/*------------------------------------------------------------------------
* lfflush - flush data block and index blocks for an open file
* (assumes file mutex is held)
*------------------------------------------------------------------------
*/
status lfflush (
struct lflcblk *lfptr /* ptr to file pseudo device */
)
{
if (lfptr->lfstate == LF_FREE) {
return SYSERR;
}
/* Write data block if it has changed */
if (lfptr->lfdbdirty) {
write(Lf_data.lf_dskdev, lfptr->lfdblock, lfptr->lfdnum);
lfptr->lfdbdirty = FALSE;
}
/* Write i-block if it has changed */
if (lfptr->lfibdirty) {
lfibput(Lf_data.lf_dskdev, lfptr->lfinum, &lfptr->lfiblock);
lfptr->lfibdirty = FALSE;
}
return OK;
}
/*------------------------------------------------------------------------
* lfscreate -- Create an initially-empty file system on a disk
*------------------------------------------------------------------------
*/
status lfscreate (
did32 disk, /* ID of an open disk device */
ibid32 lfiblks, /* num. of index blocks on disk */
uint32 dsiz /* total size of disk in bytes */
)
{
uint32 sectors; /* number of sectors to use */
uint32 ibsectors; /* number of sectors of i-blocks*/
uint32 ibpersector; /* number of i-blocks per sector*/
struct lfdir dir; /* Buffer to hold the directory */
uint32 dblks; /* total free data blocks */
struct lfiblk iblock; /* space for one i-block */
struct lfdbfree dblock; /* data block on the free list */
dbid32 dbindex; /* index for data blocks */
int32 retval; /* return value from func call */
int32 i; /* loop index */
//ibid32 nextib;
//dbid32 nextdb;
//int32 lfiblks_free; /* total free index blocks */
/* Compute total sectors on disk */
sectors = dsiz / LF_BLKSIZ; /* truncate to full sector */
/* Compute number of sectors comprising i-blocks */
ibpersector = LF_BLKSIZ / sizeof(struct lfiblk);
ibsectors = (lfiblks+(ibpersector-1)) / ibpersector; /* round up*/
lfiblks = ibsectors * ibpersector;
if (ibsectors > sectors/2) { /* invalid arguments */
//kprintf("ibsectors > sectors/2 - invalid arguments\r\n");
return SYSERR;
}
/* Create an initial sector 0 */
memset((char *)&dir, NULLCH, sizeof(struct lfdir));
//dir.lfd_nfiles = 0;
dbindex= (dbid32)(ibsectors + 1);
dir.lfd_ifree = 1;
dir.lfd_dfree = dbindex + 1;
dblks = sectors - ibsectors - 1;
/* Initialize root directory entry */
(dir.root_entry).ld_size = 0;
(dir.root_entry).ld_ilist = 0;
(dir.root_entry).ld_name[0] = '/';
(dir.root_entry).ld_name[1] = NULLCH;
(dir.root_entry).ld_type = LF_TYPE_DIR;
retval = write(disk,(char *)&dir, LF_AREA_DIR);
if (retval == SYSERR) {
//kprintf("cannot create an initial directory\r\n");
return SYSERR;
}
/* Create an initial root directory index block 0 */
memset((char *)&iblock, NULLCH, sizeof(struct lfiblk));
lfibclear(&iblock, 0);
iblock.ib_next = LF_INULL;
iblock.ib_dba[0] = dbindex; /* point to first data blk */
for(i =1; i < LF_IBLEN; i++) {
iblock.ib_dba[i] = LF_DNULL;
}
lfibput(disk, 0, &iblock);
/* Create list of free i-blocks on disk from i-bloack 1 */
lfibclear(&iblock, 0);
for (i=1; i<lfiblks-1; i++) {
iblock.ib_next = (ibid32)(i + 1);
lfibput(disk, i, &iblock);
}
iblock.ib_next = LF_INULL;
lfibput(disk, i, &iblock);
/* Create an initial root directory data block 0 */
memset((char *)&dblock, NULLCH, LF_BLKSIZ);
write(disk, (char *)&dblock, dbindex);
/* Create list of free data blocks on disk */
memset((char*)&dblock, NULLCH, LF_BLKSIZ);
for (i=1; i<dblks-1; i++) {
dblock.lf_nextdb = dbindex + 2;
retval = write(disk, (char *)&dblock, dbindex+1);
if (retval == SYSERR) {
//kprintf("cannot create list of free data blocks on disk\r\n");
return SYSERR;
}
dbindex++;
}
dblock.lf_nextdb = LF_DNULL;
retval = write(disk, (char *)&dblock, dbindex+1);
if (retval == SYSERR) {
//kprintf("cannot create list of free data blocks on disk\r\n");
return SYSERR;
}
//close(disk);
/* //kprintf("lfscreate Done\r\n");
retval = read(disk,(char *)&dir, LF_AREA_DIR);
lfiblks_free = 0;
nextib = dir.lfd_ifree;
//kprintf("initial index block is %d\n\r", nextib);
while (nextib != LF_INULL) {
lfiblks_free++;
lfibget(disk, nextib, &iblock);
nextib = iblock.ib_next;
}
ibsectors = (lfiblks_free + 6) /7;
//kprintf("Found %d index blocks (%d sectors)\n\r", lfiblks_free, ibsectors); */
/* Follow data block list */
/* dblks = 0;
nextdb = dir.lfd_dfree;
//kprintf("initial data block is %d\n\r", nextdb);
while (nextdb != LF_DNULL) {
dblks++;
read(disk, (char *)&dblock, nextdb);
nextdb = dblock.lf_nextdb;
}
//kprintf("Found %d data blocks\n\r", dblks);*/
return OK;
}
/*------------------------------------------------------------------------
* lfsetup - Set a file's index block and data block for the current
* file position (assumes file mutex held)
*------------------------------------------------------------------------
*/
status lfsetup (
struct lflcblk *lfptr /* Pointer to slave file device */
)
{
dbid32 dnum; /* Data block to fetch */
ibid32 ibnum; /* I-block number during search */
struct ldentry *ldptr; /* Ptr to file entry in dir. */
struct lfiblk *ibptr; /* Ptr to in-memory index block */
uint32 newoffset; /* Computed data offset for */
/* next index block */
int32 dindex; /* Index into array in an index */
/* block */
/* Obtain exclusive access to the directory */
wait(Lf_data.lf_mutex);
/* Get pointers to in-memory directory, file's entry in the */
/* directory, and the in-memory index block */
ldptr = lfptr->lfdirptr;
ibptr = &lfptr->lfiblock;
/* If existing index block or data block changed, write to disk */
if (lfptr->lfibdirty || lfptr->lfdbdirty) {
lfflush(lfptr);
}
ibnum = lfptr->lfinum; /* Get ID of curr. index block */
/* If there is no index block in memory (e.g., because the file */
/* was just opened), either load the first index block of */
/* the file or allocate a new first index block */
if (ibnum == LF_INULL) {
/* Check directory entry to see if index block exists */
ibnum = ldptr->ld_ilist;
if (ibnum == LF_INULL) { /* Empty file - get new i-block*/
ibnum = lfiballoc();
lfibclear(ibptr, 0);
ldptr->ld_ilist = ibnum;
lfptr->lfibdirty = TRUE;
} else { /* Nonempty - read first i-block*/
lfibget(Lf_data.lf_dskdev, ibnum, ibptr);
}
lfptr->lfinum = ibnum;
/* Otherwise, if current file position has been moved to an */
/* offset before the current index block, start at the */
/* beginning of the index list for the file */
} else if (lfptr->lfpos < ibptr->ib_offset) {
/* Load initial index block for the file (we know that */
/* at least one index block exists) */
ibnum = ldptr->ld_ilist;
lfibget(Lf_data.lf_dskdev, ibnum, ibptr);
lfptr->lfinum = ibnum;
}
/* At this point, an index block is in memory, but may cover */
/* an offset less than the current file position. Loop until */
/* the index block covers the current file position. */
while ((lfptr->lfpos & ~LF_IMASK) > ibptr->ib_offset ) {
ibnum = ibptr->ib_next;
if (ibnum == LF_INULL) {
/* Allocate new index block to extend file */
ibnum = lfiballoc();
ibptr->ib_next = ibnum;
lfibput(Lf_data.lf_dskdev, lfptr->lfinum, ibptr);
lfptr->lfinum = ibnum;
newoffset = ibptr->ib_offset + LF_IDATA;
lfibclear(ibptr, newoffset);
lfptr->lfibdirty = TRUE;
} else {
lfibget(Lf_data.lf_dskdev, ibnum, ibptr);
lfptr->lfinum = ibnum;
}
lfptr->lfdnum = LF_DNULL; /* Invalidate old data block */
}
/* At this point, the index block in lfiblock covers the */
/* current file position (i.e., position lfptr->lfpos). The */
/* next step consists of loading the correct data block. */
dindex = (lfptr->lfpos & LF_IMASK) >> 9;
/* If data block index does not match current data block, read */
/* the correct data block from disk */
dnum = lfptr->lfiblock.ib_dba[dindex];
if (dnum == LF_DNULL) { /* Allocate new data block */
dnum = lfdballoc((struct lfdbfree *)&lfptr->lfdblock);
lfptr->lfiblock.ib_dba[dindex] = dnum;
lfptr->lfibdirty = TRUE;
} else if ( dnum != lfptr->lfdnum) {
read(Lf_data.lf_dskdev, (char *)lfptr->lfdblock, dnum);
lfptr->lfdbdirty = FALSE;
}
lfptr->lfdnum = dnum;
/* Use current file offset to set the pointer to the next byte */
/* within the data block */
lfptr->lfbyte = &lfptr->lfdblock[lfptr->lfpos & LF_DMASK];
signal(Lf_data.lf_mutex);
return OK;
}
/*------------------------------------------------------------------------
* lftruncate - truncate a file by freeing its index and data blocks
* (assumes directory mutex held)
*------------------------------------------------------------------------
*/
status lftruncate (
struct lflcblk *lfptr /* ptr to file's cntl blk entry */
)
{
//struct ldentry *ldptr; /* pointer to file's dir. entry */
struct lfiblk iblock; /* buffer for one index block */
ibid32 ifree; /* start of index blk free list */
ibid32 firstib; /* first index blk of the file */
ibid32 nextib; /* walks down list of the */
/* file's index blocks */
dbid32 nextdb; /* next data block to free */
int32 i; /* moves through data blocks in */
/* a given index block */
//ldptr = lfptr->lfdirptr; /* Get pointer to dir. entry */
if (lfptr->lfsize == 0) { /* file is already empty */
return OK;
}
/* Clean up the open local file first */
if ( (lfptr->lfibdirty) || (lfptr->lfdbdirty) ) {
lfflush(lfptr);
}
lfptr->lfpos = 0;
lfptr->lfinum = LF_INULL;
lfptr->lfdnum = LF_DNULL;
lfptr->lfbyte = &lfptr->lfdblock[LF_BLKSIZ];
/* Obtain ID of first index block on free list */
ifree = Lf_data.lf_dir.lfd_ifree;
/* Record file's first i-block and clear directory entry */
firstib = lfptr->lffirstib;
lfptr->lffirstib= LF_INULL;
lfptr->lfsize = 0;
Lf_data.lf_dirdirty = TRUE;
/* Walk along index block list, disposing of each data block */
/* and clearing the corresponding pointer. A note on loop */
/* termination: last pointer is set to ifree below. */
for (nextib=firstib; nextib!=ifree; nextib=iblock.ib_next) {
/* Obtain a copy of current index block from disk */
lfibget(Lf_data.lf_dskdev, nextib, &iblock);
/* Free each data block in the index block */
for (i=0; i<LF_IBLEN; i++) { /* for each d-block */
/* Free the data block */
nextdb = iblock.ib_dba[i];
if (nextdb != LF_DNULL) {
lfdbfree(Lf_data.lf_dskdev, nextdb);
}
/* Clear entry in i-block for this d-block */
iblock.ib_dba[i] = LF_DNULL;
}
/* Clear offset (just to make debugging easier) */
iblock.ib_offset = 0;
/* For the last index block on the list, make it point */
/* to the current free list */
if (iblock.ib_next == LF_INULL) {
iblock.ib_next = ifree;
}
/* Write cleared i-block back to disk */
lfibput(Lf_data.lf_dskdev, nextib, &iblock);
}
/* Last index block on the file list now points to first node */
/* on the current free list. Once we make the free list */
/* point to the first index block on the file list, the */
/* entire set of index blocks will be on the free list */
Lf_data.lf_dir.lfd_ifree = firstib;
/* Indicate that directory has changed and return */
Lf_data.lf_dirdirty = TRUE;
return OK;
}
/*------------------------------------------------------------------------
* lfscreate - Create an initially-empty file system on a disk
*------------------------------------------------------------------------
*/
status lfscreate (
did32 disk, /* ID of an open disk device */
ibid32 lfiblks, /* Num. of index blocks on disk */
uint32 dsiz /* Total size of disk in bytes */
)
{
uint32 sectors; /* Number of sectors to use */
uint32 ibsectors; /* Number of sectors of i-blocks*/
uint32 ibpersector; /* Number of i-blocks per sector*/
struct lfdir dir; /* Buffer to hold the directory */
uint32 dblks; /* Total free data blocks */
struct lfiblk iblock; /* Space for one i-block */
struct lfdbfree dblock; /* Data block on the free list */
dbid32 dbindex; /* Index for data blocks */
int32 retval; /* Return value from func call */
int32 i; /* Loop index */
/* Compute total sectors on disk */
sectors = dsiz / LF_BLKSIZ; /* Truncate to full sector */
/* Compute number of sectors comprising i-blocks */
ibpersector = LF_BLKSIZ / sizeof(struct lfiblk);
ibsectors = (lfiblks+(ibpersector-1)) / ibpersector;/* Round up */
lfiblks = ibsectors * ibpersector;
if (ibsectors > sectors/2) { /* Invalid arguments */
return SYSERR;
}
/* Create an initial directory */
memset((char *)&dir, NULLCH, sizeof(struct lfdir));
dir.lfd_nfiles = 0;
dbindex= (dbid32)(ibsectors + 1);
dir.lfd_dfree = dbindex;
dblks = sectors - ibsectors - 1;
retval = write(disk,(char *)&dir, LF_AREA_DIR);
if (retval == SYSERR) {
return SYSERR;
}
/* Create list of free i-blocks on disk */
lfibclear(&iblock, 0);
for (i=0; i<lfiblks-1; i++) {
iblock.ib_next = (ibid32)(i + 1);
lfibput(disk, i, &iblock);
}
iblock.ib_next = LF_INULL;
lfibput(disk, i, &iblock);
/* Create list of free data blocks on disk */
memset((char*)&dblock, NULLCH, LF_BLKSIZ);
for (i=0; i<dblks-1; i++) {
dblock.lf_nextdb = dbindex + 1;
write(disk, (char *)&dblock, dbindex);
dbindex++;
}
dblock.lf_nextdb = LF_DNULL;
write(disk, (char *)&dblock, dbindex);
close(disk);
return OK;
}
/*------------------------------------------------------------------------
* lfstruncate - truncate a file by freeing its index and data blocks
* (assumes directory mutex held)
*------------------------------------------------------------------------
*/
status lfstruncate (
char *name /* file name to truncate */
)
{
char *nam, *cmp; /* ptrs used during comparison */
int32 i; /* general loop index */
struct lflcblk *lfptr; /* ptr to open file table entry */
struct lfdir *dirptr; /* ptr to in-memory directory */
bool8 found; /* was the name found? */
int32 retval; /* value returned from function */
struct ldentry *ldptr; /* ptr to an entry in directory */
ibid32 ifree; /* start of index blk free list */
ibid32 firstib; /* first index blk of the file */
ibid32 nextib; /* walks down list of the */
/* file's index blocks */
dbid32 nextdb; /* next data block to free */
struct lfiblk iblock; /* buffer for one index block */
/* Check length of name file (leaving space for NULLCH */
nam = name;
for (i=0; i< LF_NAME_LEN; i++) {
if (*nam++ == NULLCH) {
break;
}
}
if (i >= LF_NAME_LEN) { /* name is too long */
//kprintf("Name is too long\r\n");
return SYSERR;
}
/* Check if named file is open */
for (i=0; i<Nlfl; i++) { /* search file pseudo-devices */
lfptr = &lfltab[i];
if (lfptr->lfstate == LF_USED) {
/* Compare requested name to name of open file */
nam = name;
cmp = lfptr->lfname;
while(*nam != NULLCH) {
if (*nam != *cmp) {
break;
}
nam++;
cmp++;
}
/* if named file is open, call lftruncate directly */
if ( (*nam==NULLCH) && (*cmp == NULLCH) ) {
//kprintf("file to truncate is open\r\n");
wait(lfptr->lfmutex);
retval = lftruncate(lfptr);
signal(lfptr->lfmutex);
//kprintf("truncated the open file\r\n");
return retval;
}
}
}
/* Named file is not open */
/* Obtain copy of directory if not already present in memory */
dirptr = &Lf_data.lf_dir;
if (! Lf_data.lf_dirpresent) {
retval = read(Lf_data.lf_dskdev,(char *)dirptr,LF_AREA_DIR);
if (retval == SYSERR ) {
//kprintf("Cannot not read directory into memory\r\n");
return SYSERR;
}
Lf_data.lf_dirpresent = TRUE;
}
/* Search directory to see if file exists */
found = FALSE;
for (i=0; i<dirptr->lfd_nfiles; i++) {
ldptr = &dirptr->lfd_files[i];
nam = name;
cmp = ldptr->ld_name;
while(*nam != NULLCH) {
if (*nam != *cmp) {
break;
}
nam++;
cmp++;
}
if ( (*nam==NULLCH) && (*cmp==NULLCH) ) { /* name found */
found = TRUE;
break;
}
}
/* if file does not exist, return SYSERR */
if (! found) {
signal(Lf_data.lf_mutex);
//kprintf("Named file to truncate does not exist\r\n");
return SYSERR;
}
/* if file is in directory, free its index and data blocks */
else {
if (ldptr->ld_size == 0) { /* file is already empty */
return OK;
}
/* Obtain ID of first index block on free list */
ifree = Lf_data.lf_dir.lfd_ifree;
/* Record file's first i-block and clear directory entry */
firstib = ldptr->ld_ilist;
ldptr->ld_ilist = LF_INULL;
ldptr->ld_size = 0;
Lf_data.lf_dirdirty = TRUE;
/* Walk along index block list, disposing of each data block*/
/* and clearing the corresponding pointer. A note on loop */
/* termination: last pointer is set to ifree below. */
for (nextib=firstib; nextib!=ifree; nextib=iblock.ib_next) {
/* Obtain a copy of current index block from disk */
lfibget(Lf_data.lf_dskdev, nextib, &iblock);
/* Free each data block in the index block */
for (i=0; i<LF_IBLEN; i++) { /* for each d-block */
/* Free the data block */
nextdb = iblock.ib_dba[i];
if (nextdb != LF_DNULL) {
lfdbfree(Lf_data.lf_dskdev, nextdb);
}
/* Clear entry in i-block for this d-block */
iblock.ib_dba[i] = LF_DNULL;
}
/* Clear offset (just to make debugging easier) */
iblock.ib_offset = 0;
/* For the last index block on the list, make it point */
/* to the current free list */
if (iblock.ib_next == LF_INULL) {
iblock.ib_next = ifree;
}
/* Write cleared i-block back to disk */
lfibput(Lf_data.lf_dskdev, nextib, &iblock);
}
/* Last index block on the file list now points to first node */
/* on the current free list. Once we make the free list */
/* point to the first index block on the file list, the */
/* entire set of index blocks will be on the free list */
Lf_data.lf_dir.lfd_ifree = firstib;
/* Indicate that directory has changed and return */
Lf_data.lf_dirdirty = TRUE;
return OK;
}
}
