Initial transfer.

common/system/prober/probe_unix.go

+// 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")
+}