0,0 → 1,852 |
/* |
* 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 <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> |
|
#define BS_BLOCK 0 |
#define BS_SIZE 512 |
|
/** 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 |
|
#define min(a, b) ((a) < (b) ? (a) : (b)) |
|
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) |
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]; |
} |
*buf = '\0'; |
} |
|
static int dev_phone = -1; /* FIXME */ |
static void *dev_buffer = NULL; /* FIXME */ |
|
/* TODO move somewhere else */ |
typedef struct { |
void *data; |
size_t size; |
} block_t; |
|
static block_t *block_get(dev_handle_t dev_handle, off_t offset, size_t bs) |
{ |
/* FIXME */ |
block_t *b; |
off_t bufpos = 0; |
size_t buflen = 0; |
off_t pos = offset * bs; |
|
assert(dev_phone != -1); |
assert(dev_buffer); |
|
b = malloc(sizeof(block_t)); |
if (!b) |
return NULL; |
|
b->data = malloc(bs); |
if (!b->data) { |
free(b); |
return NULL; |
} |
b->size = bs; |
|
if (!libfs_blockread(dev_phone, dev_buffer, &bufpos, &buflen, &pos, |
b->data, bs, bs)) { |
free(b->data); |
free(b); |
return NULL; |
} |
|
return b; |
} |
|
static void block_put(block_t *block) |
{ |
/* FIXME */ |
free(block->data); |
free(block); |
} |
|
#define FAT_BS(b) ((fat_bs_t *)((b)->data)) |
|
#define FAT_CLST_RES0 0x0000 |
#define FAT_CLST_RES1 0x0001 |
#define FAT_CLST_FIRST 0x0002 |
#define FAT_CLST_BAD 0xfff7 |
#define FAT_CLST_LAST1 0xfff8 |
#define FAT_CLST_LAST8 0xffff |
|
/* internally used to mark root directory's parent */ |
#define FAT_CLST_ROOTPAR FAT_CLST_RES0 |
/* internally used to mark root directory */ |
#define FAT_CLST_ROOT FAT_CLST_RES1 |
|
#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, BS_SIZE); |
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_ROOT) { |
/* root directory special case */ |
assert(offset < rds); |
b = block_get(dev_handle, rscnt + fatcnt * sf + offset, bps); |
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, bps); |
clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]); |
assert(clst != FAT_CLST_BAD); |
assert(clst < FAT_CLST_LAST1); |
block_put(b); |
} |
|
b = block_get(dev_handle, ssa + (clst - FAT_CLST_FIRST) * spc + |
offset % spc, bps); |
|
return b; |
} |
|
/** Return number of blocks allocated to a file. |
* |
* @param dev_handle Device handle of the device with the file. |
* @param firstc First cluster of the file. |
* |
* @return Number of blocks allocated to the file. |
*/ |
static uint16_t |
_fat_blcks_get(dev_handle_t dev_handle, fat_cluster_t firstc) |
{ |
block_t *bb; |
block_t *b; |
unsigned bps; |
unsigned spc; |
unsigned rscnt; /* block address of the first FAT */ |
unsigned clusters = 0; |
fat_cluster_t clst = firstc; |
|
bb = block_get(dev_handle, BS_BLOCK, BS_SIZE); |
bps = uint16_t_le2host(FAT_BS(bb)->bps); |
spc = FAT_BS(bb)->spc; |
rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt); |
block_put(bb); |
|
if (firstc == FAT_CLST_RES0) { |
/* No space allocated to the file. */ |
return 0; |
} |
|
while (clst < FAT_CLST_LAST1) { |
unsigned fsec; /* sector offset relative to FAT1 */ |
unsigned fidx; /* FAT1 entry index */ |
|
assert(clst >= FAT_CLST_FIRST); |
fsec = (clst * sizeof(fat_cluster_t)) / bps; |
fidx = clst % (bps / sizeof(fat_cluster_t)); |
/* read FAT1 */ |
b = block_get(dev_handle, rscnt + fsec, bps); |
clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]); |
assert(clst != FAT_CLST_BAD); |
block_put(b); |
clusters++; |
} |
|
return clusters * spc; |
} |
|
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, BS_SIZE); |
assert(bb != NULL); |
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 = NULL; |
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(&idxp->nodep->ffn_link); |
futex_up(&idxp->nodep->lock); |
return idxp->nodep; |
} |
|
/* |
* We must instantiate the node from the file system. |
*/ |
|
assert(idxp->pfc); |
|
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); |
assert(b); |
|
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 * _fat_blcks_get(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; |
} |
|
/** 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 (stricmp(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 fat_node_get(dev_handle, 0); |
} |
|
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_mounted(ipc_callid_t rid, ipc_call_t *request) |
{ |
dev_handle_t dev_handle = (dev_handle_t) IPC_GET_ARG1(*request); |
block_t *bb; |
uint16_t bps; |
uint16_t rde; |
int rc; |
|
/* |
* For now, we don't bother to remember dev_handle, dev_phone or |
* dev_buffer in some data structure. We use global variables because we |
* know there will be at most one mount on this file system. |
* Of course, this is a huge TODO item. |
*/ |
dev_buffer = mmap(NULL, BS_SIZE, PROTO_READ | PROTO_WRITE, |
MAP_ANONYMOUS | MAP_PRIVATE, 0, 0); |
|
if (!dev_buffer) { |
ipc_answer_0(rid, ENOMEM); |
return; |
} |
|
dev_phone = ipc_connect_me_to(PHONE_NS, SERVICE_DEVMAP, |
DEVMAP_CONNECT_TO_DEVICE, dev_handle); |
|
if (dev_phone < 0) { |
munmap(dev_buffer, BS_SIZE); |
ipc_answer_0(rid, dev_phone); |
return; |
} |
|
rc = ipc_share_out_start(dev_phone, dev_buffer, |
AS_AREA_READ | AS_AREA_WRITE); |
if (rc != EOK) { |
munmap(dev_buffer, BS_SIZE); |
ipc_answer_0(rid, rc); |
return; |
} |
|
/* Read the number of root directory entries. */ |
bb = block_get(dev_handle, BS_BLOCK, BS_SIZE); |
bps = uint16_t_le2host(FAT_BS(bb)->bps); |
rde = uint16_t_le2host(FAT_BS(bb)->root_ent_max); |
block_put(bb); |
|
if (bps != BS_SIZE) { |
munmap(dev_buffer, BS_SIZE); |
ipc_answer_0(rid, ENOTSUP); |
return; |
} |
|
rc = fat_idx_init_by_dev_handle(dev_handle); |
if (rc != EOK) { |
munmap(dev_buffer, BS_SIZE); |
ipc_answer_0(rid, rc); |
return; |
} |
|
/* Initialize the root node. */ |
fat_node_t *rootp = (fat_node_t *)malloc(sizeof(fat_node_t)); |
if (!rootp) { |
munmap(dev_buffer, BS_SIZE); |
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) { |
munmap(dev_buffer, BS_SIZE); |
free(rootp); |
fat_idx_fini_by_dev_handle(dev_handle); |
ipc_answer_0(rid, ENOMEM); |
return; |
} |
assert(ridxp->index == 0); |
/* 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); |
uint16_t bps = fat_bps_get(dev_handle); |
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; |
} |
|
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. |
*/ |
bytes = min(len, bps - pos % bps); |
b = fat_block_get(nodep, pos / bps); |
(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(nodep, bnum); |
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: |
continue; |
case FAT_DENTRY_LAST: |
block_put(b); |
goto miss; |
default: |
case FAT_DENTRY_VALID: |
dentry_name_canonify(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); |
} |
|
/** |
* @} |
*/ |