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// Copyright 2012 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.
package dwarf
import (
"fmt"
"strconv"
)
// Parse the type units stored in a DWARF4 .debug_types section. Each
// type unit defines a single primary type and an 8-byte signature.
// Other sections may then use formRefSig8 to refer to the type.
// The typeUnit format is a single type with a signature. It holds
// the same data as a compilation unit.
type typeUnit struct {
unit
toff Offset // Offset to signature type within data.
name string // Name of .debug_type section.
cache Type // Cache the type, nil to start.
}
// Parse a .debug_types section.
func (d *Data) parseTypes(name string, types []byte) error {
b := makeBuf(d, unknownFormat{}, name, 0, types)
for len(b.data) > 0 {
base := b.off
n, dwarf64 := b.unitLength()
if n != Offset(uint32(n)) {
b.error("type unit length overflow")
return b.err
}
hdroff := b.off
vers := int(b.uint16())
if vers != 4 {
b.error("unsupported DWARF version " + strconv.Itoa(vers))
return b.err
}
var ao uint32
if !dwarf64 {
ao = b.uint32()
} else {
ao64 := b.uint64()
if ao64 != uint64(uint32(ao64)) {
b.error("type unit abbrev offset overflow")
return b.err
}
ao = uint32(ao64)
}
atable, err := d.parseAbbrev(ao, vers)
if err != nil {
return err
}
asize := b.uint8()
sig := b.uint64()
var toff uint32
if !dwarf64 {
toff = b.uint32()
} else {
to64 := b.uint64()
if to64 != uint64(uint32(to64)) {
b.error("type unit type offset overflow")
return b.err
}
toff = uint32(to64)
}
boff := b.off
d.typeSigs[sig] = &typeUnit{
unit: unit{
base: base,
off: boff,
data: b.bytes(int(n - (b.off - hdroff))),
atable: atable,
asize: int(asize),
vers: int(vers),
is64: dwarf64,
},
toff: Offset(toff),
name: name,
}
if b.err != nil {
return b.err
}
}
return nil
}
// Return the type for a type signature.
func (d *Data) sigToType(sig uint64) (Type, error) {
tu := d.typeSigs[sig]
if tu == nil {
return nil, fmt.Errorf("no type unit with signature %v", sig)
}
if tu.cache != nil {
return tu.cache, nil
}
b := makeBuf(d, tu, tu.name, tu.off, tu.data)
r := &typeUnitReader{d: d, tu: tu, b: b}
t, err := d.readType(tu.name, r, Offset(tu.toff), make(map[Offset]Type), nil)
if err != nil {
return nil, err
}
tu.cache = t
return t, nil
}
// typeUnitReader is a typeReader for a tagTypeUnit.
type typeUnitReader struct {
d *Data
tu *typeUnit
b buf
err error
}
// Seek to a new position in the type unit.
func (tur *typeUnitReader) Seek(off Offset) {
tur.err = nil
doff := off - tur.tu.off
if doff < 0 || doff >= Offset(len(tur.tu.data)) {
tur.err = fmt.Errorf("%s: offset %d out of range; max %d", tur.tu.name, doff, len(tur.tu.data))
return
}
tur.b = makeBuf(tur.d, tur.tu, tur.tu.name, off, tur.tu.data[doff:])
}
// AddressSize returns the size in bytes of addresses in the current type unit.
func (tur *typeUnitReader) AddressSize() int {
return tur.tu.unit.asize
}
// Next reads the next Entry from the type unit.
func (tur *typeUnitReader) Next() (*Entry, error) {
if tur.err != nil {
return nil, tur.err
}
if len(tur.tu.data) == 0 {
return nil, nil
}
e := tur.b.entry(tur.tu.atable, tur.tu.base)
if tur.b.err != nil {
tur.err = tur.b.err
return nil, tur.err
}
return e, nil
}
// clone returns a new reader for the type unit.
func (tur *typeUnitReader) clone() typeReader {
return &typeUnitReader{
d: tur.d,
tu: tur.tu,
b: makeBuf(tur.d, tur.tu, tur.tu.name, tur.tu.off, tur.tu.data),
}
}
// offset returns the current offset.
func (tur *typeUnitReader) offset() Offset {
return tur.b.off
}
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