Fix stream_seek::sk_stream_absolute behaviour when attempting to seek forward

Author: Chaosvex

include/hexi/binary_stream.h

@@ -622,9 +622,15 @@ class binary_stream final {
 	void write_seek(const stream_seek direction, const offset_type offset)
 		requires(seekable<buf_type> && writeable<buf_type>) {
 		if(direction == stream_seek::sk_stream_absolute) {
-			write_seek(buffer_seek::sk_backward, total_write_ - offset);
+			if(offset >= total_write_) {
+				buffer_.write_seek(buffer_seek::sk_forward, offset - total_write_);
+			} else {
+				buffer_.write_seek(buffer_seek::sk_backward, total_write_ - offset);
+			}
+
+			total_write_ = offset;
 		} else {
-			write_seek(static_cast<buffer_seek>(direction), offset);
+			buffer_.write_seek(static_cast<buffer_seek>(direction), offset);
 		}
 	}
 

include/hexi/pmc/binary_stream_writer.h

@@ -220,7 +220,13 @@ class binary_stream_writer : virtual public stream_base {
 	 */
 	void write_seek(const stream_seek direction, const std::size_t offset) {
 		if(direction == stream_seek::sk_stream_absolute) {
-			buffer_.write_seek(buffer_seek::sk_backward, total_write_ - offset);
+			if(offset >= total_write_) {
+				buffer_.write_seek(buffer_seek::sk_forward, offset - total_write_);
+			} else {
+				buffer_.write_seek(buffer_seek::sk_backward, total_write_ - offset);
+			}
+
+			total_write_ = offset;
 		} else {
 			buffer_.write_seek(static_cast<buffer_seek>(direction), offset);
 		}

single_include/hexi.h

@@ -1151,9 +1151,15 @@ class binary_stream final {
 	void write_seek(const stream_seek direction, const offset_type offset)
 		requires(seekable<buf_type> && writeable<buf_type>) {
 		if(direction == stream_seek::sk_stream_absolute) {
-			write_seek(buffer_seek::sk_backward, total_write_ - offset);
+			if(offset >= total_write_) {
+				buffer_.write_seek(buffer_seek::sk_forward, offset - total_write_);
+			} else {
+				buffer_.write_seek(buffer_seek::sk_backward, total_write_ - offset);
+			}
+
+			total_write_ = offset;
 		} else {
-			write_seek(static_cast<buffer_seek>(direction), offset);
+			buffer_.write_seek(static_cast<buffer_seek>(direction), offset);
 		}
 	}
 
@@ -4625,7 +4631,13 @@ class binary_stream_writer : virtual public stream_base {
 	 */
 	void write_seek(const stream_seek direction, const std::size_t offset) {
 		if(direction == stream_seek::sk_stream_absolute) {
-			buffer_.write_seek(buffer_seek::sk_backward, total_write_ - offset);
+			if(offset >= total_write_) {
+				buffer_.write_seek(buffer_seek::sk_forward, offset - total_write_);
+			} else {
+				buffer_.write_seek(buffer_seek::sk_backward, total_write_ - offset);
+			}
+
+			total_write_ = offset;
 		} else {
 			buffer_.write_seek(static_cast<buffer_seek>(direction), offset);
 		}