Initial transfer.

common/system/prober/probe_unix.go

Index: common/system/prober/probe_unix.go
diff --git a/common/system/prober/probe_unix.go b/common/system/prober/probe_unix.go
new file mode 100644
index 0000000000000000000000000000000000000000..e3681a101b17c7d7ab0cf96b525ed05e9dbccec6
--- /dev/null
+++ b/common/system/prober/probe_unix.go
@@ -0,0 +1,52 @@
+// Copyright 2017 The LUCI 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 darwin dragonfly freebsd linux nacl netbsd openbsd solaris
+
+package prober
+
+import (
+	"os"
+	"path/filepath"
+
+	"github.com/luci/luci-go/common/errors"
+	"github.com/luci/luci-go/common/system/environ"
+)
+
+func findExecutable(file string) error {
+	d, err := os.Stat(file)
+	if err != nil {
+		return err
+	}
+	if m := d.Mode(); !m.IsDir() && m&0111 != 0 {
+		return nil
+	}
+	return os.ErrPermission
+}
+
+// findInDir is a paraphrased and trimmed version of "exec.LookPath"
+// (for Windows),
+//
+// Copied from:
+// https://github.com/golang/go/blob/d234f9a75413fdae7643e4be9471b4aeccf02478/src/os/exec/lp_unix.go
+//
+// Modified to:
+//	- Use a supplied "dir" instead of scanning through PATH.
+//	- Not consider cases where "file" is an absolute path
+//	- Ignore the possibility that "file" may be in the CWD; only look in "dir".
+func findInDir(file, dir string, env environ.Env) (string, error) {
+	// NOTE(rsc): I wish we could use the Plan 9 behavior here
+	// (only bypass the path if file begins with / or ./ or ../)
+	// but that would not match all the Unix shells.
+
+	if dir == "" {
+		// Unix shell semantics: path element "" means "."
+		dir = "."
+	}
+	path := filepath.Join(dir, file)
+	if err := findExecutable(path); err == nil {
+		return path, nil
+	}
+	return "", errors.New("not found")
+}