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#include	<u.h>
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#include	<libc.h>
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#include	<bio.h>
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static	Biobufhdr*	wbufs[20];
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static	int		atexitflag;
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static
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void
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batexit(void)
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{
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	Biobufhdr *bp;
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	int i;
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	for(i=0; i<nelem(wbufs); i++) {
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		bp = wbufs[i];
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		if(bp != 0) {
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			wbufs[i] = 0;
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			Bflush(bp);
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		}
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	}
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}
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static
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void
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deinstall(Biobufhdr *bp)
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{
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	int i;
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	for(i=0; i<nelem(wbufs); i++)
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		if(wbufs[i] == bp)
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			wbufs[i] = 0;
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}
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static
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void
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install(Biobufhdr *bp)
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{
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	int i;
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	deinstall(bp);
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	for(i=0; i<nelem(wbufs); i++)
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		if(wbufs[i] == 0) {
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			wbufs[i] = bp;
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			break;
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		}
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	if(atexitflag == 0) {
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		atexitflag = 1;
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		atexit(batexit);
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	}
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}
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int
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Binits(Biobufhdr *bp, int f, int mode, uchar *p, int size)
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{
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	p += Bungetsize;	/* make room for Bungets */
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	size -= Bungetsize;
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	switch(mode&~(OCEXEC|ORCLOSE|OTRUNC)) {
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	default:
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		fprint(2, "Binits: unknown mode %d\n", mode);
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		return Beof;
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	case OREAD:
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		bp->state = Bractive;
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		bp->ocount = 0;
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		break;
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	case OWRITE:
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		install(bp);
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		bp->state = Bwactive;
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		bp->ocount = -size;
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		break;
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	}
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	bp->bbuf = p;
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	bp->ebuf = p+size;
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	bp->bsize = size;
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	bp->icount = 0;
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	bp->gbuf = bp->ebuf;
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	bp->fid = f;
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	bp->flag = 0;
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	bp->rdline = 0;
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	bp->offset = 0;
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	bp->runesize = 0;
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	return 0;
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}
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int
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Binit(Biobuf *bp, int f, int mode)
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{
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	return Binits(bp, f, mode, bp->b, sizeof(bp->b));
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}
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Biobuf*
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Bopen(char *name, int mode)
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{
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	Biobuf *bp;
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	int f;
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	switch(mode&~(OCEXEC|ORCLOSE|OTRUNC)) {
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	default:
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		fprint(2, "Bopen: unknown mode %#x\n", mode);
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		return 0;
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	case OREAD:
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		f = open(name, mode);
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		break;
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	case OWRITE:
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		f = create(name, mode, 0666);
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		break;
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	}
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	if(f < 0)
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		return 0;
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	bp = malloc(sizeof(Biobuf));
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	Binits(bp, f, mode, bp->b, sizeof(bp->b));
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	bp->flag = Bmagic;			/* mark bp open & malloced */
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	return bp;
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}
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int
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Bterm(Biobufhdr *bp)
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{
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	int r;
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	deinstall(bp);
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	r = Bflush(bp);
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	if(bp->flag == Bmagic) {
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		bp->flag = 0;
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		close(bp->fid);
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		bp->fid = -1;			/* prevent accidents */
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		free(bp);
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	}
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	/* otherwise opened with Binit(s) */
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	return r;
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}