/* WARNING: This write function is far beyond complete,
* data block allocation and vnode expansion support should be added
*/
ssize_t write(int fildes, void *buf, size_t nbyte)
{
blkcnt_t blk, oldblk;
off_t disp;
size_t xfer = nbyte, i=0;
struct scache *scp;
struct ofile *ofp = (struct ofile*)fildes;
/* do the data copy */
while(xfer) {
/* calculate pos defined block number
* and displacement.
*/
blk = ofp->pos/ofp->mount->blksize;
blk += ofp->node->blkentry;
blk += fs_daddr(ofp->mount->fs, ofp->mount->sblk);
disp = ofp->pos%ofp->mount->blksize;
/* load block to cache if not loaded */
if(oldblk != blk) {
scp = scache_get(ofp->node->dev,
blk, ofp->mount->blksize);
oldblk = blk;
}
/* do the copy */
if((xfer+disp) > ofp->mount->blksize) {
memcpy(&scp->buf[disp], &((char*)buf)[i],
ofp->mount->blksize - disp);
scp->mode |= S_CHANGED;
ofp->pos += ofp->mount->blksize - disp;
disp = 0;
xfer -= ofp->mount->blksize - disp;
i += ofp->mount->blksize - disp;
} else {
memcpy(&scp->buf[disp], &((char*)buf)[i], xfer);
scp->mode |= S_CHANGED;
ofp->pos += xfer;
disp = 0;
xfer -= xfer;
i += xfer;
}
/* check end of file with pos */
if(ofp->pos > ofp->node->size) {
ofp->pos = ofp->node->size;
break;
}
}
return nbyte;
}
interface_info* get_iinfo(const char* iname, bool add_if_need)
{
interface_info *ret = 0;
ret = scache_get(&statistic, iname, 0);
if (!ret && add_if_need)
{
ret = (interface_info*)malloc(sizeof(interface_info));
ret->ibytes = 0;
ret->obytes = 0;
ret->last_time = 0;
scache_set(&statistic, iname, ret);
}
return ret;
}
off_t lseek(int fildes, off_t offset, int whence)
{
blkcnt_t blk;
struct ofile *ofp = (struct ofile*)fildes;
/* general methods:
* 1. setup displacement
* 2. update sector buffer
*/
switch(whence) {
case SEEK_SET:
ofp->pos = offset;
break;
case SEEK_CUR:
ofp->pos+= offset;
break;
case SEEK_END:
ofp->pos = ofp->node->size;
ofp->pos+= offset;
break;
}
/* boundary checks */
if((ofp->pos > ofp->node->size) ||
(ofp->pos < 0)) {
return -1; /* offset out of boundary */
}
/* calculate block index */
blk = ofp->pos/ofp->mount->blksize;
blk+= ofp->node->blkentry;
blk+= fs_daddr(ofp->mount->fs, ofp->mount->sblk);
/* load block if not in buffer */
scache_get(ofp->node->dev, blk, ofp->mount->blksize);
return ofp->pos;
}
/* flags to support:
* O_RDONLY
* O_WRONLY
* O_RDWR
* O_CREAT
* O_EXCL
* O_TRUNC
* O_APPEND
*/
int open(char *path, int oflag, ...)
{
struct vnode *vp;
struct scache *scp;
struct mountab *mtp;
struct ofile *ofp;
/* first, find the corresponding vnode of *path */
vp = vget(path, 0);
if((vp == (struct vnode*)-1)||(vp == 0)) {
/* file not found */
if(oflag&O_CREAT) {
if((oflag&O_EXCL) == O_EXCL) {
return 0;
}
/* create the file and continue the process */
}
} else if(((oflag&O_CREAT) == O_CREAT) && ((oflag&O_EXCL) == O_EXCL)) {
return -1;
}
/* checking read/write permitions,
* kernel is the owner of all files */
if(((oflag&O_RDONLY) == O_RDONLY) && ((vp->mode&S_IRUSR) != S_IRUSR)) {
return -1;
}
if(((oflag&O_WRONLY) == O_WRONLY) && ((vp->mode&S_IWUSR) != S_IWUSR)) {
return -1;
}
/* load sectors containing the requested data position */
mtp = mountab_get(vp->dev);
if(mtp == 0) {
return -1; /* mount point not found */
}
scp = scache_get(vp->dev, vp->blkentry, mtp->blksize);
if(scp == 0) {
return -1; /* cannot locate data block */
}
/* request a open file descriptor
* describing kernel file operation,
* which containing vnode data,
* mount data and beginning sector cache data*/
ofp = ofile_alloc();
if(ofp == 0) {
MSG(1, "no open file descriptor available\n");
return -1; /* no ofile available */
}
ofp->node = vp;
ofp->mount = mtp;
ofp->oflag = oflag;
/* setup pos value, load pos sector to buffer */
if((oflag&&O_APPEND) == O_APPEND) {
/* set pos to end of file */
ofp->pos = vp->size;
} else if((oflag&&O_TRUNC) == O_TRUNC) {
/* release all data blocks allocated,
* setup file size to 0 and block data to 0*/
ofp->pos = 0;
vp->size = 0;
blkcnt_t bc;
for(bc=vp->blkentry; bc<=vp->blkentry+vp->blocks; bc++) {
fs_dfree(mtp->fs, mtp->sblk, vp->dev, bc);
}
vp->blkentry = 0;
vp->blocks = 0;
} else {
ofp->pos = 0;
}
lseek((int)ofp, ofp->pos, SEEK_SET);
return (int)ofp;
}
