Add wrappers around readsome and peek methods in std istream

include/aws/crt/io/Stream.h

@@ -114,6 +114,19 @@ namespace Aws
                  */
                 virtual bool ReadImpl(ByteBuf &buffer) noexcept = 0;
 
+                /***
+                 * Read up-to buffer::capacity - buffer::len immediately available bytes into buffer::buffer
+                 * Increment buffer::len by the amount you read in.
+                 *
+                 * @return true if nothing went wrong.
+                 * Return true even if you read 0 bytes because the end-of-file has been reached.
+                 * Return true even if you read 0 bytes because data is not currently available.
+                 *
+                 * Return false if an actual failure condition occurs,
+                 * you SHOULD also raise an error via aws_raise_error().
+                 */
+                virtual bool ReadSomeImpl(ByteBuf &buffer) noexcept = 0;
+
                 /**
                  * @return the current status of the stream.
                  */
@@ -136,6 +149,15 @@ namespace Aws
                  */
                 virtual bool SeekImpl(int64_t offset, StreamSeekBasis seekBasis) noexcept = 0;
 
+                /**
+                 * Peeks the stream
+                 *
+                 * Essentially calls peek on the underlying istream
+                 *
+                 * @return return value of the underlying istream::peek
+                 */
+                virtual int64_t PeekImpl() const noexcept = 0;
+
               private:
                 static int s_Seek(aws_input_stream *stream, int64_t offset, enum aws_stream_seek_basis basis);
                 static int s_Read(aws_input_stream *stream, aws_byte_buf *dest);
@@ -161,9 +183,11 @@ namespace Aws
 
               protected:
                 bool ReadImpl(ByteBuf &buffer) noexcept override;
+                bool ReadSomeImpl(ByteBuf &buffer) noexcept override;
                 StreamStatus GetStatusImpl() const noexcept override;
                 int64_t GetLengthImpl() const noexcept override;
                 bool SeekImpl(OffsetType offsetType, StreamSeekBasis seekBasis) noexcept override;
+                int64_t PeekImpl() const noexcept override;
 
               private:
                 std::shared_ptr<Aws::Crt::Io::IStream> m_stream;

source/io/Stream.cpp

@@ -5,6 +5,7 @@
 
 #include <aws/crt/StlAllocator.h>
 #include <aws/crt/io/Stream.h>
+#include <iostream>
 
 #include <aws/io/stream.h>
 
@@ -150,6 +151,26 @@ namespace Aws
                 return status.is_valid && !status.is_end_of_stream;
             }
 
+            bool StdIOStreamInputStream::ReadSomeImpl(ByteBuf &buffer) noexcept
+            {
+                // I have no idea why "readsome() doesn't work at all" for the original dev. It works well for me
+                // Jokes aside, read will always block and try to read till eof
+                // readsome will return available bytes without waiting for eof and without closing the stream.
+                auto actuallyRead = m_stream->readsome(
+                    reinterpret_cast<char *>(buffer.buffer + buffer.len), buffer.capacity - buffer.len);
+
+                buffer.len += static_cast<size_t>(actuallyRead);
+
+                if (actuallyRead > 0 || (actuallyRead == 0 && m_stream->eof()))
+                {
+                    return true;
+                }
+
+                auto status = GetStatusImpl();
+
+                return status.is_valid && !status.is_end_of_stream;
+            }
+
             StreamStatus StdIOStreamInputStream::GetStatusImpl() const noexcept
             {
                 StreamStatus status;
@@ -206,6 +227,11 @@ namespace Aws
 
                 return true;
             }
+
+            int64_t StdIOStreamInputStream::PeekImpl() const noexcept
+            {
+                return m_stream->peek();
+            }
         } // namespace Io
     } // namespace Crt
 } // namespace Aws