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/* 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
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