More cleanup of Skippers

SabreTools.Library/Skippers/SkipperFile.cs

@@ -78,6 +78,7 @@ namespace SabreTools.Library.Skippers
         /// Parse an XML document in as a SkipperFile
         /// </summary>
         /// <param name="xtr">XmlReader representing the document</param>
+        /// <returns>True if the file could be parsed, false otherwise</returns>
         private bool Parse(XmlReader xtr)
         {
             if (xtr == null)
@@ -136,6 +137,7 @@ namespace SabreTools.Library.Skippers
         /// Parse an XML document in as a SkipperRule
         /// </summary>
         /// <param name="xtr">XmlReader representing the document</param>
+        /// <returns>Filled SkipperRule on success, null otherwise</returns>
         private SkipperRule ParseRule(XmlReader xtr)
         {
             if (xtr == null)
@@ -206,6 +208,34 @@ namespace SabreTools.Library.Skippers
                         if (subreader.NodeType != XmlNodeType.Element)
                             subreader.Read();
 
+                        SkipperTest test = ParseTest(xtr);
+
+                        // Add the created test to the rule
+                        rule.Tests.Add(test);
+                        subreader.Read();
+                    }
+                }
+
+                return rule;
+            }
+            catch
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// Parse an XML document in as a SkipperTest
+        /// </summary>
+        /// <param name="xtr">XmlReader representing the document</param>
+        /// <returns>Filled SkipperTest on success, null otherwise</returns>
+        private SkipperTest ParseTest(XmlReader xtr)
+        {
+            if (xtr == null)
+                return null;
+
+            try
+            {
                 // Get the test type
                 SkipperTest test = new SkipperTest
                 {
@@ -216,7 +246,8 @@ namespace SabreTools.Library.Skippers
                     Size = 0,
                     Operator = HeaderSkipTestFileOperator.Equal,
                 };
-                        switch (subreader.Name.ToLowerInvariant())
+
+                switch (xtr.Name.ToLowerInvariant())
                 {
                     case "data":
                         test.Type = HeaderSkipTest.Data;
@@ -239,23 +270,23 @@ namespace SabreTools.Library.Skippers
                         break;
 
                     default:
-                                subreader.Read();
+                        xtr.Read();
                         break;
                 }
 
                 // Now populate all the parts that we can
-                        if (subreader.GetAttribute("offset") != null)
+                if (xtr.GetAttribute("offset") != null)
                 {
-                            string offset = subreader.GetAttribute("offset");
+                    string offset = xtr.GetAttribute("offset");
                     if (offset.ToLowerInvariant() == "eof")
                         test.Offset = null;
                     else
                         test.Offset = Convert.ToInt64(offset, 16);
                 }
 
-                        if (subreader.GetAttribute("value") != null)
+                if (xtr.GetAttribute("value") != null)
                 {
-                            string value = subreader.GetAttribute("value");
+                    string value = xtr.GetAttribute("value");
 
                     // http://stackoverflow.com/questions/321370/how-can-i-convert-a-hex-string-to-a-byte-array
                     test.Value = new byte[value.Length / 2];
@@ -266,18 +297,18 @@ namespace SabreTools.Library.Skippers
                     }
                 }
 
-                        if (subreader.GetAttribute("result") != null)
+                if (xtr.GetAttribute("result") != null)
                 {
-                            string result = subreader.GetAttribute("result");
+                    string result = xtr.GetAttribute("result");
                     if (!bool.TryParse(result, out bool resultBool))
                         resultBool = true;
 
                     test.Result = resultBool;
                 }
 
-                        if (subreader.GetAttribute("mask") != null)
+                if (xtr.GetAttribute("mask") != null)
                 {
-                            string mask = subreader.GetAttribute("mask");
+                    string mask = xtr.GetAttribute("mask");
 
                     // http://stackoverflow.com/questions/321370/how-can-i-convert-a-hex-string-to-a-byte-array
                     test.Mask = new byte[mask.Length / 2];
@@ -288,18 +319,18 @@ namespace SabreTools.Library.Skippers
                     }
                 }
 
-                        if (subreader.GetAttribute("size") != null)
+                if (xtr.GetAttribute("size") != null)
                 {
-                            string size = subreader.GetAttribute("size");
+                    string size = xtr.GetAttribute("size");
                     if (size.ToLowerInvariant() == "po2")
                         test.Size = null;
                     else
                         test.Size = Convert.ToInt64(size, 16);
                 }
 
-                        if (subreader.GetAttribute("operator") != null)
+                if (xtr.GetAttribute("operator") != null)
                 {
-                            string oper = subreader.GetAttribute("operator");
+                    string oper = xtr.GetAttribute("operator");
 #if NET_FRAMEWORK
                     switch (oper.ToLowerInvariant())
                     {
@@ -325,13 +356,7 @@ namespace SabreTools.Library.Skippers
 #endif
                 }
 
-                        // Add the created test to the rule
+                return test;
-                        rule.Tests.Add(test);
-                        subreader.Read();
-                    }
-                }
-
-                return rule;
             }
             catch
             {
@@ -340,5 +365,55 @@ namespace SabreTools.Library.Skippers
         }
 
         #endregion
+
+        #region Matching
+
+        /// <summary>
+        /// Get the SkipperRule associated with a given stream
+        /// </summary>
+        /// <param name="input">Stream to be checked</param>
+        /// <param name="skipperName">Name of the skipper to be used, blank to find a matching skipper</param>
+        /// <returns>The SkipperRule that matched the stream, null otherwise</returns>
+        public SkipperRule GetMatchingRule(Stream input, string skipperName)
+        {
+            // If we have no name supplied, try to blindly match
+            if (string.IsNullOrWhiteSpace(skipperName))
+                return GetMatchingRule(input);
+
+            // If the name matches the internal name of the skipper
+            else if (string.Equals(skipperName, Name, StringComparison.OrdinalIgnoreCase))
+                return GetMatchingRule(input);
+
+            // If the name matches the source file name of the skipper
+            else if (string.Equals(skipperName, SourceFile, StringComparison.OrdinalIgnoreCase))
+                return GetMatchingRule(input);
+
+            // Otherwise, nothing matches by default
+            return null;
+        }
+
+        /// <summary>
+        /// Get the matching SkipperRule from all Rules, if possible
+        /// </summary>
+        /// <param name="input">Stream to be checked</param>
+        /// <returns>The SkipperRule that matched the stream, null otherwise</returns>
+        private SkipperRule GetMatchingRule(Stream input)
+        {
+            // Loop through the rules until one is found that works
+            foreach (SkipperRule rule in Rules)
+            {
+                // Always reset the stream back to the original place
+                input.Seek(0, SeekOrigin.Begin);
+
+                // If all tests in the rule pass, we return this rule
+                if (rule.PassesAllTests(input))
+                    return rule;
+            }
+
+            // If nothing passed, we return null by default
+            return null;
+        }
+
+        #endregion
     }
 }

SabreTools.Library/Skippers/SkipperRule.cs

@@ -38,6 +38,23 @@ namespace SabreTools.Library.Skippers
 
         #endregion
 
+        /// <summary>
+        /// Check if a Stream passes all tests in the SkipperRule
+        /// </summary>
+        /// <param name="input">Stream to check</param>
+        /// <returns>True if all tests passed, false otherwise</returns>
+        public bool PassesAllTests(Stream input)
+        {
+            bool success = true;
+            foreach (SkipperTest test in Tests)
+            {
+                bool result = test.Passes(input);
+                success &= result;
+            }
+
+            return success;
+        }
+
         /// <summary>
         /// Transform an input file using the given rule
         /// </summary>

SabreTools.Library/Skippers/SkipperTest.cs

@@ -1,12 +1,17 @@
+using System;
+using System.IO;
+
 using SabreTools.Library.Data;
 
 namespace SabreTools.Library.Skippers
 {
     /// <summary>
-    /// Intermediate class for storing Skipper Test information
+    /// Individual test that applies to a SkipperRule
     /// </summary>
-    public struct SkipperTest
+    public class SkipperTest
     {
+        #region Fields
+
         /// <summary>
         /// Type of test to be run
         /// </summary>
@@ -15,7 +20,8 @@ namespace SabreTools.Library.Skippers
         /// <summary>
         /// File offset to run the test
         /// </summary>
-        public long? Offset { get; set; } // null is EOF
+        /// <remarks>null is EOF</remarks>
+        public long? Offset { get; set; }
 
         /// <summary>
         /// Static value to be checked at the offset
@@ -41,5 +47,259 @@ namespace SabreTools.Library.Skippers
         /// Expected range value for the input byte array size, used with Size
         /// </summary>
         public HeaderSkipTestFileOperator Operator { get; set; }
+
+        #endregion
+
+        /// <summary>
+        /// Check if a stream passes the test
+        /// </summary>
+        /// <param name="input">Stream to check rule against</param>
+        /// <remarks>The Stream is assumed to be in the proper position for a given test</remarks>
+        public bool Passes(Stream input)
+        {
+            bool result = true;
+            switch (Type)
+            {
+                case HeaderSkipTest.And:
+                    return CheckAnd(input);
+                case HeaderSkipTest.Data:
+                    return CheckData(input);
+                case HeaderSkipTest.File:
+                    return CheckFile(input);
+                case HeaderSkipTest.Or:
+                    return CheckOr(input);
+                case HeaderSkipTest.Xor:
+                    return CheckXor(input);
+            }
+
+            return result;
+        }
+
+        #region Checking Helpers
+
+        /// <summary>
+        /// Run an And test against an input stream
+        /// </summary>
+        /// <param name="input">Stream to check rule against</param>
+        /// <returns>True if the stream passed, false otherwise</returns>
+        private bool CheckAnd(Stream input)
+        {
+            // First seek to the correct position
+            Seek(input);
+
+            bool result = true;
+            try
+            {
+                // Then apply the mask if it exists
+                byte[] read = new byte[Mask.Length];
+                input.Read(read, 0, Mask.Length);
+
+                byte[] masked = new byte[Mask.Length];
+                for (int i = 0; i < read.Length; i++)
+                {
+                    masked[i] = (byte)(read[i] & Mask[i]);
+                }
+
+                // Finally, compare it against the value
+                for (int i = 0; i < Value.Length; i++)
+                {
+                    if (masked[i] != Value[i])
+                    {
+                        result = false;
+                        break;
+                    }
+                }
+            }
+            catch
+            {
+                result = false;
+            }
+
+            // Return if the expected and actual results match
+            return result == Result;
+        }
+
+        /// <summary>
+        /// Run a Data test against an input stream
+        /// </summary>
+        /// <param name="input">Stream to check rule against</param>
+        /// <returns>True if the stream passed, false otherwise</returns>
+        private bool CheckData(Stream input)
+        {
+            // First seek to the correct position
+            if (!Seek(input))
+                return false;
+
+            // Then read and compare bytewise
+            bool result = true;
+            for (int i = 0; i < Value.Length; i++)
+            {
+                try
+                {
+                    if (input.ReadByte() != Value[i])
+                    {
+                        result = false;
+                        break;
+                    }
+                }
+                catch
+                {
+                    result = false;
+                    break;
+                }
+            }
+
+            // Return if the expected and actual results match
+            return result == Result;
+        }
+
+        /// <summary>
+        /// Run a File test against an input stream
+        /// </summary>
+        /// <param name="input">Stream to check rule against</param>
+        /// <returns>True if the stream passed, false otherwise</returns>
+        private bool CheckFile(Stream input)
+        {
+            // First get the file size from stream
+            long size = input.Length;
+
+            // If we have a null size, check that the size is a power of 2
+            bool result = true;
+            if (Size == null)
+            {
+                // http://stackoverflow.com/questions/600293/how-to-check-if-a-number-is-a-power-of-2
+                result = (((ulong)size & ((ulong)size - 1)) == 0);
+            }
+            else if (Operator == HeaderSkipTestFileOperator.Less)
+            {
+                result = (size < Size);
+            }
+            else if (Operator == HeaderSkipTestFileOperator.Greater)
+            {
+                result = (size > Size);
+            }
+            else if (Operator == HeaderSkipTestFileOperator.Equal)
+            {
+                result = (size == Size);
+            }
+
+            // Return if the expected and actual results match
+            return result == Result;
+        }
+
+        /// <summary>
+        /// Run an Or test against an input stream
+        /// </summary>
+        /// <param name="input">Stream to check rule against</param>
+        /// <returns>True if the stream passed, false otherwise</returns>
+        private bool CheckOr(Stream input)
+        {
+            // First seek to the correct position
+            Seek(input);
+
+            bool result = true;
+            try
+            {
+                // Then apply the mask if it exists
+                byte[] read = new byte[Mask.Length];
+                input.Read(read, 0, Mask.Length);
+
+                byte[] masked = new byte[Mask.Length];
+                for (int i = 0; i < read.Length; i++)
+                {
+                    masked[i] = (byte)(read[i] | Mask[i]);
+                }
+
+                // Finally, compare it against the value
+                for (int i = 0; i < Value.Length; i++)
+                {
+                    if (masked[i] != Value[i])
+                    {
+                        result = false;
+                        break;
+                    }
+                }
+            }
+            catch
+            {
+                result = false;
+            }
+
+            // Return if the expected and actual results match
+            return result == Result;
+        }
+
+        /// <summary>
+        /// Run an Xor test against an input stream
+        /// </summary>
+        /// <param name="input">Stream to check rule against</param>
+        /// <returns>True if the stream passed, false otherwise</returns>
+        private bool CheckXor(Stream input)
+        {
+            // First seek to the correct position
+            Seek(input);
+
+            bool result = true;
+            try
+            {
+                // Then apply the mask if it exists
+                byte[] read = new byte[Mask.Length];
+                input.Read(read, 0, Mask.Length);
+
+                byte[] masked = new byte[Mask.Length];
+                for (int i = 0; i < read.Length; i++)
+                {
+                    masked[i] = (byte)(read[i] ^ Mask[i]);
+                }
+
+                // Finally, compare it against the value
+                for (int i = 0; i < Value.Length; i++)
+                {
+                    if (masked[i] != Value[i])
+                    {
+                        result = false;
+                        break;
+                    }
+                }
+            }
+            catch
+            {
+                result = false;
+            }
+
+            // Return if the expected and actual results match
+            return result == Result;
+        }
+
+        /// <summary>
+        /// Seek an input stream based on the test value
+        /// </summary>
+        /// <param name="input">Stream to seek</param>
+        /// <returns>True if the stream could seek, false on error</returns>
+        private bool Seek(Stream input)
+        {
+            try
+            {
+                // Null offset means EOF
+                if (Offset == null)
+                    input.Seek(0, SeekOrigin.End);
+
+                // Positive offset means from beginning
+                else if (Offset >= 0 && Offset <= input.Length)
+                    input.Seek(Offset.Value, SeekOrigin.Begin);
+
+                // Negative offset means from end
+                else if (Offset < 0 && Math.Abs(Offset.Value) <= input.Length)
+                    input.Seek(Offset.Value, SeekOrigin.End);
+
+                return true;
+            }
+            catch
+            {
+                return false;
+            }
+        }
+
+        #endregion
     }
 }

SabreTools.Library/Skippers/Transform.cs

@@ -1,4 +1,3 @@
-using System;
 using System.Collections.Generic;
 using System.IO;
 
@@ -183,7 +182,6 @@ namespace SabreTools.Library.Skippers
         /// </summary>
         /// <param name="input">Name of the file to be checked</param>
         /// <param name="skipperName">Name of the skipper to be used, blank to find a matching skipper</param>
-        /// <param name="logger">Logger object for file and console output</param>
         /// <param name="keepOpen">True if the underlying stream should be kept open, false otherwise</param>
         /// <returns>The SkipperRule that matched the file</returns>
         public static SkipperRule GetMatchingRule(Stream input, string skipperName, bool keepOpen = false)
@@ -199,154 +197,27 @@ namespace SabreTools.Library.Skippers
             List<SkipperFile> tempList = new List<SkipperFile>();
             tempList.AddRange(List);
 
+            // Loop through all known SkipperFiles
             foreach (SkipperFile skipper in tempList)
             {
-                // If we're searching for the skipper OR we have a match to an inputted one
+                skipperRule = skipper.GetMatchingRule(input, skipperName);
-                if (string.IsNullOrWhiteSpace(skipperName)
+                if (skipperRule != null)
-                    || (!string.IsNullOrWhiteSpace(skipper.Name) && skipperName.ToLowerInvariant() == skipper.Name.ToLowerInvariant())
-                    || (!string.IsNullOrWhiteSpace(skipper.Name) && skipperName.ToLowerInvariant() == skipper.SourceFile.ToLowerInvariant()))
-                {
-                    // Loop through the rules until one is found that works
-                    BinaryReader br = new BinaryReader(input);
-
-                    foreach (SkipperRule rule in skipper.Rules)
-                    {
-                        // Always reset the stream back to the original place
-                        input.Seek(0, SeekOrigin.Begin);
-
-                        // For each rule, make sure it passes each test
-                        bool success = true;
-                        foreach (SkipperTest test in rule.Tests)
-                        {
-                            bool result = true;
-                            switch (test.Type)
-                            {
-                                case HeaderSkipTest.Data:
-                                    // First seek to the correct position
-                                    if (test.Offset == null)
-                                        input.Seek(0, SeekOrigin.End);
-                                    else if (test.Offset > 0 && test.Offset <= input.Length)
-                                        input.Seek((long)test.Offset, SeekOrigin.Begin);
-                                    else if (test.Offset < 0 && Math.Abs((long)test.Offset) <= input.Length)
-                                        input.Seek((long)test.Offset, SeekOrigin.End);
-
-                                    // Then read and compare bytewise
-                                    result = true;
-                                    for (int i = 0; i < test.Value.Length; i++)
-                                    {
-                                        try
-                                        {
-                                            if (br.ReadByte() != test.Value[i])
-                                            {
-                                                result = false;
                     break;
             }
-                                        }
-                                        catch
-                                        {
-                                            result = false;
-                                            break;
-                                        }
-                                    }
-
-                                    // Return if the expected and actual results match
-                                    success &= (result == test.Result);
-                                    break;
-
-                                case HeaderSkipTest.Or:
-                                case HeaderSkipTest.Xor:
-                                case HeaderSkipTest.And:
-                                    // First seek to the correct position
-                                    if (test.Offset == null)
-                                        input.Seek(0, SeekOrigin.End);
-                                    else if (test.Offset > 0 && test.Offset <= input.Length)
-                                        input.Seek((long)test.Offset, SeekOrigin.Begin);
-                                    else if (test.Offset < 0 && Math.Abs((long)test.Offset) <= input.Length)
-                                        input.Seek((long)test.Offset, SeekOrigin.End);
-
-                                    result = true;
-                                    try
-                                    {
-                                        // Then apply the mask if it exists
-                                        byte[] read = br.ReadBytes(test.Mask.Length);
-                                        byte[] masked = new byte[test.Mask.Length];
-                                        for (int i = 0; i < read.Length; i++)
-                                        {
-                                            masked[i] = (byte)(test.Type == HeaderSkipTest.And ? read[i] & test.Mask[i] :
-                                                (test.Type == HeaderSkipTest.Or ? read[i] | test.Mask[i] : read[i] ^ test.Mask[i])
-                                            );
-                                        }
-
-                                        // Finally, compare it against the value
-                                        for (int i = 0; i < test.Value.Length; i++)
-                                        {
-                                            if (masked[i] != test.Value[i])
-                                            {
-                                                result = false;
-                                                break;
-                                            }
-                                        }
-                                    }
-                                    catch
-                                    {
-                                        result = false;
-                                    }
-
-                                    // Return if the expected and actual results match
-                                    success &= (result == test.Result);
-                                    break;
-
-                                case HeaderSkipTest.File:
-                                    // First get the file size from stream
-                                    long size = input.Length;
-
-                                    // If we have a null size, check that the size is a power of 2
-                                    result = true;
-                                    if (test.Size == null)
-                                    {
-                                        // http://stackoverflow.com/questions/600293/how-to-check-if-a-number-is-a-power-of-2
-                                        result = (((ulong)size & ((ulong)size - 1)) == 0);
-                                    }
-                                    else if (test.Operator == HeaderSkipTestFileOperator.Less)
-                                    {
-                                        result = (size < test.Size);
-                                    }
-                                    else if (test.Operator == HeaderSkipTestFileOperator.Greater)
-                                    {
-                                        result = (size > test.Size);
-                                    }
-                                    else if (test.Operator == HeaderSkipTestFileOperator.Equal)
-                                    {
-                                        result = (size == test.Size);
-                                    }
-
-                                    // Return if the expected and actual results match
-                                    success &= (result == test.Result);
-                                    break;
-                            }
-                        }
-
-                        // If we still have a success, then return this rule
-                        if (success)
-                        {
-                            // If we're not keeping the stream open, dispose of the binary reader
-                            if (!keepOpen)
-                                input.Dispose();
-
-                            Globals.Logger.User(" Matching rule found!");
-                            return rule;
-                        }
-                    }
-                }
-            }
 
             // If we're not keeping the stream open, dispose of the binary reader
             if (!keepOpen)
                 input.Dispose();
 
+            // If the SkipperRule is null, make it empty
+            if (skipperRule == null)
+                skipperRule = new SkipperRule();
+
             // If we have a blank rule, inform the user
             if (skipperRule.Tests == null)
                 Globals.Logger.Verbose("No matching rule found!");
+            else
+                Globals.Logger.User("Matching rule found!");
 
             return skipperRule;
         }