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Fix a few dwarf64 parsing problems. Nothing fancy. #27

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Fix a few dwarf64 parsing problems. Nothing fancy. #27

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059806e
Fix a few dwarf64 parsing problems. Nothing fancy.
Jul 19, 2017
9c4c1b2
Fix a few dwarf64 parsing problems.
Jul 21, 2017
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7 changes: 7 additions & 0 deletions src/debug/dwarf/open.go
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Original file line number Diff line number Diff line change
Expand Up @@ -58,7 +58,14 @@ func New(abbrev, aranges, frame, info, line, pubnames, ranges, str []byte) (*Dat
if len(d.info) < 6 {
return nil, DecodeError{"info", Offset(len(d.info)), "too short"}
}
// 32-bit dwarf has 4 byte size then 2 byte version
x, y := d.info[4], d.info[5]
if d.info[0] == 255 && d.info[1] == 255 {
// 64-bit DWARF has 4 bytes of FF, then 8 byte size,
// then 2 byte version
x = d.info[12]
y = d.info[13]
}
switch {
case x == 0 && y == 0:
return nil, DecodeError{"info", 4, "unsupported version 0"}
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17 changes: 15 additions & 2 deletions src/debug/dwarf/unit.go
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Original file line number Diff line number Diff line change
Expand Up @@ -62,12 +62,24 @@ func (d *Data) parseUnits() ([]unit, error) {
var n Offset
n, u.is64 = b.unitLength()
vers := b.uint16()
// Count the bytes of header read, not counting size
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Rather than counting bytes, I'd suggest following what parseTypes does. Here, just say "hdroff := b.off", then below say "b.bytes(int(n - (b.off - hdroff)))".

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I had actually suggested the same thing to Chris offline :-)

var hbcount uint
hbcount = 2 // Not counting size
if vers != 2 && vers != 3 && vers != 4 {
b.error("unsupported DWARF version " + strconv.Itoa(int(vers)))
break
}
u.vers = int(vers)
atable, err := d.parseAbbrev(b.uint32(), u.vers)
var aoff uint32
if !u.is64 {
aoff = b.uint32()
hbcount += 4
} else {
// For now, ignore the high bits
aoff = uint32(b.uint64())
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I'd recommend checking for overflow here. See the equivalent code in Data.parseTypes.

hbcount += 8
}
atable, err := d.parseAbbrev(aoff, u.vers)
if err != nil {
if b.err == nil {
b.err = err
Expand All @@ -76,8 +88,9 @@ func (d *Data) parseUnits() ([]unit, error) {
}
u.atable = atable
u.asize = int(b.uint8())
hbcount += 1
u.off = b.off
u.data = b.bytes(int(n - (2 + 4 + 1)))
u.data = b.bytes(int(n - Offset(hbcount)))
}
if b.err != nil {
return nil, b.err
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