = symname
|
|
// A note on the "_main" exclusion below: the main routine
|
|
// defined by the Go runtime is named "_main", not "main", so
|
|
// when reading references to _main from a host object we want
|
|
// to avoid rewriting "_main" to "main" in this specific
|
|
// instance. See #issuecomment-1143698749 on #35006 for more
|
|
// details on this problem.
|
|
if state.arch.Family == sys.I386 && name[0] == '_' && name != "_main" && !strings.HasPrefix(name, "__imp_") {
|
|
name = name[1:] // _Name => Name
|
|
}
|
|
}
|
|
|
|
// remove last @XXX
|
|
if i := strings.LastIndex(name, "@"); i >= 0 {
|
|
name = name[:i]
|
|
}
|
|
|
|
var s loader.Sym
|
|
var bld *loader.SymbolBuilder
|
|
// Microsoft's PE documentation is contradictory. It says that the symbol's complex type
|
|
// is stored in the pesym.Type most significant byte, but MSVC, LLVM, and mingw store it
|
|
// in the 4 high bits of the less significant byte.
|
|
switch uint8(pesym.Type&0xf0) >> 4 {
|
|
default:
|
|
return nil, 0, fmt.Errorf("%s: invalid symbol type %d", symname, pesym.Type)
|
|
|
|
case IMAGE_SYM_DTYPE_FUNCTION, IMAGE_SYM_DTYPE_NULL:
|
|
switch pesym.StorageClass {
|
|
case IMAGE_SYM_CLASS_EXTERNAL: //global
|
|
s = state.l.LookupOrCreateCgoExport(name, 0)
|
|
|
|
case IMAGE_SYM_CLASS_NULL, IMAGE_SYM_CLASS_STATIC, IMAGE_SYM_CLASS_LABEL:
|
|
s = state.l.LookupOrCreateCgoExport(name, state.localSymVersion)
|
|
bld = makeUpdater(state.l, bld, s)
|
|
bld.SetDuplicateOK(true)
|
|
|
|
default:
|
|
return nil, 0, fmt.Errorf("%s: invalid symbol binding %d", symname, pesym.StorageClass)
|
|
}
|
|
}
|
|
|
|
if s != 0 && state.l.SymType(s) == 0 && (pesym.StorageClass != IMAGE_SYM_CLASS_STATIC || pesym.Value != 0) {
|
|
bld = makeUpdater(state.l, bld, s)
|
|
bld.SetType(sym.SXREF)
|
|
}
|
|
|
|
return bld, s, nil
|
|
}
|
|
|
|
// preprocessSymbols walks the COFF symbols for the PE file we're
|
|
// reading and looks for cases where we have both a symbol definition
|
|
// for "XXX" and an "__imp_XXX" symbol, recording these cases in a map
|
|
// in the state struct. This information will be used in readpesym()
|
|
// above to give such symbols special treatment. This function also
|
|
// gathers information about COMDAT sections/symbols for later use
|
|
// in readpesym().
|
|
func (state *peLoaderState) preprocessSymbols() error {
|
|
|
|
// Locate comdat sections.
|
|
state.comdats = make(map[uint16]int64)
|
|
for i, s := range state.f.Sections {
|
|
if s.Characteristics&uint32(pe.IMAGE_SCN_LNK_COMDAT) != 0 {
|
|
state.comdats[uint16(i)] = int64(s.Size)
|
|
}
|
|
}
|
|
|
|
// Examine symbol defs.
|
|
for i, numaux := 0, 0; i < len(state.f.COFFSymbols); i += numaux + 1 {
|
|
pesym := &state.f.COFFSymbols[i]
|
|
numaux = int(pesym.NumberOfAuxSymbols)
|
|
if pesym.SectionNumber == 0 { // extern
|
|
continue
|
|
}
|
|
symname, err := pesym.FullName(state.f.StringTable)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if _, isc := state.comdats[uint16(pesym.SectionNumber-1)]; !isc {
|
|
continue
|
|
}
|
|
if pesym.StorageClass != uint8(IMAGE_SYM_CLASS_STATIC) {
|
|
continue
|
|
}
|
|
// This symbol corresponds to a COMDAT section. Read the
|
|
// aux data for it.
|
|
auxsymp, err := state.f.COFFSymbolReadSectionDefAux(i)
|
|
if err != nil {
|
|
return fmt.Errorf("unable to read aux info for section def symbol %d %s: pe.COFFSymbolReadComdatInfo returns %v", i, symname, err)
|
|
}
|
|
if auxsymp.Selection == pe.IMAGE_COMDAT_SELECT_SAME_SIZE {
|
|
// This is supported.
|
|
} else if auxsymp.Selection == pe.IMAGE_COMDAT_SELECT_ANY {
|
|
// Also supported.
|
|
state.comdats[uint16(pesym.SectionNumber-1)] = int64(-1)
|
|
} else {
|
|
// We don't support any of the other strategies at the
|
|
// moment. I suspect that we may need to also support
|
|
// "associative", we'll see.
|
|
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)
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// LookupBaseFromImport examines the symbol "s" to see if it
|
|
// corresponds to an import symbol (name of the form "__imp_XYZ") and
|
|
// if so, it looks up the underlying target of the import symbol and
|
|
// returns it. An error is returned if the symbol is of the form
|
|
// "__imp_XYZ" but no XYZ can be found.
|
|
func LookupBaseFromImport(s loader.Sym, ldr *loader.Loader, arch *sys.Arch) (loader.Sym, error) {
|
|
sname := ldr.SymName(s)
|
|
if !strings.HasPrefix(sname, "__imp_") {
|
|
return 0, nil
|
|
}
|
|
basename := sname[len("__imp_"):]
|
|
if arch.Family == sys.I386 && basename[0] == '_' {
|
|
basename = basename[1:] // _Name => Name
|
|
}
|
|
isym := ldr.Lookup(basename, 0)
|
|
if isym == 0 {
|
|
return 0, fmt.Errorf("internal error: import symbol %q with no underlying sym", sname)
|
|
}
|
|
return isym, nil
|
|
}
|