os: adjust TempDir for Z:\

If TMP environment variable is set to Z:\, TempDir returns Z:.
But Z: refers to current directory on Z:, while Z:\ refers to root
directory on Z:. Adjust TempDir to return Z:\.

Fixes #29291

Change-Id: If04d0c7977a8ac2d9d558307502e81beb68776ef
Reviewed-on: https://go-review.googlesource.com/c/154384
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/os/file_windows.go b/src/os/file_windows.go
index 7ed4fe2f389d99f6058465a200872b35af3aeffb..85f248774c77e3f210d0c18eddf6089c335fd094 100644 (file)
--- a/src/os/file_windows.go
+++ b/src/os/file_windows.go
@@ -325,7 +325,10 @@ func tempDir() string {
                if n > uint32(len(b)) {
                        continue
                }
-               if n > 0 && b[n-1] == '\\' {
+               if n == 3 && b[1] == ':' && b[2] == '\\' {
+                       // Do nothing for path, like C:\.
+               } else if n > 0 && b[n-1] == '\\' {
+                       // Otherwise remove terminating \.
                        n--
                }
                return string(utf16.Decode(b[:n]))

diff --git a/src/os/os_windows_test.go b/src/os/os_windows_test.go
index c5553694880eefb4a1d2a7612fb0bbf190de4d0f..1023b25e22584b60cad9e79775fa3f1984b960cd 100644 (file)
--- a/src/os/os_windows_test.go
+++ b/src/os/os_windows_test.go
@@ -5,6 +5,7 @@
 package os_test
 
 import (
+       "errors"
        "fmt"
        "internal/poll"
        "internal/syscall/windows"
@@ -1003,3 +1004,46 @@ func TestStatOfInvalidName(t *testing.T) {
                t.Fatal(`os.Stat("*.go") unexpectedly succeeded`)
        }
 }
+
+// findUnusedDriveLetter searches mounted drive list on the system
+// (starting from Z: and ending at D:) for unused drive letter.
+// It returns path to the found drive root directory (like Z:\) or error.
+func findUnusedDriveLetter() (string, error) {
+       // Do not use A: and B:, because they are reserved for floppy drive.
+       // Do not use C:, becasue it is normally used for main drive.
+       for l := 'Z'; l >= 'D'; l-- {
+               p := string(l) + `:\`
+               _, err := os.Stat(p)
+               if os.IsNotExist(err) {
+                       return p, nil
+               }
+       }
+       return "", errors.New("Could not find unused drive letter.")
+}
+
+func TestRootDirAsTemp(t *testing.T) {
+       testenv.MustHaveExec(t)
+
+       if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" {
+               fmt.Print(os.TempDir())
+               os.Exit(0)
+       }
+
+       newtmp, err := findUnusedDriveLetter()
+       if err != nil {
+               t.Fatal(err)
+       }
+
+       cmd := osexec.Command(os.Args[0], "-test.run=TestRootDirAsTemp")
+       cmd.Env = os.Environ()
+       cmd.Env = append(cmd.Env, "GO_WANT_HELPER_PROCESS=1")
+       cmd.Env = append(cmd.Env, "TMP="+newtmp)
+       cmd.Env = append(cmd.Env, "TEMP="+newtmp)
+       output, err := cmd.CombinedOutput()
+       if err != nil {
+               t.Fatalf("Failed to spawn child process: %v %q", err, string(output))
+       }
+       if want, have := newtmp, string(output); have != want {
+               t.Fatalf("unexpected child process output %q, want %q", have, want)
+       }
+}