syscall: optimize Getwd on aix

When looking for \0, use clen which may be optimized.

Also, return EINVAL when returned string is empty.

This makes it similar to how it is implemented in *bsd and solaris.

Change-Id: I3e37ed25f47110eafd12c80291f7746de9db7b23
Reviewed-on: https://go-review.googlesource.com/c/go/+/606902
TryBot-Bypass: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>

diff --git a/src/syscall/syscall_aix.go b/src/syscall/syscall_aix.go
index a9bd7a37336ddef8d8c33f68788287cc0a3f644a..36dfd90678804f104d6ba40756cc3a6620e9e0ba 100644 (file)
--- a/src/syscall/syscall_aix.go
+++ b/src/syscall/syscall_aix.go
@@ -119,11 +119,11 @@ func Getwd() (ret string, err error) {
                b := make([]byte, len)
                err := getcwd(&b[0], len)
                if err == nil {
-                       i := 0
-                       for b[i] != 0 {
-                               i++
+                       n := clen(b[:])
+                       if n < 1 {
+                               return "", EINVAL
                        }
-                       return string(b[0:i]), nil
+                       return string(b[:n]), nil
                }
                if err != ERANGE {
                        return "", err