Align provider root path resolving with ASP.NET Core

Author: ronaldbarendse

src/ImageSharp.Web/Caching/PhysicalFileSystemCache.cs

@@ -94,7 +94,10 @@ public async Task SetAsync(string key, Stream stream, ImageCacheMetadata metadat
             string directory = Path.GetDirectoryName(path);
 
             // Ensure cache directory is created before creating files
-            Directory.CreateDirectory(directory);
+            if (!Directory.Exists(directory))
+            {
+                Directory.CreateDirectory(directory);
+            }
 
             using (FileStream fileStream = File.Create(imagePath))
             {

src/ImageSharp.Web/Providers/PhysicalFileSystemProvider.cs

@@ -47,6 +47,12 @@ public PhysicalFileSystemProvider(
 
             this.providerRootPath = GetProviderRoot(options.Value, environment.WebRootPath, environment.ContentRootPath);
             this.formatUtilities = formatUtilities;
+
+            // Disable provider by default when no root path is configured or webroot doesn't exist
+            if (this.providerRootPath == null)
+            {
+                this.Match = _ => false;
+            }
         }
 
         /// <inheritdoc/>
@@ -87,12 +93,32 @@ public Task<IImageResolver> GetAsync(HttpContext context)
         /// <returns><see cref="string"/> representing the fully qualified provider root path.</returns>
         internal static string GetProviderRoot(PhysicalFileSystemProviderOptions providerOptions, string webRootPath, string contentRootPath)
         {
-            string providerRoot = providerOptions.ProviderRootPath ?? webRootPath ?? "wwwroot";
-            string fullPath = Path.IsPathFullyQualified(providerRoot)
-                ? providerRoot
-                : Path.GetFullPath(providerRoot, contentRootPath);
+            string providerRootPath = providerOptions.ProviderRootPath ?? webRootPath;
+            if (providerRootPath == null)
+            {
+                // Default to /wwwroot if it exists
+                string wwwroot = Path.Combine(contentRootPath, "wwwroot");
+                if (Directory.Exists(wwwroot))
+                {
+                    providerRootPath = wwwroot;
+                }
+            }
+
+            if (!string.IsNullOrEmpty(providerRootPath))
+            {
+                string fullPath = Path.IsPathFullyQualified(providerRootPath)
+                    ? providerRootPath
+                    : Path.GetFullPath(providerRootPath, contentRootPath);
+
+                if (!Directory.Exists(fullPath))
+                {
+                    Directory.CreateDirectory(fullPath);
+                }
+
+                return EnsureTrailingSlash(fullPath);
+            }
 
-            return EnsureTrailingSlash(fullPath);
+            return null;
         }
 
         internal static string EnsureTrailingSlash(string path)