debug/dwarf: better handling for DW_FORM_indirect

Fix a buglet in abbrev processing related to DW_FORM_indirect. When
reading an abbrev entry if we encounter an attribute with form
DW_FORM_indirect, leave the class as ClassUnknown, then when the
abbrev is walked during the reading of the DIE fill in the class based
on the value read at that point (code for handling DW_FORM_indirect
seems to be already partially in place in the DIE reader).

Updates #33488.

Change-Id: I9dc89abf5cc8d7ea96824c0011bef979de0540bf
Reviewed-on: https://go-review.googlesource.com/c/go/+/190158
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

diff --git a/src/debug/dwarf/entry.go b/src/debug/dwarf/entry.go
index dfc2f44abc756a33371ea6a804159307c8196589..43043f60dd8cd007940e29cf7a576f750239993f 100644 (file)
--- a/src/debug/dwarf/entry.go
+++ b/src/debug/dwarf/entry.go
@@ -160,6 +160,9 @@ func formToClass(form format, attr Attr, vers int, b *buf) Class {
                b.error("cannot determine class of unknown attribute form")
                return 0
 
+       case formIndirect:
+               return ClassUnknown
+
        case formAddr, formAddrx, formAddrx1, formAddrx2, formAddrx3, formAddrx4:
                return ClassAddress
 
@@ -402,7 +405,7 @@ type Offset uint32
 
 // Entry reads a single entry from buf, decoding
 // according to the given abbreviation table.
-func (b *buf) entry(cu *Entry, atab abbrevTable, ubase Offset) *Entry {
+func (b *buf) entry(cu *Entry, atab abbrevTable, ubase Offset, vers int) *Entry {
        off := b.off
        id := uint32(b.uint())
        if id == 0 {
@@ -425,6 +428,7 @@ func (b *buf) entry(cu *Entry, atab abbrevTable, ubase Offset) *Entry {
                fmt := a.field[i].fmt
                if fmt == formIndirect {
                        fmt = format(b.uint())
+                       e.Field[i].Class = formToClass(fmt, a.field[i].attr, vers, b)
                }
                var val interface{}
                switch fmt {
@@ -784,7 +788,7 @@ func (r *Reader) Next() (*Entry, error) {
                return nil, nil
        }
        u := &r.d.unit[r.unit]
-       e := r.b.entry(r.cu, u.atable, u.base)
+       e := r.b.entry(r.cu, u.atable, u.base, u.vers)
        if r.b.err != nil {
                r.err = r.b.err
                return nil, r.err
@@ -929,7 +933,7 @@ func (d *Data) Ranges(e *Entry) ([][2]uint64, error) {
                        }
                        u := &d.unit[i]
                        b := makeBuf(d, u, "info", u.off, u.data)
-                       cu = b.entry(nil, u.atable, u.base)
+                       cu = b.entry(nil, u.atable, u.base, u.vers)
                        if b.err != nil {
                                return nil, b.err
                        }

diff --git a/src/debug/dwarf/typeunit.go b/src/debug/dwarf/typeunit.go
index a03dc84c832c199449619a4c61d753d0234d602f..27aa0784f02bcfaa80b2428024f959771b6e3c45 100644 (file)
--- a/src/debug/dwarf/typeunit.go
+++ b/src/debug/dwarf/typeunit.go
@@ -137,7 +137,7 @@ func (tur *typeUnitReader) Next() (*Entry, error) {
        if len(tur.tu.data) == 0 {
                return nil, nil
        }
-       e := tur.b.entry(nil, tur.tu.atable, tur.tu.base)
+       e := tur.b.entry(nil, tur.tu.atable, tur.tu.base, tur.tu.vers)
        if tur.b.err != nil {
                tur.err = tur.b.err
                return nil, tur.err