C++ azure-storage 库，stream_buf can_read 返回 false

如何解决C++ azure-storage 库，stream_buf can_read 返回 false

问题如上，下面附上代码：

=IF(ISERROR(INDEX(LInesT(Infilt,sqrtTime^{1,2},FALSE),1,1)),"---",INDEX(LInesT(Infilt,1))

被星号包围的部分打印

cloud_storage_account storage_account = cloud_storage_account::parse(CONNECTION_STRING);
cloud_blob_client blob_client = storage_account.create_cloud_blob_client();  
cloud_blob_container container = blob_client.get_container_reference(U(CONTAINER));
std::string blob_name = key_string + ".jpg";
cloud_block_blob block_blob = container.get_block_blob_reference(U(blob_name));
std::unique_ptr<ImageFrame> frame = std::make_unique<ImageFrame>(vcss_value->get_key_ref(),vcss_value->blob);

****
concurrency::streams::rawptr_buffer<uint8_t> buffer(reinterpret_cast<unsigned char*>(frame->bytes),frame->size);
std::cout << "frame size: " << std::to_string(frame->size) << std::endl;
std::cout << "buffer can read: " << buffer.can_read() << std::endl;
****

concurrency::streams::istream inputStream(buffer);
block_blob.upload_from_stream(inputStream);
inputStream.close().wait();
buffer.close().wait();

这里 ImageFrame 扩展自 Blob，它包含一个名为 bytes 的 char * 字段。它在转换为 concurrency::streams::istream 时也会抛出 std::runtime_error。我想知道缓冲区无法读取的问题是什么？谢谢！