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#include "sam.h"
static Block *blist;
#if 0
static int
tempdisk(void)
{
char buf[128];
int i, fd;
snprint(buf, sizeof buf, "/tmp/X%d.%.4ssam", getpid(), getuser());
for(i='A'; i<='Z'; i++){
buf[5] = i;
if(access(buf, AEXIST) == 0)
continue;
fd = create(buf, ORDWR|ORCLOSE|OCEXEC, 0600);
if(fd >= 0)
return fd;
}
return -1;
}
#else
extern int tempdisk(void);
#endif
Disk*
diskinit(void)
{
Disk *d;
d = emalloc(sizeof(Disk));
d->fd = tempdisk();
if(d->fd < 0){
fprint(2, "sam: can't create temp file: %r\n");
exits("diskinit");
}
return d;
}
static
uint
ntosize(uint n, uint *ip)
{
uint size;
if(n > Maxblock)
panic("internal error: ntosize");
size = n;
if(size & (Blockincr-1))
size += Blockincr - (size & (Blockincr-1));
/* last bucket holds blocks of exactly Maxblock */
if(ip)
*ip = size/Blockincr;
return size * sizeof(Rune);
}
Block*
disknewblock(Disk *d, uint n)
{
uint i, j, size;
Block *b;
size = ntosize(n, &i);
b = d->free[i];
if(b)
d->free[i] = b->u.next;
else{
/* allocate in chunks to reduce malloc overhead */
if(blist == nil){
blist = emalloc(100*sizeof(Block));
for(j=0; j<100-1; j++)
blist[j].u.next = &blist[j+1];
}
b = blist;
blist = b->u.next;
b->addr = d->addr;
d->addr += size;
}
b->u.n = n;
return b;
}
void
diskrelease(Disk *d, Block *b)
{
uint i;
ntosize(b->u.n, &i);
b->u.next = d->free[i];
d->free[i] = b;
}
void
diskwrite(Disk *d, Block **bp, Rune *r, uint n)
{
int size, nsize;
Block *b;
b = *bp;
size = ntosize(b->u.n, nil);
nsize = ntosize(n, nil);
if(size != nsize){
diskrelease(d, b);
b = disknewblock(d, n);
*bp = b;
}
if(pwrite(d->fd, r, n*sizeof(Rune), b->addr) != n*sizeof(Rune))
panic("write error to temp file");
b->u.n = n;
}
void
diskread(Disk *d, Block *b, Rune *r, uint n)
{
if(n > b->u.n)
panic("internal error: diskread");
ntosize(b->u.n, nil); /* called only for sanity check on Maxblock */
if(pread(d->fd, r, n*sizeof(Rune), b->addr) != n*sizeof(Rune))
panic("read error from temp file");
}
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