From 3e4f4208b2331c09495d6803bce03a233e6315b5 Mon Sep 17 00:00:00 2001
From: UbitUmarov <ajlduarte@sapo.pt>
Date: Sat, 11 May 2024 14:09:08 +0100
Subject: [PATCH] improve broken llBase64ToInteger

---
 .../Shared/Api/Implementation/LSL_Api.cs      | 76 +++++++++----------
 1 file changed, 35 insertions(+), 41 deletions(-)

diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
index efcf32fb99..16b13ad225 100644
--- a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
@@ -12047,8 +12047,7 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api
         //  redundancy).
         //  </para>
         //  <para>
-        //  LSL requires a base64 string to be 8
-        //  characters in length. LSL also uses '/'
+        // LSL also uses '/'
         //  rather than '-' (MIME compliant).
         //  </para>
         //  <para>
@@ -12060,6 +12059,7 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api
         //  these functions, so the string to integer
         //  conversion returns '0' if an invalid
         //  character is encountered during conversion.
+        //  Only full bytes are considered, partial are counted as 0
         //  </para>
         //  <para>
         //  References
@@ -12213,59 +12213,53 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api
 
         public LSL_Integer llBase64ToInteger(string str)
         {
-            int number = 0;
-            int digit;
-
-
-            //    Require a well-fromed base64 string
-
-            if (str.Length > 8)
+            if (str is null || str.Length < 2 || str.Length > 8)
                 return 0;
 
-            //    The loop is unrolled in the interests
-            //    of performance and simple necessity.
-            //
-            //    MUST find 6 digits to be well formed
-            //      -1 == invalid
-            //       0 == padding
-
+            int digit;
             if ((digit = c2itable[str[0]]) <= 0)
-            {
-                return digit < 0 ? (int)0 : number;
-            }
-            number += --digit<<26;
+                return 0;
+
+            int number = --digit << 26;
 
             if ((digit = c2itable[str[1]]) <= 0)
-            {
-                return digit < 0 ? (int)0 : number;
-            }
-            number += --digit<<20;
+                return 0;
+
+            if (str.Length == 2)
+                return number | (--digit & 0x30) << 20;
+
+            int next = --digit << 20;
 
             if ((digit = c2itable[str[2]]) <= 0)
-            {
-                return digit < 0 ? (int)0 : number;
-            }
-            number += --digit<<14;
+                return number;
+
+            number |= next;
+            if (str.Length == 3)
+                return number | (--digit & 0x3C) << 14;
+
+            next = --digit << 14;
 
             if ((digit = c2itable[str[3]]) <= 0)
-            {
-                return digit < 0 ? (int)0 : number;
-            }
-            number += --digit<<8;
+                return number;
+
+            number |= next;
+            number |= --digit << 8;
+            if (str.Length == 4)
+                return number;
 
             if ((digit = c2itable[str[4]]) <= 0)
-            {
-                return digit < 0 ? (int)0 : number;
-            }
-            number += --digit<<2;
+                return number;
+
+            if (str.Length == 5)
+                return number;
+
+            next = --digit << 2;
 
             if ((digit = c2itable[str[5]]) <= 0)
-            {
-                return digit < 0 ? (int)0 : number;
-            }
-            number += --digit>>4;
+                return number;
 
-            // ignore trailing padding
+            number |= next;
+            number |= --digit >> 4;
 
             return number;
         }