2 files changed, 45 insertions, 2 deletions
diff --git a/src/buildtool/execution_api/remote/bazel/bazel_network.cpp b/src/buildtool/execution_api/remote/bazel/bazel_network.cpp
index a5574c77..bdb4f3be 100644
--- a/src/buildtool/execution_api/remote/bazel/bazel_network.cpp
+++ b/src/buildtool/execution_api/remote/bazel/bazel_network.cpp
@@ -191,8 +191,11 @@ auto BazelNetwork::BlobReader::Next() noexcept -> std::vector<BazelBlob> {
     std::vector<BazelBlob> blobs{};
 
     while (current_ != ids_.end()) {
-        size += gsl::narrow<std::size_t>(current_->size_bytes());
-        if (size > kMaxBatchTransferSize) {
+        auto blob_size = gsl::narrow<std::size_t>(current_->size_bytes());
+        size += blob_size;
+        // read if size is 0 (unknown) or exceeds transfer size
+        if (blob_size == 0 or size > kMaxBatchTransferSize) {
+            // perform read of range [begin_, current_)
             if (begin_ == current_) {
                 auto blob = cas_->ReadSingleBlob(instance_name_, *begin_);
                 if (blob) {
diff --git a/test/buildtool/execution_api/bazel/bazel_network.test.cpp b/test/buildtool/execution_api/bazel/bazel_network.test.cpp
index b67013a0..28bfcdc2 100644
--- a/test/buildtool/execution_api/bazel/bazel_network.test.cpp
+++ b/test/buildtool/execution_api/bazel/bazel_network.test.cpp
@@ -43,3 +43,43 @@ TEST_CASE("Bazel network: write/read blobs", "[execution_api]") {
     CHECK(blobs[3].data == content_bar);
     CHECK(blobs[4].data == content_foo);
 }
+
+TEST_CASE("Bazel network: read blobs with unknown size", "[execution_api]") {
+    if (Compatibility::IsCompatible()) {
+        // only supported in native mode
+        return;
+    }
+
+    auto const& info = RemoteExecutionConfig::RemoteAddress();
+    std::string instance_name{"remote-execution"};
+    auto network = BazelNetwork{instance_name, info->host, info->port, {}};
+
+    std::string content_foo("foo");
+    std::string content_bar(kLargeSize, 'x');  // single larger blob
+
+    BazelBlob foo{ArtifactDigest::Create(content_foo), content_foo};
+    BazelBlob bar{ArtifactDigest::Create(content_bar), content_bar};
+
+    // Upload blobs
+    REQUIRE(network.UploadBlobs(BlobContainer{{foo, bar}}));
+
+    // Set size to unknown
+    foo.digest.set_size_bytes(0);
+    bar.digest.set_size_bytes(0);
+
+    // Read blobs
+    auto reader = network.ReadBlobs({foo.digest, bar.digest});
+    std::vector<BazelBlob> blobs{};
+    while (true) {
+        auto next = reader.Next();
+        if (next.empty()) {
+            break;
+        }
+        blobs.insert(blobs.end(), next.begin(), next.end());
+    }
+
+    // Check order maintained
+    REQUIRE(blobs.size() == 2);
+    CHECK(blobs[0].data == content_foo);
+    CHECK(blobs[1].data == content_bar);
+}