int umsdos_emd_dir_readentry (struct file *filp, struct umsdos_dirent *entry)
{
int ret;
Printk ((KERN_DEBUG "umsdos_emd_dir_readentry /mn/: entering.\n"));
ret = umsdos_emd_dir_read (filp, (char *) entry, UMSDOS_REC_SIZE);
if (ret == 0) { /* if no error */
/* Variable size record. Maybe, we have to read some more */
int recsize = umsdos_evalrecsize (entry->name_len);
if (recsize > UMSDOS_REC_SIZE) {
Printk ((KERN_DEBUG "umsdos_emd_dir_readentry /mn/: %d > %d!\n",
recsize, UMSDOS_REC_SIZE));
ret = umsdos_emd_dir_read (filp,
((char *) entry) + UMSDOS_REC_SIZE,
recsize - UMSDOS_REC_SIZE);
}
}
Printk (("umsdos_emd_dir_readentry /mn/: ret=%d.\n", ret));
if (entry && ret == 0) {
Printk (("umsdos_emd_dir_readentry /mn/: returning len=%d,name=%.*s\n",
(int) entry->name_len, (int) entry->name_len, entry->name));
}
return ret;
}
/*
Read an entry from the EMD file.
Support variable length record.
Return -EIO if error, 0 if ok.
*/
int umsdos_emd_dir_readentry (
struct inode *emd_dir,
struct file *filp,
struct umsdos_dirent *entry)
{
int ret = umsdos_emd_dir_read(emd_dir,filp,(char*)entry,UMSDOS_REC_SIZE);
if (ret == 0){
/* Variable size record. Maybe, we have to read some more */
int recsize = umsdos_evalrecsize (entry->name_len);
if (recsize > UMSDOS_REC_SIZE){
ret = umsdos_emd_dir_read(emd_dir,filp
,((char*)entry)+UMSDOS_REC_SIZE,recsize - UMSDOS_REC_SIZE);
}
}
return ret;
}
static int umsdos_find (struct dentry *parent, struct umsdos_info *info)
{
struct umsdos_dirent *entry = &info->entry;
int recsize = info->recsize;
struct dentry *demd;
struct inode *emd_dir;
int ret = -ENOENT;
struct find_buffer buf;
struct {
off_t posok; /* Position available to store the entry */
int found; /* A valid empty position has been found. */
off_t one; /* One empty position -> maybe <- large enough */
int onesize; /* size of empty region starting at one */
} empty;
Printk (("umsdos_find: locating %s in %s/%s\n",
entry->name, parent->d_parent->d_name.name, parent->d_name.name));
/*
* Lookup the EMD file in the parent directory.
*/
demd = umsdos_get_emd_dentry(parent);
ret = PTR_ERR(demd);
if (IS_ERR(demd))
goto out;
/* make sure there's an EMD file ... */
ret = -ENOENT;
emd_dir = demd->d_inode;
if (!emd_dir)
goto out_dput;
Printk(("umsdos_find: found EMD file %s/%s, ino=%p\n",
demd->d_parent->d_name.name, demd->d_name.name, emd_dir));
fill_new_filp (&buf.filp, demd);
buf.pos = 0;
buf.size = 0;
empty.found = 0;
empty.posok = emd_dir->i_size;
empty.onesize = 0;
while (1) {
struct umsdos_dirent *rentry = (struct umsdos_dirent *)
(buf.buffer + buf.pos);
int file_pos = buf.filp.f_pos - buf.size + buf.pos;
if (buf.pos == buf.size) {
ret = umsdos_fillbuf (&buf);
if (ret < 0) {
/* Not found, so note where it can be added */
info->f_pos = empty.posok;
break;
}
} else if (rentry->name_len == 0) {
/* We are looking for an empty section at least */
/* as large as recsize. */
if (entry->name_len == 0) {
info->f_pos = file_pos;
ret = 0;
break;
} else if (!empty.found) {
if (empty.onesize == 0) {
/* This is the first empty record of a section. */
empty.one = file_pos;
}
/* grow the empty section */
empty.onesize += UMSDOS_REC_SIZE;
if (empty.onesize == recsize) {
/* Here is a large enough section. */
empty.posok = empty.one;
empty.found = 1;
}
}
buf.pos += UMSDOS_REC_SIZE;
} else {
int entry_size = umsdos_evalrecsize (rentry->name_len);
if (buf.pos + entry_size > buf.size) {
ret = umsdos_fillbuf (&buf);
if (ret < 0) {
/* Not found, so note where it can be added */
info->f_pos = empty.posok;
break;
}
} else {
empty.onesize = 0; /* Reset the free slot search. */
if (entry->name_len == rentry->name_len
&& memcmp (entry->name, rentry->name, rentry->name_len) == 0) {
info->f_pos = file_pos;
*entry = *rentry;
ret = 0;
break;
} else {
buf.pos += entry_size;
}
}
}
}
Printk(("umsdos_find: ready to mangle %s, len=%d, pos=%ld\n",
entry->name, entry->name_len, (long)info->f_pos));
umsdos_manglename (info);
out_dput:
dput(demd);
out:
Printk (("umsdos_find: returning %d\n", ret));
return ret;
}
/*
General search, locate a name in the EMD file or an empty slot to
store it. if info->entry.name_len == 0, search the first empty
slot (of the proper size).
Caller must do iput on *pt_emd_dir.
Return 0 if found, -ENOENT if not found, another error code if
other problem.
So this routine is used to either find an existing entry or to
create a new one, while making sure it is a new one. After you
get -ENOENT, you make sure the entry is stuffed correctly and
call umsdos_writeentry().
To delete an entry, you find it, zero out the entry (memset)
and call umsdos_writeentry().
All this to say that umsdos_writeentry must be call after this
function since it rely on the f_pos field of info.
*/
static int umsdos_find (
struct inode *dir,
struct umsdos_info *info, /* Hold name and name_len */
/* Will hold the entry found */
struct inode **pt_emd_dir) /* Will hold the emd_dir inode */
/* or NULL if not found */
{
/* #Specification: EMD file structure
The EMD file uses a fairly simple layout. It is made of records
(UMSDOS_REC_SIZE == 64). When a name can't be written is a single
record, multiple contiguous record are allocated.
*/
int ret = -ENOENT;
struct inode *emd_dir = umsdos_emd_dir_lookup(dir,1);
if (emd_dir != NULL){
struct umsdos_dirent *entry = &info->entry;
int recsize = info->recsize;
struct {
off_t posok; /* Position available to store the entry */
int found; /* A valid empty position has been found */
off_t one; /* One empty position -> maybe <- large enough */
int onesize; /* size of empty region starting at one */
}empty;
/* Read several entries at a time to speed up the search */
struct find_buffer buf;
buf.pos = 0;
buf.size = 0;
buf.filp.f_pos = 0;
buf.filp.f_reada = 1;
empty.found = 0;
empty.posok = emd_dir->i_size;
empty.onesize = 0;
while (1){
struct umsdos_dirent *rentry = (struct umsdos_dirent*)
(buf.buffer + buf.pos);
int file_pos = buf.filp.f_pos - buf.size + buf.pos;
if (buf.pos == buf.size){
ret = umsdos_fillbuf (emd_dir,&buf);
if (ret < 0){
/* Not found, so note where it can be added */
info->f_pos = empty.posok;
break;
}
}else if (rentry->name_len == 0){
/* We are looking for an empty section at least */
/* recsize large */
if (entry->name_len == 0){
info->f_pos = file_pos;
ret = 0;
break;
}else if (!empty.found){
if (empty.onesize == 0){
/* This is the first empty record of a section */
empty.one = file_pos;
}
/* grow the empty section */
empty.onesize += UMSDOS_REC_SIZE;
if (empty.onesize == recsize){
/* here is a large enough section */
empty.posok = empty.one;
empty.found = 1;
}
}
buf.pos += UMSDOS_REC_SIZE;
}else{
int entry_size = umsdos_evalrecsize(rentry->name_len);
if (buf.pos+entry_size > buf.size){
ret = umsdos_fillbuf (emd_dir,&buf);
if (ret < 0){
/* Not found, so note where it can be added */
info->f_pos = empty.posok;
break;
}
}else{
empty.onesize = 0; /* Reset the free slot search */
if (entry->name_len == rentry->name_len
&& memcmp(entry->name,rentry->name,rentry->name_len)
==0){
info->f_pos = file_pos;
*entry = *rentry;
ret = 0;
break;
}else{
buf.pos += entry_size;
}
}
}
}
umsdos_manglename(info);
}
*pt_emd_dir = emd_dir;
return ret;
}