addressing review comments

Author: Local Merge

sdk/storage/azure-storage-blob/src/main/java/com/azure/storage/blob/models/BlobDownloadHeaders.java

@@ -146,6 +146,10 @@ public List<ObjectReplicationPolicy> getObjectReplicationSourcePolicies() {
     /**
      * Get the contentLength property: The number of bytes present in the response body.
      *
+     * <p>When content validation is enabled, the storage client transparently decodes the structured message
+     * framing before returning the response. In that case this value reflects the size of the decoded payload
+     * that callers will actually read — not the larger wire size of the encoded message.</p>
+     *
      * @return the contentLength value.
      */
     public Long getContentLength() {

sdk/storage/azure-storage-common/src/main/java/com/azure/storage/common/policy/DecodedResponse.java

@@ -15,13 +15,13 @@
 import java.nio.charset.Charset;
 
 /**
- * {@link HttpResponse} wrapper that exposes a decoded body stream while preserving the request, status code, and
- * headers of the original response.
+ * {@link HttpResponse} wrapper that exposes a decoded body stream while preserving the request and status code of
+ * the original response.
  *
  * <p>The policy hands this class a Flux that already represents validated, framing-stripped bytes (produced by the
  * decoder pipeline). This class's only job is to make that Flux look like the body of the original
- * {@link HttpResponse}. Status code, headers, and request remain identical to the underlying response so callers
- * cannot distinguish a validated download from a normal one – the validation is transparent.</p>
+ * {@link HttpResponse}. {@code Content-Length} is overridden to the decoded payload size so it matches what callers
+ * will actually read; all other headers are forwarded verbatim. The validation is transparent to callers.</p>
  */
 class DecodedResponse extends HttpResponse {
     private final HttpResponse originalResponse;
@@ -77,7 +77,7 @@ public Mono<byte[]> getBodyAsByteArray() {
     @Override
     public Mono<String> getBodyAsString() {
         return getBodyAsByteArray()
-            .map(b -> CoreUtils.bomAwareToString(b, originalResponse.getHeaderValue(HttpHeaderName.CONTENT_TYPE)));
+            .map(b -> CoreUtils.bomAwareToString(b, adjustedHeaders.getValue(HttpHeaderName.CONTENT_TYPE)));
     }
 
     @Override

sdk/storage/azure-storage-common/src/main/java/com/azure/storage/common/policy/StorageContentValidationDecoderPolicy.java

@@ -70,14 +70,9 @@ public Mono<HttpResponse> process(HttpPipelineCallContext context, HttpPipelineN
                 return httpResponse;
             }
 
-            // Confirm the service actually honored our structured-body request before we hand the body to the decoder.
-            validateStructuredMessageHeaders(httpResponse);
-
-            Long decodedContentLength = getStructuredContentLength(httpResponse.getHeaders());
-            if (decodedContentLength == null) {
-                throw LOGGER.logExceptionAsError(new IllegalStateException(
-                    "x-ms-structured-content-length header is present but could not be parsed as a long."));
-            }
+            // Confirm the service honored our structured-body request and parse the decoded length in one step,
+            // failing fast with a consistent error if either header is absent or unparseable.
+            long decodedContentLength = validateAndGetDecodedContentLength(httpResponse);
 
             // Fresh decoder per response so retries each get a clean state machine.
             StructuredMessageDecoder decoder = new StructuredMessageDecoder(contentLength);
@@ -98,11 +93,14 @@ private boolean shouldApplyDecoding(HttpPipelineCallContext context) {
     }
 
     /**
-     * Verifies the response acknowledges the structured-body request: presence of the
-     * {@code x-ms-structured-body} header and the {@code x-ms-structured-content-length} 
-     * header. If either is missing, the service is sending us a normal body and we must not run the decoder over it.
+     * Verifies the response acknowledges the structured-body request ({@code x-ms-structured-body} present) and
+     * parses {@code x-ms-structured-content-length} in one step. Throws with a consistent error message if either
+     * header is absent or the length value is not parseable as a {@code long}, matching the fail-fast behaviour
+     * used for other validation failures.
+     *
+     * @return the decoded payload size declared by the service.
      */
-    private void validateStructuredMessageHeaders(HttpResponse httpResponse) {
+    private long validateAndGetDecodedContentLength(HttpResponse httpResponse) {
         String structuredBody
             = httpResponse.getHeaders().getValue(Constants.HeaderConstants.STRUCTURED_BODY_TYPE_HEADER_NAME);
         String structuredContentLength
@@ -111,6 +109,12 @@ private void validateStructuredMessageHeaders(HttpResponse httpResponse) {
             throw LOGGER.logExceptionAsError(
                 new IllegalStateException("Structured message was requested but the response did not acknowledge it."));
         }
+        try {
+            return Long.parseLong(structuredContentLength);
+        } catch (NumberFormatException e) {
+            throw LOGGER.logExceptionAsError(new IllegalStateException("x-ms-structured-content-length header value '"
+                + structuredContentLength + "' could not be parsed as a long.", e));
+        }
     }
 
     /**
@@ -129,22 +133,6 @@ private static Long getContentLength(HttpHeaders headers) {
         return null;
     }
 
-    /**
-     * Reads {@code x-ms-structured-content-length} as a {@code Long}, returning {@code null} if missing or
-     * unparseable.
-     */
-    private static Long getStructuredContentLength(HttpHeaders headers) {
-        String value = headers.getValue(Constants.HeaderConstants.STRUCTURED_CONTENT_LENGTH_HEADER_NAME);
-        if (value != null) {
-            try {
-                return Long.parseLong(value);
-            } catch (NumberFormatException e) {
-                // Malformed header; fall through to null.
-            }
-        }
-        return null;
-    }
-
     /**
      * @return true for a 2xx response to a GET request, the only response shape that carries a body we
      * can decode. 206 (Partial Content) on retried range downloads is included.

sdk/storage/azure-storage-common/src/test/java/com/azure/storage/common/policy/DecodedResponseTests.java

@@ -217,11 +217,10 @@ public void inheritedGetBodyAsBinaryDataReturnsDecodedBytes() {
     public void contentLengthIsOverriddenToDecodedSize() {
         long wireSize = 500L;
         long decodedSize = 300L;
-        HttpHeaders h = new HttpHeaders()
-            .set(HttpHeaderName.CONTENT_LENGTH, String.valueOf(wireSize))
+        HttpHeaders h = new HttpHeaders().set(HttpHeaderName.CONTENT_LENGTH, String.valueOf(wireSize))
             .set(CUSTOM_HEADER, "preserve-me");
-        DecodedResponse wrapper = new DecodedResponse(mockResponse(200, h, new byte[0]), fluxOf(new byte[0]),
-            decodedSize);
+        DecodedResponse wrapper
+            = new DecodedResponse(mockResponse(200, h, new byte[0]), fluxOf(new byte[0]), decodedSize);
 
         assertEquals(String.valueOf(decodedSize), wrapper.getHeaders().getValue(HttpHeaderName.CONTENT_LENGTH));
         assertEquals("preserve-me", wrapper.getHeaders().getValue(CUSTOM_HEADER));