/*
* 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>
#include <libadt/hash_table.h>
#include <libadt/list.h>
#include <assert.h>
#include <futex.h>
#define BS_BLOCK 0
/** Futex protecting the list of cached free FAT nodes. */
static futex_t ffn_futex = FUTEX_INITIALIZER;
/** List of cached free FAT nodes. */
static LIST_INITIALIZE(ffn_head);
#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 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 void block_put(block_t *block)
{
/* TODO */
}
#define FAT_BS(b) ((fat_bs_t *)((b)->data))
#define FAT_CLST_RES0 0x0000
#define FAT_CLST_RES1 0x0001 /* internally used to mark root directory */
#define FAT_CLST_FIRST 0x0002
#define FAT_CLST_BAD 0xfff7
#define FAT_CLST_LAST1 0xfff8
#define FAT_CLST_LAST8 0xffff
#define fat_block_get(np, off) \
_fat_block_get((np)->idx->dev_handle, (np)->firstc, (off))
static block_t *
_fat_block_get(dev_handle_t dev_handle, fat_cluster_t firstc, off_t offset)
{
block_t *bb;
block_t *b;
unsigned bps;
unsigned spc;
unsigned rscnt; /* block address of the first FAT */
unsigned fatcnt;
unsigned rde;
unsigned rds; /* root directory size */
unsigned sf;
unsigned ssa; /* size of the system area */
unsigned clusters;
fat_cluster_t clst = firstc;
unsigned i;
bb = block_get(dev_handle, BS_BLOCK);
bps = uint16_t_le2host(FAT_BS(bb)->bps);
spc = FAT_BS(bb)->spc;
rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt);
fatcnt = FAT_BS(bb)->fatcnt;
rde = uint16_t_le2host(FAT_BS(bb)->root_ent_max);
sf = uint16_t_le2host(FAT_BS(bb)->sec_per_fat);
block_put(bb);
rds = (sizeof(fat_dentry_t) * rde) / bps;
rds += ((sizeof(fat_dentry_t) * rde) % bps != 0);
ssa = rscnt + fatcnt * sf + rds;
if (firstc == FAT_CLST_RES1) {
/* root directory special case */
b = block_get(dev_handle, rscnt + fatcnt * sf + offset);
return b;
}
clusters = offset / spc;
for (i = 0; i < clusters; i++) {
unsigned fsec; /* sector offset relative to FAT1 */
unsigned fidx; /* FAT1 entry index */
assert(clst
>= FAT_CLST_FIRST
&& clst
< FAT_CLST_BAD
); fsec = (clst * sizeof(fat_cluster_t)) / bps;
fidx = clst % (bps / sizeof(fat_cluster_t));
/* read FAT1 */
b = block_get(dev_handle, rscnt + fsec);
clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
assert(clst
< FAT_CLST_LAST1
); block_put(b);
}
b = block_get(dev_handle, ssa + (clst - FAT_CLST_FIRST) * spc +
offset % spc);
return b;
}
static void fat_node_initialize(fat_node_t *node)
{
futex_initialize(&node->lock, 1);
node->idx = NULL;
node->type = 0;
link_initialize(&node->ffn_link);
node->size = 0;
node->lnkcnt = 0;
node->refcnt = 0;
node->dirty = false;
}
static uint16_t fat_bps_get(dev_handle_t dev_handle)
{
block_t *bb;
uint16_t bps;
bb = block_get(dev_handle, BS_BLOCK);
bps = uint16_t_le2host(FAT_BS(bb)->bps);
block_put(bb);
return bps;
}
typedef enum {
FAT_DENTRY_SKIP,
FAT_DENTRY_LAST,
FAT_DENTRY_VALID
} fat_dentry_clsf_t;
static fat_dentry_clsf_t fat_classify_dentry(fat_dentry_t *d)
{
if (d->attr & FAT_ATTR_VOLLABEL) {
/* volume label entry */
return FAT_DENTRY_SKIP;
}
if (d->name[0] == FAT_DENTRY_ERASED) {
/* not-currently-used entry */
return FAT_DENTRY_SKIP;
}
if (d->name[0] == FAT_DENTRY_UNUSED) {
/* never used entry */
return FAT_DENTRY_LAST;
}
if (d->name[0] == FAT_DENTRY_DOT) {
/*
* Most likely '.' or '..'.
* It cannot occur in a regular file name.
*/
return FAT_DENTRY_SKIP;
}
return FAT_DENTRY_VALID;
}
static void fat_node_sync(fat_node_t *node)
{
/* TODO */
}
/** Internal version of fat_node_get().
*
* @param idxp Locked index structure.
*/
static void *fat_node_get_core(fat_idx_t *idxp)
{
block_t *b;
fat_dentry_t *d;
fat_node_t *nodep;
unsigned bps;
unsigned dps;
if (idxp->nodep) {
/*
* We are lucky.
* The node is already instantiated in memory.
*/
futex_down(&idxp->nodep->lock);
if (!idxp->nodep->refcnt++)
list_remove(&nodep->ffn_link);
futex_up(&idxp->nodep->lock);
return idxp->nodep;
}
/*
* We must instantiate the node from the file system.
*/
futex_down(&ffn_futex);
if (!list_empty(&ffn_head)) {
/* Try to use a cached free node structure. */
fat_idx_t *idxp_tmp;
nodep = list_get_instance(ffn_head.next, fat_node_t, ffn_link);
if (futex_trydown(&nodep->lock) == ESYNCH_WOULD_BLOCK)
goto skip_cache;
idxp_tmp = nodep->idx;
if (futex_trydown(&idxp_tmp->lock) == ESYNCH_WOULD_BLOCK) {
futex_up(&nodep->lock);
goto skip_cache;
}
list_remove(&nodep->ffn_link);
futex_up(&ffn_futex);
if (nodep->dirty)
fat_node_sync(nodep);
idxp_tmp->nodep = NULL;
futex_up(&nodep->lock);
futex_up(&idxp_tmp->lock);
} else {
skip_cache:
/* Try to allocate a new node structure. */
futex_up(&ffn_futex);
nodep
= (fat_node_t
*)malloc(sizeof(fat_node_t
)); if (!nodep)
return NULL;
}
fat_node_initialize(nodep);
bps = fat_bps_get(idxp->dev_handle);
dps = bps / sizeof(fat_dentry_t);
/* Read the block that contains the dentry of interest. */
b = _fat_block_get(idxp->dev_handle, idxp->pfc,
(idxp->pdi * sizeof(fat_dentry_t)) / bps);
d = ((fat_dentry_t *)b->data) + (idxp->pdi % dps);
if (d->attr & FAT_ATTR_SUBDIR) {
/*
* The only directory which does not have this bit set is the
* root directory itself. The root directory node is handled
* and initialized elsewhere.
*/
nodep->type = FAT_DIRECTORY;
} else {
nodep->type = FAT_FILE;
}
nodep->firstc = uint16_t_le2host(d->firstc);
nodep->size = uint32_t_le2host(d->size);
nodep->lnkcnt = 1;
nodep->refcnt = 1;
block_put(b);
/* Link the idx structure with the node structure. */
nodep->idx = idxp;
idxp->nodep = nodep;
return nodep;
}
/** Instantiate a FAT in-core node. */
static void *fat_node_get(dev_handle_t dev_handle, fs_index_t index)
{
void *node;
fat_idx_t *idxp;
idxp = fat_idx_get_by_index(dev_handle, index);
if (!idxp)
return NULL;
/* idxp->lock held */
node = fat_node_get_core(idxp);
futex_up(&idxp->lock);
return node;
}
static void fat_node_put(void *node)
{
fat_node_t *nodep = (fat_node_t *)node;
futex_down(&nodep->lock);
if (!--nodep->refcnt) {
futex_down(&ffn_futex);
list_append(&nodep->ffn_link, &ffn_head);
futex_up(&ffn_futex);
}
futex_up(&nodep->lock);
}
static void *fat_create(int flags)
{
return NULL; /* not supported at the moment */
}
static int fat_destroy(void *node)
{
return ENOTSUP; /* not supported at the moment */
}
static bool fat_link(void *prnt, void *chld, const char *name)
{
return false; /* not supported at the moment */
}
static int fat_unlink(void *prnt, void *chld)
{
return ENOTSUP; /* not supported at the moment */
}
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 *b;
futex_down(&parentp->idx->lock);
bps = fat_bps_get(parentp->idx->dev_handle);
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);
dentries = (i == blocks - 1) ?
parentp->size % sizeof(fat_dentry_t) :
dps;
for (j = 0; j < dentries; j++) {
d = ((fat_dentry_t *)b->data) + j;
switch (fat_classify_dentry(d)) {
case FAT_DENTRY_SKIP:
continue;
case FAT_DENTRY_LAST:
block_put(b);
futex_up(&parentp->idx->lock);
return NULL;
default:
case FAT_DENTRY_VALID:
dentry_name_canonify(d, name);
break;
}
if (strcmp(name
, component
) == 0) { /* hit */
void *node;
/*
* Assume tree hierarchy for locking. We
* already have the parent and now we are going
* to lock the child. Never lock in the oposite
* order.
*/
fat_idx_t *idx = fat_idx_get_by_pos(
parentp->idx->dev_handle, parentp->firstc,
i * dps + j);
futex_up(&parentp->idx->lock);
if (!idx) {
/*
* Can happen if memory is low or if we
* run out of 32-bit indices.
*/
block_put(b);
return NULL;
}
node = fat_node_get_core(idx);
futex_up(&idx->lock);
block_put(b);
return node;
}
}
block_put(b);
}
futex_up(&parentp->idx->lock);
return NULL;
}
static fs_index_t fat_index_get(void *node)
{
fat_node_t *fnodep = (fat_node_t *)node;
if (!fnodep)
return 0;
return fnodep->idx->index;
}
static size_t fat_size_get(void *node)
{
return ((fat_node_t *)node)->size;
}
static unsigned fat_lnkcnt_get(void *node)
{
return ((fat_node_t *)node)->lnkcnt;
}
static bool fat_has_children(void *node)
{
fat_node_t *nodep = (fat_node_t *)node;
unsigned bps;
unsigned dps;
unsigned blocks;
block_t *b;
unsigned i, j;
if (nodep->type != FAT_DIRECTORY)
return false;
futex_down(&nodep->idx->lock);
bps = fat_bps_get(nodep->idx->dev_handle);
dps = bps / sizeof(fat_dentry_t);
blocks = nodep->size / bps + (nodep->size % bps != 0);
for (i = 0; i < blocks; i++) {
unsigned dentries;
fat_dentry_t *d;
b = fat_block_get(nodep, i);
dentries = (i == blocks - 1) ?
nodep->size % sizeof(fat_dentry_t) :
dps;
for (j = 0; j < dentries; j++) {
d = ((fat_dentry_t *)b->data) + j;
switch (fat_classify_dentry(d)) {
case FAT_DENTRY_SKIP:
continue;
case FAT_DENTRY_LAST:
block_put(b);
futex_up(&nodep->idx->lock);
return false;
default:
case FAT_DENTRY_VALID:
block_put(b);
futex_up(&nodep->idx->lock);
return true;
}
block_put(b);
futex_up(&nodep->idx->lock);
return true;
}
block_put(b);
}
futex_up(&nodep->idx->lock);
return false;
}
static void *fat_root_get(dev_handle_t dev_handle)
{
return NULL; /* TODO */
}
static char fat_plb_get_char(unsigned pos)
{
return fat_reg.plb_ro[pos % PLB_SIZE];
}
static bool fat_is_directory(void *node)
{
return ((fat_node_t *)node)->type == FAT_DIRECTORY;
}
static bool fat_is_file(void *node)
{
return ((fat_node_t *)node)->type == FAT_FILE;
}
/** libfs operations */
libfs_ops_t fat_libfs_ops = {
.match = fat_match,
.node_get = fat_node_get,
.node_put = fat_node_put,
.create = fat_create,
.destroy = fat_destroy,
.link = fat_link,
.unlink = fat_unlink,
.index_get = fat_index_get,
.size_get = fat_size_get,
.lnkcnt_get = fat_lnkcnt_get,
.has_children = fat_has_children,
.root_get = fat_root_get,
.plb_get_char = fat_plb_get_char,
.is_directory = fat_is_directory,
.is_file = fat_is_file
};
void fat_lookup(ipc_callid_t rid, ipc_call_t *request)
{
libfs_lookup(&fat_libfs_ops, fat_reg.fs_handle, rid, request);
}
/**
* @}
*/