Tolerate missing x-ms-blob-type response header

[clee704]

Fixes #7180.

Description

BlobClient::GetProperties() and BlobClient::Download() throw std::out_of_range when a successful (2xx) response omits the x-ms-blob-type header, because it is generated as a required header (an unguarded GetHeaders().at("x-ms-blob-type")). The SDK then crashes — with a non-StorageException — on an otherwise-valid 200, e.g. from the OneLake / ADLS Gen2 *.dfs. endpoint serving the Blob API, which returns 200 without that header.

This marks x-ms-blob-type optional on the Blob_GetProperties and Blob_Download responses so the generator guards it with the existing count(...) != 0 idiom — the same treatment ETag / Last-Modified already receive on those responses — and applies the matching guard in the generated rest_client.cpp. When the header is absent, BlobType defaults to an empty Models::BlobType and the read otherwise succeeds.

Mirrors the "striped blob" compatibility fix for x-ms-blob-sequence-number (PR #3932, commit 0e00a3a): same class of problem, same mechanism (an x-nullable directive plus the matching generated-file guard, committed together).

rest_client.cpp is AutoRest-generated and the C++ emitter is not publicly runnable, so the generated-file edit here is by hand to match the directive (as #3932 did). Please regenerate to confirm the directive reproduces this output.

Pull Request Checklist

• C++ Guidelines
• Doxygen docs — N/A (no public API surface change)
• Unit tests — not added, mirroring Compatibility improvement for striped blob #3932 (which changed only these two files). A mock-transport test (per storage_retry_policy_test.cpp) asserting GetProperties/Download tolerate a 200 without x-ms-blob-type can be added if preferred.
• No unwanted commits/changes
• Descriptive title/description
  • PR is single purpose
  • Related issue listed
• Comments in source — N/A (generated file)
• No typos
• Update changelog
• Not work-in-progress
• External references or docs updated — N/A
• Self review of PR done
• Any breaking changes? — No

[github-actions]

Thank you for your contribution @clee704! We will review the pull request and get back to you soon.

[Copilot]

Pull request overview

This PR fixes a crash in azure-storage-blobs when the service returns a successful response (200/206) that omits the x-ms-blob-type header. It makes the header optional in the Swagger customization and updates the generated protocol-layer response parsing to guard header access, preventing a std::out_of_range from std::map::at.

Changes:

• Updated the Swagger AutoRest directives to mark x-ms-blob-type as x-nullable (and set a default) for Blob_GetProperties and Blob_Download responses.
• Updated rest_client.cpp deserialization to read x-ms-blob-type only when present (consistent with existing optional-header handling).
• Added a changelog entry describing the bug fix.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
sdk/storage/azure-storage-blobs/swagger/README.md	Adds an AutoRest directive to mark x-ms-blob-type optional for the affected operations so generation guards header access.
sdk/storage/azure-storage-blobs/src/rest_client.cpp	Guards x-ms-blob-type header reads in the Download and GetProperties response parsers to avoid std::out_of_range.
sdk/storage/azure-storage-blobs/CHANGELOG.md	Documents the crash fix in the Unreleased “Bugs Fixed” section.

[Jinming-Hu]

I'm sorry, but we cannot modify generated code like this. I'll look into the issue later today.

[Jinming-Hu]

@clee704 Could you please update your PR with the patch below and leave this change out of the CHANGELOG? We don't officially support using this SDK with OneLake, and I don't want to send the wrong signal or create confusion by implying that we do.

diff --git a/sdk/storage/azure-storage-blobs/src/rest_client.cpp b/sdk/storage/azure-storage-blobs/src/rest_client.cpp
index 27a65870b..ab0a62b47 100644
--- a/sdk/storage/azure-storage-blobs/src/rest_client.cpp
+++ b/sdk/storage/azure-storage-blobs/src/rest_client.cpp
@@ -3814,7 +3814,10 @@ namespace Azure { namespace Storage { namespace Blobs {
         response.Details.SequenceNumber
             = std::stoll(pRawResponse->GetHeaders().at("x-ms-blob-sequence-number"));
       }
-      response.BlobType = Models::BlobType(pRawResponse->GetHeaders().at("x-ms-blob-type"));
+      if (pRawResponse->GetHeaders().count("x-ms-blob-type") != 0)
+      {
+        response.BlobType = Models::BlobType(pRawResponse->GetHeaders().at("x-ms-blob-type"));
+      }
       if (pRawResponse->GetHeaders().count("x-ms-copy-completion-time") != 0)
       {
         response.Details.CopyCompletedOn = DateTime::Parse(
@@ -4060,7 +4063,10 @@ namespace Azure { namespace Storage { namespace Blobs {
         response.ObjectReplicationDestinationPolicyId
             = pRawResponse->GetHeaders().at("x-ms-or-policy-id");
       }
-      response.BlobType = Models::BlobType(pRawResponse->GetHeaders().at("x-ms-blob-type"));
+      if (pRawResponse->GetHeaders().count("x-ms-blob-type") != 0)
+      {
+        response.BlobType = Models::BlobType(pRawResponse->GetHeaders().at("x-ms-blob-type"));
+      }
       if (pRawResponse->GetHeaders().count("x-ms-copy-completion-time") != 0)
       {
         response.CopyCompletedOn = DateTime::Parse(
diff --git a/sdk/storage/azure-storage-blobs/swagger/README.md b/sdk/storage/azure-storage-blobs/swagger/README.md
index 9370cb051..4a55faaf9 100644
--- a/sdk/storage/azure-storage-blobs/swagger/README.md
+++ b/sdk/storage/azure-storage-blobs/swagger/README.md
@@ -1044,6 +1044,8 @@ directive:
         $[status_code].headers["x-ms-legal-hold"]["x-nullable"] = true;
         $[status_code].headers["x-ms-immutability-policy-until-date"]["x-ms-client-path"] = "Details.ImmutabilityPolicy.ExpiresOn";
         $[status_code].headers["x-ms-immutability-policy-mode"]["x-ms-client-path"] = "Details.ImmutabilityPolicy.PolicyMode";
+        $[status_code].headers["x-ms-blob-type"]["x-nullable"] = true;
+        $[status_code].headers["x-ms-blob-type"]["x-ms-client-default"] = "";
         delete $[status_code].headers["Accept-Ranges"];
         delete $[status_code].headers["Content-Length"];
         delete $[status_code].headers["Content-Range"];
@@ -1150,6 +1152,8 @@ directive:
       $["x-ms-legal-hold"]["x-ms-client-name"] = "HasLegalHold";
       $["x-ms-legal-hold"]["x-ms-client-default"] = false;
       $["x-ms-legal-hold"]["x-nullable"] = true;
+      $["x-ms-blob-type"]["x-nullable"] = true;
+      $["x-ms-blob-type"]["x-ms-client-default"] = "";
       delete $["Accept-Ranges"];
       delete $["x-ms-or"];

[clee704]

Thanks @Jinming-Hu — done. I've updated the PR with your patch (folded the x-nullable / x-ms-client-default into the existing Blob_GetProperties and Blob_Download response directives) and dropped the CHANGELOG entry. The PR now touches only rest_client.cpp and swagger/README.md, matching your diff. Appreciate you taking a look at the underlying issue.