internal/syscall/windows: increase registry.ExpandString buffer

ExpandString correctly loops on the syscall until it reaches the
required buffer size but truncates it before converting it back to
string. The truncation limit is increased to 2^15 bytes which is the
documented maximum ExpandEnvironmentStrings output size.

This fixes TestExpandString on systems where len($PATH) > 1024.

Change-Id: I2a6f184eeca939121b458bcffe1a436a50f3298e
Reviewed-on: https://go-review.googlesource.com/9805
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/internal/syscall/windows/registry/value.go b/src/internal/syscall/windows/registry/value.go
index 1c1771d30e40abb272bb977f9435bb7e8f260d72..b2b28aadf8ac572177113bd52104493c29d9020b 100644 (file)
--- a/src/internal/syscall/windows/registry/value.go
+++ b/src/internal/syscall/windows/registry/value.go
@@ -130,7 +130,7 @@ func ExpandString(value string) (string, error) {
                        return "", err
                }
                if n <= uint32(len(r)) {
-                       u := (*[1 << 10]uint16)(unsafe.Pointer(&r[0]))[:]
+                       u := (*[1 << 15]uint16)(unsafe.Pointer(&r[0]))[:]
                        return syscall.UTF16ToString(u), nil
                }
                r = make([]uint16, n)