path/filepath: fix evaluation of symlinks to paths under /tmp on macOS

For symlinks created from symlinks under the root directory created
as the relative path (e.g., symbolic links under /tmp), we update vol and volLen.

Fixes #57905

Change-Id: I45affd1db3b93109de51bf19b181f3cdba061109
Reviewed-on: https://go-review.googlesource.com/c/go/+/461761
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>

diff --git a/src/path/filepath/path_test.go b/src/path/filepath/path_test.go
index 66474448526675cea863ddbadae5fd2fb693934d..e6a92709098d055641658a42f2f04d2c9a34de79 100644 (file)
--- a/src/path/filepath/path_test.go
+++ b/src/path/filepath/path_test.go
@@ -1193,6 +1193,37 @@ func TestIssue13582(t *testing.T) {
        }
 }
 
+// Issue 57905.
+func TestRelativeSymlinkToAbsolute(t *testing.T) {
+       testenv.MustHaveSymlink(t)
+       // Not parallel: uses os.Chdir.
+
+       tmpDir := t.TempDir()
+       chdir(t, tmpDir)
+
+       // Create "link" in the current working directory as a symlink to an arbitrary
+       // absolute path. On macOS, this path is likely to begin with a symlink
+       // itself: generally either in /var (symlinked to "private/var") or /tmp
+       // (symlinked to "private/tmp").
+       if err := os.Symlink(tmpDir, "link"); err != nil {
+               t.Fatal(err)
+       }
+       t.Logf(`os.Symlink(%q, "link")`, tmpDir)
+
+       p, err := filepath.EvalSymlinks("link")
+       if err != nil {
+               t.Fatalf(`EvalSymlinks("link"): %v`, err)
+       }
+       want, err := filepath.EvalSymlinks(tmpDir)
+       if err != nil {
+               t.Fatalf(`EvalSymlinks(%q): %v`, tmpDir, err)
+       }
+       if p != want {
+               t.Errorf(`EvalSymlinks("link") = %q; want %q`, p, want)
+       }
+       t.Logf(`EvalSymlinks("link") = %q`, p)
+}
+
 // Test directories relative to temporary directory.
 // The tests are run in absTestDirs[0].
 var absTestDirs = []string{

diff --git a/src/path/filepath/symlink.go b/src/path/filepath/symlink.go
index 6fefd15977e8af62cbffbfe6ca830941a5c1735f..f9435e0d5b9007c6de53967d0ea85bcc6a890d8e 100644 (file)
--- a/src/path/filepath/symlink.go
+++ b/src/path/filepath/symlink.go
@@ -126,6 +126,8 @@ func walkSymlinks(path string) (string, error) {
                        // Symlink to absolute path.
                        dest = link[:1]
                        end = 1
+                       vol = link[:1]
+                       volLen = 1
                } else {
                        // Symlink to relative path; replace last
                        // path component in dest.