libgo: update to go1.7rc3

    
    Reviewed-on: https://go-review.googlesource.com/25150

From-SVN: r238662

1 files changed, 24 insertions, 7 deletions

diff --git a/libgo/go/runtime/cgocheck.go b/libgo/go/runtime/cgocheck.go
index aebce1506d1..2d064145a41 100644
--- a/libgo/go/runtime/cgocheck.go
+++ b/libgo/go/runtime/cgocheck.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 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.
 
@@ -89,17 +89,25 @@ func cgoCheckSliceCopy(typ *_type, dst, src slice, n int) {
 }
 
 // cgoCheckTypedBlock checks the block of memory at src, for up to size bytes,
-// and throws if it finds a Go pointer.  The type of the memory is typ,
+// and throws if it finds a Go pointer. The type of the memory is typ,
 // and src is off bytes into that type.
 //go:nosplit
 //go:nowritebarrier
 func cgoCheckTypedBlock(typ *_type, src unsafe.Pointer, off, size uintptr) {
+	// Anything past typ.ptrdata is not a pointer.
+	if typ.ptrdata <= off {
+		return
+	}
+	if ptrdataSize := typ.ptrdata - off; size > ptrdataSize {
+		size = ptrdataSize
+	}
+
 	if typ.kind&kindGCProg == 0 {
 		cgoCheckBits(src, typ.gcdata, off, size)
 		return
 	}
 
-	// The type has a GC program.  Try to find GC bits somewhere else.
+	// The type has a GC program. Try to find GC bits somewhere else.
 	for datap := &firstmoduledata; datap != nil; datap = datap.next {
 		if cgoInRange(src, datap.data, datap.edata) {
 			doff := uintptr(src) - datap.data
@@ -148,8 +156,8 @@ func cgoCheckTypedBlock(typ *_type, src unsafe.Pointer, off, size uintptr) {
 }
 
 // cgoCheckBits checks the block of memory at src, for up to size
-// bytes, and throws if it finds a Go pointer.  The gcbits mark each
-// pointer value.  The src pointer is off bytes into the gcbits.
+// bytes, and throws if it finds a Go pointer. The gcbits mark each
+// pointer value. The src pointer is off bytes into the gcbits.
 //go:nosplit
 //go:nowritebarrier
 func cgoCheckBits(src unsafe.Pointer, gcbits *byte, off, size uintptr) {
@@ -184,15 +192,24 @@ func cgoCheckBits(src unsafe.Pointer, gcbits *byte, off, size uintptr) {
 
 // cgoCheckUsingType is like cgoCheckTypedBlock, but is a last ditch
 // fall back to look for pointers in src using the type information.
-// We only this when looking at a value on the stack when the type
+// We only use this when looking at a value on the stack when the type
 // uses a GC program, because otherwise it's more efficient to use the
-// GC bits.  This is called on the system stack.
+// GC bits. This is called on the system stack.
 //go:nowritebarrier
 //go:systemstack
 func cgoCheckUsingType(typ *_type, src unsafe.Pointer, off, size uintptr) {
 	if typ.kind&kindNoPointers != 0 {
 		return
 	}
+
+	// Anything past typ.ptrdata is not a pointer.
+	if typ.ptrdata <= off {
+		return
+	}
+	if ptrdataSize := typ.ptrdata - off; size > ptrdataSize {
+		size = ptrdataSize
+	}
+
 	if typ.kind&kindGCProg == 0 {
 		cgoCheckBits(src, typ.gcdata, off, size)
 		return