Updated the KeyExists from aws keep the response metadata in the image resolver.

Author: mdupras

src/ImageSharp.Web.Providers.AWS/Providers/AWSS3StorageImageProvider.cs

@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using Amazon.S3;
 using Amazon.S3.Model;
@@ -29,7 +28,7 @@ private readonly Dictionary<string, AmazonS3Client> buckets
         = new();
 
     private readonly AWSS3StorageImageProviderOptions storageOptions;
-    private Func<HttpContext, bool> match;
+    private Func<HttpContext, bool>? match;
 
     /// <summary>
     /// Contains various helper methods based on the current configuration.
@@ -70,17 +69,23 @@ public bool IsValidRequest(HttpContext context)
         => this.formatUtilities.TryGetExtensionFromUri(context.Request.GetDisplayUrl(), out _);
 
     /// <inheritdoc />
-    public async Task<IImageResolver> GetAsync(HttpContext context)
+    public async Task<IImageResolver?> GetAsync(HttpContext context)
     {
         // Strip the leading slash and bucket name from the HTTP request path and treat
         // the remaining path string as the key.
         // Path has already been correctly parsed before here.
         string bucketName = string.Empty;
-        IAmazonS3 s3Client = null;
+        IAmazonS3? s3Client = null;
 
         // We want an exact match here to ensure that bucket names starting with
         // the same prefix are not mixed up.
-        string path = context.Request.Path.Value.TrimStart(SlashChars);
+        string? path = context.Request.Path.Value?.TrimStart(SlashChars);
+
+        if (path is null)
+        {
+            return null;
+        }
+
         int index = path.IndexOfAny(SlashChars);
         string nameToMatch = index != -1 ? path.Substring(0, index) : path;
 
@@ -108,19 +113,26 @@ public async Task<IImageResolver> GetAsync(HttpContext context)
             return null;
         }
 
-        if (!await KeyExists(s3Client, bucketName, key))
+        KeyExistsResult keyExists = await KeyExists(s3Client, bucketName, key);
+        if (!keyExists.Exists)
         {
             return null;
         }
 
-        return new AWSS3StorageImageResolver(s3Client, bucketName, key);
+        return new AWSS3StorageImageResolver(s3Client, bucketName, key, keyExists.Metadata);
     }
 
     private bool IsMatch(HttpContext context)
     {
         // Only match loosly here for performance.
         // Path matching conflicts should be dealt with by configuration.
-        string path = context.Request.Path.Value.TrimStart(SlashChars);
+        string? path = context.Request.Path.Value?.TrimStart(SlashChars);
+
+        if (path is null)
+        {
+            return false;
+        }
+
         foreach (string bucket in this.buckets.Keys)
         {
             if (path.StartsWith(bucket, StringComparison.OrdinalIgnoreCase))
@@ -133,39 +145,40 @@ private bool IsMatch(HttpContext context)
     }
 
     // ref https://github.com/aws/aws-sdk-net/blob/master/sdk/src/Services/S3/Custom/_bcl/IO/S3FileInfo.cs#L118
-    private static async Task<bool> KeyExists(IAmazonS3 s3Client, string bucketName, string key)
+    private static async Task<KeyExistsResult> KeyExists(IAmazonS3 s3Client, string bucketName, string key)
     {
         try
         {
-            GetObjectMetadataRequest request = new()
-            {
-                BucketName = bucketName,
-                Key = key
-            };
+            GetObjectMetadataRequest request = new() { BucketName = bucketName, Key = key };
 
             // If the object doesn't exist then a "NotFound" will be thrown
-            await s3Client.GetObjectMetadataAsync(request);
-            return true;
+            GetObjectMetadataResponse metadata = await s3Client.GetObjectMetadataAsync(request);
+            return new KeyExistsResult(metadata);
         }
         catch (AmazonS3Exception e)
         {
             if (string.Equals(e.ErrorCode, "NoSuchBucket", StringComparison.Ordinal))
             {
-                return false;
+                return default;
             }
 
             if (string.Equals(e.ErrorCode, "NotFound", StringComparison.Ordinal))
             {
-                return false;
+                return default;
             }
 
             // If the object exists but the client is not authorized to access it, then a "Forbidden" will be thrown.
             if (string.Equals(e.ErrorCode, "Forbidden", StringComparison.Ordinal))
             {
-                return false;
+                return default;
             }
 
             throw;
         }
     }
+
+    private readonly record struct KeyExistsResult(GetObjectMetadataResponse? Metadata)
+    {
+        public bool Exists => this.Metadata is not null;
+    }
 }

src/ImageSharp.Web.Providers.AWS/Resolvers/AWSS3StorageImageResolver.cs

@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Net.Http.Headers;
 using Amazon.S3;
@@ -16,29 +15,32 @@ public class AWSS3StorageImageResolver : IImageResolver
     private readonly IAmazonS3 amazonS3;
     private readonly string bucketName;
     private readonly string imagePath;
+    private readonly GetObjectMetadataResponse? metadataResponse;
 
     /// <summary>
     /// Initializes a new instance of the <see cref="AWSS3StorageImageResolver"/> class.
     /// </summary>
     /// <param name="amazonS3">The Amazon S3 Client</param>
     /// <param name="bucketName">The bucket name.</param>
     /// <param name="imagePath">The image path.</param>
-    public AWSS3StorageImageResolver(IAmazonS3 amazonS3, string bucketName, string imagePath)
+    /// <param name="metadataResponse">Optional metadata response.</param>
+    public AWSS3StorageImageResolver(IAmazonS3 amazonS3, string bucketName, string imagePath, GetObjectMetadataResponse? metadataResponse = null)
     {
         this.amazonS3 = amazonS3;
         this.bucketName = bucketName;
         this.imagePath = imagePath;
+        this.metadataResponse = metadataResponse;
     }
 
     /// <inheritdoc />
     public async Task<ImageMetadata> GetMetaDataAsync()
     {
-        GetObjectMetadataResponse metadata = await this.amazonS3.GetObjectMetadataAsync(this.bucketName, this.imagePath);
+        GetObjectMetadataResponse metadata = this.metadataResponse ?? await this.amazonS3.GetObjectMetadataAsync(this.bucketName, this.imagePath);
 
         // Try to parse the max age from the source. If it's not zero then we pass it along
         // to set the cache control headers for the response.
         TimeSpan maxAge = TimeSpan.MinValue;
-        if (CacheControlHeaderValue.TryParse(metadata.Headers.CacheControl, out CacheControlHeaderValue cacheControl))
+        if (CacheControlHeaderValue.TryParse(metadata.Headers.CacheControl, out CacheControlHeaderValue? cacheControl))
         {
             // Weirdly passing null to TryParse returns true.
             if (cacheControl?.MaxAge.HasValue == true)