From 2370355b3013474b3730e4125fb1259991c5c093 Mon Sep 17 00:00:00 2001
From: Levi Broderick <levib@microsoft.com>
Date: Wed, 14 Oct 2020 14:38:23 -0700
Subject: [PATCH] Remove unsafe code from HttpEncoder

---
 .../src/System/Web/Util/HttpEncoder.cs        | 87 +++++++++----------
 1 file changed, 39 insertions(+), 48 deletions(-)

diff --git a/src/libraries/System.Web.HttpUtility/src/System/Web/Util/HttpEncoder.cs b/src/libraries/System.Web.HttpUtility/src/System/Web/Util/HttpEncoder.cs
index 68cc875b29d86..b97df74673f80 100644
--- a/src/libraries/System.Web.HttpUtility/src/System/Web/Util/HttpEncoder.cs
+++ b/src/libraries/System.Web.HttpUtility/src/System/Web/Util/HttpEncoder.cs
@@ -64,7 +64,7 @@ internal static void HtmlAttributeEncode(string? value, TextWriter output)
             HtmlAttributeEncodeInternal(value, output);
         }
 
-        private static unsafe void HtmlAttributeEncodeInternal(string s, TextWriter output)
+        private static void HtmlAttributeEncodeInternal(string s, TextWriter output)
         {
             int index = IndexOfHtmlAttributeEncodingChars(s, 0);
             if (index == -1)
@@ -73,44 +73,37 @@ private static unsafe void HtmlAttributeEncodeInternal(string s, TextWriter outp
             }
             else
             {
-                int cch = s.Length - index;
-                fixed (char* str = s)
-                {
-                    char* pch = str;
-                    while (index-- > 0)
-                    {
-                        output.Write(*pch++);
-                    }
+                output.Write(s.AsSpan(0, index));
 
-                    while (cch-- > 0)
+                ReadOnlySpan<char> remaining = s.AsSpan(index);
+                for (int i = 0; i < remaining.Length; i++)
+                {
+                    char ch = remaining[i];
+                    if (ch <= '<')
                     {
-                        char ch = *pch++;
-                        if (ch <= '<')
-                        {
-                            switch (ch)
-                            {
-                                case '<':
-                                    output.Write("&lt;");
-                                    break;
-                                case '"':
-                                    output.Write("&quot;");
-                                    break;
-                                case '\'':
-                                    output.Write("&#39;");
-                                    break;
-                                case '&':
-                                    output.Write("&amp;");
-                                    break;
-                                default:
-                                    output.Write(ch);
-                                    break;
-                            }
-                        }
-                        else
+                        switch (ch)
                         {
-                            output.Write(ch);
+                            case '<':
+                                output.Write("&lt;");
+                                break;
+                            case '"':
+                                output.Write("&quot;");
+                                break;
+                            case '\'':
+                                output.Write("&#39;");
+                                break;
+                            case '&':
+                                output.Write("&amp;");
+                                break;
+                            default:
+                                output.Write(ch);
+                                break;
                         }
                     }
+                    else
+                    {
+                        output.Write(ch);
+                    }
                 }
             }
         }
@@ -141,25 +134,23 @@ internal static void HtmlEncode(string? value, TextWriter output)
             output.Write(WebUtility.HtmlEncode(value));
         }
 
-        private static unsafe int IndexOfHtmlAttributeEncodingChars(string s, int startPos)
+        private static int IndexOfHtmlAttributeEncodingChars(string s, int startPos)
         {
             Debug.Assert(0 <= startPos && startPos <= s.Length, "0 <= startPos && startPos <= s.Length");
-            int cch = s.Length - startPos;
-            fixed (char* str = s)
+
+            ReadOnlySpan<char> span = s.AsSpan(startPos);
+            for (int i = 0; i < span.Length; i++)
             {
-                for (char* pch = &str[startPos]; cch > 0; pch++, cch--)
+                char ch = span[i];
+                if (ch <= '<')
                 {
-                    char ch = *pch;
-                    if (ch <= '<')
+                    switch (ch)
                     {
-                        switch (ch)
-                        {
-                            case '<':
-                            case '"':
-                            case '\'':
-                            case '&':
-                                return s.Length - cch;
-                        }
+                        case '<':
+                        case '"':
+                        case '\'':
+                        case '&':
+                            return startPos + i;
                     }
                 }
             }