fix bug in encryption handler. couple of code style tweaks

src/UglyToad.PdfPig/Encryption/EncryptionHandler.cs

@@ -467,18 +467,21 @@
 
         private static StringToken GetStringTokenFromDecryptedData(byte[] data)
         {
-            if (data[0] == 0xFE && data[1] == 0xFF)
+            if (data.Length >= 2)
             {
-                var str  = Encoding.BigEndianUnicode.GetString(data).Substring(1);
+                if (data[0] == 0xFE && data[1] == 0xFF)
+                {
+                    var str = Encoding.BigEndianUnicode.GetString(data).Substring(1);
 
-                return new StringToken(str, StringToken.Encoding.Utf16BE);
-            }
-            
-            if (data[0] == 0xFF && data[1] == 0xFE)
-            {
-                var str = Encoding.Unicode.GetString(data).Substring(1);
+                    return new StringToken(str, StringToken.Encoding.Utf16BE);
+                }
 
-                return new StringToken(str, StringToken.Encoding.Utf16);
+                if (data[0] == 0xFF && data[1] == 0xFE)
+                {
+                    var str = Encoding.Unicode.GetString(data).Substring(1);
+
+                    return new StringToken(str, StringToken.Encoding.Utf16);
+                }
             }
 
             return new StringToken(OtherEncodings.BytesAsLatin1String(data), StringToken.Encoding.Iso88591);

src/UglyToad.PdfPig/Filters/CcittFaxDecoderStream.cs

@@ -2,8 +2,8 @@
 {
     using System;
     using System.IO;
-    using UglyToad.PdfPig.IO;
-    using UglyToad.PdfPig.Util;
+    using IO;
+    using Util;
 
     /// <summary>
     /// CCITT Modified Huffman RLE, Group 3 (T4) and Group 4 (T6) fax compression.
@@ -30,7 +30,7 @@
         private int changesReferenceRowCount;
         private int changesCurrentRowCount;
 
-        private int lastChangingElement = 0;
+        private int lastChangingElement;
 
         private int buffer = -1;
         private int bufferPos = -1;
@@ -78,7 +78,7 @@
                 {
                     DecodeRow();
                 }
-                catch (IOException)
+                catch (InvalidOperationException)
                 {
                     if (decodedLength != 0)
                     {
@@ -344,7 +344,7 @@
 
             if (index != columns)
             {
-                throw new IOException("Sum of run-lengths does not equal scan line width: " + index + " > " + columns);
+                throw new InvalidOperationException("Sum of run-lengths does not equal scan line width: " + index + " > " + columns);
             }
 
             decodedLength = (index + 7) / 8;
@@ -363,7 +363,7 @@
 
                 if (node == null)
                 {
-                    throw new IOException("Unknown code in Huffman RLE stream");
+                    throw new InvalidOperationException("Unknown code in Huffman RLE stream");
                 }
 
                 if (node.IsLeaf)
@@ -398,7 +398,7 @@
 
                 if (buffer == -1)
                 {
-                    throw new IOException("Unexpected end of Huffman RLE stream");
+                    throw new InvalidOperationException("Unexpected end of Huffman RLE stream");
                 }
 
                 bufferPos = 0;
@@ -528,7 +528,7 @@
                     }
                     else if (next.IsLeaf)
                     {
-                        throw new IOException("node is leaf, no other following");
+                        throw new InvalidOperationException("node is leaf, no other following");
                     }
 
                     current = next;
@@ -565,7 +565,7 @@
                     }
                     else if (next.IsLeaf)
                     {
-                        throw new IOException("node is leaf, no other following");
+                        throw new InvalidOperationException("node is leaf, no other following");
                     }
 
                     current = next;

src/UglyToad.PdfPig/Filters/DefaultFilterProvider.cs

@@ -1,124 +1,124 @@
-namespace UglyToad.PdfPig.Filters
-{
-    using System;
-    using System.Collections.Generic;
-    using System.Linq;
-    using Core;
+namespace UglyToad.PdfPig.Filters
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using Core;
     using Tokens;
     using UglyToad.PdfPig.Util;
 
-    /// <inheritdoc />
-    /// <summary>
-    /// The default implementation of the <see cref="T:UglyToad.PdfPig.Filters.IFilterProvider" />.
-    /// </summary>
-    public class DefaultFilterProvider : IFilterProvider
-    {
-        private readonly IReadOnlyDictionary<string, IFilter> filterInstances; 
-
-        /// <summary>
-        /// The single instance of this provider.
-        /// </summary>
-        public static readonly IFilterProvider Instance = new DefaultFilterProvider();
-
-        private DefaultFilterProvider()
-        {
-            var ascii85 = new Ascii85Filter();
-            var asciiHex = new AsciiHexDecodeFilter();
-            var ccitt = new CcittFaxDecodeFilter();
-            var dct = new DctDecodeFilter();
-            var flate = new FlateFilter();
-            var jbig2 = new Jbig2DecodeFilter();
-            var jpx = new JpxDecodeFilter();
-            var runLength = new RunLengthFilter();
-            var lzw = new LzwFilter();
-
-            filterInstances = new Dictionary<string, IFilter>
-            {
-                {NameToken.Ascii85Decode.Data, ascii85},
-                {NameToken.Ascii85DecodeAbbreviation.Data, ascii85},
-                {NameToken.AsciiHexDecode.Data, asciiHex},
-                {NameToken.AsciiHexDecodeAbbreviation.Data, asciiHex},
-                {NameToken.CcittfaxDecode.Data, ccitt},
-                {NameToken.CcittfaxDecodeAbbreviation.Data, ccitt},
-                {NameToken.DctDecode.Data, dct},
-                {NameToken.DctDecodeAbbreviation.Data, dct},
-                {NameToken.FlateDecode.Data, flate},
-                {NameToken.FlateDecodeAbbreviation.Data, flate},
-                {NameToken.Jbig2Decode.Data, jbig2},
-                {NameToken.JpxDecode.Data, jpx},
-                {NameToken.RunLengthDecode.Data, runLength},
-                {NameToken.RunLengthDecodeAbbreviation.Data, runLength},
-                {NameToken.LzwDecode, lzw},
-                {NameToken.LzwDecodeAbbreviation, lzw}
-            };
-        }
-
-        /// <inheritdoc />
-        public IReadOnlyList<IFilter> GetFilters(DictionaryToken dictionary)
-        {
-            if (dictionary == null)
-            {
-                throw new ArgumentNullException(nameof(dictionary));
-            }
-
-            var token = dictionary.GetObjectOrDefault(NameToken.Filter, NameToken.F);
-            if (token == null)
-            {
-                return EmptyArray<IFilter>.Instance;
-            }
-
-            switch (token)
-            {
-                case ArrayToken filters:
-                    var result = new IFilter[filters.Data.Count];
-                    for (var i = 0; i < filters.Data.Count; i++)
-                    {
-                        var filterToken = filters.Data[i];
-                        var filterName = ((NameToken) filterToken).Data;
-                        result[i] = GetFilterStrict(filterName);
-                    }
-
-                    return result;
-                case NameToken name:
-                    return new[] { GetFilterStrict(name.Data) };
-                default:
-                    throw new PdfDocumentFormatException($"The filter for the stream was not a valid object. Expected name or array, instead got: {token}.");
-            }
-        }
-
-        /// <inheritdoc />
-        public IReadOnlyList<IFilter> GetNamedFilters(IReadOnlyList<NameToken> names)
-        {
-            if (names == null)
-            {
-                throw new ArgumentNullException(nameof(names));
-            }
-
-            var result = new List<IFilter>();
-
-            foreach (var name in names)
-            {
-                result.Add(GetFilterStrict(name));
-            }
-
-            return result;
-        }
-        
-        private IFilter GetFilterStrict(string name)
-        {
-            if (!filterInstances.TryGetValue(name, out var factory))
-            {
-                throw new NotSupportedException($"The filter with the name {name} is not supported yet. Please raise an issue.");
-            }
-
-            return factory;
-        }
-
-        /// <inheritdoc />
-        public IReadOnlyList<IFilter> GetAllFilters()
-        {
-            return filterInstances.Values.Distinct().ToList();
-        }
-
-    }
+    /// <inheritdoc />
+    /// <summary>
+    /// The default implementation of the <see cref="T:UglyToad.PdfPig.Filters.IFilterProvider" />.
+    /// </summary>
+    public class DefaultFilterProvider : IFilterProvider
+    {
+        private readonly IReadOnlyDictionary<string, IFilter> filterInstances; 
+
+        /// <summary>
+        /// The single instance of this provider.
+        /// </summary>
+        public static readonly IFilterProvider Instance = new DefaultFilterProvider();
+
+        private DefaultFilterProvider()
+        {
+            var ascii85 = new Ascii85Filter();
+            var asciiHex = new AsciiHexDecodeFilter();
+            var ccitt = new CcittFaxDecodeFilter();
+            var dct = new DctDecodeFilter();
+            var flate = new FlateFilter();
+            var jbig2 = new Jbig2DecodeFilter();
+            var jpx = new JpxDecodeFilter();
+            var runLength = new RunLengthFilter();
+            var lzw = new LzwFilter();
+
+            filterInstances = new Dictionary<string, IFilter>
+            {
+                {NameToken.Ascii85Decode.Data, ascii85},
+                {NameToken.Ascii85DecodeAbbreviation.Data, ascii85},
+                {NameToken.AsciiHexDecode.Data, asciiHex},
+                {NameToken.AsciiHexDecodeAbbreviation.Data, asciiHex},
+                {NameToken.CcittfaxDecode.Data, ccitt},
+                {NameToken.CcittfaxDecodeAbbreviation.Data, ccitt},
+                {NameToken.DctDecode.Data, dct},
+                {NameToken.DctDecodeAbbreviation.Data, dct},
+                {NameToken.FlateDecode.Data, flate},
+                {NameToken.FlateDecodeAbbreviation.Data, flate},
+                {NameToken.Jbig2Decode.Data, jbig2},
+                {NameToken.JpxDecode.Data, jpx},
+                {NameToken.RunLengthDecode.Data, runLength},
+                {NameToken.RunLengthDecodeAbbreviation.Data, runLength},
+                {NameToken.LzwDecode, lzw},
+                {NameToken.LzwDecodeAbbreviation, lzw}
+            };
+        }
+
+        /// <inheritdoc />
+        public IReadOnlyList<IFilter> GetFilters(DictionaryToken dictionary)
+        {
+            if (dictionary == null)
+            {
+                throw new ArgumentNullException(nameof(dictionary));
+            }
+
+            var token = dictionary.GetObjectOrDefault(NameToken.Filter, NameToken.F);
+            if (token == null)
+            {
+                return EmptyArray<IFilter>.Instance;
+            }
+
+            switch (token)
+            {
+                case ArrayToken filters:
+                    var result = new IFilter[filters.Data.Count];
+                    for (var i = 0; i < filters.Data.Count; i++)
+                    {
+                        var filterToken = filters.Data[i];
+                        var filterName = ((NameToken) filterToken).Data;
+                        result[i] = GetFilterStrict(filterName);
+                    }
+
+                    return result;
+                case NameToken name:
+                    return new[] { GetFilterStrict(name.Data) };
+                default:
+                    throw new PdfDocumentFormatException($"The filter for the stream was not a valid object. Expected name or array, instead got: {token}.");
+            }
+        }
+
+        /// <inheritdoc />
+        public IReadOnlyList<IFilter> GetNamedFilters(IReadOnlyList<NameToken> names)
+        {
+            if (names == null)
+            {
+                throw new ArgumentNullException(nameof(names));
+            }
+
+            var result = new List<IFilter>();
+
+            foreach (var name in names)
+            {
+                result.Add(GetFilterStrict(name));
+            }
+
+            return result;
+        }
+        
+        private IFilter GetFilterStrict(string name)
+        {
+            if (!filterInstances.TryGetValue(name, out var factory))
+            {
+                throw new NotSupportedException($"The filter with the name {name} is not supported yet. Please raise an issue.");
+            }
+
+            return factory;
+        }
+
+        /// <inheritdoc />
+        public IReadOnlyList<IFilter> GetAllFilters()
+        {
+            return filterInstances.Values.Distinct().ToList();
+        }
+
+    }
 }

src/UglyToad.PdfPig/IO/StreamWrapper.cs

@@ -36,39 +36,24 @@
             Stream.Write(buffer, offset, count);
         }
 
-        public override bool CanRead
-        {
-            get { return Stream.CanRead; }
-        }
+        public override bool CanRead => Stream.CanRead;
 
-        public override bool CanSeek
-        {
-            get { return Stream.CanSeek; }
-        }
+        public override bool CanSeek => Stream.CanSeek;
 
-        public override bool CanWrite
-        {
-            get { return Stream.CanWrite; }
-        }
+        public override bool CanWrite => Stream.CanWrite;
 
-        public override long Length
-        {
-            get { return Stream.Length; }
-        }
+        public override long Length => Stream.Length;
 
         public override long Position
         {
-            get { return Stream.Position; }
-            set { Stream.Position = value; }
+            get => Stream.Position;
+            set => Stream.Position = value;
         }
 
         protected override void Dispose(bool disposing)
         {
             base.Dispose(disposing);
-            // dispose stream
-            using (Stream)
-            {
-            }
+            Stream?.Dispose();
         }
     }
 }