From 4953673caf97170724cd7e663c05d82b26a3588b Mon Sep 17 00:00:00 2001
From: Matt Nadareski <mnadareski@outlook.com>
Date: Thu, 7 Jul 2022 11:37:53 -0700
Subject: [PATCH] Start writing CAB extraction

---
 BurnOutSharp/FileType/MicrosoftCAB.cs | 74 +++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)

diff --git a/BurnOutSharp/FileType/MicrosoftCAB.cs b/BurnOutSharp/FileType/MicrosoftCAB.cs
index 9112e17e..32b0b0a1 100644
--- a/BurnOutSharp/FileType/MicrosoftCAB.cs
+++ b/BurnOutSharp/FileType/MicrosoftCAB.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Concurrent;
 using System.IO;
+using System.Text;
 using BurnOutSharp.Interfaces;
 using BurnOutSharp.Tools;
 using WixToolset.Dtf.Compression.Cab;
@@ -262,6 +263,49 @@ namespace BurnOutSharp.FileType
             }
 
             #endregion
+
+            #region Public Functionality
+
+            /// <summary>
+            /// Extract a single file from the archive to <paramref name="outputDirectory"/>
+            /// </summary>
+            public bool ExtractFile(string filePath, string outputDirectory, bool exact = false)
+            {
+                // Perform sanity checks
+                if (Header == null || Files == null || Files.Length == 0)
+                    return false;
+
+                // Check the file exists
+                int fileIndex = -1;
+                for (int i = 0; i < Files.Length; i++)
+                {
+                    CFFILE tempFile = Files[i];
+                    if (tempFile == null)
+                        continue;
+
+                    // Check for a match
+                    if (exact ? tempFile.NameAsString == filePath : tempFile.NameAsString.EndsWith(filePath, StringComparison.OrdinalIgnoreCase))
+                    {
+                        fileIndex = i;
+                        break;
+                    }
+                }
+
+                // -1 is an invalid file index
+                if (fileIndex == -1)
+                    return false;
+
+                // Get the file to extract
+                CFFILE file = Files[fileIndex];
+                string outputPath = Path.Combine(outputDirectory, file.NameAsString);
+
+                // TODO: We don't check for other cabinets here yet
+                // TODO: Read and decompress data blocks
+
+                return true;
+            }
+
+            #endregion
         }
 
         /// <summary>
@@ -745,6 +789,36 @@ namespace BurnOutSharp.FileType
 
             #endregion
 
+            #region Generated Properties
+
+            /// <summary>
+            /// Name value as a string (not null-terminated)
+            /// </summary>
+            public string NameAsString
+            {
+                get
+                {
+                    // Perform sanity checks
+                    if (Name == null || Name.Length == 0)
+                        return null;
+
+                    // Attempt to respect the attribute flag for UTF-8
+                    if (Attributes.HasFlag(FileAttributes.NAME_IS_UTF))
+                    {
+                        try
+                        {
+                            return Encoding.UTF8.GetString(Name).TrimEnd('\0');
+                        }
+                        catch { }
+                    }
+
+                    // Default case uses local encoding
+                    return Encoding.Default.GetString(Name).TrimEnd('\0');
+                }
+            }
+
+            #endregion
+
             #region Serialization
 
             /// <summary>