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filesys.c
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#undef DEBUG
#include <kernel.h>
#include <kdata.h>
#include <printf.h>
/*
* There are only two places in the core kernel that know about buffer
* data and manipulate it directly. This is one of them, and mm.c is the
* other. Please keep it that way if at all possible because at some point
* we will begin supporting out of memory map buffers.
*/
/* N_open is given a string containing a path name in user space,
* and returns an inode table pointer. If it returns NULL, the file
* did not exist. If the parent existed, and parent is not null,
* parent will be filled in with the parents inoptr. Otherwise, parent
* will be set to NULL.
* The last node parsed is saved in lastname and is useful to some system
* calls as they want a parent and to create the new node.
*/
uint8_t lastname[31];
static uint_fast8_t n_open_fault;
static uint_fast8_t n_fault_type;
static uint8_t *name, *nameend;
static uint8_t getcf(void)
{
if (name == nameend) {
udata.u_error = n_fault_type;
n_open_fault = 1;
return 0;
}
return (uint8_t)_ugetc(name);
}
inoptr n_open(uint8_t *namep, inoptr *parent)
{
staticfast inoptr wd; /* the directory we are currently searching. */
staticfast inoptr ninode;
regptr uint8_t *fp;
regptr inoptr temp;
uint8_t c;
usize_t len;
if (parent)
*parent = NULLINODE;
/* Check the user address and length. If it's shorter than 512 bytes this
is fine, but set nameeend accordingly. This allows us to use _ugetc
in the hot path which saves us a ton of cycles */
len = valaddr_r(namep, 512);
if (len == 0)
return NULLINODE;
name = namep;
nameend = namep + len;
n_open_fault = 0;
/* What error do we return if we hit nameend - are we overlong, or out
of memory space */
if (len == 512)
n_fault_type = ENAMETOOLONG;
else
n_fault_type = EACCES;
if(getcf() == '/')
wd = udata.u_root;
else
wd = udata.u_cwd;
ninode = i_ref(wd);
i_ref(ninode);
for(;;)
{
/* ninode is the inode we are walking from at this point and wd
the parent. They may be the same. We hold one reference to each */
if(ninode)
magic(ninode);
/* cheap way to spot rename inside yourself */
if (udata.u_rename == ninode)
udata.u_rename = NULLINODE;
/* See if we are at a mount point.
If we are a mount point then we swap the parent inode for
the child inode and swap the reference to the child
Q: could we set an incore inode flag for mountpoint to speed
this up ? */
if(ninode)
ninode = srch_mt(ninode);
/* Skip any slashes between nodes. The standards say there can be
multiple slashes */
while((c = getcf()) == '/')
++name;
/* It is acceptable to end a file path with / */
if(!c || n_open_fault) /* No more components of path? */
break;
/* If we failed to find our node we are done */
if(!ninode){
udata.u_error = ENOENT;
goto nodir;
}
/* Drop the reference to the old parent */
i_deref(wd);
/* Make the parent our own node. We now hold a single reference to
wd/ninode */
wd = ninode;
/* If we are still searching and the parent node is not a directory
we are done and we failed */
if(getmode(wd) != MODE_R(F_DIR)){
udata.u_error = ENOTDIR;
goto nodir;
}
/* If we are now allowed to access the directory then we are done */
if(!(getperm(wd) & OTH_EX)){
udata.u_error = EACCES;
goto nodir;
}
/* Walk the filename until / or end. Store the filename of up to
30 characters in lastname which is also used by our callers. It
is permissible to give longer name that matches the first 30 */
fp = lastname;
while((c = getcf()) != '\0') {
if (c == '/')
break;
if (fp != lastname + 30)
*fp++ = c;
++name;
}
/* Terminate the lastname buffer with \0 */
*fp = 0;
/* We are going up through a mount point if
either:
- We are accessing the root inode
- We are accessing the root inode number of a device
and:
- Our path is ..
FIXME: re-order tests for speed */
if((wd == udata.u_root || (wd->c_num == ROOTINODE && wd->c_dev != root_dev)) &&
lastname[0] == '.' && lastname[1] == '.' && lastname[2] == '\0') {
/* We are doing /../ */
if (wd == udata.u_root) {
i_ref(wd);
continue;
}
/* Find the mount point inode, which is hidden by the mount */
temp = fs_tab[wd->c_super].m_mntpt;
/* Take a reference to it */
i_ref(temp);
/* Drop the old directory */
i_deref(wd);
/* Fall through so we walk the mount point directory .. entry */
wd = temp;
}
/* Find the entry in the directory. ninode will be NULL if we failed or
valid and referenced if it existed */
ninode = srch_dir(wd, lastname);
}
/* If we faulted then treat it as invalid */
if (n_open_fault) {
udata.u_error = n_fault_type;
goto nodir;
}
/* Return the parent node if requested. This is needed by callers that
do directory manipulation */
if(parent)
*parent = wd;
else
i_deref(wd);
/* Check if we failed */
if(!(parent || ninode))
udata.u_error = ENOENT;
/* Return the target node if found. NULL with a valid parent is quite
possible and indicates the directory exists but the filename is new */
return ninode;
nodir:
if(parent)
*parent = NULLINODE;
i_deref(wd);
return NULLINODE;
}
/* Srch_dir is given an inode pointer of an open directory and a string
* containing a filename, and searches the directory for the file. If
* it exists, it opens it and returns the inode pointer, otherwise NULL.
* This depends on the fact that ba_read will return unallocated blocks
* as zero-filled, and a partially allocated block will be padded with
* zeroes.
*/
inoptr srch_dir(register inoptr wd, uint8_t *compname)
{
register struct direct *d;
register blkno_t curblock;
register struct blkbuf *buf;
uint_fast8_t curentry;
int nblocks;
uint16_t inum;
i_lock(wd);
nblocks = inode_blocks(wd);
for(curblock=0; curblock < nblocks; ++curblock) {
buf = bread(wd->c_dev, bmap(wd, curblock, 1), 0);
if (buf == NULL)
break;
for(curentry = 0; curentry < (BLKSIZE / DIR_LEN); ++curentry) {
d = blkptr(buf, curentry * DIR_LEN, DIR_LEN);
if(namecomp(compname, d->d_name)) {
inum = d->d_ino;
brelse(buf);
i_unlock(wd);
return i_open(wd->c_dev, inum);
}
}
brelse(buf);
}
i_unlock(wd);
return NULLINODE;
}
/* Srch_mt sees if the given inode is a mount point. If so it
* dereferences it, and references and returns a pointer to the
* root of the mounted filesystem.
*/
inoptr srch_mt(register inoptr ino)
{
register uint_fast8_t j;
register struct mount *m = &fs_tab[0];
for(j=0; j < NMOUNTS; ++j){
if(m->m_dev != NO_DEVICE && m->m_mntpt == ino) {
i_deref(ino);
return i_open(m->m_dev, ROOTINODE);
}
m++;
};
return ino;
}
/* I_open is given an inode number and a device number,
* and makes an entry in the inode table for them, or
* increases it reference count if it is already there.
* An inode # of zero means a newly allocated inode.
*
* Once we support sleeping on bigger boxes during I/O we will need
* a lock (superblock lock perhaps) to cover allocation of blocks and
* inodes.
*/
inoptr i_open(register uint16_t dev, uint16_t ino)
{
register inoptr nindex;
register inoptr j;
struct mount *m;
bool isnew = false;
validchk(dev, PANIC_IOPEN);
if(!ino){ /* ino==0 means we want a new one */
isnew = true;
ino = i_alloc(dev);
if(!ino) {
udata.u_error = ENOSPC;
return NULLINODE;
}
}
m = fs_tab_get(dev);
/* Maybe make this DEBUG only eventually - the fs_tab_get cost
is higher than ideal */
if(ino < ROOTINODE || ino >= (m->m_fs.s_isize - 2) * INO_PER_BLOCK) {
kputs("i_open: bad inode number\n");
return NULLINODE;
}
nindex = NULLINODE;
for(j = i_tab; j<i_tab + ITABSIZE; j++){
if(!j->c_refs) // free slot?
nindex = j;
if(j->c_dev == dev && j->c_num == ino) {
nindex = j;
goto found;
}
}
/* Not already in the table. */
if(!nindex){ /* No unrefed slots in inode table */
udata.u_error = ENFILE;
return(NULLINODE);
}
if (breadi(dev, ino, &nindex->c_node))
return NULLINODE;
nindex->c_dev = dev;
nindex->c_num = ino;
nindex->c_super = m - fs_tab;
nindex->c_magic = CMAGIC;
nindex->c_flags = (m->m_flags & MS_RDONLY) ? CRDONLY : 0;
found:
if(isnew) {
if(nindex->c_node.i_nlink || nindex->c_node.i_mode & F_MASK)
goto badino;
} else {
if(!(nindex->c_node.i_nlink && nindex->c_node.i_mode & F_MASK))
goto badino;
}
nindex->c_refs++;
return nindex;
badino:
kputs("i_open: bad disk inode\n");
return NULLINODE;
}
bool emptydir(register inoptr wd)
{
struct direct curentry;
i_islocked(wd);
udata.u_offset = 2 * DIR_LEN; /* . .. ignored */
do
{
udata.u_count = DIR_LEN;
udata.u_base = (uint8_t *)&curentry;
udata.u_sysio = true;
readi(wd, 0);
/* Read until EOF or name is found. readi() advances udata.u_offset */
if (*curentry.d_name)
return false;
} while(udata.u_done == DIR_LEN);
return true;
}
/* Ch_link modifies or makes a new entry in the directory for the name
* and inode pointer given. The directory is searched for oldname. When
* found, it is changed to newname, and it inode # is that of *nindex.
* A oldname of "" matches a unused slot, and a nindex of NULLINODE
* means an inode # of 0. A return status of 0 means there was no
* space left in the filesystem, or a non-empty oldname was not found,
* or the user did not have write permission.
*/
bool ch_link(register inoptr wd, uint8_t *oldname, uint8_t *newname, inoptr nindex)
{
struct direct curentry;
register int i;
i_islocked(wd);
if (wd->c_flags & CRDONLY) {
udata.u_error = EROFS;
return false;
}
/* FIXME: for modern style permissions we should also check whether
wd has the sticky bit set and if so require ownership or root */
if(!(getperm(wd) & OTH_WR))
{
udata.u_error = EACCES;
return false;
}
/* Inserting a new blank entry ? */
if (!*newname && nindex != NULLINODE) {
udata.u_error = EEXIST;
return false;
}
/* Search the directory for the desired slot. */
udata.u_offset = 0;
for(;;)
{
udata.u_count = DIR_LEN;
udata.u_base =(uint8_t *)&curentry;
udata.u_sysio = true;
readi(wd, 0);
/* Read until EOF or name is found. readi() advances udata.u_offset */
if(udata.u_done == 0 || namecomp(oldname, curentry.d_name))
break;
}
if(udata.u_done == 0 && *oldname) {
udata.u_error = ENOENT;
return false; /* Entry not found */
}
memcpy(curentry.d_name, newname, FILENAME_LEN);
/* FIXME: add strncpy and use for this */
for(i = 0; i < FILENAME_LEN; ++i)
if(curentry.d_name[i] == '\0')
break;
for(; i < FILENAME_LEN; ++i)
curentry.d_name[i] = '\0';
if(nindex)
curentry.d_ino = nindex->c_num;
else
curentry.d_ino = 0;
/* If an existing slot is being used, we must back up the file offset */
if(udata.u_done){
udata.u_offset -= DIR_LEN;
}
udata.u_count = DIR_LEN;
udata.u_base = (unsigned char*)&curentry;
udata.u_sysio = true;
writei(wd, 0);
if(udata.u_error)
return false;
setftime(wd, A_TIME|M_TIME|C_TIME); /* Sets CDIRTY */
/* Update file length to next block */
if(BLKOFF(wd->c_node.i_size))
wd->c_node.i_size += BLKSIZE - BLKOFF(wd->c_node.i_size);
return true; // success
}
/* Namecomp compares two strings to see if they are the same file name.
* It stops at FILENAME_LEN chars or a null or a slash. It returns 0 for difference.
*
* TODO: This generates crap code on most compilers so we probably ought to
* turn it into platform asm code.
*/
bool namecomp(uint8_t *n1, uint8_t *n2) // return true if n1 == n2
{
uint_fast8_t n; // do we have enough variables called n?
n = FILENAME_LEN;
while(*n1 && *n1 != '/')
{
if(*n1++ != *n2++)
return false; // mismatch
n--;
if(n==0)
return true; // match
}
return (*n2 == '\0' || *n2 == '/');
}
/* Newfile is given a pointer to a directory and a name, and creates
* an entry in the directory for the name, dereferences the parent,
* and returns a pointer to the new inode. It allocates an inode
* number, and creates a new entry in the inode table for the new
* file, and initializes the inode table entry for the new file.
* The new file will have one reference, and 0 links to it.
* Better make sure there isn't already an entry with the same name.
*
* Returns the new inode locked so nobody can access it before ready. We need
* to think hard about newfile taking a callback to fix up the ino struct so
* it's cleaner ???
*/
inoptr newfile(register inoptr pino, uint8_t *name)
{
register inoptr nindex;
register uint_fast8_t j;
/* No parent? */
if (!pino) {
udata.u_error = ENXIO;
goto nogood;
}
/* We check getperm before CRDONLY because if you reverse these two
it breaks gcc 68hc11 3.4 */
if (!(getperm(pino) & OTH_WR)) {
udata.u_error = EPERM;
goto nogood;
}
/* First see if parent is writeable */
if (pino->c_flags & CRDONLY) {
udata.u_error = EROFS;
goto nogood;
}
if (!(nindex = i_open(pino->c_dev, 0))) {
udata.u_error = ENFILE;
goto nogood;
}
i_lock(pino); /* Lock in tree order */
i_lock(ino);
/* This does not implement BSD style "sticky" groups */
nindex->c_node.i_uid = udata.u_euid;
nindex->c_node.i_gid = udata.u_egid;
nindex->c_node.i_mode = F_REG; /* For the time being */
nindex->c_node.i_nlink = 1;
nindex->c_node.i_size = 0;
for (j = 0; j < 20; j++) {
nindex->c_node.i_addr[j] = 0;
}
wr_inode(nindex);
if (!ch_link(pino, (uint8_t *)"", name, nindex)) {
i_deref(nindex);
/* ch_link sets udata.u_error */
goto nogood;
}
i_unlock_deref(pino);
return nindex;
nogood:
i_unlock_deref(pino);
return NULLINODE;
}
/* Check the given device number, and return its address in the mount
* table. Also time-stamp the superblock of dev, and mark it modified.
* Used when freeing and allocating blocks and inodes.
*/
fsptr getdev(uint16_t dev)
{
register struct mount *mnt;
time_t t;
mnt = fs_tab_get(dev);
if (!mnt || mnt->m_fs.s_mounted == 0) {
panic(PANIC_GD_BAD);
/* Return needed to persuade SDCC all is ok */
return NULL;
}
if (!(mnt->m_flags & MS_RDONLY)) {
rdtime(&t);
mnt->m_fs.s_time = t.low;
mnt->m_fs.s_timeh = t.high;
mnt->m_fs.s_fmod = FMOD_DIRTY;
}
return &mnt->m_fs;
}
/* Returns true if the magic number of a superblock is corrupt. */
bool inline baddev(fsptr dev)
{
return(dev->s_mounted != SMOUNTED);
}
/* I_alloc finds an unused inode number, and returns it, or 0
* if there are no more inodes available.
*
* This will need to happen under the superblock lock once we do sleeping
*/
uint16_t i_alloc(uint16_t devno)
{
staticfast fsptr dev;
staticfast blkno_t blk;
register struct dinode *di;
staticfast uint16_t j;
register struct blkbuf *buf;
uint16_t k;
unsigned ino;
if(baddev(dev = getdev(devno)))
goto corrupt;
tryagain:
if(dev->s_ninode) {
if(!(dev->s_tinode))
goto corrupt;
ino = dev->s_inode[--dev->s_ninode];
if(ino < 2 || ino >=(dev->s_isize-2)*8)
goto corrupt;
--dev->s_tinode;
return(ino);
}
/* We must scan the inodes, and fill up the table */
sync(); /* Make on-disk inodes consistent */
k = 0;
for(blk = 2; blk < dev->s_isize; blk++) {
buf = bread(devno, blk, 0);
if (buf == NULL)
goto corrupt;
for(j=0; j < INO_PER_BLOCK; j++) {
/* Optimisation: add offsetof and use that to reduce blkptr range */
di = blkptr(buf, sizeof(struct dinode) * j, sizeof(struct dinode));
if(!(di->i_mode || di->i_nlink))
dev->s_inode[k++] = INO_PER_BLOCK * (blk - 2) + j;
if(k == FILESYS_TABSIZE) {
brelse(buf);
goto done;
}
}
brelse(buf);
}
done:
if(!k) {
if(dev->s_tinode)
goto corrupt;
udata.u_error = ENOSPC;
return(0);
}
dev->s_ninode = k;
goto tryagain;
corrupt:
kputs("i_alloc: corrupt superblock\n");
dev->s_mounted = 1;
udata.u_error = ENOSPC;
return(0);
}
/* I_free is given a device and inode number, and frees the inode.
* It is assumed that there are no references to the inode in the
* inode table or in the filesystem.
*
* This will need to happen under the superblock lock once we do sleeping
*/
void i_free(uint16_t devno, uint16_t ino)
{
register fsptr dev;
if(baddev(dev = getdev(devno)))
return;
if(ino < 2 || ino >=(dev->s_isize-2)*8)
panic(PANIC_IFREE_BADI);
++dev->s_tinode;
if(dev->s_ninode < FILESYS_TABSIZE)
dev->s_inode[dev->s_ninode++] = ino;
}
/* Blk_alloc is given a device number, and allocates an unused block
* from it. A returned block number of zero means no more blocks.
*
* This will need to happen under the superblock lock once we do sleeping
*/
blkno_t blk_alloc(uint16_t devno)
{
register fsptr dev;
register struct blkbuf *buf;
blkno_t newno;
if(baddev(dev = getdev(devno)))
goto corrupt2;
if(dev->s_nfree <= 0 || dev->s_nfree > FILESYS_TABSIZE)
goto corrupt;
newno = dev->s_free[--dev->s_nfree];
if(!newno)
{
if(dev->s_tfree != 0)
goto corrupt;
udata.u_error = ENOSPC;
++dev->s_nfree;
return(0);
}
/* See if we must refill the s_free array */
if(!dev->s_nfree)
{
buf = bread(devno, newno, 0);
if (buf == NULL)
goto corrupt;
blktok(&dev->s_nfree, buf, 0,
sizeof(int) + FILESYS_TABSIZE * sizeof(blkno_t));
/* This assumes no padding: this is an UZI era assumption */
brelse(buf);
}
validblk(devno, newno);
if(!dev->s_tfree)
goto corrupt;
--dev->s_tfree;
/*
* FIXME: When we implement the rest of the bigger block size fs support
* this routine is responsible for zeroing the entire extent not just the
* BLKSIZE byte block
*/
/* Zero out the new block */
buf = bread(devno, newno, 2);
if (buf == NULL)
goto corrupt;
blkzero(buf);
bawrite(buf);
return newno;
corrupt:
kputs("blk_alloc: corrupt\n");
dev->s_mounted = 1;
corrupt2:
udata.u_error = ENOSPC;
return 0;
}
/* Blk_free is given a device number and a block number,
* and frees the block.
*
* This will need to happen under the superblock lock once we do sleeping
*/
void blk_free(uint16_t devno, blkno_t blk)
{
fsptr dev;
struct blkbuf *buf;
if(!blk)
return;
if(baddev(dev = getdev(devno)))
return;
validblk(devno, blk);
if(dev->s_nfree == FILESYS_TABSIZE) {
buf = bread(devno, blk, 1);
if (buf) {
/* nfree must directly preceed the blocks and without padding. That's
the assumption UZI always had */
blkfromk(&dev->s_nfree, buf, 0, sizeof(int) + 50 * sizeof(blkno_t));
bawrite(buf);
dev->s_nfree = 0;
} else
dev->s_mounted = 1;
}
++dev->s_tfree;
dev->s_free[(dev->s_nfree)++] = blk;
}
/* Oft_alloc and oft_deref allocate and dereference(and possibly free)
* entries in the open file table.
*/
int_fast8_t oft_alloc(void)
{
register uint_fast8_t j;
for(j=0; j < OFTSIZE ; ++j) {
if(of_tab[j].o_refs == 0) {
of_tab[j].o_refs = 1;
of_tab[j].o_inode = NULLINODE;
return j;
}
}
udata.u_error = ENFILE;
return -1;
}
/*
* To minimise storage we don't track exclusive locks explicitly. We know
* that if we are dropping an exclusive lock then we must be the owner,
* and if we are dropping a lock that is not exclusive we must own one of
* the non exclusive locks.
*/
void deflock(register struct oft *ofptr)
{
register inoptr i = ofptr->o_inode;
register uint_fast8_t c = i->c_flags & CFLOCK;
if (ofptr->o_access & O_FLOCK) {
if (c == CFLEX)
c = 0;
else
c--;
i->c_flags = (i->c_flags & ~CFLOCK) | c;
wakeup(&i->c_flags);
}
}
/*
* Drop a reference in the open file table. If this is the last reference
* from a user file table then drop any file locks, dereference the inode
* and mark empty
*/
void oft_deref(uint_fast8_t of)
{
register struct oft *ofptr;
ofptr = of_tab + of;
if(!(--ofptr->o_refs) && ofptr->o_inode) {
deflock(ofptr);
i_deref(ofptr->o_inode);
ofptr->o_inode = NULLINODE;
}
}
/* Uf_alloc finds an unused slot in the user file table.*/
int_fast8_t uf_alloc_n(uint_fast8_t base)
{
register uint_fast8_t j;
for(j=base; j < UFTSIZE ; ++j) {
if(udata.u_files[j] == NO_FILE) {
return j;
}
}
udata.u_error = EMFILE;
return -1;
}
int_fast8_t uf_alloc(void)
{
return uf_alloc_n(0);
}
/* I_deref decreases the reference count of an inode, and frees it from
* the table if there are no more references to it. If it also has no
* links, the inode itself and its blocks(if not a device) is freed.
*/
void i_deref(register inoptr ino)
{
uint_fast8_t mode = getmode(ino);
magic(ino);
if(!ino->c_refs)
panic(PANIC_INODE_FREED);
if (mode == MODE_R(F_PIPE))
wakeup((uint8_t *)ino);
/* If the inode has no links and no refs, it must have
its blocks freed. */
if(!(--ino->c_refs || ino->c_node.i_nlink))
/*
SN (mcy)
*/
if (mode == MODE_R(F_REG) || mode == MODE_R(F_DIR) || mode == MODE_R(F_PIPE))
f_trunc(ino);
/* If the inode was modified, we must write it to disk. */
if(!(ino->c_refs) && (ino->c_flags & CDIRTY))
{
if(!(ino->c_node.i_nlink))
{
ino->c_node.i_mode = 0;
i_free(ino->c_dev, ino->c_num);
}
wr_inode(ino);
}
}
void corrupt_fs(uint16_t devno)
{
struct mount *mnt = fs_tab_get(devno);
mnt->m_fs.s_mounted = 1;
kputs("filesystem corrupt.\n");
}
/* Wr_inode writes out the given inode in the inode table out to disk,
* and resets its dirty bit.
*/
void wr_inode(register inoptr ino)
{
/* struct blkbuf *buf;
blkno_t blkno;
*/
magic(ino);
if (bwritei(ino))
corrupt_fs(ino->c_dev);
else
ino->c_flags &= ~CDIRTY;
}
/* isdevice(ino) returns true if ino points to a device */
bool isdevice(inoptr ino)
{
return !!(ino->c_node.i_mode & F_CDEV);
}
/* This returns the device number of an inode representing a device */
uint16_t devnum(inoptr ino)
{
return (uint16_t)ino->c_node.i_addr[0];
}
/*
* f_trunc_blocks frees all the blocks associated with the file, if it
* is a disk file. The blocks are freed in reverse order. This is
* very important so that they end up on the freelist in the
* order we want to allocate them.
*/
int f_trunc_blocks(register inoptr ino, uint16_t nblock)
{
register uint16_t dev;
register int_fast8_t j;
uint16_t map1 = 0;
uint16_t map2 = 0;
if (ino->c_flags & CRDONLY) {
udata.u_error = EROFS;
return -1;
}
/* Block offsets are
0-17 direct
18 256 blocks (18-273)
19 256 * 256 blocks (274-65810)
(We only allow 65535 block offset in order to keep a lot of stuff
uint16_t - FIXME to fix u writei())
We don't support triple indirect blocks.
When we are called nblock is the number of blocks that will
remain in the file when we truncate it
We set map1 to the number of blocks we must purge for single
indirect. We set map2 for the number of blocks we must purge
of double indirect.
freeblk frees full subblocks above the block passed, and then frees
blocks >> 8 on the last iteration to partially clear the last set
*/
if (nblock > 17 && nblock < 274)
map1 = (nblock - 18) << 8;
else if (nblock > 273)
map2 = nblock - 273;
dev = ino->c_dev;
/* FIXME: ideally zero the indirect pointers before we write the
free lists */
/* First deallocate the double indirect blocks */
freeblk(dev, ino->c_node.i_addr[19], 2, map2);
if (map2)
ino->c_node.i_addr[19] = 0;
/* Also deallocate the indirect blocks */
freeblk(dev, ino->c_node.i_addr[18], 1, map1);
if (map1 == 0 && map2 == 0) /* ???? should this just be if map1 */
ino->c_node.i_addr[18] = 0;
/* Finally, free the direct blocks */
/* FIXME: use pointers for efficiency ? */
/* At this point nblock is definitely < 0x8000 so forcing a signed
compare does what we want */
for(j = 17; j >= (int)nblock; --j) {
freeblk(dev, ino->c_node.i_addr[j], 0, 0);
ino->c_node.i_addr[j] = 0;
}
ino->c_flags |= CDIRTY;
return 0;
}
/* Truncate a file back to nothing using f_trunc_blocks and then write
the inode size as 0 */
int f_trunc(regptr inoptr ino)