[Xen-devel] [PATCH 6/9] golang/xenlight: Errors are negative

[George Dunlap <george.dunlap@citrix.com>]

Commit 871e51d2d4 changed the sign on the xenlight error types (making
the values negative, same as the C-generated constants), but failed to
flip the sign in the Error() string function.  The result is that
ErrorNonspecific.String() prints "libxl error: 1" rather than the
human-readable error message.

Get the error message index by inverting the error number once.

Also, always print the actual error value, rather than the inverted
value, for clarity.

Signed-off-by: George Dunlap <george.dunlap@citrix.com>
---
CC: Nick Rosbrook <rosbrookn@ainfosec.com>
---
 tools/golang/xenlight/xenlight.go | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/golang/xenlight/xenlight.go b/tools/golang/xenlight/xenlight.go
index 99de68320b..c80f622e6b 100644
--- a/tools/golang/xenlight/xenlight.go
+++ b/tools/golang/xenlight/xenlight.go
@@ -65,13 +65,14 @@ var libxlErrors = [...]string{
 }
 
 func (e Error) Error() string {
-	if 0 < int(e) && int(e) < len(libxlErrors) {
-		s := libxlErrors[e]
+	eidx := -int(e)
+	if 0 < eidx && eidx < len(libxlErrors) {
+		s := libxlErrors[eidx]
 		if s != "" {
 			return s
 		}
 	}
-	return fmt.Sprintf("libxl error: %d", -e)
+	return fmt.Sprintf("libxl error: %d", e)
 }
 
 // Context represents a libxl_ctx.
-- 
2.24.0


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