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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Parsing of XCOFF executable (AIX)
package objfile
import (
"debug/dwarf"
"fmt"
"internal/xcoff"
"io"
"unicode"
)
type xcoffFile struct {
xcoff *xcoff.File
}
func openXcoff(r io.ReaderAt) (rawFile, error) {
f, err := xcoff.NewFile(r)
if err != nil {
return nil, err
}
return &xcoffFile{f}, nil
}
func (f *xcoffFile) symbols() ([]Sym, error) {
var syms []Sym
for _, s := range f.xcoff.Symbols {
const (
N_UNDEF = 0 // An undefined (extern) symbol
N_ABS = -1 // An absolute symbol (e_value is a constant, not an address)
N_DEBUG = -2 // A debugging symbol
)
sym := Sym{Name: s.Name, Addr: s.Value, Code: '?'}
switch s.SectionNumber {
case N_UNDEF:
sym.Code = 'U'
case N_ABS:
sym.Code = 'C'
case N_DEBUG:
sym.Code = '?'
default:
if s.SectionNumber < 0 || len(f.xcoff.Sections) < int(s.SectionNumber) {
return nil, fmt.Errorf("invalid section number in symbol table")
}
sect := f.xcoff.Sections[s.SectionNumber-1]
// debug/xcoff returns an offset in the section not the actual address
sym.Addr += sect.VirtualAddress
if s.AuxCSect.SymbolType&0x3 == xcoff.XTY_LD {
// The size of a function is contained in the
// AUX_FCN entry
sym.Size = s.AuxFcn.Size
} else {
sym.Size = s.AuxCSect.Length
}
sym.Size = s.AuxCSect.Length
switch sect.Type {
case xcoff.STYP_TEXT:
if s.AuxCSect.StorageMappingClass == xcoff.XMC_RO {
sym.Code = 'R'
} else {
sym.Code = 'T'
}
case xcoff.STYP_DATA:
sym.Code = 'D'
case xcoff.STYP_BSS:
sym.Code = 'B'
}
if s.StorageClass == xcoff.C_HIDEXT {
// Local symbol
sym.Code = unicode.ToLower(sym.Code)
}
}
syms = append(syms, sym)
}
return syms, nil
}
func (f *xcoffFile) pcln() (textStart uint64, symtab, pclntab []byte, err error) {
if sect := f.xcoff.Section(".text"); sect != nil {
textStart = sect.VirtualAddress
}
if pclntab, err = loadXCOFFTable(f.xcoff, "runtime.pclntab", "runtime.epclntab"); err != nil {
return 0, nil, nil, err
}
symtab, _ = loadXCOFFTable(f.xcoff, "runtime.symtab", "runtime.esymtab") // ignore error, this symbol is not useful anyway
return textStart, symtab, pclntab, nil
}
func (f *xcoffFile) text() (textStart uint64, text []byte, err error) {
sect := f.xcoff.Section(".text")
if sect == nil {
return 0, nil, fmt.Errorf("text section not found")
}
textStart = sect.VirtualAddress
text, err = sect.Data()
return
}
func findXCOFFSymbol(f *xcoff.File, name string) (*xcoff.Symbol, error) {
for _, s := range f.Symbols {
if s.Name != name {
continue
}
if s.SectionNumber <= 0 {
return nil, fmt.Errorf("symbol %s: invalid section number %d", name, s.SectionNumber)
}
if len(f.Sections) < int(s.SectionNumber) {
return nil, fmt.Errorf("symbol %s: section number %d is larger than max %d", name, s.SectionNumber, len(f.Sections))
}
return s, nil
}
return nil, fmt.Errorf("no %s symbol found", name)
}
func loadXCOFFTable(f *xcoff.File, sname, ename string) ([]byte, error) {
ssym, err := findXCOFFSymbol(f, sname)
if err != nil {
return nil, err
}
esym, err := findXCOFFSymbol(f, ename)
if err != nil {
return nil, err
}
if ssym.SectionNumber != esym.SectionNumber {
return nil, fmt.Errorf("%s and %s symbols must be in the same section", sname, ename)
}
sect := f.Sections[ssym.SectionNumber-1]
data, err := sect.Data()
if err != nil {
return nil, err
}
return data[ssym.Value:esym.Value], nil
}
func (f *xcoffFile) goarch() string {
switch f.xcoff.TargetMachine {
case xcoff.U802TOCMAGIC:
return "ppc"
case xcoff.U64_TOCMAGIC:
return "ppc64"
}
return ""
}
func (f *xcoffFile) loadAddress() (uint64, error) {
return 0, fmt.Errorf("unknown load address")
}
func (f *xcoffFile) dwarf() (*dwarf.Data, error) {
return f.xcoff.DWARF()
}
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