/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include "sam.h" static	Block	*blist; static inttempdisk(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;} Disk*diskinit(){	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;} staticuintntosize(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->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].next = &blist[j+1];		}		b = blist;		blist = b->next;		b->addr = d->addr;		d->addr += size;	}	b->n = n;	return b;} voiddiskrelease(Disk *d, Block *b){	uint i; 	ntosize(b->n, &i);	b->next = d->free[i];	d->free[i] = b;} voiddiskwrite(Disk *d, Block **bp, Rune *r, uint n){	int size, nsize;	Block *b; 	b = *bp;	size = ntosize(b->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->n = n;} voiddiskread(Disk *d, Block *b, Rune *r, uint n){	if(n > b->n)		panic("internal error: diskread"); 	ntosize(b->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");}