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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	tmpfs_ops.c

 * @brief	Implementation of VFS operations for the TMPFS file system

 *		server.

 */

#include "tmpfs.h"

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

#include <ipc/ipc.h>

#include <async.h>

#include <errno.h>

#include <atomic.h>

#include <stdlib.h>

#include <string.h>

#include <stdio.h>

#include <assert.h>

#include <sys/types.h>

#include <adt/hash_table.h>

#include <as.h>

#include <libfs.h>

#define min(a, b)		((a) < (b) ? (a) : (b))

#define max(a, b)		((a) > (b) ? (a) : (b))

#define NODES_BUCKETS	256

/** All root nodes have index 0. */

#define TMPFS_SOME_ROOT		0

/** Global counter for assigning node indices. Shared by all instances. */

fs_index_t tmpfs_next_index = 1;

/*

 * Implementation of the libfs interface.

 */

/* Forward declarations of static functions. */

static fs_node_t *tmpfs_match(fs_node_t *, const char *);

static fs_node_t *tmpfs_node_get(dev_handle_t, fs_index_t);

static void tmpfs_node_put(fs_node_t *);

static fs_node_t *tmpfs_create_node(dev_handle_t, int);

static int tmpfs_link_node(fs_node_t *, fs_node_t *, const char *);

static int tmpfs_unlink_node(fs_node_t *, fs_node_t *, const char *);

static int tmpfs_destroy_node(fs_node_t *);

/* Implementation of helper functions. */

static fs_index_t tmpfs_index_get(fs_node_t *fn)

{

	return TMPFS_NODE(fn)->index;

}

static size_t tmpfs_size_get(fs_node_t *fn)

{

	return TMPFS_NODE(fn)->size;

}

static unsigned tmpfs_lnkcnt_get(fs_node_t *fn)

{

	return TMPFS_NODE(fn)->lnkcnt;

}

static bool tmpfs_has_children(fs_node_t *fn)

{

	return !list_empty(&TMPFS_NODE(fn)->cs_head);

}

static fs_node_t *tmpfs_root_get(dev_handle_t dev_handle)

{

	return tmpfs_node_get(dev_handle, TMPFS_SOME_ROOT); 

}

static char tmpfs_plb_get_char(unsigned pos)

{

	return tmpfs_reg.plb_ro[pos % PLB_SIZE];

}

static bool tmpfs_is_directory(fs_node_t *fn)

{

	return TMPFS_NODE(fn)->type == TMPFS_DIRECTORY;

}

static bool tmpfs_is_file(fs_node_t *fn)

{

	return TMPFS_NODE(fn)->type == TMPFS_FILE;

}

/** libfs operations */

libfs_ops_t tmpfs_libfs_ops = {

	.match = tmpfs_match,

	.node_get = tmpfs_node_get,

	.node_put = tmpfs_node_put,

	.create = tmpfs_create_node,

	.destroy = tmpfs_destroy_node,

	.link = tmpfs_link_node,

	.unlink = tmpfs_unlink_node,

	.index_get = tmpfs_index_get,

	.size_get = tmpfs_size_get,

	.lnkcnt_get = tmpfs_lnkcnt_get,

	.has_children = tmpfs_has_children,

	.root_get = tmpfs_root_get,

	.plb_get_char = tmpfs_plb_get_char,

	.is_directory = tmpfs_is_directory,

	.is_file = tmpfs_is_file

};

/** Hash table of all TMPFS nodes. */

hash_table_t nodes;

#define NODES_KEY_INDEX	0

#define NODES_KEY_DEV	1

/* Implementation of hash table interface for the nodes hash table. */

static hash_index_t nodes_hash(unsigned long key[])

{

	return key[NODES_KEY_INDEX] % NODES_BUCKETS;

}

static int nodes_compare(unsigned long key[], hash_count_t keys, link_t *item)

{

	tmpfs_node_t *nodep = hash_table_get_instance(item, tmpfs_node_t,

	    nh_link);

	return (nodep->index == key[NODES_KEY_INDEX] &&

	    nodep->dev_handle == key[NODES_KEY_DEV]);

}

static void nodes_remove_callback(link_t *item)

{

}

/** TMPFS nodes hash table operations. */

hash_table_operations_t nodes_ops = {

	.hash = nodes_hash,

	.compare = nodes_compare,

	.remove_callback = nodes_remove_callback

};

static void tmpfs_node_initialize(tmpfs_node_t *nodep)

{

	nodep->bp = NULL;

	nodep->index = 0;

	nodep->dev_handle = 0;

	nodep->type = TMPFS_NONE;

	nodep->lnkcnt = 0;

	nodep->size = 0;

	nodep->data = NULL;

	link_initialize(&nodep->nh_link);

	list_initialize(&nodep->cs_head);

}

static void tmpfs_dentry_initialize(tmpfs_dentry_t *dentryp)

{

	link_initialize(&dentryp->link);

	dentryp->name = NULL;

	dentryp->node = NULL;

}

bool tmpfs_init(void)

{

	if (!hash_table_create(&nodes, NODES_BUCKETS, 2, &nodes_ops))

		return false;

	return true;

}

static bool tmpfs_instance_init(dev_handle_t dev_handle)

{

	fs_node_t *rfn;

	rfn = tmpfs_create_node(dev_handle, L_DIRECTORY);

	if (!rfn) 

		return false;

	TMPFS_NODE(rfn)->lnkcnt = 0;	/* FS root is not linked */

	return true;

}

fs_node_t *tmpfs_match(fs_node_t *pfn, const char *component)

{

	tmpfs_node_t *parentp = TMPFS_NODE(pfn);

	link_t *lnk;

	for (lnk = parentp->cs_head.next; lnk != &parentp->cs_head;

	    lnk = lnk->next) {

		tmpfs_dentry_t *dentryp = list_get_instance(lnk, tmpfs_dentry_t,

		    link);

		if (!str_cmp(dentryp->name, component))

			return FS_NODE(dentryp->node);

	}

	return NULL;

}

fs_node_t *tmpfs_node_get(dev_handle_t dev_handle, fs_index_t index)

{

	unsigned long key[] = {

		[NODES_KEY_INDEX] = index,

		[NODES_KEY_DEV] = dev_handle

	};

	link_t *lnk = hash_table_find(&nodes, key);

	if (!lnk)

		return NULL;

	return FS_NODE(hash_table_get_instance(lnk, tmpfs_node_t, nh_link));

}

void tmpfs_node_put(fs_node_t *fn)

{

	/* nothing to do */

}

fs_node_t *tmpfs_create_node(dev_handle_t dev_handle, int lflag)

{

	assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));

	tmpfs_node_t *nodep = malloc(sizeof(tmpfs_node_t));

	if (!nodep)

		return NULL;

	tmpfs_node_initialize(nodep);

	nodep->bp = malloc(sizeof(fs_node_t));

	if (!nodep->bp) {

		free(nodep);

		return NULL;

	}

	fs_node_initialize(nodep->bp);

	nodep->bp->data = nodep;	/* link the FS and TMPFS nodes */

	if (!tmpfs_root_get(dev_handle))

		nodep->index = TMPFS_SOME_ROOT;

	else

		nodep->index = tmpfs_next_index++;

	nodep->dev_handle = dev_handle;

	if (lflag & L_DIRECTORY) 

		nodep->type = TMPFS_DIRECTORY;

	else 

		nodep->type = TMPFS_FILE;

	/* Insert the new node into the nodes hash table. */

	unsigned long key[] = {

		[NODES_KEY_INDEX] = nodep->index,

		[NODES_KEY_DEV] = nodep->dev_handle

	};

	hash_table_insert(&nodes, key, &nodep->nh_link);

	return FS_NODE(nodep);

}

int tmpfs_link_node(fs_node_t *pfn, fs_node_t *cfn, const char *nm)

{

	tmpfs_node_t *parentp = TMPFS_NODE(pfn);

	tmpfs_node_t *childp = TMPFS_NODE(cfn);

	tmpfs_dentry_t *dentryp;

	link_t *lnk;

	assert(parentp->type == TMPFS_DIRECTORY);

	/* Check for duplicit entries. */

	for (lnk = parentp->cs_head.next; lnk != &parentp->cs_head;

	    lnk = lnk->next) {

		dentryp = list_get_instance(lnk, tmpfs_dentry_t, link);	

		if (!str_cmp(dentryp->name, nm))

			return EEXIST;

	}

	/* Allocate and initialize the dentry. */

	dentryp = malloc(sizeof(tmpfs_dentry_t));

	if (!dentryp)

		return ENOMEM;

	tmpfs_dentry_initialize(dentryp);

	/* Populate and link the new dentry. */

	size_t size = str_size(nm);

	dentryp->name = malloc(size + 1);

	if (!dentryp->name) {

		free(dentryp);

		return ENOMEM;

	}

	str_cpy(dentryp->name, size + 1, nm);

	dentryp->node = childp;

	childp->lnkcnt++;

	list_append(&dentryp->link, &parentp->cs_head);

	return EOK;

}

int tmpfs_unlink_node(fs_node_t *pfn, fs_node_t *cfn, const char *nm)

{

	tmpfs_node_t *parentp = TMPFS_NODE(pfn);

	tmpfs_node_t *childp = NULL;

	tmpfs_dentry_t *dentryp;

	link_t *lnk;

	if (!parentp)

		return EBUSY;

	for (lnk = parentp->cs_head.next; lnk != &parentp->cs_head;

	    lnk = lnk->next) {

		dentryp = list_get_instance(lnk, tmpfs_dentry_t, link);

		if (!str_cmp(dentryp->name, nm)) {

			childp = dentryp->node;

			assert(FS_NODE(childp) == cfn);

			break;

		}	

	}

	if (!childp)

		return ENOENT;

	if ((childp->lnkcnt == 1) && !list_empty(&childp->cs_head))

		return ENOTEMPTY;

	list_remove(&dentryp->link);

	free(dentryp);

	childp->lnkcnt--;

	return EOK;

}

int tmpfs_destroy_node(fs_node_t *fn)

{

	tmpfs_node_t *nodep = TMPFS_NODE(fn);

	assert(!nodep->lnkcnt);

	assert(list_empty(&nodep->cs_head));

	unsigned long key[] = {

		[NODES_KEY_INDEX] = nodep->index,

		[NODES_KEY_DEV] = nodep->dev_handle

	};

	hash_table_remove(&nodes, key, 2);

	if (nodep->type == TMPFS_FILE)

		free(nodep->data);

	free(nodep->bp);

	free(nodep);

	return EOK;

}

void tmpfs_mounted(ipc_callid_t rid, ipc_call_t *request)

{

	dev_handle_t dev_handle = (dev_handle_t) IPC_GET_ARG1(*request);

	/* accept the mount options */

	ipc_callid_t callid;

	size_t size;

	if (!ipc_data_write_receive(&callid, &size)) {

		ipc_answer_0(callid, EINVAL);

		ipc_answer_0(rid, EINVAL);

		return;

	}

	char *opts = malloc(size + 1);

	if (!opts) {

		ipc_answer_0(callid, ENOMEM);

		ipc_answer_0(rid, ENOMEM);

		return;

	}

	ipcarg_t retval = ipc_data_write_finalize(callid, opts, size);

	if (retval != EOK) {

		ipc_answer_0(rid, retval);

		free(opts);

		return;

	}

	opts[size] = '\0';

	/* Initialize TMPFS instance. */

	if (!tmpfs_instance_init(dev_handle)) {

		ipc_answer_0(rid, ENOMEM);

		return;

	}

	tmpfs_node_t *rootp = TMPFS_NODE(tmpfs_root_get(dev_handle));

	if (str_cmp(opts, "restore") == 0) {

		if (tmpfs_restore(dev_handle))

			ipc_answer_3(rid, EOK, rootp->index, rootp->size,

			    rootp->lnkcnt);

		else

			ipc_answer_0(rid, ELIMIT);

	} else {

		ipc_answer_3(rid, EOK, rootp->index, rootp->size,

		    rootp->lnkcnt);

	}

}

void tmpfs_mount(ipc_callid_t rid, ipc_call_t *request)

{

	libfs_mount(&tmpfs_libfs_ops, tmpfs_reg.fs_handle, rid, request);

}

void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)

{

	libfs_lookup(&tmpfs_libfs_ops, tmpfs_reg.fs_handle, rid, request);

}

void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)

{

	dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);

	fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);

	off_t pos = (off_t)IPC_GET_ARG3(*request);

	/*

	 * Lookup the respective TMPFS node.

	 */

	link_t *hlp;

	unsigned long key[] = {

		[NODES_KEY_INDEX] = index,

		[NODES_KEY_DEV] = dev_handle,

	};

	hlp = hash_table_find(&nodes, key);

	if (!hlp) {

		ipc_answer_0(rid, ENOENT);

		return;

	}

	tmpfs_node_t *nodep = hash_table_get_instance(hlp, tmpfs_node_t,

	    nh_link);

	/*

	 * Receive the read request.

	 */

	ipc_callid_t callid;

	size_t size;

	if (!ipc_data_read_receive(&callid, &size)) {

		ipc_answer_0(callid, EINVAL);	

		ipc_answer_0(rid, EINVAL);

		return;

	}

	size_t bytes;

	if (nodep->type == TMPFS_FILE) {

		bytes = max(0, min(nodep->size - pos, size));

		(void) ipc_data_read_finalize(callid, nodep->data + pos,

		    bytes);

	} else {

		tmpfs_dentry_t *dentryp;

		link_t *lnk;

		int i;

		assert(nodep->type == TMPFS_DIRECTORY);

		/*

		 * Yes, we really use O(n) algorithm here.

		 * If it bothers someone, it could be fixed by introducing a

		 * hash table.

		 */

		for (i = 0, lnk = nodep->cs_head.next;

		    i < pos && lnk != &nodep->cs_head;

		    i++, lnk = lnk->next)

			;

		if (lnk == &nodep->cs_head) {

			ipc_answer_0(callid, ENOENT);

			ipc_answer_1(rid, ENOENT, 0);

			return;

		}

		dentryp = list_get_instance(lnk, tmpfs_dentry_t, link);

		(void) ipc_data_read_finalize(callid, dentryp->name,

		    str_size(dentryp->name) + 1);

		bytes = 1;

	}

	/*

	 * Answer the VFS_READ call.

	 */

	ipc_answer_1(rid, EOK, bytes);

}

void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)

{

	dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);

	fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);

	off_t pos = (off_t)IPC_GET_ARG3(*request);

	/*

	 * Lookup the respective TMPFS node.

	 */

	link_t *hlp;

	unsigned long key[] = {

		[NODES_KEY_INDEX] = index,

		[NODES_KEY_DEV] = dev_handle

	};

	hlp = hash_table_find(&nodes, key);

	if (!hlp) {

		ipc_answer_0(rid, ENOENT);

		return;

	}

	tmpfs_node_t *nodep = hash_table_get_instance(hlp, tmpfs_node_t,

	    nh_link);

	/*

	 * Receive the write request.

	 */

	ipc_callid_t callid;

	size_t size;

	if (!ipc_data_write_receive(&callid, &size)) {

		ipc_answer_0(callid, EINVAL);	

		ipc_answer_0(rid, EINVAL);

		return;

	}

	/*

	 * Check whether the file needs to grow.

	 */

	if (pos + size <= nodep->size) {

		/* The file size is not changing. */

		(void) ipc_data_write_finalize(callid, nodep->data + pos, size);

		ipc_answer_2(rid, EOK, size, nodep->size);

		return;

	}

	size_t delta = (pos + size) - nodep->size;

	/*

	 * At this point, we are deliberately extremely straightforward and

	 * simply realloc the contents of the file on every write that grows the

	 * file. In the end, the situation might not be as bad as it may look:

	 * our heap allocator can save us and just grow the block whenever

	 * possible.

	 */

	void *newdata = realloc(nodep->data, nodep->size + delta);

	if (!newdata) {

		ipc_answer_0(callid, ENOMEM);

		ipc_answer_2(rid, EOK, 0, nodep->size);

		return;

	}

	/* Clear any newly allocated memory in order to emulate gaps. */

	memset(newdata + nodep->size, 0, delta);

	nodep->size += delta;

	nodep->data = newdata;

	(void) ipc_data_write_finalize(callid, nodep->data + pos, size);

	ipc_answer_2(rid, EOK, size, nodep->size);

}

void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)

{

	dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);

	fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);

	size_t size = (off_t)IPC_GET_ARG3(*request);

	/*

	 * Lookup the respective TMPFS node.

	 */

	link_t *hlp;

	unsigned long key[] = {

		[NODES_KEY_INDEX] = index,

		[NODES_KEY_DEV] = dev_handle

	};

	hlp = hash_table_find(&nodes, key);

	if (!hlp) {

		ipc_answer_0(rid, ENOENT);

		return;

	}

	tmpfs_node_t *nodep = hash_table_get_instance(hlp, tmpfs_node_t,

	    nh_link);

	if (size == nodep->size) {

		ipc_answer_0(rid, EOK);

		return;

	}

	void *newdata = realloc(nodep->data, size);

	if (!newdata) {

		ipc_answer_0(rid, ENOMEM);

		return;

	}

	if (size > nodep->size) {

		size_t delta = size - nodep->size;

		memset(newdata + nodep->size, 0, delta);

	}

	nodep->size = size;

	nodep->data = newdata;

	ipc_answer_0(rid, EOK);

}

void tmpfs_close(ipc_callid_t rid, ipc_call_t *request)

{

	ipc_answer_0(rid, EOK);

}

void tmpfs_destroy(ipc_callid_t rid, ipc_call_t *request)

{

	dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);

	fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);

	int rc;

	link_t *hlp;

	unsigned long key[] = {

		[NODES_KEY_INDEX] = index,

		[NODES_KEY_DEV] = dev_handle

	};

	hlp = hash_table_find(&nodes, key);

	if (!hlp) {

		ipc_answer_0(rid, ENOENT);

		return;

	}

	tmpfs_node_t *nodep = hash_table_get_instance(hlp, tmpfs_node_t,

	    nh_link);

	rc = tmpfs_destroy_node(FS_NODE(nodep));

	ipc_answer_0(rid, rc);

}

void tmpfs_open_node(ipc_callid_t rid, ipc_call_t *request)

{

	libfs_open_node(&tmpfs_libfs_ops, tmpfs_reg.fs_handle, rid, request);

}

void tmpfs_stat(ipc_callid_t rid, ipc_call_t *request)

{

	libfs_stat(&tmpfs_libfs_ops, tmpfs_reg.fs_handle, rid, request);

}

void tmpfs_sync(ipc_callid_t rid, ipc_call_t *request)

{

	/* Dummy implementation */

	ipc_answer_0(rid, EOK);

}

/**

 * @}

 */