From afcecc73f1f1f24112021596db287ffb4e5de43e Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Sun, 3 Nov 2013 09:57:26 -0700
Subject: [PATCH] {string,bytes}->path-element: error on empty [byte] string

---
 .../racket-test/tests/racket/path.rktl        |  3 +++
 racket/collects/racket/HISTORY.txt            |  2 ++
 racket/src/racket/src/file.c                  | 19 ++++++++++++-------
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/pkgs/racket-pkgs/racket-test/tests/racket/path.rktl b/pkgs/racket-pkgs/racket-test/tests/racket/path.rktl
index 4165782fbe..1c92d800a6 100644
--- a/pkgs/racket-pkgs/racket-test/tests/racket/path.rktl
+++ b/pkgs/racket-pkgs/racket-test/tests/racket/path.rktl
@@ -897,6 +897,9 @@
 (err/rt-test (bytes->path-element "a/b" 'unix))
 (err/rt-test (bytes->path-element "a\\b" 'windows))
 
+(err/rt-test (bytes->path-element #""))
+(err/rt-test (string->path-element ""))
+
 (test #"\\\\?\\REL\\\\a/b" path->bytes (bytes->path-element #"a/b" 'windows))
 
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
diff --git a/racket/collects/racket/HISTORY.txt b/racket/collects/racket/HISTORY.txt
index 63992dfd20..6bf4c31cfd 100644
--- a/racket/collects/racket/HISTORY.txt
+++ b/racket/collects/racket/HISTORY.txt
@@ -1,5 +1,7 @@
 Version 5.90.0.10
 Added chaperone-channel and impersonate-channel
+Change string->path-element and bytes->path-element to raise an
+ exception for an empty [byte-]string argument
 
 Version 5.90.0.9
 Allow hash table chaperones and impersonators to support efficient
diff --git a/racket/src/racket/src/file.c b/racket/src/racket/src/file.c
index e8209da0c7..656e6aa2db 100644
--- a/racket/src/racket/src/file.c
+++ b/racket/src/racket/src/file.c
@@ -1036,19 +1036,24 @@ static Scheme_Object *do_bytes_to_path_element(const char *name, Scheme_Object *
     }
   }
 
-  if (i >= len)
-    p = make_protected_sized_offset_path(1, SCHEME_BYTE_STR_VAL(s),
-                                         0, len,
-                                         SCHEME_MUTABLEP(s), 0,
-                                         kind);
-  else
+  if (i >= len) {
+    if (len == 0)
+      p = NULL;
+    else
+      p = make_protected_sized_offset_path(1, SCHEME_BYTE_STR_VAL(s),
+                                           0, len,
+                                           SCHEME_MUTABLEP(s), 0,
+                                           kind);
+  } else
     p = NULL;
   
   if (!p || !is_path_element(p))
     scheme_contract_error(name,
                           "cannot be converted to a path element",
                           "path", 1, argv[0],
-                          "explanation", 0, "path can be split, is not relative, or names a special element",
+                          "explanation", 0, (len 
+                                             ? "path can be split, is not relative, or names a special element"
+                                             : "path element cannot be empty"),
                           NULL);
 
   return p;