os: add js/wasm architecture

This commit adds the js/wasm architecture to the os package.

Access to the actual file system is supported through Node.js.

Updates #18892

Change-Id: I6fa642fb294ca020b2c545649d4324d981aa0408
Reviewed-on: https://go-review.googlesource.com/109977
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/src/os/exec/lp_js.go b/src/os/exec/lp_js.go
new file mode 100644
index 0000000000..6750fb99b0
--- /dev/null
+++ b/src/os/exec/lp_js.go
@@ -0,0 +1,23 @@
+// Copyright 2018 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.
+
+// +build js,wasm
+
+package exec
+
+import (
+	"errors"
+)
+
+// ErrNotFound is the error resulting if a path search failed to find an executable file.
+var ErrNotFound = errors.New("executable file not found in $PATH")
+
+// LookPath searches for an executable named file in the
+// directories named by the PATH environment variable.
+// If file contains a slash, it is tried directly and the PATH is not consulted.
+// The result may be an absolute path or a path relative to the current directory.
+func LookPath(file string) (string, error) {
+	// Wasm can not execute processes, so act as if there are no executables at all.
+	return "", &Error{file, ErrNotFound}
+}