Core - PathCheck rewrite to match Chromium FilePath::IsAbsolute

Resovles #3102

CefSharp.Test/Framework/PathCheckFacts.cs

@@ -21,14 +21,15 @@ public void IsPathAbsoluteValid()
             Assert.True(PathCheck.IsAbsolute(@"C:/foo1"));
             Assert.True(PathCheck.IsAbsolute(@"c:\"));
             Assert.True(PathCheck.IsAbsolute(@"C:/foo2"));
+            Assert.True(PathCheck.IsAbsolute(@"C:\Users\appveyor\AppData\Local\CefSharp\Tests\Cache"));
+
         }
 
         [Fact]
         public void IsPathAbsoluteInValid()
         {
             Assert.False(PathCheck.IsAbsolute(@"\"));
             Assert.False(PathCheck.IsAbsolute(@"/"));
-            Assert.False(PathCheck.IsAbsolute(@"C:foo.txt"));
             Assert.False(PathCheck.IsAbsolute(@"C:"));
             Assert.False(PathCheck.IsAbsolute(@"."));
             Assert.False(PathCheck.IsAbsolute(@".."));
@@ -39,10 +40,10 @@ public void IsPathAbsoluteInValid()
         [Fact]
         public void AssertPathAbsoluteInValid()
         {
-            Assert.Throws<Exception>(() => PathCheck.IsAbsolute(@"\"));
-            Assert.Throws<Exception>(() => PathCheck.IsAbsolute(@"c:foo"));
-            Assert.Throws<Exception>(() => PathCheck.IsAbsolute(@"cache"));
-            Assert.Throws<Exception>(() => PathCheck.IsAbsolute(@"locales\"));
+            Assert.Throws<Exception>(() => PathCheck.AssertAbsolute(@"\", "Path"));
+            Assert.Throws<Exception>(() => PathCheck.AssertAbsolute(@"c:foo", "Path"));
+            Assert.Throws<Exception>(() => PathCheck.AssertAbsolute(@"cache", "Path"));
+            Assert.Throws<Exception>(() => PathCheck.AssertAbsolute(@"locales\", "Path"));
         }
     }
 }

CefSharp/Internals/PathCheck.cs

@@ -2,8 +2,12 @@
 //
 // Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
 
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
 using System;
-using System.IO;
+using System.Runtime.CompilerServices;
 
 namespace CefSharp.Internals
 {
@@ -13,6 +17,9 @@ namespace CefSharp.Internals
     //TODO: Better name
     public static class PathCheck
     {
+        internal const char DirectorySeparatorChar = '\\';
+        internal const char AltDirectorySeparatorChar = '/';
+
         /// <summary>
         /// Allow user to disable the assert.
         /// As a temporary measure we'll allow users to disable the assert
@@ -21,6 +28,25 @@ public static class PathCheck
         [Obsolete("This will be removed after further testing.")]
         public static bool EnableAssert = true;
 
+        internal static int FindDriveLetter(string path)
+        {
+            if (path.Length >= 2 && path[1] == ':' &&
+                ((path[0] >= 'A' && path[0] <= 'Z') || (path[0] >= 'a' && path[0] <= 'z')))
+            {
+                return 1;
+            }
+            return -1;
+        }
+
+        /// <summary>
+        /// True if the given character is a directory separator.
+        /// </summary>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        internal static bool IsDirectorySeparator(char c)
+        {
+            return c == DirectorySeparatorChar || c == AltDirectorySeparatorChar;
+        }
+
         /// <summary>
         /// Throw exception if the path provided is non-asbolute
         /// CEF now explicitly requires absolute paths
@@ -36,36 +62,30 @@ public static void AssertAbsolute(string path, string settingName)
             if (!string.IsNullOrEmpty(path) && EnableAssert)
             {
                 //IsPathRooted will return true for paths that start with a single slash, e.g. \programfiles
-                if (IsAbsolute(path))
+                if (!IsAbsolute(path))
                 {
                     throw new Exception(settingName + " now requires an absolute path, the path provided is non-absolute. You can use System.IO.Path.GetFullPath to obtain an absolute path. Current value:" + path);
                 }
             }
         }
 
         /// <summary>
-        /// Throw exception if the path provided is non-asbolute
-        /// CEF now explicitly requires absolute paths
-        /// https://bitbucket.org/chromiumembedded/cef/issues/2916/not-persisting-in-local-stoage-when-using
-        /// Empty paths are ignored
+        /// Valid path is absolute, based on Chromium implementation.
         /// </summary>
         /// <param name="path">path</param>
         public static bool IsAbsolute(string path)
         {
-            const string directorySeperator = "\\";
-
-            //We don't have access to Path.IsPathFullyQualified as it's not in .Net 4.5.2 so we have to implement our own check
-            //If this isn't sufficent then we can import the code for .Net Core
-            //https://github.com/dotnet/runtime/blob/4f9ae42d861fcb4be2fcd5d3d55d5f227d30e723/src/libraries/System.Private.CoreLib/src/System/IO/Path.cs#L290
-
-            //IsPathRooted will return true for paths that start with a single slash, e.g. \programfiles
-            //Based on https://stackoverflow.com/a/35046453/4583726
-            if (!Path.IsPathRooted(path) || Path.GetPathRoot(path).Equals(directorySeperator, StringComparison.Ordinal))
+            //Based on Chromium FilePath::IsAbolsute
+            //https://source.chromium.org/chromium/chromium/src/+/master:base/files/file_path.cc;drc=1c097f5f790782b2ad0b897cd9e2921ce9713585;l=97?q=IsAbsolute&ss=chromium&originalUrl=https:%2F%2Fcs.chromium.org%2F
+            var pos = FindDriveLetter(path);
+            if (pos != -1)
             {
-                return false;
+                // Look for a separator right after the drive specification.
+                return path.Length > (pos + 1) && IsDirectorySeparator(path[pos + 1]);
             }
 
-            return true;
+            // Look for a pair of leading separators.
+            return path.Length > 1 && IsDirectorySeparator(path[0]) && IsDirectorySeparator(path[1]);
         }
     }
 }