Fixes: U4-2627 Ensure that the plugins cache files are named with the machine name

src/Umbraco.Core/NetworkHelper.cs

@@ -0,0 +1,50 @@
+using System;
+
+namespace Umbraco.Core
+{
+    /// <summary>
+    /// Currently just used to get the machine name in med trust and to format a machine name for use with file names
+    /// </summary>
+    internal class NetworkHelper
+    {
+        /// <summary>
+        /// Returns the machine name that is safe to use in file paths.
+        /// </summary>
+        /// <remarks>
+        /// see: https://github.com/Shandem/ClientDependency/issues/4
+        /// </remarks>
+        public static string FileSafeMachineName
+        {
+            get { return MachineName.ReplaceNonAlphanumericChars('-'); }
+        }
+
+        /// <summary>
+        /// Returns the current machine name
+        /// </summary>
+        /// <remarks>
+        /// Tries to resolve the machine name, if it cannot it uses the config section.
+        /// </remarks>
+        public static string MachineName
+        {
+            get
+            {
+                try
+                {
+                    return Environment.MachineName;
+                }
+                catch
+                {
+                    try
+                    {
+                        return System.Net.Dns.GetHostName();
+                    }
+                    catch
+                    {
+                        //if we get here it means we cannot access the machine name
+                        throw new ApplicationException("Cannot resolve the current machine name eithe by Environment.MachineName or by Dns.GetHostname()");
+                    }
+                }
+            }
+        }
+    }
+}

src/Umbraco.Core/PluginManager.cs

@@ -20,7 +20,6 @@ using File = System.IO.File;
 
 namespace Umbraco.Core
 {
-
     /// <summary>
     /// Used to resolve all plugin types and cache them and is also used to instantiate plugin types
     /// </summary>
@@ -307,15 +306,15 @@ namespace Umbraco.Core
                _appContext.ApplicationCache.ClearCacheItem("umbraco-plugins.list");
             }
         }
-
+        
         private string GetPluginListFilePath()
         {
-            return Path.Combine(_tempFolder, "umbraco-plugins.list");
+            return Path.Combine(_tempFolder, string.Format("umbraco-plugins.{0}.list", NetworkHelper.FileSafeMachineName));
         }
 
         private string GetPluginHashFilePath()
         {
-            return Path.Combine(_tempFolder, "umbraco-plugins.hash");
+            return Path.Combine(_tempFolder, string.Format("umbraco-plugins.{0}.hash", NetworkHelper.FileSafeMachineName));
         }
 
         /// <summary>

src/Umbraco.Core/StringExtensions.cs

@@ -28,6 +28,17 @@ namespace Umbraco.Core
         [UmbracoWillObsolete("Do not use this constants. See IShortStringHelper.CleanStringForSafeAliasJavaScriptCode.")]
         public const string UmbracoInvalidFirstCharacters = "01234567890";
 
+        internal static string ReplaceNonAlphanumericChars(this string input, char replacement)
+        {
+            //any character that is not alphanumeric, convert to a hyphen
+            var mName = input;
+            foreach (var c in mName.ToCharArray().Where(c => !char.IsLetterOrDigit(c)))
+            {
+                mName = mName.Replace(c, replacement);
+            }
+            return mName;
+        }
+
         public static string ExceptChars(this string str, HashSet<char> toExclude)
         {
             var sb = new StringBuilder(str.Length);

src/Umbraco.Core/Umbraco.Core.csproj

@@ -238,6 +238,7 @@
     <Compile Include="Models\UmbracoEntity.cs" />
     <Compile Include="Models\UmbracoObjectTypes.cs" />
     <Compile Include="Models\UmbracoObjectTypesExtensions.cs" />
+    <Compile Include="NetworkHelper.cs" />
     <Compile Include="ObjectResolution\ApplicationEventsResolver.cs" />
     <Compile Include="ObjectResolution\ResolverCollection.cs" />
     <Compile Include="Persistence\Caching\InMemoryCacheProvider.cs" />