// Copyright 2009 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 dwarf
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import (
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"sort"
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"strconv"
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)
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// DWARF debug info is split into a sequence of compilation units.
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// Each unit has its own abbreviation table and address size.
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type unit struct {
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base Offset // byte offset of header within the aggregate info
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off Offset // byte offset of data within the aggregate info
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data []byte
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atable abbrevTable
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asize int
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vers int
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is64 bool // True for 64-bit DWARF format
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}
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// Implement the dataFormat interface.
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func (u *unit) version() int {
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return u.vers
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}
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func (u *unit) dwarf64() (bool, bool) {
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return u.is64, true
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}
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func (u *unit) addrsize() int {
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return u.asize
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}
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func (d *Data) parseUnits() ([]unit, error) {
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// Count units.
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nunit := 0
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b := makeBuf(d, unknownFormat{}, "info", 0, d.info)
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for len(b.data) > 0 {
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len, _ := b.unitLength()
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if len != Offset(uint32(len)) {
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b.error("unit length overflow")
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break
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}
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b.skip(int(len))
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nunit++
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}
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if b.err != nil {
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return nil, b.err
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}
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// Again, this time writing them down.
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b = makeBuf(d, unknownFormat{}, "info", 0, d.info)
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units := make([]unit, nunit)
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for i := range units {
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u := &units[i]
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u.base = b.off
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var n Offset
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n, u.is64 = b.unitLength()
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dataOff := b.off
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vers := b.uint16()
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if vers != 2 && vers != 3 && vers != 4 {
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b.error("unsupported DWARF version " + strconv.Itoa(int(vers)))
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break
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}
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u.vers = int(vers)
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var abbrevOff uint64
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if u.is64 {
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abbrevOff = b.uint64()
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} else {
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abbrevOff = uint64(b.uint32())
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}
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atable, err := d.parseAbbrev(abbrevOff, u.vers)
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if err != nil {
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if b.err == nil {
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b.err = err
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}
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break
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}
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u.atable = atable
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u.asize = int(b.uint8())
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u.off = b.off
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u.data = b.bytes(int(n - (b.off - dataOff)))
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}
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if b.err != nil {
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return nil, b.err
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}
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return units, nil
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}
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// offsetToUnit returns the index of the unit containing offset off.
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// It returns -1 if no unit contains this offset.
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func (d *Data) offsetToUnit(off Offset) int {
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// Find the unit after off
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next := sort.Search(len(d.unit), func(i int) bool {
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return d.unit[i].off > off
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})
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if next == 0 {
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return -1
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}
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u := &d.unit[next-1]
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if u.off <= off && off < u.off+Offset(len(u.data)) {
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return next - 1
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}
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return -1
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}
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