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#include <u.h>
#include <libc.h>
#include <diskfs.h>
#include <venti.h>
extern void vtlibthread(void);
typedef struct DiskVenti DiskVenti;
struct DiskVenti
{
Disk disk;
VtEntry e;
VtCache *c;
};
extern int nfilereads;
/*
* This part is like file.c but doesn't require storing the root block
* in the cache permanently and doesn't care about locking since
* all the blocks are read-only. Perhaps at some point this functionality
* should go into libvac in some form.
*/
static int
vtfileindices(VtEntry *e, u32int bn, int *index)
{
int i, np;
memset(index, 0, VtPointerDepth*sizeof(int));
np = e->psize/VtScoreSize;
memset(index, 0, sizeof(index));
for(i=0; bn > 0; i++){
if(i >= VtPointerDepth){
werrstr("bad block number %lud", (ulong)bn);
return -1;
}
index[i] = bn % np;
bn /= np;
}
return i;
}
static VtBlock*
_vtfileblock(VtCache *c, VtEntry *e, u32int bn)
{
VtBlock *b, *bb;
int i, d, index[VtPointerDepth+1], t;
i = vtfileindices(e, bn, index);
if(i < 0)
return nil;
d = (e->type&VtTypeDepthMask);
if(i > d){
werrstr("bad address %d > %d (%x %x)", i, d, e->type, e->flags);
return nil;
}
/*fprint(2, "vtread %V\n", e->score); */
b = vtcacheglobal(c, e->score, e->type);
if(b == nil)
return nil;
for(i=d-1; i>=0; i--){
t = VtDataType+i;
/*fprint(2, "vtread %V\n", b->data+index[i]*VtScoreSize); */
bb = vtcacheglobal(c, b->data+index[i]*VtScoreSize, t);
vtblockput(b);
if(bb == nil)
return nil;
b = bb;
}
return b;
}
static void
diskventiblockput(Block *b)
{
vtblockput(b->priv);
free(b);
}
static Block*
diskventiread(Disk *dd, u32int len, u64int offset)
{
DiskVenti *d = (DiskVenti*)dd;
VtBlock *vb;
Block *b;
int frag;
nfilereads++;
vb = _vtfileblock(d->c, &d->e, offset/d->e.dsize);
if(vb == nil)
return nil;
b = mallocz(sizeof(Block), 1);
if(b == nil){
vtblockput(vb);
return nil;
}
b->priv = vb;
b->_close = diskventiblockput;
frag = offset%d->e.dsize;
b->data = (uchar*)vb->data + frag;
b->len = d->e.dsize - frag;
if(b->len > len)
b->len = len;
return b;
}
static void
diskventiclose(Disk *dd)
{
DiskVenti *d = (DiskVenti*)dd;
free(d);
}
Disk*
diskopenventi(VtCache *c, uchar score[VtScoreSize])
{
DiskVenti *d;
VtEntry e;
VtRoot root;
VtBlock *b;
if((b = vtcacheglobal(c, score, VtRootType)) == nil)
goto Err;
if(vtrootunpack(&root, b->data) < 0)
goto Err;
if(root.blocksize < 512 || (root.blocksize&(root.blocksize-1))){
werrstr("bad blocksize %d", root.blocksize);
goto Err;
}
vtblockput(b);
if((b = vtcacheglobal(c, root.score, VtDirType)) == nil)
goto Err;
if(vtentryunpack(&e, b->data, 0) < 0)
goto Err;
vtblockput(b);
b = nil;
if((e.type&VtTypeBaseMask) != VtDataType){
werrstr("not a single file");
goto Err;
}
d = mallocz(sizeof(DiskVenti), 1);
if(d == nil)
goto Err;
d->disk._read = diskventiread;
d->disk._close = diskventiclose;
d->e = e;
d->c = c;
return &d->disk;
Err:
if(b)
vtblockput(b);
return nil;
}
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