From 656834ca4cdf69df5be76fd2d1a33b78920affa3 Mon Sep 17 00:00:00 2001
From: Manish Goregaokar <manishsmail@gmail.com>
Date: Mon, 21 Nov 2016 15:43:20 -0800
Subject: [PATCH] Don't go out of bounds when slicing (fixes #241)

---
 src/lib.rs     |  2 +-
 src/slicing.rs | 17 +++++++++++++++--
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 5d9de6809..89e08c3c2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -498,7 +498,7 @@ impl Url {
     /// as is typically the case of `data:` and `mailto:` URLs.
     #[inline]
     pub fn cannot_be_a_base(&self) -> bool {
-        self.byte_at(self.path_start) != b'/'
+        !self.slice(self.path_start..).starts_with('/')
     }
 
     /// Return the username for this URL (typically the empty string)
diff --git a/src/slicing.rs b/src/slicing.rs
index 926f3c796..32b7a6f1c 100644
--- a/src/slicing.rs
+++ b/src/slicing.rs
@@ -26,14 +26,14 @@ impl Index<RangeFrom<Position>> for Url {
 impl Index<RangeTo<Position>> for Url {
     type Output = str;
     fn index(&self, range: RangeTo<Position>) -> &str {
-        &self.serialization[..self.index(range.end)]
+        &self.serialization[..self.clamp(self.index(range.end))]
     }
 }
 
 impl Index<Range<Position>> for Url {
     type Output = str;
     fn index(&self, range: Range<Position>) -> &str {
-        &self.serialization[self.index(range.start)..self.index(range.end)]
+        &self.serialization[self.index(range.start)..self.clamp(self.index(range.end))]
     }
 }
 
@@ -98,6 +98,19 @@ pub enum Position {
 }
 
 impl Url {
+    #[inline]
+    fn clamp(&self, index: usize) -> usize {
+        if index >= self.serialization.len() {
+            if self.serialization.len() == 0 {
+                0
+            } else {
+                self.serialization.len() - 1
+            }
+        } else {
+            index
+        }
+    }
+
     #[inline]
     fn index(&self, position: Position) -> usize {
         match position {