// SPDX-License-Identifier: GPL-2.0-or-later

/* PASST - Plug A Simple Socket Transport
 *  for qemu/UNIX domain socket mode
 *
 * PASTA - Pack A Subtle Tap Abstraction
 *  for network namespace/tap device mode
 *
 * PESTO - Programmable Extensible Socket Translation Orchestrator
 *  front-end for passt(1) and pasta(1) forwarding configuration
 *
 * serialise.c - Serialisation of data structures over bytestreams
 *
 * Copyright Red Hat
 * Author: David Gibson <david@gibson.dropbear.id.au>
 */

#include <assert.h>
#include <endian.h>
#include <errno.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>

#include "serialise.h"

/**
 * seread_buf() - Fill a whole buffer from a file descriptor
 * @fd:		File descriptor
 * @buf:	Pointer to base of buffer
 * @len:	Length of buffer
 *
 * Return: 0 on success, -1 on error (with errno set)
 *
 * #syscalls read
 */
int seread_buf(int fd, void *buf, size_t len)
{
	size_t left = len;
	char *p = buf;

	while (left) {
		ssize_t rc;

		assert(left <= len);

		do
			rc = read(fd, p, left);
		while ((rc < 0) && errno == EINTR);

		if (rc < 0)
			return -1;

		if (rc == 0) {
			errno = ENODATA;
			return -1;
		}

		p += rc;
		left -= rc;
	}
	return 0;
}

/**
 * sewrite_buf() - write all of a buffer to an fd
 * @fd:		File descriptor
 * @buf:	Pointer to base of buffer
 * @len:	Length of buffer
 *
 * Return: 0 on success, -1 on error (with errno set)
 *
 * #syscalls write
 */
int sewrite_buf(int fd, const void *buf, size_t len)
{
	const char *p = buf;
	size_t left = len;

	while (left) {
		ssize_t rc;

		do
			rc = write(fd, p, left);
		while ((rc < 0) && errno == EINTR);

		if (rc < 0)
			return -1;

		p += rc;
		left -= rc;
	}
	return 0;
}

/**
 * seread_uXXX() - Receive a uXXX value from an fd
 * @fd:		File descriptor to read from
 * @valp:	Pointer to variable to update with read value
 *
 * Return: 0 on success, -1 on error
 */
/**
 * sewrite_uXXX() - Send a uXXX value to an fd
 * @fd:		File descriptor to write to
 * @val:	Value to send
 *
 * Return: 0 on success, -1 on error
 */
#define SERIALISE_UINT(bits)						\
	int seread_u##bits(int fd, uint##bits##_t *val)			\
	{								\
		uint##bits##_t beval;					\
		if (seread_var(fd, &beval) < 0)				\
			return -1;					\
		*val = be##bits##toh(beval);				\
		return 0;						\
	}								\
	int sewrite_u##bits(int fd, uint##bits##_t val)			\
	{								\
		uint##bits##_t beval = htobe##bits(val);		\
		return sewrite_var(fd, &beval);				\
	}

#define be8toh(x)	(x)
#define htobe8(x)	(x)

SERIALISE_UINT(8)
SERIALISE_UINT(32)

#undef SERIALISE_UNIT

/**
 * sewrite_str() - Write a string to an fd in length/value format
 * @fd:		Socket to the client
 * @s:		String to send
 *
 * Return: 0 on success, -1 on error
 */
int sewrite_str(int fd, const char *s)
{
	uint32_t len = strlen(s) + 1; /* Include \0 */

	if (sewrite_u32(fd, len) < 0)
		return -1;
	return sewrite_buf(fd, s, len);
}