[U-Boot] [BUG] cb8af8af5ba0 "fs: fat: support write with non-zero offset" leads to link error

On 9/11/18 8:59 AM, Akashi, Takahiro wrote:

From: AKASHI Takahiro takahiro.akashi@linaro.org

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

fs/fat/fat_write.c | 288 ++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 273 insertions(+), 15 deletions(-)

diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c index c22d8c7a46a1..651c7866debc 100644 --- a/fs/fat/fat_write.c +++ b/fs/fat/fat_write.c @@ -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));

This patch was merged as cb8af8af5ba03ae8e0a7315b66bfcc46d5c55627

When compiled with DEBUG=1 the line above leads to a link error:

fs/fat/fat_write.c:831: undefined reference to `__aeabi_ldivmod'

We should use function do_div() for the division.

Best regards

Heinrich