Implement atomic conditional puts for azureblob-sdk

.gitignore

@@ -20,3 +20,8 @@ s3proxy.iml
 # virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
 hs_err_pid*
 target/
+
+# files created during tests
+__blobstorage__/
+AzuriteConfig
+__azurite_db*

README.md

@@ -140,7 +140,7 @@ S3Proxy has broad compatibility with the S3 API, however, it does not support:
 
 S3Proxy emulates the following operations:
 
-* conditional PUT object when using If-Match or If-None-Match
+* conditional PUT object when using If-Match or If-None-Match, unless the `azureblob-sdk` provider is used
 * copy multi-part objects, see [#76](https://github.com/gaul/s3proxy/issues/76)
 
 S3Proxy has basic CORS preflight and actual request/response handling. It can be configured within the properties

src/main/java/org/gaul/s3proxy/PutOptions2.java

@@ -0,0 +1,109 @@
+/*
+ * Copyright 2014-2025 Andrew Gaul <andrew@gaul.org>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.gaul.s3proxy;
+
+import javax.annotation.Nullable;
+
+import com.google.common.util.concurrent.ListeningExecutorService;
+
+import org.jclouds.blobstore.domain.BlobAccess;
+import org.jclouds.blobstore.options.PutOptions;
+
+/**
+ * This class extends jclouds' PutOptions to support conditional put operations via
+ * the If-Match and If-None-Match headers.
+ */
+public final class PutOptions2 extends PutOptions {
+    @Nullable
+    private String ifMatch;
+    @Nullable
+    private String ifNoneMatch;
+
+    public PutOptions2() {
+        super();
+    }
+
+    public PutOptions2(PutOptions options) {
+        super(options.isMultipart(), options.getUseCustomExecutor(),
+                options.getCustomExecutor());
+        this.setBlobAccess(options.getBlobAccess());
+
+        if (options instanceof PutOptions2) {
+            PutOptions2 other = (PutOptions2) options;
+            this.ifMatch = other.ifMatch;
+            this.ifNoneMatch = other.ifNoneMatch;
+        }
+    }
+
+    @Nullable
+    public String getIfMatch() {
+        return ifMatch;
+    }
+
+    public PutOptions2 setIfMatch(@Nullable String etag) {
+        this.ifMatch = etag;
+        return this;
+    }
+
+    @Nullable
+    public String getIfNoneMatch() {
+        return ifNoneMatch;
+    }
+
+    public PutOptions2 setIfNoneMatch(@Nullable String etag) {
+        this.ifNoneMatch = etag;
+        return this;
+    }
+
+    @Override
+    public PutOptions2 setBlobAccess(BlobAccess blobAccess) {
+        super.setBlobAccess(blobAccess);
+        return this;
+    }
+
+    @Override
+    public PutOptions2 multipart() {
+        super.multipart();
+        return this;
+    }
+
+    @Override
+    public PutOptions2 multipart(boolean val) {
+        super.multipart(val);
+        return this;
+    }
+
+    @Override
+    public PutOptions2 multipart(ListeningExecutorService customExecutor) {
+        super.multipart(customExecutor);
+        return this;
+    }
+
+    @Override
+    public PutOptions2 setCustomExecutor(ListeningExecutorService customExecutor) {
+        super.setCustomExecutor(customExecutor);
+        return this;
+    }
+
+    @Override
+    public String toString() {
+        String s = super.toString();
+        return s.substring(0, s.length() - 1) +
+                ", ifMatch=" + ifMatch +
+                ", ifNoneMatch=" + ifNoneMatch + "]";
+    }
+}

src/main/java/org/gaul/s3proxy/S3ProxyHandler.java

@@ -1994,15 +1994,26 @@ private void handlePutBlob(HttpServletRequest request,
             throw new S3Exception(S3ErrorCode.ENTITY_TOO_LARGE);
         }
 
-        // Handle If-Match and If-None-Match headers for PUT operations.
-        // Unlike GET operations which use GetOptions to pass these conditions
-        // to jclouds, PUT operations lack a PutOptions equivalent in jclouds.
-        // Therefore, we manually fetch the blob metadata and validate ETags.
-        // TODO: this is an emulated operation and therefore not atomic.
         String ifMatch = request.getHeader(HttpHeaders.IF_MATCH);
         String ifNoneMatch = request.getHeader(HttpHeaders.IF_NONE_MATCH);
+        String blobStoreType = getBlobStoreType(blobStore);
+
+        // Azure only supports If-None-Match: *, not If-Match: *
+        // Handle If-Match: * manually for the azureblob-sdk provider.
+        // Note: this is a non-atomic operation (HEAD then PUT).
+        if (ifMatch != null && ifMatch.equals("*") &&
+                blobStoreType.equals("azureblob-sdk")) {
+            BlobMetadata metadata = blobStore.blobMetadata(containerName, blobName);
+            if (metadata == null) {
+                throw new S3Exception(S3ErrorCode.PRECONDITION_FAILED);
+            }
+            ifMatch = null;
+        }
 
-        if (ifMatch != null || ifNoneMatch != null) {
+        // Emulate conditional put for backends without native support.
+        // Note: this is a non-atomic operation (HEAD then PUT).
+        if ((ifMatch != null || ifNoneMatch != null) &&
+                !blobStoreType.equals("azureblob-sdk")) {
             BlobMetadata metadata = blobStore.blobMetadata(containerName, blobName);
             if (ifMatch != null) {
                 if (ifMatch.equals("*")) {
@@ -2055,9 +2066,10 @@ private void handlePutBlob(HttpServletRequest request,
             return;
         }
 
-        var options = new PutOptions().setBlobAccess(access);
-
-        String blobStoreType = getBlobStoreType(blobStore);
+        var options = new PutOptions2()
+                .setBlobAccess(access)
+                .setIfMatch(ifMatch)
+                .setIfNoneMatch(ifNoneMatch);
         if (blobStoreType.equals("azureblob") &&
                 contentLength > 256 * 1024 * 1024) {
             options.multipart(true);

src/main/java/org/gaul/s3proxy/azureblob/AzureBlobStore.java

@@ -66,6 +66,7 @@
 import jakarta.inject.Singleton;
 import jakarta.ws.rs.core.Response.Status;
 
+import org.gaul.s3proxy.PutOptions2;
 import org.jclouds.blobstore.BlobStoreContext;
 import org.jclouds.blobstore.ContainerNotFoundException;
 import org.jclouds.blobstore.KeyNotFoundException;
@@ -395,6 +396,17 @@ public String putBlob(String container, Blob blob, PutOptions options) {
                         blob.getMetadata().getTier()));
             }
 
+            if (options instanceof PutOptions2) {
+                var putOptions2 = (PutOptions2) options;
+                String ifMatch = putOptions2.getIfMatch();
+                String ifNoneMatch = putOptions2.getIfNoneMatch();
+                if (ifMatch != null || ifNoneMatch != null) {
+                    azureOptions.setRequestConditions(new BlobRequestConditions()
+                            .setIfMatch(ifMatch)
+                            .setIfNoneMatch(ifNoneMatch));
+                }
+            }
+
             try (var os = client.getBlobOutputStream(
                     azureOptions, /*context=*/ null)) {
                 is.transferTo(os);
@@ -749,6 +761,16 @@ private void translateAndRethrowException(BlobStorageException bse,
                     .build();
             throw new HttpResponseException(
                     new HttpCommand(request), response, bse);
+        } else if (code.equals(BlobErrorCode.BLOB_ALREADY_EXISTS)) {
+            var request = HttpRequest.builder()
+                    .method("PUT")
+                    .endpoint(endpoint)
+                    .build();
+            var response = HttpResponse.builder()
+                    .statusCode(Status.PRECONDITION_FAILED.getStatusCode())
+                    .build();
+            throw new HttpResponseException(
+                    new HttpCommand(request), response, bse);
         } else if (code.equals(BlobErrorCode.INVALID_OPERATION)) {
             var request = HttpRequest.builder()
                     .method("GET")