Whitebox
/
u-boot
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

fs: fat: support write with non-zero offset

Browse Source 
In this patch, all the necessary code for allowing for a file offset
at write is implemented. What plays a major roll here is get_set_cluster(),
which, in contrast to its counterpart, set_cluster(), only operates on
already-allocated clusters, overwriting with data.

So, with a file offset specified, set_contents() seeks and writes data
with set_get_cluster() until the end of a file, and, once it reaches
there, continues writing with set_cluster() for the rest.

Please note that a file will be trimmed as a result of write operation if
write ends before reaching file's end. This is an intended behavior
in order to maintain compatibility with the current interface.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
lime2-spi
AKASHI Takahiro 6 years ago committed by Alexander Graf
parent 704df6aa0a
commit cb8af8af5b
1 changed files with 273 additions and 15 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Show Stats Download Patch File Download Diff File
  1. 288
      fs/fat/fat_write.c

288
fs/fat/fat_write.c
Unescape View File

@ -450,6 +450,121 @@ set_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer,
return 0;
}
static __u8 tmpbuf_cluster[MAX_CLUSTSIZE] __aligned(ARCH_DMA_MINALIGN);
/*
* Read and modify data on existing and consecutive cluster blocks
*/
static int
get_set_cluster(fsdata *mydata, __u32 clustnum, loff_t pos, __u8 *buffer,
loff_t size, loff_t *gotsize)
{
unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
__u32 startsect;
loff_t wsize;
int clustcount, i, ret;
*gotsize = 0;
if (!size)
return 0;
assert(pos < bytesperclust);
startsect = clust_to_sect(mydata, clustnum);
debug("clustnum: %d, startsect: %d, pos: %lld\n",
clustnum, startsect, pos);
/* partial write at beginning */
if (pos) {
wsize = min(bytesperclust - pos, size);
ret = disk_read(startsect, mydata->clust_size, tmpbuf_cluster);
if (ret != mydata->clust_size) {
debug("Error reading data (got %d)\n", ret);
return -1;
}
memcpy(tmpbuf_cluster + pos, buffer, wsize);
ret = disk_write(startsect, mydata->clust_size, tmpbuf_cluster);
if (ret != mydata->clust_size) {
debug("Error writing data (got %d)\n", ret);
return -1;
}
size -= wsize;
buffer += wsize;
*gotsize += wsize;
startsect += mydata->clust_size;
if (!size)
return 0;
}
/* full-cluster write */
if (size >= bytesperclust) {
clustcount = lldiv(size, bytesperclust);
if (!((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1))) {
wsize = clustcount * bytesperclust;
ret = disk_write(startsect,
clustcount * mydata->clust_size,
buffer);
if (ret != clustcount * mydata->clust_size) {
debug("Error writing data (got %d)\n", ret);
return -1;
}
size -= wsize;
buffer += wsize;
*gotsize += wsize;
startsect += clustcount * mydata->clust_size;
} else {
for (i = 0; i < clustcount; i++) {
memcpy(tmpbuf_cluster, buffer, bytesperclust);
ret = disk_write(startsect,
mydata->clust_size,
tmpbuf_cluster);
if (ret != mydata->clust_size) {
debug("Error writing data (got %d)\n",
ret);
return -1;
}
size -= bytesperclust;
buffer += bytesperclust;
*gotsize += bytesperclust;
startsect += mydata->clust_size;
}
}
}
/* partial write at end */
if (size) {
wsize = size;
ret = disk_read(startsect, mydata->clust_size, tmpbuf_cluster);
if (ret != mydata->clust_size) {
debug("Error reading data (got %d)\n", ret);
return -1;
}
memcpy(tmpbuf_cluster, buffer, wsize);
ret = disk_write(startsect, mydata->clust_size, tmpbuf_cluster);
if (ret != mydata->clust_size) {
debug("Error writing data (got %d)\n", ret);
return -1;
}
size -= wsize;
buffer += wsize;
*gotsize += wsize;
}
assert(!size);
return 0;
}
/*
* Find the first empty cluster
*/
@ -578,26 +693,158 @@ set_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos, __u8 *buffer,
unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
__u32 curclust = START(dentptr);
__u32 endclust = 0, newclust = 0;
loff_t actsize;
loff_t cur_pos, offset, actsize, wsize;
*gotsize = 0;
filesize = maxsize;
filesize = pos + maxsize;
debug("%llu bytes\n", filesize);
if (curclust) {
/*
* release already-allocated clusters anyway
*/
if (clear_fatent(mydata, curclust)) {
printf("Error: clearing FAT entries\n");
if (!filesize) {
if (!curclust)
return 0;
if (!CHECK_CLUST(curclust, mydata->fatsize) ||
IS_LAST_CLUST(curclust, mydata->fatsize)) {
clear_fatent(mydata, curclust);
set_start_cluster(mydata, dentptr, 0);
return 0;
}
debug("curclust: 0x%x\n", curclust);
debug("Invalid FAT entry\n");
return -1;
}
if (!curclust) {
assert(pos == 0);
goto set_clusters;
}
/* go to cluster at pos */
cur_pos = bytesperclust;
while (1) {
if (pos <= cur_pos)
break;
if (IS_LAST_CLUST(curclust, mydata->fatsize))
break;
newclust = get_fatent(mydata, curclust);
if (!IS_LAST_CLUST(newclust, mydata->fatsize) &&
CHECK_CLUST(newclust, mydata->fatsize)) {
debug("curclust: 0x%x\n", curclust);
debug("Invalid FAT entry\n");
return -1;
}
cur_pos += bytesperclust;
curclust = newclust;
}
if (IS_LAST_CLUST(curclust, mydata->fatsize)) {
assert(pos == cur_pos);
goto set_clusters;
}
curclust = find_empty_cluster(mydata);
set_start_cluster(mydata, dentptr, curclust);
assert(pos < cur_pos);
cur_pos -= bytesperclust;
/* overwrite */
assert(IS_LAST_CLUST(curclust, mydata->fatsize) ||
!CHECK_CLUST(curclust, mydata->fatsize));
while (1) {
/* search for allocated consecutive clusters */
actsize = bytesperclust;
endclust = curclust;
while (1) {
if (filesize <= (cur_pos + actsize))
break;
newclust = get_fatent(mydata, endclust);
if (IS_LAST_CLUST(newclust, mydata->fatsize))
break;
if (CHECK_CLUST(newclust, mydata->fatsize)) {
debug("curclust: 0x%x\n", curclust);
debug("Invalid FAT entry\n");
return -1;
}
actsize += bytesperclust;
endclust = newclust;
}
/* overwrite to <curclust..endclust> */
if (pos < cur_pos)
offset = 0;
else
offset = pos - cur_pos;
wsize = min(cur_pos + actsize, filesize) - pos;
if (get_set_cluster(mydata, curclust, offset,
buffer, wsize, &actsize)) {
printf("Error get-and-setting cluster\n");
return -1;
}
buffer += wsize;
*gotsize += wsize;
cur_pos += offset + wsize;
if (filesize <= cur_pos)
break;
/* CHECK: newclust = get_fatent(mydata, endclust); */
if (IS_LAST_CLUST(newclust, mydata->fatsize))
/* no more clusters */
break;
curclust = newclust;
}
if (filesize <= cur_pos) {
/* no more write */
newclust = get_fatent(mydata, endclust);
if (!IS_LAST_CLUST(newclust, mydata->fatsize)) {
/* truncate the rest */
clear_fatent(mydata, newclust);
/* Mark end of file in FAT */
if (mydata->fatsize == 12)
newclust = 0xfff;
else if (mydata->fatsize == 16)
newclust = 0xffff;
else if (mydata->fatsize == 32)
newclust = 0xfffffff;
set_fatent_value(mydata, endclust, newclust);
}
return 0;
}
curclust = endclust;
filesize -= cur_pos;
assert(!(cur_pos % bytesperclust));
set_clusters:
/* allocate and write */
assert(!pos);
/* Assure that curclust is valid */
if (!curclust) {
curclust = find_empty_cluster(mydata);
set_start_cluster(mydata, dentptr, curclust);
} else {
newclust = get_fatent(mydata, curclust);
if (IS_LAST_CLUST(newclust, mydata->fatsize)) {
newclust = determine_fatent(mydata, curclust);
set_fatent_value(mydata, curclust, newclust);
curclust = newclust;
} else {
debug("error: something wrong\n");
return -1;
}
}
/* TODO: already partially written */
if (check_overflow(mydata, curclust, filesize)) {
printf("Error: no space left: %llu\n", filesize);
return -1;
@ -849,6 +1096,16 @@ int file_fat_write_at(const char *filename, loff_t pos, void *buffer,
goto exit;
}
/* A file exists */
if (pos == -1)
/* Append to the end */
pos = FAT2CPU32(retdent->size);
if (pos > retdent->size) {
/* No hole allowed */
ret = -EINVAL;
goto exit;
}
/* Update file size in a directory entry */
retdent->size = cpu_to_le32(pos + size);
} else {
@ -869,6 +1126,12 @@ int file_fat_write_at(const char *filename, loff_t pos, void *buffer,
goto exit;
}
if (pos) {
/* No hole allowed */
ret = -EINVAL;
goto exit;
}
memset(itr->dent, 0, sizeof(*itr->dent));
/* Set short name to set alias checksum field in dir_slot */
@ -918,10 +1181,5 @@ exit:
int file_fat_write(const char *filename, void *buffer, loff_t offset,
loff_t maxsize, loff_t *actwrite)
{
if (offset != 0) {
printf("Error: non zero offset is currently not supported.\n");
return -EINVAL;
}
return file_fat_write_at(filename, offset, buffer, maxsize, actwrite);
}

Write Preview
Loading…
Cancel
Save