From a9aebc0cd4131e5ece4db30a7e04f79b84815f80 Mon Sep 17 00:00:00 2001
From: Eric Sink <eric@sourcegear.com>
Date: Wed, 26 Jun 2019 15:00:57 -0500
Subject: [PATCH] make sz more robust in handling edge cases, null pointers
 #273

---
 Directory.Build.props         |  2 +-
 src/SQLitePCLRaw.core/util.cs | 42 +++++++++++++++++++++++++++++++----
 2 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/Directory.Build.props b/Directory.Build.props
index 2acfadf0..f35985a4 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -4,7 +4,7 @@
     <Copyright>Copyright 2014-2019 SourceGear, LLC</Copyright>
     <Company>SourceGear</Company>
     <Authors>Eric Sink</Authors>
-    <Version>2.0.0-pre20190626125110</Version>
+    <Version>2.0.0-pre20190626145402</Version>
     <AssemblyVersion>2.0.0.541</AssemblyVersion>
     <FileVersion>2.0.0.541</FileVersion>
     <Description>SQLitePCLRaw is a Portable Class Library (PCL) for low-level (raw) access to SQLite</Description>
diff --git a/src/SQLitePCLRaw.core/util.cs b/src/SQLitePCLRaw.core/util.cs
index bc21756b..61c3ff55 100644
--- a/src/SQLitePCLRaw.core/util.cs
+++ b/src/SQLitePCLRaw.core/util.cs
@@ -41,7 +41,10 @@ public ref readonly byte GetPinnableReference()
 
         sz(ReadOnlySpan<byte> a)
         {
-            if (a[a.Length - 1] != 0)
+            if (
+                (a.Length > 0)
+                && (a[a.Length - 1] != 0)
+                )
             {
                 throw new ArgumentException("zero terminated string required");
             }
@@ -50,7 +53,14 @@ public ref readonly byte GetPinnableReference()
 
         public static sz FromString(string s)
         {
-            return new sz(s.to_utf8_with_z());
+            if (s == null)
+            {
+                return new sz(ReadOnlySpan<byte>.Empty);
+            }
+            else
+            {
+                return new sz(s.to_utf8_with_z());
+            }
         }
 
         unsafe static long my_strlen(byte* p)
@@ -76,16 +86,35 @@ unsafe static ReadOnlySpan<byte> to_span(IntPtr p)
 
         unsafe public static sz FromPtr(byte* p)
         {
-            return new sz(to_span(p));
+            if (p == null)
+            {
+                return new sz(ReadOnlySpan<byte>.Empty);
+            }
+            else
+            {
+                return new sz(to_span(p));
+            }
         }
 
         public static sz FromIntPtr(IntPtr p)
         {
-            return new sz(to_span(p));
+            if (p == IntPtr.Zero)
+            {
+                return new sz(ReadOnlySpan<byte>.Empty);
+            }
+            else
+            {
+                return new sz(to_span(p));
+            }
         }
 
         public override string ToString()
         {
+            if (sp.Length == 0)
+            {
+                return null;
+            }
+
             unsafe
             {
                 fixed (byte* q = sp)
@@ -98,6 +127,11 @@ public override string ToString()
 
     static class util
     {
+        public static sz to_sz(this string s)
+        {
+            return sz.FromString(s);
+        }
+
         public static byte[] to_utf8_with_z(this string sourceText)
         {
             if (sourceText == null)