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/*

 * Copyright (c) 2008 Jakub Jermar

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - 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.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * 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.

 */

/** @addtogroup fs

 * @{

 */ 

/**

 * @file	fat_ops.c

 * @brief	Implementation of VFS operations for the FAT file system server.

 */

#include "fat.h"

#include "../../vfs/vfs.h"

#include <libfs.h>

#include <ipc/ipc.h>

#include <async.h>

#include <errno.h>

#include <string.h>

#include <byteorder.h>

#define FAT_NAME_LEN		8

#define FAT_EXT_LEN		3

#define FAT_PAD			' ' 

#define FAT_DENTRY_UNUSED	0x00

#define FAT_DENTRY_E5_ESC	0x05

#define FAT_DENTRY_DOT		0x2e

#define FAT_DENTRY_ERASED	0xe5

static void dentry_name_canonify(fat_dentry_t *d, char *buf)

{

	int i;

	for (i = 0; i < FAT_NAME_LEN; i++) {

		if (d->name[i] == FAT_PAD) {

			buf++;

			break;

		}

		if (d->name[i] == FAT_DENTRY_E5_ESC)

			*buf++ = 0xe5;

		else

			*buf++ = d->name[i];

	}

	if (d->ext[0] != FAT_PAD)

		*buf++ = '.';

	for (i = 0; i < FAT_EXT_LEN; i++) {

		if (d->ext[i] == FAT_PAD) {

			*buf = '\0';

			return;

		}

		if (d->ext[i] == FAT_DENTRY_E5_ESC)

			*buf++ = 0xe5;

		else

			*buf++ = d->ext[i];

	}

}

/* TODO and also move somewhere else */

typedef struct {

	void *data;

} block_t;

static block_t *block_get(dev_handle_t dev_handle, off_t offset)

{

	return NULL;	/* TODO */

}

static block_t *fat_block_get(fat_node_t *node, off_t offset) {

	return NULL;	/* TODO */

}

static void block_put(block_t *block)

{

	/* TODO */

}

static void *fat_node_get(dev_handle_t dev_handle, fs_index_t index)

{

	return NULL;	/* TODO */

}

#define BS_BLOCK	0

static void *fat_match(void *prnt, const char *component)

{

	fat_node_t *parentp = (fat_node_t *)prnt;

	char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];

	unsigned i, j;

	unsigned bps;		/* bytes per sector */

	unsigned dps;		/* dentries per sector */

	unsigned blocks;

	fat_dentry_t *d;

	block_t *bb;

	block_t *b;

	bb = block_get(parentp->dev_handle, BS_BLOCK);

	if (!bb)

		return NULL;

	bps = uint16_t_le2host(((fat_bs_t *)bb->data)->bps);

	block_put(bb);

	dps = bps / sizeof(fat_dentry_t);

	blocks = parentp->size / bps + (parentp->size % bps != 0);

	for (i = 0; i < blocks; i++) {

		unsigned dentries;

		b = fat_block_get(parentp, i);

		if (!b) 

			return NULL;

		dentries = (i == blocks - 1) ?

		    parentp->size % sizeof(fat_dentry_t) :

		    dps;

		for (j = 0; j < dentries; j++) { 

			d = ((fat_dentry_t *)b->data) + j;

			if (d->attr & FAT_ATTR_VOLLABEL) {

				/* volume label entry */

				continue;

			}

			if (d->name[0] == FAT_DENTRY_ERASED) {

				/* not-currently-used entry */

				continue;

			}

			if (d->name[0] == FAT_DENTRY_UNUSED) {

				/* never used entry */

				block_put(b);

				return NULL;

			}

			if (d->name[0] == FAT_DENTRY_DOT) {

				/*

				 * Most likely '.' or '..'.

				 * It cannot occur in a regular file name.

				 */

				continue;

			}

			dentry_name_canonify(d, name);

			if (strcmp(name, component) == 0) {

				/* hit */

				void *node = fat_node_get(parentp->dev_handle,

				    (fs_index_t)uint16_t_le2host(d->firstc));

				block_put(b);

				return node;

			}

		}

		block_put(b);

	}

	return NULL;

}

/** libfs operations */

libfs_ops_t fat_libfs_ops = {

	.match = fat_match,

	.node_get = fat_node_get,

	.create = NULL,

	.destroy = NULL,

	.link = NULL,

	.unlink = NULL,

	.index_get = NULL,

	.size_get = NULL,

	.lnkcnt_get = NULL,

	.has_children = NULL,

	.root_get = NULL,

	.plb_get_char =	NULL,

	.is_directory = NULL,

	.is_file = NULL

};

void fat_lookup(ipc_callid_t rid, ipc_call_t *request)

{

	libfs_lookup(&fat_libfs_ops, fat_reg.fs_handle, rid, request);

}

/**

 * @}

 */