/*
* 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 "fat_dentry.h"
#include "fat_fat.h"
#include "../../vfs/vfs.h"
#include <libfs.h>
#include <libblock.h>
#include <ipc/ipc.h>
#include <ipc/services.h>
#include <ipc/devmap.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>
#include <sys/mman.h>
#include <align.h>
/** 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);
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 void fat_node_sync(fat_node_t *node)
{
block_t *b;
fat_bs_t *bs;
fat_dentry_t *d;
uint16_t bps;
unsigned dps;
bs = block_bb_get(node->idx->dev_handle);
bps = uint16_t_le2host(bs->bps);
dps = bps / sizeof(fat_dentry_t);
/* Read the block that contains the dentry of interest. */
b = _fat_block_get(bs, node->idx->dev_handle, node->idx->pfc,
(node->idx->pdi * sizeof(fat_dentry_t)) / bps, BLOCK_FLAGS_NONE);
d = ((fat_dentry_t *)b->data) + (node->idx->pdi % dps);
d->firstc = host2uint16_t_le(node->firstc);
if (node->type == FAT_FILE) {
d->size = host2uint32_t_le(node->size);
} else if (node->type == FAT_DIRECTORY) {
d->attr = FAT_ATTR_SUBDIR;
}
/* TODO: update other fields? (e.g time fields) */
b->dirty = true; /* need to sync block */
block_put(b);
}
static fat_node_t *fat_node_get_new(void)
{
fat_node_t *nodep;
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);
return nodep;
}
/** 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_bs_t *bs;
fat_dentry_t *d;
fat_node_t *nodep = NULL;
unsigned bps;
unsigned spc;
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(&idxp->nodep->ffn_link);
futex_up(&idxp->nodep->lock);
return idxp->nodep;
}
/*
* We must instantiate the node from the file system.
*/
nodep = fat_node_get_new();
if (!nodep)
return NULL;
bs = block_bb_get(idxp->dev_handle);
bps = uint16_t_le2host(bs->bps);
spc = bs->spc;
dps = bps / sizeof(fat_dentry_t);
/* Read the block that contains the dentry of interest. */
b = _fat_block_get(bs, idxp->dev_handle, idxp->pfc,
(idxp->pdi * sizeof(fat_dentry_t)) / bps, BLOCK_FLAGS_NONE);
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;
/*
* Unfortunately, the 'size' field of the FAT dentry is not
* defined for the directory entry type. We must determine the
* size of the directory by walking the FAT.
*/
nodep->size = bps * spc * fat_clusters_get(bs, idxp->dev_handle,
uint16_t_le2host(d->firstc));
} else {
nodep->type = FAT_FILE;
nodep->size = uint32_t_le2host(d->size);
}
nodep->firstc = uint16_t_le2host(d->firstc);
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;
}
/*
* Forward declarations of FAT libfs operations.
*/
static void *fat_node_get(dev_handle_t, fs_index_t);
static void fat_node_put(void *);
static void *fat_create_node(dev_handle_t, int);
static int fat_destroy_node(void *);
static int fat_link(void *, void *, const char *);
static int fat_unlink(void *, void *);
static void *fat_match(void *, const char *);
static fs_index_t fat_index_get(void *);
static size_t fat_size_get(void *);
static unsigned fat_lnkcnt_get(void *);
static bool fat_has_children(void *);
static void *fat_root_get(dev_handle_t);
static char fat_plb_get_char(unsigned);
static bool fat_is_directory(void *);
static bool fat_is_file(void *node);
/*
* FAT libfs operations.
*/
/** Instantiate a FAT in-core node. */
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;
}
void fat_node_put(void *node)
{
fat_node_t *nodep = (fat_node_t *)node;
bool destroy = false;
futex_down(&nodep->lock);
if (!--nodep->refcnt) {
if (nodep->idx) {
futex_down(&ffn_futex);
list_append(&nodep->ffn_link, &ffn_head);
futex_up(&ffn_futex);
} else {
/*
* The node does not have any index structure associated
* with itself. This can only mean that we are releasing
* the node after a failed attempt to allocate the index
* structure for it.
*/
destroy = true;
}
}
futex_up(&nodep->lock);
if (destroy)
}
void *fat_create_node(dev_handle_t dev_handle, int flags)
{
fat_idx_t *idxp;
fat_node_t *nodep;
fat_bs_t *bs;
fat_cluster_t mcl, lcl;
uint16_t bps;
int rc;
bs = block_bb_get(dev_handle);
bps = uint16_t_le2host(bs->bps);
if (flags & L_DIRECTORY) {
/* allocate a cluster */
rc = fat_alloc_clusters(bs, dev_handle, 1, &mcl, &lcl);
if (rc != EOK)
return NULL;
}
nodep = fat_node_get_new();
if (!nodep) {
fat_free_clusters(bs, dev_handle, mcl);
return NULL;
}
idxp = fat_idx_get_new(dev_handle);
if (!idxp) {
fat_free_clusters(bs, dev_handle, mcl);
fat_node_put(nodep);
return NULL;
}
/* idxp->lock held */
if (flags & L_DIRECTORY) {
int i;
block_t *b;
/*
* Populate the new cluster with unused dentries.
*/
for (i = 0; i < bs->spc; i++) {
b = _fat_block_get(bs, dev_handle, mcl, i,
BLOCK_FLAGS_NOREAD);
/* mark all dentries as never-used */
b->dirty = false;
block_put(b);
}
nodep->type = FAT_DIRECTORY;
nodep->firstc = mcl;
nodep->size = bps * bs->spc;
} else {
nodep->type = FAT_FILE;
nodep->firstc = FAT_CLST_RES0;
nodep->size = 0;
}
nodep->lnkcnt = 0; /* not linked anywhere */
nodep->refcnt = 1;
nodep->dirty = true;
nodep->idx = idxp;
idxp->nodep = nodep;
futex_up(&idxp->lock);
return nodep;
}
int fat_destroy_node(void *node)
{
fat_node_t *nodep = (fat_node_t *)node;
fat_bs_t *bs;
/*
* The node is not reachable from the file system. This means that the
* link count should be zero and that the index structure cannot be
* found in the position hash. Obviously, we don't need to lock the node
* nor its index structure.
*/
/*
* The node may not have any children.
*/
assert(fat_has_children
(node
) == false);
bs = block_bb_get(nodep->idx->dev_handle);
if (nodep->firstc != FAT_CLST_RES0) {
/* Free all clusters allocated to the node. */
fat_free_clusters(bs, nodep->idx->dev_handle, nodep->firstc);
}
fat_idx_destroy(nodep->idx);
return EOK;
}
int fat_link(void *prnt, void *chld, const char *name)
{
fat_node_t *parentp = (fat_node_t *)prnt;
fat_node_t *childp = (fat_node_t *)chld;
fat_dentry_t *d;
fat_bs_t *bs;
block_t *b;
int i, j;
uint16_t bps;
unsigned dps;
unsigned blocks;
futex_down(&childp->lock);
if (childp->lnkcnt == 1) {
/*
* On FAT, we don't support multiple hard links.
*/
futex_up(&childp->lock);
return EMLINK;
}
futex_up(&childp->lock);
if (!fat_dentry_name_verify(name)) {
/*
* Attempt to create unsupported name.
*/
return ENOTSUP;
}
/*
* Get us an unused parent node's dentry or grow the parent and allocate
* a new one.
*/
futex_down(&parentp->idx->lock);
bs = block_bb_get(parentp->idx->dev_handle);
bps = uint16_t_le2host(bs->bps);
dps = bps / sizeof(fat_dentry_t);
blocks = parentp->size / bps;
for (i = 0; i < blocks; i++) {
b = fat_block_get(bs, parentp, i, BLOCK_FLAGS_NONE);
for (j = 0; j < dps; j++) {
d = ((fat_dentry_t *)b->data) + j;
switch (fat_classify_dentry(d)) {
case FAT_DENTRY_SKIP:
case FAT_DENTRY_VALID:
/* skipping used and meta entries */
continue;
case FAT_DENTRY_FREE:
case FAT_DENTRY_LAST:
/* found an empty slot */
goto hit;
}
}
block_put(b);
}
/*
* We need to grow the parent in order to create a new unused dentry.
*/
futex_up(&parentp->idx->lock);
return ENOTSUP; /* XXX */
hit:
/*
* At this point we only establish the link between the parent and the
* child. The dentry, except of the name and the extension, will remain
* uninitialized until the the corresponding node is synced. Thus the
* valid dentry data is kept in the child node structure.
*/
memset(d
, 0, sizeof(fat_dentry_t
)); fat_dentry_name_set(d, name);
b->dirty = true; /* need to sync block */
block_put(b);
futex_up(&parentp->idx->lock);
futex_down(&childp->idx->lock);
/*
* If possible, create the Sub-directory Identifier Entry and the
* Sub-directory Parent Pointer Entry (i.e. "." and ".."). These entries
* are not mandatory according to Standard ECMA-107 and HelenOS VFS does
* not use them anyway, so this is rather a sign of our good will.
*/
b = fat_block_get(bs, childp, 0, BLOCK_FLAGS_NONE);
d = (fat_dentry_t *)b->data;
if (fat_classify_dentry(d) == FAT_DENTRY_LAST ||
strcmp(d
->name
, FAT_NAME_DOT
) == 0) { memset(d
, 0, sizeof(fat_dentry_t
)); strcpy(d
->name
, FAT_NAME_DOT
); d->attr = FAT_ATTR_SUBDIR;
d->firstc = host2uint16_t_le(childp->firstc);
/* TODO: initialize also the date/time members. */
}
d++;
if (fat_classify_dentry(d) == FAT_DENTRY_LAST ||
strcmp(d
->name
, FAT_NAME_DOT_DOT
) == 0) { memset(d
, 0, sizeof(fat_dentry_t
)); strcpy(d
->name
, FAT_NAME_DOT_DOT
); d->attr = FAT_ATTR_SUBDIR;
d->firstc = (parentp->firstc == FAT_CLST_ROOT) ?
host2uint16_t_le(FAT_CLST_RES0) :
host2uint16_t_le(parentp->firstc);
/* TODO: initialize also the date/time members. */
}
b->dirty = true; /* need to sync block */
block_put(b);
childp->idx->pfc = parentp->firstc;
childp->idx->pdi = i * dps + j;
futex_up(&childp->idx->lock);
futex_down(&childp->lock);
childp->lnkcnt = 1;
childp->dirty = true; /* need to sync node */
futex_up(&childp->lock);
/*
* Hash in the index structure into the position hash.
*/
fat_idx_hashin(childp->idx);
return EOK;
}
int fat_unlink(void *prnt, void *chld)
{
fat_node_t *parentp = (fat_node_t *)prnt;
fat_node_t *childp = (fat_node_t *)chld;
fat_bs_t *bs;
fat_dentry_t *d;
uint16_t bps;
block_t *b;
futex_down(&parentp->lock);
futex_down(&childp->lock);
futex_down(&childp->idx->lock);
bs = block_bb_get(childp->idx->dev_handle);
bps = uint16_t_le2host(bs->bps);
b = _fat_block_get(bs, childp->idx->dev_handle, childp->idx->pfc,
(childp->idx->pdi * sizeof(fat_dentry_t)) / bps,
BLOCK_FLAGS_NONE);
d = (fat_dentry_t *)b->data +
(childp->idx->pdi % (bps / sizeof(fat_dentry_t)));
/* mark the dentry as not-currently-used */
d->name[0] = FAT_DENTRY_ERASED;
b->dirty = true; /* need to sync block */
block_put(b);
/* remove the index structure from the position hash */
fat_idx_hashout(childp->idx);
/* clear position information */
childp->idx->pfc = FAT_CLST_RES0;
childp->idx->pdi = 0;
futex_up(&childp->idx->lock);
childp->lnkcnt = 0;
childp->dirty = true;
futex_up(&childp->lock);
futex_up(&parentp->lock);
return EOK;
}
void *fat_match(void *prnt, const char *component)
{
fat_bs_t *bs;
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);
bs = block_bb_get(parentp->idx->dev_handle);
bps = uint16_t_le2host(bs->bps);
dps = bps / sizeof(fat_dentry_t);
blocks = parentp->size / bps;
for (i = 0; i < blocks; i++) {
b = fat_block_get(bs, parentp, i, BLOCK_FLAGS_NONE);
for (j = 0; j < dps; j++) {
d = ((fat_dentry_t *)b->data) + j;
switch (fat_classify_dentry(d)) {
case FAT_DENTRY_SKIP:
case FAT_DENTRY_FREE:
continue;
case FAT_DENTRY_LAST:
block_put(b);
futex_up(&parentp->idx->lock);
return NULL;
default:
case FAT_DENTRY_VALID:
fat_dentry_name_get(d, name);
break;
}
if (fat_dentry_namecmp(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;
}
fs_index_t fat_index_get(void *node)
{
fat_node_t *fnodep = (fat_node_t *)node;
if (!fnodep)
return 0;
return fnodep->idx->index;
}
size_t fat_size_get(void *node)
{
return ((fat_node_t *)node)->size;
}
unsigned fat_lnkcnt_get(void *node)
{
return ((fat_node_t *)node)->lnkcnt;
}
bool fat_has_children(void *node)
{
fat_bs_t *bs;
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);
bs = block_bb_get(nodep->idx->dev_handle);
bps = uint16_t_le2host(bs->bps);
dps = bps / sizeof(fat_dentry_t);
blocks = nodep->size / bps;
for (i = 0; i < blocks; i++) {
fat_dentry_t *d;
b = fat_block_get(bs, nodep, i, BLOCK_FLAGS_NONE);
for (j = 0; j < dps; j++) {
d = ((fat_dentry_t *)b->data) + j;
switch (fat_classify_dentry(d)) {
case FAT_DENTRY_SKIP:
case FAT_DENTRY_FREE:
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;
}
void *fat_root_get(dev_handle_t dev_handle)
{
return fat_node_get(dev_handle, 0);
}
char fat_plb_get_char(unsigned pos)
{
return fat_reg.plb_ro[pos % PLB_SIZE];
}
bool fat_is_directory(void *node)
{
return ((fat_node_t *)node)->type == FAT_DIRECTORY;
}
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_node,
.destroy = fat_destroy_node,
.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
};
/*
* VFS operations.
*/
void fat_mounted(ipc_callid_t rid, ipc_call_t *request)
{
dev_handle_t dev_handle = (dev_handle_t) IPC_GET_ARG1(*request);
fat_bs_t *bs;
uint16_t bps;
uint16_t rde;
int rc;
/* initialize libblock */
rc = block_init(dev_handle, BS_SIZE);
if (rc != EOK) {
ipc_answer_0(rid, rc);
return;
}
/* prepare the boot block */
rc = block_bb_read(dev_handle, BS_BLOCK * BS_SIZE, BS_SIZE);
if (rc != EOK) {
block_fini(dev_handle);
ipc_answer_0(rid, rc);
return;
}
/* get the buffer with the boot sector */
bs = block_bb_get(dev_handle);
/* Read the number of root directory entries. */
bps = uint16_t_le2host(bs->bps);
rde = uint16_t_le2host(bs->root_ent_max);
if (bps != BS_SIZE) {
block_fini(dev_handle);
ipc_answer_0(rid, ENOTSUP);
return;
}
/* Initialize the block cache */
rc = block_cache_init(dev_handle, bps, 0 /* XXX */);
if (rc != EOK) {
block_fini(dev_handle);
ipc_answer_0(rid, rc);
return;
}
rc = fat_idx_init_by_dev_handle(dev_handle);
if (rc != EOK) {
block_fini(dev_handle);
ipc_answer_0(rid, rc);
return;
}
/* Initialize the root node. */
fat_node_t
*rootp
= (fat_node_t
*)malloc(sizeof(fat_node_t
)); if (!rootp) {
block_fini(dev_handle);
fat_idx_fini_by_dev_handle(dev_handle);
ipc_answer_0(rid, ENOMEM);
return;
}
fat_node_initialize(rootp);
fat_idx_t *ridxp = fat_idx_get_by_pos(dev_handle, FAT_CLST_ROOTPAR, 0);
if (!ridxp) {
block_fini(dev_handle);
fat_idx_fini_by_dev_handle(dev_handle);
ipc_answer_0(rid, ENOMEM);
return;
}
/* ridxp->lock held */
rootp->type = FAT_DIRECTORY;
rootp->firstc = FAT_CLST_ROOT;
rootp->refcnt = 1;
rootp->lnkcnt = 0; /* FS root is not linked */
rootp->size = rde * sizeof(fat_dentry_t);
rootp->idx = ridxp;
ridxp->nodep = rootp;
futex_up(&ridxp->lock);
ipc_answer_3(rid, EOK, ridxp->index, rootp->size, rootp->lnkcnt);
}
void fat_mount(ipc_callid_t rid, ipc_call_t *request)
{
ipc_answer_0(rid, ENOTSUP);
}
void fat_lookup(ipc_callid_t rid, ipc_call_t *request)
{
libfs_lookup(&fat_libfs_ops, fat_reg.fs_handle, rid, request);
}
void fat_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);
fat_node_t *nodep = (fat_node_t *)fat_node_get(dev_handle, index);
fat_bs_t *bs;
uint16_t bps;
size_t bytes;
block_t *b;
if (!nodep) {
ipc_answer_0(rid, ENOENT);
return;
}
ipc_callid_t callid;
size_t len;
if (!ipc_data_read_receive(&callid, &len)) {
fat_node_put(nodep);
ipc_answer_0(callid, EINVAL);
ipc_answer_0(rid, EINVAL);
return;
}
bs = block_bb_get(dev_handle);
bps = uint16_t_le2host(bs->bps);
if (nodep->type == FAT_FILE) {
/*
* Our strategy for regular file reads is to read one block at
* most and make use of the possibility to return less data than
* requested. This keeps the code very simple.
*/
if (pos >= nodep->size) {
/* reading beyond the EOF */
bytes = 0;
(void) ipc_data_read_finalize(callid, NULL, 0);
} else {
bytes = min(len, bps - pos % bps);
bytes = min(bytes, nodep->size - pos);
b = fat_block_get(bs, nodep, pos / bps,
BLOCK_FLAGS_NONE);
(void) ipc_data_read_finalize(callid, b->data + pos % bps,
bytes);
block_put(b);
}
} else {
unsigned bnum;
off_t spos = pos;
char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];
fat_dentry_t *d;
assert(nodep
->type
== FAT_DIRECTORY
); assert(nodep
->size
% bps
== 0); assert(bps
% sizeof(fat_dentry_t
) == 0);
/*
* Our strategy for readdir() is to use the position pointer as
* an index into the array of all dentries. On entry, it points
* to the first unread dentry. If we skip any dentries, we bump
* the position pointer accordingly.
*/
bnum = (pos * sizeof(fat_dentry_t)) / bps;
while (bnum < nodep->size / bps) {
off_t o;
b = fat_block_get(bs, nodep, bnum, BLOCK_FLAGS_NONE);
for (o = pos % (bps / sizeof(fat_dentry_t));
o < bps / sizeof(fat_dentry_t);
o++, pos++) {
d = ((fat_dentry_t *)b->data) + o;
switch (fat_classify_dentry(d)) {
case FAT_DENTRY_SKIP:
case FAT_DENTRY_FREE:
continue;
case FAT_DENTRY_LAST:
block_put(b);
goto miss;
default:
case FAT_DENTRY_VALID:
fat_dentry_name_get(d, name);
block_put(b);
goto hit;
}
}
block_put(b);
bnum++;
}
miss:
fat_node_put(nodep);
ipc_answer_0(callid, ENOENT);
ipc_answer_1(rid, ENOENT, 0);
return;
hit:
(void) ipc_data_read_finalize
(callid
, name
, strlen(name
) + 1); bytes = (pos - spos) + 1;
}
fat_node_put(nodep);
ipc_answer_1(rid, EOK, (ipcarg_t)bytes);
}
void fat_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);
fat_node_t *nodep = (fat_node_t *)fat_node_get(dev_handle, index);
fat_bs_t *bs;
size_t bytes;
block_t *b;
uint16_t bps;
unsigned spc;
unsigned bpc; /* bytes per cluster */
off_t boundary;
int flags = BLOCK_FLAGS_NONE;
if (!nodep) {
ipc_answer_0(rid, ENOENT);
return;
}
ipc_callid_t callid;
size_t len;
if (!ipc_data_write_receive(&callid, &len)) {
fat_node_put(nodep);
ipc_answer_0(callid, EINVAL);
ipc_answer_0(rid, EINVAL);
return;
}
bs = block_bb_get(dev_handle);
bps = uint16_t_le2host(bs->bps);
spc = bs->spc;
bpc = bps * spc;
/*
* In all scenarios, we will attempt to write out only one block worth
* of data at maximum. There might be some more efficient approaches,
* but this one greatly simplifies fat_write(). Note that we can afford
* to do this because the client must be ready to handle the return
* value signalizing a smaller number of bytes written.
*/
bytes = min(len, bps - pos % bps);
if (bytes == bps)
flags |= BLOCK_FLAGS_NOREAD;
boundary = ROUND_UP(nodep->size, bpc);
if (pos < boundary) {
/*
* This is the easier case - we are either overwriting already
* existing contents or writing behind the EOF, but still within
* the limits of the last cluster. The node size may grow to the
* next block size boundary.
*/
fat_fill_gap(bs, nodep, FAT_CLST_RES0, pos);
b = fat_block_get(bs, nodep, pos / bps, flags);
(void) ipc_data_write_finalize(callid, b->data + pos % bps,
bytes);
b->dirty = true; /* need to sync block */
block_put(b);
if (pos + bytes > nodep->size) {
nodep->size = pos + bytes;
nodep->dirty = true; /* need to sync node */
}
ipc_answer_2(rid, EOK, bytes, nodep->size);
fat_node_put(nodep);
return;
} else {
/*
* This is the more difficult case. We must allocate new
* clusters for the node and zero them out.
*/
int status;
unsigned nclsts;
fat_cluster_t mcl, lcl;
nclsts = (ROUND_UP(pos + bytes, bpc) - boundary) / bpc;
/* create an independent chain of nclsts clusters in all FATs */
status = fat_alloc_clusters(bs, dev_handle, nclsts, &mcl, &lcl);
if (status != EOK) {
/* could not allocate a chain of nclsts clusters */
fat_node_put(nodep);
ipc_answer_0(callid, status);
ipc_answer_0(rid, status);
return;
}
/* zero fill any gaps */
fat_fill_gap(bs, nodep, mcl, pos);
b = _fat_block_get(bs, dev_handle, lcl, (pos / bps) % spc,
flags);
(void) ipc_data_write_finalize(callid, b->data + pos % bps,
bytes);
b->dirty = true; /* need to sync block */
block_put(b);
/*
* Append the cluster chain starting in mcl to the end of the
* node's cluster chain.
*/
fat_append_clusters(bs, nodep, mcl);
nodep->size = pos + bytes;
nodep->dirty = true; /* need to sync node */
ipc_answer_2(rid, EOK, bytes, nodep->size);
fat_node_put(nodep);
return;
}
}
void fat_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);
fat_node_t *nodep = (fat_node_t *)fat_node_get(dev_handle, index);
fat_bs_t *bs;
uint16_t bps;
uint8_t spc;
unsigned bpc; /* bytes per cluster */
int rc;
if (!nodep) {
ipc_answer_0(rid, ENOENT);
return;
}
bs = block_bb_get(dev_handle);
bps = uint16_t_le2host(bs->bps);
spc = bs->spc;
bpc = bps * spc;
if (nodep->size == size) {
rc = EOK;
} else if (nodep->size < size) {
/*
* The standard says we have the freedom to grow the node.
* For now, we simply return an error.
*/
rc = EINVAL;
} else if (ROUND_UP(nodep->size, bpc) == ROUND_UP(size, bpc)) {
/*
* The node will be shrunk, but no clusters will be deallocated.
*/
nodep->size = size;
nodep->dirty = true; /* need to sync node */
rc = EOK;
} else {
/*
* The node will be shrunk, clusters will be deallocated.
*/
if (size == 0) {
fat_chop_clusters(bs, nodep, FAT_CLST_RES0);
} else {
fat_cluster_t lastc;
(void) fat_cluster_walk(bs, dev_handle, nodep->firstc,
&lastc, (size - 1) / bpc);
fat_chop_clusters(bs, nodep, lastc);
}
nodep->size = size;
nodep->dirty = true; /* need to sync node */
rc = EOK;
}
fat_node_put(nodep);
ipc_answer_0(rid, rc);
return;
}
void fat_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;
fat_node_t *nodep = fat_node_get(dev_handle, index);
if (!nodep) {
ipc_answer_0(rid, ENOENT);
return;
}
rc = fat_destroy_node(nodep);
ipc_answer_0(rid, rc);
}
/**
* @}
*/