1 files changed, 133 insertions, 0 deletions
diff --git a/types-message.h b/types-message.h
new file mode 100644
index 0000000..5d479b7
--- /dev/null
+++ b/types-message.h
@@ -0,0 +1,133 @@
+/* See LICENSE file for copyright and license details. */
+#ifndef TYPES_MESSAGE_H
+#define TYPES_MESSAGE_H
+
+#include <stddef.h>
+#include <limits.h>
+
+#ifndef GCC_ONLY
+# if defined(__GNUC__) && !defined(__clang__)
+#  define GCC_ONLY(...) __VA_ARGS__
+# else
+#  define GCC_ONLY(...) /* nothing */
+# endif
+#endif
+
+/**
+ * Message passed between a server and a client
+ */
+struct message {
+	/**
+	 * The headers in the message, each element in this list
+	 * as an unparsed header, it consists of both the header
+	 * name and its associated value, joined by ": ". A header
+	 * cannot be `NULL` (unless its memory allocation failed,)
+	 * but `headers` itself is `NULL` if there are no headers.
+	 * The "Length" header should be included in this list.
+	 */
+	char **restrict headers;
+
+	/**
+	 * The number of headers in the message
+	 */
+	size_t header_count;
+
+	/**
+	 * The payload of the message, `NULL` if none (of zero-length)
+	 */
+	char *restrict payload;
+
+	/**
+	 * The size of the payload
+	 */
+	size_t payload_size;
+
+	/**
+	 * How much of the payload that has been stored (internal data)
+	 */
+	size_t payload_ptr;
+
+	/**
+	 * Internal buffer for the reading function (internal data)
+	 */
+	char *restrict buffer;
+
+	/**
+	 * The size allocated to `buffer` (internal data)
+	 */
+	size_t buffer_size;
+
+	/**
+	 * The number of bytes used in `buffer` (internal data)
+	 */
+	size_t buffer_ptr;
+
+	/**
+	 * 0 while reading headers, 1 while reading payload, and 2 when done (internal data)
+	 */
+	int stage;
+
+#if INT_MAX != LONG_MAX
+	int padding__;
+#endif
+};
+
+/**
+ * Initialise a message slot so that it can
+ * be used by to read messages
+ * 
+ * @param   this  Memory slot in which to store the new message
+ * @return        Non-zero on error, `errno` will be set accordingly
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+int message_initialise(struct message *restrict this);
+
+/**
+ * Release all resources in a message, should
+ * be done even if initialisation fails
+ * 
+ * @param  this  The message
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+void message_destroy(struct message *restrict this);
+
+/**
+ * Marshal a message for state serialisation
+ * 
+ * @param  this  The message
+ * @param  buf   Output buffer for the marshalled data,
+ *               `NULL` just measure how large the buffers
+ *               needs to be
+ * @return       The number of marshalled byte
+ */
+GCC_ONLY(__attribute__((__nonnull__(1))))
+size_t message_marshal(const struct message *restrict this, void *restrict buf);
+
+/**
+ * Unmarshal a message for state deserialisation
+ * 
+ * @param   this  Memory slot in which to store the new message
+ * @param   buf   In buffer with the marshalled data
+ * @return        The number of unmarshalled bytes, 0 on error
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+size_t message_unmarshal(struct message *restrict this, const void *restrict buf);
+
+/**
+ * Read the next message from a file descriptor
+ * 
+ * @param   this  Memory slot in which to store the new message
+ * @param   fd    The file descriptor
+ * @return        0:  At least one message is available
+ *                -1: Exceptional connection:
+ *                  EINTR:        System call interrupted
+ *                  EAGAIN:       No message is available
+ *                  EWOULDBLOCK:  No message is available
+ *                  ECONNRESET:   Connection closed
+ *                  Other:        Failure
+ *                -2: Corrupt message (unrecoverable)
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+int message_read(struct message *restrict this, int fd);
+
+#endif