/*
Truncate a file to 0 length.
*/
static void UMSDOS_truncate(struct inode *inode)
{
PRINTK (("UMSDOS_truncate\n"));
msdos_truncate (inode);
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
inode->i_dirt = 1;
}
/*
Write to a file either from user space
*/
int msdos_file_write(
struct inode *inode,
struct file *filp,
const char *buf,
int count)
{
struct super_block *sb = inode->i_sb;
int sector,offset,size,left,written;
int error,carry;
char *start,*to,ch;
struct buffer_head *bh;
int binary_mode = MSDOS_I(inode)->i_binary;
if (!inode) {
printk("msdos_file_write: inode = NULL\n");
return -EINVAL;
}
/* S_ISLNK allows for UMSDOS. Should never happen for normal MSDOS */
if (!S_ISREG(inode->i_mode) && !S_ISLNK(inode->i_mode)) {
printk("msdos_file_write: mode = %07o\n",inode->i_mode);
return -EINVAL;
}
/*
* ok, append may not work when many processes are writing at the same time
* but so what. That way leads to madness anyway.
*/
if (filp->f_flags & O_APPEND) filp->f_pos = inode->i_size;
if (count <= 0) return 0;
error = carry = 0;
for (start = (char *)buf; count || carry; count -= size) {
while (!(sector = msdos_smap(inode,filp->f_pos >> SECTOR_BITS)))
if ((error = msdos_add_cluster(inode)) < 0) break;
if (error) {
msdos_truncate(inode);
break;
}
offset = filp->f_pos & (SECTOR_SIZE-1);
size = MIN(SECTOR_SIZE-offset,MAX(carry,count));
if (binary_mode
&& offset == 0
&& (size == SECTOR_SIZE
|| filp->f_pos + size >= inode->i_size)){
/* No need to read the block first since we will */
/* completely overwrite it */
/* or at least write past the end of file */
if (!(bh = getblk(inode->i_dev,sector,SECTOR_SIZE))){
error = -EIO;
break;
}
}else if (!(bh = bread(inode->i_dev,sector,SECTOR_SIZE))) {
error = -EIO;
break;
}
if (binary_mode) {
memcpy_fromfs(bh->b_data+offset,buf,written = size);
buf += size;
}
else {
written = left = SECTOR_SIZE-offset;
to = (char *) bh->b_data+(filp->f_pos & (SECTOR_SIZE-1));
if (carry) {
*to++ = '\n';
left--;
carry = 0;
}
for (size = 0; size < count && left; size++) {
if ((ch = get_fs_byte(buf++)) == '\n') {
*to++ = '\r';
left--;
}
if (!left) carry = 1;
else {
*to++ = ch;
left--;
}
}
written -= left;
}
filp->f_pos += written;
if (filp->f_pos > inode->i_size) {
inode->i_size = filp->f_pos;
inode->i_dirt = 1;
}
msdos_set_uptodate(sb,bh,1);
mark_buffer_dirty(bh, 0);
brelse(bh);
}
if (start == buf)
return error;
inode->i_mtime = inode->i_ctime = FS_CURRENT_TIME;
MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
inode->i_dirt = 1;
return buf-start;
}
