Fixed issue where browsers are missing "ApplicationName" values in the registry, such as Internet Explorer, weren't recognised.

Author: sampalmer

SetDefaultBrowser/ApplicationCapabilities.cs

@@ -2,9 +2,20 @@
 {
     public class Browser
     {
+        /// <summary>
+        /// Uniquely identifies the browser for Windows' "Set Default Programs" applet.
+        /// Not suitable for display to user.
+        /// </summary>
         public string UniqueApplicationName { get; set; }
-        public ApplicationCapabilities Capabilities { get; set; }
 
-        public override string ToString() => Capabilities.DisplayName;
+        public string DisplayName { get; set; }
+
+        /// <summary>
+        /// File extensions are in the form ".abc".
+        /// Protocols are in the form "abc".
+        /// </summary>
+        public string[] Associations { get; set; }
+
+        public override string ToString() => DisplayName;
     }
 }

SetDefaultBrowser/Browser.cs

@@ -1,6 +1,7 @@
 using Microsoft.Win32;
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
@@ -18,17 +19,20 @@ public static Browser[] GetInstalledBrowsers()
             {
                 var capabilities = TryGetCapabilities(registeredApplication.Value);
                 if (capabilities != null)
-                    if (
-                        capabilities.DisplayName != null
-                        &&
-                        // These protocols are needed for Windows to see it as a web browser.
-                        new[] { "http", "https" }.All(protocol => capabilities.Associations.Contains(protocol, StringComparer.OrdinalIgnoreCase))
-                    )
-                        results.Add(new Browser
-                        {
-                            UniqueApplicationName = registeredApplication.Key,
-                            Capabilities = capabilities,
-                        });
+                {
+                    var associations = capabilities.Associations.Select(association => association.Association).ToArray();
+                    if (new[] { "http", "https" }.All(protocol => associations.Contains(protocol, StringComparer.OrdinalIgnoreCase)))
+                    {
+                        var displayName = TryGetDisplayName(capabilities);
+                        if (displayName != null)
+                            results.Add(new Browser
+                            {
+                                UniqueApplicationName = registeredApplication.Key,
+                                DisplayName = displayName,
+                                Associations = associations,
+                            });
+                    }
+                }
             }
 
             return results.ToArray();
@@ -66,18 +70,83 @@ private static ApplicationCapabilities TryGetCapabilities(string applicationCapa
                 {
                     var resourceValue = new StringBuilder(4096);
                     var hresult = WindowsApi.SHLoadIndirectString(rawApplicationName, resourceValue, resourceValue.Capacity, IntPtr.Zero);
-                    result.DisplayName = hresult == 0 ? resourceValue.ToString() : rawApplicationName;
+                    result.ApplicationName = hresult == 0 ? resourceValue.ToString() : rawApplicationName;
                 }
 
-                var associations = new List<string>();
+                var associations = new List<ApplicationAssociation>();
                 foreach (var subkeyName in new[] { "FileAssociations", "URLAssociations" })
                     using (var subkey = key.OpenSubKey(subkeyName))
                         if (subkey != null)
-                            associations.AddRange(subkey.GetValueNames());
+                            foreach (var association in subkey.GetValueNames())
+                            {
+                                var progId = subkey.GetValue(association) as string;
+                                associations.Add(new ApplicationAssociation
+                                {
+                                    Association = association,
+                                    ProgId = progId,
+                                });
+                            }
+
                 result.Associations = associations.ToArray();
             }
 
             return result;
         }
+
+        private static string TryGetDisplayName(ApplicationCapabilities capabilities)
+        {
+            // The display name of a registered application is optional. Internet Explorer doesn't use it, for example.
+            if (capabilities.ApplicationName != null)
+                return capabilities.ApplicationName;
+
+            foreach (var association in capabilities.Associations)
+                if (!String.IsNullOrEmpty(association.ProgId))
+                {
+                    var appName = AssocQueryString(association);
+                    if (appName != null)
+                        return appName;
+                }
+
+            return null;
+        }
+
+        private static string AssocQueryString(ApplicationAssociation association)
+        {
+            uint appNameLength = 0;
+            var result = WindowsApi.AssocQueryString(WindowsApi.AssocF.None, WindowsApi.AssocStr.FriendlyAppName, association.ProgId, null, null, ref appNameLength);
+            if (new[] { 2147943555, 2147942402 }.Contains(result)) // No application is associated with the specified file for this operation OR The system cannot find the file specified
+                return null;
+
+            if (result != 1)
+                throw new Win32Exception((int)result);
+
+            var buffer = new StringBuilder((int)appNameLength);
+            var bufferLength = (uint)buffer.Capacity;
+            result = WindowsApi.AssocQueryString(WindowsApi.AssocF.None, WindowsApi.AssocStr.FriendlyAppName, association.ProgId, null, buffer, ref bufferLength);
+            if (result != 0)
+                throw new Win32Exception((int)result);
+
+            return buffer.ToString();
+        }
+
+        private class ApplicationCapabilities
+        {
+            /// <summary>
+            /// May be <c>null</c>.
+            /// </summary>
+            public string ApplicationName { get; set; }
+            public ApplicationAssociation[] Associations { get; set; }
+        }
+
+        private class ApplicationAssociation
+        {
+            public string Association { get; set; }
+            
+            /// <summary>
+            /// May be null
+            /// </summary>
+            public string ProgId { get; set; }
+        }
+
     }
 }

SetDefaultBrowser/BrowserRegistry.cs

@@ -46,7 +46,7 @@ public static void Set(Browser browser)
                         var listView = new ListView(listViewHandle);
                         var save = Wait(() => FindDescendantBy(window, text: "Save"));
 
-                        var browserAssociations = browser.Capabilities.Associations
+                        var browserAssociations = browser.Associations
                             .Intersect(new[] { ".htm", ".html", "HTTP", "HTTPS" }, StringComparer.OrdinalIgnoreCase)
                             .ToArray();
 

SetDefaultBrowser/DefaultBrowserChanger.cs

@@ -27,7 +27,7 @@ static int Main(string[] rawArgs)
                     throw new EnvironmentException("Didn't find any web browsers installed.");
 
                 //Using a current culture string comparison here since we're comparing user input against display text.
-                var browser = browsers.FirstOrDefault(b => b.Capabilities.DisplayName.Equals(args.BrowserName, StringComparison.CurrentCulture));
+                var browser = browsers.FirstOrDefault(b => b.DisplayName.Equals(args.BrowserName, StringComparison.CurrentCulture));
                 if (browser == null)
                     throw new EnvironmentException($"Didn't find a web browser with the name '{args.BrowserName}'.\n\nPlease use one of the following:\n{FormattedInstalledBrowsers(browsers)}");
 
@@ -50,7 +50,7 @@ static int Main(string[] rawArgs)
         private static string ApplicationTitle => Assembly.GetEntryAssembly().GetCustomAttribute<AssemblyTitleAttribute>().Title;
         private static string FormattedInstalledBrowsers(IEnumerable<Browser> browsers)
         {
-            return String.Join("\n", browsers.Select(browser => "• " + browser.Capabilities.DisplayName).Distinct().OrderBy(n => n));
+            return String.Join("\n", browsers.Select(browser => "• " + browser.DisplayName).Distinct().OrderBy(n => n));
         }
     }
 }

SetDefaultBrowser/Program.cs

@@ -50,7 +50,6 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
-    <Compile Include="ApplicationCapabilities.cs" />
     <Compile Include="Args.cs" />
     <Compile Include="Browser.cs" />
     <Compile Include="DefaultBrowserChanger.cs" />

SetDefaultBrowser/SetDefaultBrowser.csproj

@@ -204,5 +204,53 @@ public struct PROCESS_INFORMATION
 
         [DllImport("shlwapi.dll", BestFitMapping = false, CharSet = CharSet.Unicode, ExactSpelling = true, SetLastError = false, ThrowOnUnmappableChar = true)]
         public static extern int SHLoadIndirectString(string pszSource, StringBuilder pszOutBuf, int cchOutBuf, IntPtr ppvReserved);
+
+        [DllImport("Shlwapi.dll", SetLastError = true, CharSet = CharSet.Auto)]
+        public static extern uint AssocQueryString(AssocF flags, AssocStr str, string pszAssoc, string pszExtra, [Out] StringBuilder pszOut, ref uint pcchOut);
+
+        [Flags]
+        public enum AssocF : uint
+        {
+            None = 0,
+            Init_NoRemapCLSID = 0x1,
+            Init_ByExeName = 0x2,
+            Open_ByExeName = 0x2,
+            Init_DefaultToStar = 0x4,
+            Init_DefaultToFolder = 0x8,
+            NoUserSettings = 0x10,
+            NoTruncate = 0x20,
+            Verify = 0x40,
+            RemapRunDll = 0x80,
+            NoFixUps = 0x100,
+            IgnoreBaseClass = 0x200,
+            Init_IgnoreUnknown = 0x400,
+            Init_FixedProgId = 0x800,
+            IsProtocol = 0x1000,
+            InitForFile = 0x2000,
+        }
+
+        public enum AssocStr
+        {
+            Command = 1,
+            Executable,
+            FriendlyDocName,
+            FriendlyAppName,
+            NoOpen,
+            ShellNewValue,
+            DDECommand,
+            DDEIfExec,
+            DDEApplication,
+            DDETopic,
+            InfoTip,
+            QuickTip,
+            TileInfo,
+            ContentType,
+            DefaultIcon,
+            ShellExtension,
+            DropTarget,
+            DelegateExecute,
+            SupportedUriProtocols,
+            Max,
+        }
     }
 }