Plan 9 support: Remove dependency on syscall.ELOOP

Provide package level ErrLoop instead.

Signed-off-by: Ronald G Minnich <[email protected]>

Author: rminnich

join.go

@@ -15,6 +15,9 @@ import (
 
 const maxSymlinkLimit = 255
 
+// ErrLoop is returned when too many symbolic links are encountered.
+var ErrLoop = errors.New("Too many symbolic links were encountered in translating the pathname")
+
 // IsNotExist tells you if err is an error that implies that either the path
 // accessed does not exist (or path components don't exist). This is
 // effectively a more broad version of [os.IsNotExist].
@@ -139,7 +142,7 @@ func SecureJoinVFS(root, unsafePath string, vfs VFS) (string, error) {
 		// to the yet-unparsed path.
 		linksWalked++
 		if linksWalked > maxSymlinkLimit {
-			return "", &os.PathError{Op: "SecureJoin", Path: root + string(filepath.Separator) + unsafePath, Err: syscall.ELOOP}
+			return "", &os.PathError{Op: "SecureJoin", Path: root + string(filepath.Separator) + unsafePath, Err: ErrLoop}
 		}
 
 		dest, err := vfs.Readlink(fullPath)