Decouple PhysicalFileSystemProvider from WebRootFileProvider

Author: JimBobSquarePants

src/ImageSharp.Web/Providers/PhysicalFileSystemProvider.cs

@@ -2,11 +2,13 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+using System.IO;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Extensions;
 using Microsoft.Extensions.FileProviders;
+using Microsoft.Extensions.Options;
 using SixLabors.ImageSharp.Web.Resolvers;
 
 namespace SixLabors.ImageSharp.Web.Providers
@@ -29,9 +31,11 @@ public class PhysicalFileSystemProvider : IImageProvider
         /// <summary>
         /// Initializes a new instance of the <see cref="PhysicalFileSystemProvider"/> class.
         /// </summary>
+        /// <param name="options">The provider configuration options.</param>
         /// <param name="environment">The environment used by this middleware.</param>
         /// <param name="formatUtilities">Contains various format helper methods based on the current configuration.</param>
         public PhysicalFileSystemProvider(
+            IOptions<PhysicalFileSystemProviderOptions> options,
 #if NETCOREAPP2_1
             IHostingEnvironment environment,
 #else
@@ -40,9 +44,18 @@ public PhysicalFileSystemProvider(
             FormatUtilities formatUtilities)
         {
             Guard.NotNull(environment, nameof(environment));
-            Guard.NotNull(environment.WebRootFileProvider, nameof(environment.WebRootFileProvider));
 
-            this.fileProvider = environment.WebRootFileProvider;
+            // ContentRootPath is never null.
+            // https://github.com/dotnet/aspnetcore/blob/b89eba6c3cda331ee98063e3c4a04267ec540315/src/Hosting/Hosting/src/WebHostBuilder.cs#L262
+            Guard.NotNullOrWhiteSpace(environment.WebRootPath, nameof(environment.WebRootPath));
+
+            // Allow configuration of the provider without having to register everything
+            PhysicalFileSystemProviderOptions providerOptions = options != null ? options.Value : new();
+            string cacheRootPath = GetProviderRoot(providerOptions, environment.WebRootPath, environment.ContentRootPath);
+
+            // Ensure provider directory is created before initializing the file provider
+            Directory.CreateDirectory(cacheRootPath);
+            this.fileProvider = new PhysicalFileProvider(cacheRootPath);
             this.formatUtilities = formatUtilities;
         }
 
@@ -71,5 +84,23 @@ public Task<IImageResolver> GetAsync(HttpContext context)
             var metadata = new ImageMetadata(fileInfo.LastModified.UtcDateTime, fileInfo.Length);
             return Task.FromResult<IImageResolver>(new PhysicalFileSystemResolver(fileInfo, metadata));
         }
+
+        /// <summary>
+        /// Determine the provider root path
+        /// </summary>
+        /// <param name="providerOptions">The provider options.</param>
+        /// <param name="webRootPath">The web root path.</param>
+        /// <param name="contentRootPath">The content root path.</param>
+        /// <returns><see cref="string"/> representing the fully qualified provider root path.</returns>
+        internal static string GetProviderRoot(PhysicalFileSystemProviderOptions providerOptions, string webRootPath, string contentRootPath)
+        {
+            string providerRoot = string.IsNullOrWhiteSpace(providerOptions.ProviderRoot)
+                ? webRootPath
+                : providerOptions.ProviderRoot;
+
+            return Path.IsPathFullyQualified(providerRoot)
+                ? providerRoot
+                : Path.GetFullPath(providerRoot, contentRootPath);
+        }
     }
 }

src/ImageSharp.Web/Providers/PhysicalFileSystemProviderOptions.cs

@@ -0,0 +1,25 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+namespace SixLabors.ImageSharp.Web.Providers
+{
+    /// <summary>
+    /// Configuration options for the <see cref="PhysicalFileSystemProvider" />.
+    /// </summary>
+    public class PhysicalFileSystemProviderOptions
+    {
+        /// <summary>
+        /// Gets or sets the optional provider root folder.
+        /// <para>
+        /// This value can be <see langword="null"/>, a fully qualified absolute path,
+        /// or a path relative to the directory that contains the application
+        /// content files.
+        /// </para>
+        /// <para>
+        /// If not set, this will default to the directory that contains the web-servable
+        /// application content files; commonly 'wwwroot'.
+        /// </para>
+        /// </summary>
+        public string ProviderRoot { get; set; }
+    }
+}

tests/ImageSharp.Web.Tests/Providers/PhysicalFileSystemProviderTests.cs

@@ -0,0 +1,43 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.Web.Providers;
+using Xunit;
+
+namespace SixLabors.ImageSharp.Web.Tests.Providers
+{
+    public class PhysicalFileSystemProviderTests
+    {
+        [Theory]
+#if OS_LINUX
+        [InlineData(null, "wwwroot", "Users/root/", "Users/root/wwwroot")]
+        [InlineData(null, "Users/WebRoot", "Users/root/", "Users/WebRoot")]
+        [InlineData("providerFolder", "../Temp", "Users/this/a/root", "Users/this/a/root/providerFolder")]
+        [InlineData("../Temp", null, "Users/this/a/root", "Users/this/a/Temp")]
+        [InlineData("Users/WebRoot", null, "Users/this/a/root", "Users/WebRoot")]
+#elif OS_OSX
+        [InlineData(null, "wwwroot", "Users/root/", "Users/root/wwwroot")]
+        [InlineData(null, "Users/WebRoot", "Users/root/", "Users/WebRoot")]
+        [InlineData("providerFolder", "../Temp", "Users/this/a/root", "Users/this/a/root/providerFolder")]
+        [InlineData("../Temp", null, "Users/this/a/root", "Users/this/a/Temp")]
+        [InlineData("Users/WebRoot", null, "Users/this/a/root", "Users/WebRoot")]
+#elif OS_WINDOWS
+        [InlineData(null, "wwwroot", "C:/root\\", "C:\\root\\wwwroot")]
+        [InlineData(null, "C:/WebRoot", "C:/root\\", "C:/WebRoot")]
+        [InlineData("providerFolder", "../Temp", "C:/this/a/root", "C:\\this\\a\\root\\providerFolder")]
+        [InlineData("../Temp", null, "C:/this/a/root", "C:\\this\\a\\Temp")]
+        [InlineData("C:/WebRoot", null, "C:/this/a/root", "C:/WebRoot")]
+#endif
+        public void CacheRootFromOptions(string providerRoot, string webRootPath, string contentRootPath, string expected)
+        {
+            var providerOptions = new PhysicalFileSystemProviderOptions
+            {
+                ProviderRoot = providerRoot,
+            };
+
+            string providerRootResult = PhysicalFileSystemProvider.GetProviderRoot(providerOptions, webRootPath, contentRootPath);
+
+            Assert.Equal(expected, providerRootResult);
+        }
+    }
+}