From: Russ Cox <rsc@golang.org>
Date: Tue, 20 Apr 2021 19:41:24 +0000 (-0400)
Subject: debug/dwarf: skip over zero-length compilation units
X-Git-Tag: go1.17beta1~472
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=073f9139497401e019e4357d110c2801c5be31e1;p=gostls13.git

debug/dwarf: skip over zero-length compilation units

DWARF sections generated by mingw-clang seem to include these
(not often - only one out of many in the binary that I am looking at).
Skipping over them, everything parses correctly.

This makes TestDefaultLinkerDWARF pass on windows/arm64.

Change-Id: Ie4a7daa1423f51cbc8c4aac88b1d27c3b52ee880
Reviewed-on: https://go-review.googlesource.com/c/go/+/312031
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
---

diff --git a/src/debug/dwarf/unit.go b/src/debug/dwarf/unit.go
index 29a744fd18..9b3d6e902d 100644
--- a/src/debug/dwarf/unit.go
+++ b/src/debug/dwarf/unit.go
@@ -48,7 +48,9 @@ func (d *Data) parseUnits() ([]unit, error) {
 			break
 		}
 		b.skip(int(len))
-		nunit++
+		if len > 0 {
+			nunit++
+		}
 	}
 	if b.err != nil {
 		return nil, b.err
@@ -61,7 +63,9 @@ func (d *Data) parseUnits() ([]unit, error) {
 		u := &units[i]
 		u.base = b.off
 		var n Offset
-		n, u.is64 = b.unitLength()
+		for n == 0 {
+			n, u.is64 = b.unitLength()
+		}
 		dataOff := b.off
 		vers := b.uint16()
 		if vers < 2 || vers > 5 {