Initial transfer.

common/system/prober/probe_windows.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.
+
+package prober
+
+import (
+        "os"
+        "path/filepath"
+        "strings"
+
+        "github.com/luci/luci-go/common/errors"
+        "github.com/luci/luci-go/common/system/environ"
+)
+
+func chkStat(file string) error {
+        d, err := os.Stat(file)
+        if err != nil {
+                return err
+        }
+        if d.IsDir() {
+                return os.ErrPermission
+        }
+        return nil
+}
+
+func hasExt(file string) bool {
+        i := strings.LastIndex(file, ".")
+        if i < 0 {
+                return false
+        }
+        return strings.LastIndexAny(file, `:\/`) < i
+}
+
+func findExecutable(file string, exts []string) (string, error) {
+        if len(exts) == 0 {
+                return file, chkStat(file)
+        }
+        if hasExt(file) {
+                if chkStat(file) == nil {
+                        return file, nil
+                }
+        }
+        for _, e := range exts {
+                if f := file + e; chkStat(f) == nil {
+                        return f, nil
+                }
+        }
+        return "", os.ErrNotExist
+}
+
+// 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_windows.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) {
+        var exts []string
+        if x, ok := env.Get(`PATHEXT`); ok {
+                for _, e := range strings.Split(strings.ToLower(x), `;`) {
+                        if e == "" {
+                                continue
+                        }
+                        if e[0] != '.' {
+                                e = "." + e
+                        }
+                        exts = append(exts, e)
+                }
+        } else {
+                exts = []string{".com", ".exe", ".bat", ".cmd"}
+        }
+
+        if f, err := findExecutable(filepath.Join(dir, file), exts); err == nil {
+                return f, nil
+        }
+        return "", errors.New("not found")
+}