/*
 * Copyright 2016 Jakub Klama <jceel@FreeBSD.org>
 * All rights reserved
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted providing that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */

/*
 * Based on libixp code: ©2007-2010 Kris Maglione <maglione.k at Gmail>
 */

#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/uio.h>
#include "lib9p.h"
#include "lib9p_impl.h"

#define N(ary)          (sizeof(ary) / sizeof(*ary))
#define STRING_SIZE(s)  (L9P_WORD + (s != NULL ? (uint16_t)strlen(s) : 0))
#define QID_SIZE        (L9P_BYTE + L9P_DWORD + L9P_QWORD)

static int l9p_iov_io(struct l9p_message *, void *, size_t);
static inline int l9p_pu8(struct l9p_message *, uint8_t *);
static inline int l9p_pu16(struct l9p_message *, uint16_t *);
static inline int l9p_pu32(struct l9p_message *, uint32_t *);
static inline int l9p_pu64(struct l9p_message *, uint64_t *);
static int l9p_pustring(struct l9p_message *, char **s);
static int l9p_pustrings(struct l9p_message *, uint16_t *, char *[], size_t);
static int l9p_puqid(struct l9p_message *, struct l9p_qid *);
static int l9p_puqids(struct l9p_message *, uint16_t *, struct l9p_qid *q);

static int
l9p_iov_io(struct l9p_message *msg, void *buffer, size_t len)
{
	size_t done = 0;
	size_t left = len;

	assert(msg != NULL);

	if (len == 0)
		return (0);

	if (msg->lm_cursor_iov >= msg->lm_niov)
		return (-1);

	assert(buffer != NULL);

	while (left > 0) {
		size_t idx = msg->lm_cursor_iov;
		size_t space = msg->lm_iov[idx].iov_len - msg->lm_cursor_offset;
		size_t towrite = MIN(space, left);

		if (msg->lm_mode == L9P_PACK) {
			memcpy((char *)msg->lm_iov[idx].iov_base + 
			    msg->lm_cursor_offset, (char *)buffer + done,
			    towrite);
		}

		if (msg->lm_mode == L9P_UNPACK) {
			memcpy((char *)buffer + done,
			    (char *)msg->lm_iov[idx].iov_base +
			    msg->lm_cursor_offset, towrite);
		}

		msg->lm_cursor_offset += towrite;

		if (space - towrite == 0) {
			/* Advance to next iov */
			msg->lm_cursor_iov++;
			msg->lm_cursor_offset = 0;

			if (msg->lm_cursor_iov > msg->lm_niov)
				return (-1);
		}

		done += towrite;
		left -= towrite;
	}

	msg->lm_size += done;
	return ((int)done);
}

static inline int
l9p_pu8(struct l9p_message *msg, uint8_t *val)
{

	return (l9p_iov_io(msg, val, sizeof (uint8_t)));
}

static inline int
l9p_pu16(struct l9p_message *msg, uint16_t *val)
{

	return (l9p_iov_io(msg, val, sizeof (uint16_t)));
}

static inline int
l9p_pu32(struct l9p_message *msg, uint32_t *val)
{

	return (l9p_iov_io(msg, val, sizeof (uint32_t)));
}

static inline int
l9p_pu64(struct l9p_message *msg, uint64_t *val)
{

	return (l9p_iov_io(msg, val, sizeof (uint64_t)));
}

static int
l9p_pustring(struct l9p_message *msg, char **s)
{
	uint16_t len;

	if (msg->lm_mode == L9P_PACK)
		len = *s != NULL ? (uint16_t)strlen(*s) : 0;

	if (l9p_pu16(msg, &len) < 0)
		return (-1);

	if (msg->lm_mode == L9P_UNPACK)
		*s = l9p_calloc(1, len + 1);

	if (l9p_iov_io(msg, *s, len) < 0)
		return (-1);

	return (len + 2);
}

static int
l9p_pustrings(struct l9p_message *msg, uint16_t *num, char *strings[],
    size_t max)
{
	size_t i;
	int ret;
	int r = 0;

	l9p_pu16(msg, num);

	for (i = 0; i < MIN(*num, max); i++) {
		ret = l9p_pustring(msg, &strings[i]);
		if (ret < 1)
			return (-1);

		r += ret;
	}

	return (r);
}

static int
l9p_puqid(struct l9p_message *msg, struct l9p_qid *qid)
{
	int r = 0;

	r += l9p_pu8(msg, (uint8_t *) & qid->type);
	r += l9p_pu32(msg, &qid->version);
	r += l9p_pu64(msg, &qid->path);

	return (r);
}

static int
l9p_puqids(struct l9p_message *msg, uint16_t *num, struct l9p_qid *qids)
{
	int i, ret, r = 0;
	l9p_pu16(msg, num);

	for (i = 0; i < *num; i++) {
		ret = l9p_puqid(msg, &qids[i]);
		if (ret < 0)
			return (-1);

		r += ret;
	}

	return (r);
}

int
l9p_pustat(struct l9p_message *msg, struct l9p_stat *stat,
    enum l9p_version version)
{
	int r = 0;
	uint16_t size;

	if (msg->lm_mode == L9P_PACK)
		size = l9p_sizeof_stat(stat, version) - 2;

	r += l9p_pu16(msg, &size);
	r += l9p_pu16(msg, &stat->type);
	r += l9p_pu32(msg, &stat->dev);
	r += l9p_puqid(msg, &stat->qid);
	r += l9p_pu32(msg, &stat->mode);
	r += l9p_pu32(msg, &stat->atime);
	r += l9p_pu32(msg, &stat->mtime);
	r += l9p_pu64(msg, &stat->length);
	r += l9p_pustring(msg, &stat->name);
	r += l9p_pustring(msg, &stat->uid);
	r += l9p_pustring(msg, &stat->gid);
	r += l9p_pustring(msg, &stat->muid);

	if (version == L9P_2000U) {
		r += l9p_pustring(msg, &stat->extension);
		r += l9p_pu32(msg, &stat->n_uid);
		r += l9p_pu32(msg, &stat->n_gid);
		r += l9p_pu32(msg, &stat->n_muid);
	}
	
	if (r < size + 2)
		return (-1);

	return (r);
}

int
l9p_pufcall(struct l9p_message *msg, union l9p_fcall *fcall,
    enum l9p_version version)
{
	uint32_t length = 0;

	l9p_pu32(msg, &length);
	l9p_pu8(msg, &fcall->hdr.type);
	l9p_pu16(msg, &fcall->hdr.tag);

	switch (fcall->hdr.type) {
		case L9P_TVERSION:
		case L9P_RVERSION:
			l9p_pu32(msg, &fcall->version.msize);
			l9p_pustring(msg, &fcall->version.version);
			break;

		case L9P_TAUTH:
			l9p_pu32(msg, &fcall->tauth.afid);
			l9p_pustring(msg, &fcall->tauth.uname);
			l9p_pustring(msg, &fcall->tauth.aname);
			if (version == L9P_2000U)
				l9p_pu32(msg, &fcall->tauth.n_uname);
			break;

		case L9P_RAUTH:
			l9p_puqid(msg, &fcall->rauth.aqid);
			break;

		case L9P_RATTACH:
			l9p_puqid(msg, &fcall->rattach.qid);
			break;

		case L9P_TATTACH:
			l9p_pu32(msg, &fcall->hdr.fid);
			l9p_pu32(msg, &fcall->tattach.afid);
			l9p_pustring(msg, &fcall->tattach.uname);
			l9p_pustring(msg, &fcall->tattach.aname);
			if (version == L9P_2000U)
				l9p_pu32(msg, &fcall->tattach.n_uname);
			break;

		case L9P_RERROR:
			l9p_pustring(msg, &fcall->error.ename);
			if (version == L9P_2000U)
				l9p_pu32(msg, &fcall->error.errnum);
			break;

		case L9P_TFLUSH:
			l9p_pu16(msg, &fcall->tflush.oldtag);
			break;

		case L9P_TWALK:
			l9p_pu32(msg, &fcall->hdr.fid);
			l9p_pu32(msg, &fcall->twalk.newfid);
			l9p_pustrings(msg, &fcall->twalk.nwname,
			    fcall->twalk.wname, N(fcall->twalk.wname));
			break;

		case L9P_RWALK:
			l9p_puqids(msg, &fcall->rwalk.nwqid, fcall->rwalk.wqid);
			break;

		case L9P_TOPEN:
			l9p_pu32(msg, &fcall->hdr.fid);
			l9p_pu8(msg, &fcall->topen.mode);
			break;

		case L9P_ROPEN:
		case L9P_RCREATE:
			l9p_puqid(msg, &fcall->ropen.qid);
			l9p_pu32(msg, &fcall->ropen.iounit);
			break;

		case L9P_TCREATE:
			l9p_pu32(msg, &fcall->hdr.fid);
			l9p_pustring(msg, &fcall->tcreate.name);
			l9p_pu32(msg, &fcall->tcreate.perm);
			l9p_pu8(msg, &fcall->tcreate.mode);
			if (version == L9P_2000U)
				l9p_pustring(msg, &fcall->tcreate.extension);
			break;

		case L9P_TREAD:
			l9p_pu32(msg, &fcall->hdr.fid);
			l9p_pu64(msg, &fcall->io.offset);
			l9p_pu32(msg, &fcall->io.count);
			break;

		case L9P_RREAD:
			l9p_pu32(msg, &fcall->io.count);
			break;

		case L9P_TWRITE:
			l9p_pu32(msg, &fcall->hdr.fid);
			l9p_pu64(msg, &fcall->io.offset);
			l9p_pu32(msg, &fcall->io.count);
			break;

		case L9P_RWRITE:
			l9p_pu32(msg, &fcall->io.count);
			break;

		case L9P_TCLUNK:
		case L9P_TSTAT:
		case L9P_TREMOVE:
			l9p_pu32(msg, &fcall->hdr.fid);
			break;

		case L9P_RSTAT:
		{
			uint16_t size = l9p_sizeof_stat(&fcall->rstat.stat,
			    version);
			l9p_pu16(msg, &size);
			l9p_pustat(msg, &fcall->rstat.stat, version);
		}
			break;

		case L9P_TWSTAT:
		{
			uint16_t size;
			l9p_pu32(msg, &fcall->hdr.fid);
			l9p_pu16(msg, &size);
			l9p_pustat(msg, &fcall->twstat.stat, version);
		}
			break;
	}

	if (msg->lm_mode == L9P_PACK) {
		/* Rewind to the beginning */
		uint32_t len = (uint32_t)msg->lm_size;
		msg->lm_cursor_offset = 0;
		msg->lm_cursor_iov = 0;

		/* 
		 * Subtract 4 bytes from message size, becase we're
		 * overwriting size (rewinding message to the beginning)
		 * and writing again.
		 */
		msg->lm_size -= sizeof (uint32_t);

		if (fcall->hdr.type == L9P_RREAD)
			len += fcall->io.count;

		l9p_pu32(msg, &len);
	}

	return (0);
}

void
l9p_freefcall(union l9p_fcall *fcall)
{
	uint16_t i;

	switch (fcall->hdr.type) {
	case L9P_TVERSION:
	case L9P_RVERSION:
		free(fcall->version.version);
		return;
	case L9P_TATTACH:
		free(fcall->tattach.aname);
		free(fcall->tattach.uname);
		return;
	case L9P_TWALK:
		for (i = 0; i < fcall->twalk.nwname; i++)
			free(fcall->twalk.wname[i]);
		return;
	case L9P_TCREATE:
	case L9P_TOPEN:
		free(fcall->tcreate.name);
		free(fcall->tcreate.extension);
		return;
	case L9P_RSTAT:
		l9p_freestat(&fcall->rstat.stat);
		return;
	case L9P_TWSTAT:
		l9p_freestat(&fcall->twstat.stat);
		return;
	}
}

void
l9p_freestat(struct l9p_stat *stat)
{
	free(stat->name);
	free(stat->extension);
	free(stat->uid);
	free(stat->gid);
	free(stat->muid);
}

uint16_t
l9p_sizeof_stat(struct l9p_stat *stat, enum l9p_version version)
{
	uint16_t size = L9P_WORD /* size */
	    + L9P_WORD /* type */
	    + L9P_DWORD /* dev */
	    + QID_SIZE /* qid */
	    + 3 * L9P_DWORD /* mode, atime, mtime */
	    + L9P_QWORD /* length */
	    + STRING_SIZE(stat->name)
	    + STRING_SIZE(stat->uid)
	    + STRING_SIZE(stat->gid)
	    + STRING_SIZE(stat->muid);

	if (version == L9P_2000U) {
		size += STRING_SIZE(stat->extension)
		    + 3 * L9P_DWORD;
	}

	return (size);
}