refactor(transfer): extract checksum retrieval into ExtractChecksum helper function

Author: pulimsr

src/aws-cpp-sdk-transfer/include/aws/transfer/TransferManager.h

@@ -338,6 +338,22 @@ namespace Aws
              */
             void SetChecksumForAlgorithm(const std::shared_ptr<PartState>& state, Aws::S3::Model::CompletedPart& part);
 
+            /**
+             * Extracts checksum from S3 outcome result.
+             * @param outcome The S3 outcome containing the result with checksums.
+             * @return The checksum string, or empty string if no checksum is available.
+             */
+            template<typename OutcomeType>
+            Aws::String ExtractChecksum(const OutcomeType& outcome) {
+                const auto& result = outcome.GetResult();
+                if (!result.GetChecksumCRC32().empty()) return result.GetChecksumCRC32();
+                if (!result.GetChecksumCRC32C().empty()) return result.GetChecksumCRC32C();
+                if (!result.GetChecksumSHA256().empty()) return result.GetChecksumSHA256();
+                if (!result.GetChecksumSHA1().empty()) return result.GetChecksumSHA1();
+                if (!result.GetChecksumCRC64NVME().empty()) return result.GetChecksumCRC64NVME();
+                return {};
+            }
+
             /**
              * Combines part checksums to calculate full object checksum for validation.
              * @param handle The transfer handle containing completed parts with checksums.

src/aws-cpp-sdk-transfer/source/transfer/TransferManager.cpp

@@ -944,23 +944,9 @@ namespace Aws
                 // Validate full object checksum if available
                 bool checksumValid = true;
                 if (!handle->GetChecksum().empty()) {
-                    const auto& getResult = getObjectOutcome.GetResult();
-                    Aws::String actualChecksum;
+                    Aws::String actualChecksum = ExtractChecksum(getObjectOutcome);
 
-                    // Get the actual checksum from GetObject response
-                    if (!getResult.GetChecksumCRC32().empty()) {
-                        actualChecksum = getResult.GetChecksumCRC32();
-                    } else if (!getResult.GetChecksumCRC32C().empty()) {
-                        actualChecksum = getResult.GetChecksumCRC32C();
-                    } else if (!getResult.GetChecksumSHA256().empty()) {
-                        actualChecksum = getResult.GetChecksumSHA256();
-                    } else if (!getResult.GetChecksumSHA1().empty()) {
-                        actualChecksum = getResult.GetChecksumSHA1();
-                    } else if (!getResult.GetChecksumCRC64NVME().empty()) {
-                        actualChecksum = getResult.GetChecksumCRC64NVME();
-                    }
-                    
-                    if (!actualChecksum.empty() && actualChecksum != handle->GetChecksum()) {
+                    if (actualChecksum != handle->GetChecksum()) {
                         checksumValid = false;
                         Aws::Client::AWSError<Aws::S3::S3Errors> checksumError(
                             Aws::S3::S3Errors::INTERNAL_FAILURE,
@@ -1069,17 +1055,9 @@ namespace Aws
                 handle->SetEtag(headObjectOutcome.GetResult().GetETag());
 
                 // Store full object checksum from HeadObject for validation
-                const auto& headResult = headObjectOutcome.GetResult();
-                if (!headResult.GetChecksumCRC32().empty()) {
-                    handle->SetChecksum(headResult.GetChecksumCRC32());
-                } else if (!headResult.GetChecksumCRC32C().empty()) {
-                    handle->SetChecksum(headResult.GetChecksumCRC32C());
-                } else if (!headResult.GetChecksumSHA256().empty()) {
-                    handle->SetChecksum(headResult.GetChecksumSHA256());
-                } else if (!headResult.GetChecksumSHA1().empty()) {
-                    handle->SetChecksum(headResult.GetChecksumSHA1());
-                } else if (!headResult.GetChecksumCRC64NVME().empty()) {
-                    handle->SetChecksum(headResult.GetChecksumCRC64NVME());
+                Aws::String checksum = ExtractChecksum(headObjectOutcome);
+                if (!checksum.empty()) {
+                    handle->SetChecksum(checksum);
                 }
 
                 /* When bucket versioning is suspended, head object will return "null" for unversioned object.
@@ -1287,17 +1265,9 @@ namespace Aws
                     Aws::String errMsg{handle->WritePartToDownloadStream(bufferStream, partState->GetRangeBegin())};
                     if (errMsg.empty()) {
                         // Store part checksum for later validation
-                        const auto& getResult = outcome.GetResult();
-                        if (!getResult.GetChecksumCRC32().empty()) {
-                            partState->SetChecksum(getResult.GetChecksumCRC32());
-                        } else if (!getResult.GetChecksumCRC32C().empty()) {
-                            partState->SetChecksum(getResult.GetChecksumCRC32C());
-                        } else if (!getResult.GetChecksumSHA256().empty()) {
-                            partState->SetChecksum(getResult.GetChecksumSHA256());
-                        } else if (!getResult.GetChecksumSHA1().empty()) {
-                            partState->SetChecksum(getResult.GetChecksumSHA1());
-                        } else if (!getResult.GetChecksumCRC64NVME().empty()) {
-                            partState->SetChecksum(getResult.GetChecksumCRC64NVME());
+                        Aws::String checksum = ExtractChecksum(outcome);
+                        if (!checksum.empty()) {
+                            partState->SetChecksum(checksum);
                         }
 
                         handle->ChangePartToCompleted(partState, outcome.GetResult().GetETag());