vac.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

			ln = smprint("%s/%s", lname, name);
			sn = smprint("%s/%s", sname, name);
			if (ln == nil || sn == nil)
				sysfatal("out of memory");

			if(vf != nil)
				vvf = vfWalk(vf, name);
			else
				vvf = nil;
			vacFile(ds, ln, sn, vvf);
			if(vvf != nil)
				vfDecRef(vvf);
			free(ln);
			free(sn);
		}
		free(dirs);
	}
	dirSinkClose(ds);
	dirSinkWriteSink(dsink, ds->sink);
	dirSinkWriteSink(dsink, ds->msink->sink);
	dirSinkFree(ds);
}

static int
vacMergeFile(DirSink *dsink, VacFile *vf, VacDir *dir, uvlong offset, uvlong *max)
{
	uchar buf[VtEntrySize];
	VtEntry dd, md;
	int e;

	if(vfRead(vf, buf, VtEntrySize, (uvlong)dir->entry*VtEntrySize) != VtEntrySize) {
		warn("could not read venti dir entry: %s\n", dir->elem);
		return 0;
	}
	vtEntryUnpack(&dd, buf, 0);

	if(dir->mode & ModeDir)	{
		e = dir->mentry;
		if(e == 0)
			e = dir->entry + 1;

		if(vfRead(vf, buf, VtEntrySize, e*VtEntrySize) != VtEntrySize) {
			warn("could not read venti dir entry: %s\n", dir->elem);
			return 0;
		}
		vtEntryUnpack(&md, buf, 0);
	}

	/* max might be incorrect in some old dumps */
	if(dir->qid >= *max) {
		warn("qid out of range: %s", dir->elem);
		*max = dir->qid;
	}

	dir->qid += offset;
	dir->entry = dsink->nentry;

	if(dir->qidSpace) {
		dir->qidOffset += offset;
	} else {
		dir->qidSpace = 1;
		dir->qidOffset = offset;
		dir->qidMax = *max;
	}

	dirSinkWrite(dsink, &dd);
	if(dir->mode & ModeDir)
		dirSinkWrite(dsink, &md);
	metaSinkWriteDir(dsink->msink, dir);

	return 1;
}

static int
vacMerge(DirSink *dsink, char *lname, char *sname)
{
	char *p;
	VacFS *fs;
	VacFile *vf;
	VacDirEnum *d;
	VacDir dir;
	uvlong max;

	p = strrchr(sname, '.');
	if(p == 0 || strcmp(p, ".vac"))
		return 0;

	d = nil;
	fs = vfsOpen(dsink->sink->z, sname, 1, 100);
	if(fs == nil)
		return 0;

	vf = vfOpen(fs, "/");
	if(vf == nil)
		goto Done;
	max = vfGetId(vf);
	d = vdeOpen(fs, "/");
	if(d == nil)
		goto Done;

	if(verbose)
		fprint(2, "%s: merging: %s\n", argv0, lname);

	if(maxbsize < vfsGetBlockSize(fs))
		maxbsize = vfsGetBlockSize(fs);

	for(;;) {
		if(vdeRead(d, &dir, 1) < 1)
			break;
		vacMergeFile(dsink, vf, &dir, fileid, &max);
		vdCleanup(&dir);
	}
	fileid += max;

Done:
	if(d != nil)
		vdeFree(d);
	if(vf != nil)
		vfDecRef(vf);
	vfsClose(fs);
	return 1;
}

Sink *
sinkAlloc(VtSession *z, int psize, int dsize)
{
	Sink *k;
	int i;

	if(psize < 512 || psize > VtMaxLumpSize)
		vtFatal("sinkAlloc: bad psize");
	if(dsize < 512 || dsize > VtMaxLumpSize)
		vtFatal("sinkAlloc: bad psize");

	psize = VtScoreSize*(psize/VtScoreSize);

	k = vtMemAllocZ(sizeof(Sink));
	k->z = z;
	k->dir.flags = VtEntryActive;
	k->dir.psize = psize;
	k->dir.dsize = dsize;
	k->buf = vtMemAllocZ(VtPointerDepth*k->dir.psize + VtScoreSize);
	for(i=0; i<=VtPointerDepth; i++)
		k->pbuf[i] = k->buf + i*k->dir.psize;
	return k;
}

void
sinkWriteScore(Sink *k, uchar score[VtScoreSize], int n)
{
	int i;
	uchar *p;
	VtEntry *d;

	memmove(k->pbuf[0], score, VtScoreSize);

	d = &k->dir;

	for(i=0; i<VtPointerDepth; i++) {
		k->pbuf[i] += VtScoreSize;
		if(k->pbuf[i] < k->buf + d->psize*(i+1))
			break;
		if(i == VtPointerDepth-1)
			vtFatal("file too big");
		p = k->buf+i*d->psize;
		stats.meta++;
		if(!vacWrite(k->z, k->pbuf[i+1], VtPointerType0+i, p, d->psize))
			vtFatal("vacWrite failed: %s", vtGetError());
		k->pbuf[i] = p;
	}

	/* round size up to multiple of dsize */
	d->size = d->dsize * ((d->size + d->dsize-1)/d->dsize);

	d->size += n;
}

void
sinkWrite(Sink *k, uchar *p, int n)
{
	int type;
	uchar score[VtScoreSize];

	if(n > k->dir.dsize)
		vtFatal("sinkWrite: size too big");

	if(k->dir.flags & VtEntryDir) {
		type = VtDirType;
		stats.meta++;
	} else {
		type = VtDataType;
		stats.data++;
	}
	if(!vacWrite(k->z, score, type, p, n))
		vtFatal("vacWrite failed: %s", vtGetError());

	sinkWriteScore(k, score, n);
}

static int
sizeToDepth(uvlong s, int psize, int dsize)
{
	int np;
	int d;

	/* determine pointer depth */
	np = psize/VtScoreSize;
	s = (s + dsize - 1)/dsize;
	for(d = 0; s > 1; d++)
		s = (s + np - 1)/np;
	return d;
}

void
sinkClose(Sink *k)
{
	int i, n;
	uchar *p;
	VtEntry *kd;

	kd = &k->dir;

	/* empty */
	if(kd->size == 0) {
		memmove(kd->score, vtZeroScore, VtScoreSize);
		return;
	}

	for(n=VtPointerDepth-1; n>0; n--)
		if(k->pbuf[n] > k->buf + kd->psize*n)
			break;

	kd->depth = sizeToDepth(kd->size, kd->psize, kd->dsize);

	/* skip full part of tree */
	for(i=0; i<n && k->pbuf[i] == k->buf + kd->psize*i; i++)
		;

	/* is the tree completely full */
	if(i == n && k->pbuf[n] == k->buf + kd->psize*n + VtScoreSize) {
		memmove(kd->score, k->pbuf[n] - VtScoreSize, VtScoreSize);
		return;
	}
	n++;

	/* clean up the edge */
	for(; i<n; i++) {
		p = k->buf+i*kd->psize;
		stats.meta++;
		if(!vacWrite(k->z, k->pbuf[i+1], VtPointerType0+i, p, k->pbuf[i]-p))
			vtFatal("vacWrite failed: %s", vtGetError());
		k->pbuf[i+1] += VtScoreSize;
	}
	memmove(kd->score, k->pbuf[i] - VtScoreSize, VtScoreSize);
}

void
sinkFree(Sink *k)
{
	vtMemFree(k->buf);
	vtMemFree(k);
}

DirSink *
dirSinkAlloc(VtSession *z, int psize, int dsize)
{
	DirSink *k;
	int ds;

	ds = VtEntrySize*(dsize/VtEntrySize);

	k = vtMemAllocZ(sizeof(DirSink));
	k->sink = sinkAlloc(z, psize, ds);
	k->sink->dir.flags |= VtEntryDir;
	k->msink = metaSinkAlloc(z, psize, dsize);
	k->buf = vtMemAlloc(ds);
	k->p = k->buf;
	k->ep = k->buf + ds;
	return k;
}

void
dirSinkWrite(DirSink *k, VtEntry *dir)
{
	if(k->p + VtEntrySize > k->ep) {
		sinkWrite(k->sink, k->buf, k->p - k->buf);
		k->p = k->buf;
	}
	vtEntryPack(dir, k->p, 0);
	k->nentry++;
	k->p += VtEntrySize;
}

void
dirSinkWriteSink(DirSink *k, Sink *sink)
{
	dirSinkWrite(k, &sink->dir);
}

int
dirSinkWriteFile(DirSink *k, VacFile *vf)
{
	VtEntry dir;

	if(!vfGetVtEntry(vf, &dir))
		return 0;
	dirSinkWrite(k, &dir);
	return 1;
}

void
dirSinkClose(DirSink *k)
{
	metaSinkClose(k->msink);
	if(k->p != k->buf)
		sinkWrite(k->sink, k->buf, k->p - k->buf);
	sinkClose(k->sink);
}

void
dirSinkFree(DirSink *k)
{
	sinkFree(k->sink);
	metaSinkFree(k->msink);
	vtMemFree(k->buf);
	vtMemFree(k);
}

MetaSink *
metaSinkAlloc(VtSession *z, int psize, int dsize)
{
	MetaSink *k;

	k = vtMemAllocZ(sizeof(MetaSink));
	k->sink = sinkAlloc(z, psize, dsize);
	k->buf = vtMemAlloc(dsize);
	k->maxindex = dsize/100;	/* 100 byte entries seems reasonable */
	if(k->maxindex < 1)
		k->maxindex = 1;
	k->rp = k->p = k->buf + MetaHeaderSize + k->maxindex*MetaIndexSize;
	k->ep = k->buf + dsize;
	return k;
}

/* hack to get base to compare routine - not reentrant */
uchar *blockBase;

int
dirCmp(void *p0, void *p1)
{
	uchar *q0, *q1;
	int n0, n1, r;

	/* name is first element of entry */
	q0 = p0;
	q0 = blockBase + (q0[0]<<8) + q0[1];
	n0 = (q0[6]<<8) + q0[7];
	q0 += 8;

	q1 = p1;
	q1 = blockBase + (q1[0]<<8) + q1[1];
	n1 = (q1[6]<<8) + q1[7];
	q1 += 8;

	if(n0 == n1)
		return memcmp(q0, q1, n0);
	else if (n0 < n1) {
		r = memcmp(q0, q1, n0);
		return (r==0)?1:r;
	} else  {
		r = memcmp(q0, q1, n1);
		return (r==0)?-1:r;
	}
}

void
metaSinkFlush(MetaSink *k)
{
	uchar *p;
	int n;
	MetaBlock mb;

	if(k->nindex == 0)
		return;
	assert(k->nindex <= k->maxindex);

	p = k->buf;
	n = k->rp - p;

	mb.size = n;
	mb.free = 0;
	mb.nindex = k->nindex;
	mb.maxindex = k->maxindex;
	mb.buf = p;
	mbPack(&mb);

	p += MetaHeaderSize;

	/* XXX this is not reentrant! */
	blockBase = k->buf;
	qsort(p, k->nindex, MetaIndexSize, dirCmp);
	p += k->nindex*MetaIndexSize;

	memset(p, 0, (k->maxindex-k->nindex)*MetaIndexSize);
	p += (k->maxindex-k->nindex)*MetaIndexSize;

	sinkWrite(k->sink, k->buf, n);

	/* move down partial entry */
	n = k->p - k->rp;
	memmove(p, k->rp, n);
	k->rp = p;
	k->p = p + n;
	k->nindex = 0;
}

void
metaSinkPutc(MetaSink *k, int c)
{
	if(k->p+1 > k->ep)
		metaSinkFlush(k);
	if(k->p+1 > k->ep)
		vtFatal("directory entry too large");
	k->p[0] = c;
	k->p++;
}

void
metaSinkPutString(MetaSink *k, char *s)
{
	int n = strlen(s);
	metaSinkPutc(k, n>>8);
	metaSinkPutc(k, n);
	metaSinkWrite(k, (uchar*)s, n);
}

void
metaSinkPutUint32(MetaSink *k, ulong x)
{
	metaSinkPutc(k, x>>24);
	metaSinkPutc(k, x>>16);
	metaSinkPutc(k, x>>8);
	metaSinkPutc(k, x);
}

void
metaSinkPutUint64(MetaSink *k, uvlong x)
{
	metaSinkPutUint32(k, x>>32);
	metaSinkPutUint32(k, x);
}

void
metaSinkWrite(MetaSink *k, uchar *data, int n)
{
	if(k->p + n > k->ep)
		metaSinkFlush(k);
	if(k->p + n > k->ep)
		vtFatal("directory entry too large");

	memmove(k->p, data, n);
	k->p += n;
}

void
metaSinkWriteDir(MetaSink *ms, VacDir *dir)
{
	metaSinkPutUint32(ms, DirMagic);
	metaSinkPutc(ms, Version>>8);
	metaSinkPutc(ms, Version);
	metaSinkPutString(ms, dir->elem);
	metaSinkPutUint32(ms, dir->entry);
	metaSinkPutUint64(ms, dir->qid);
	metaSinkPutString(ms, dir->uid);
	metaSinkPutString(ms, dir->gid);
	metaSinkPutString(ms, dir->mid);
	metaSinkPutUint32(ms, dir->mtime);
	metaSinkPutUint32(ms, dir->mcount);
	metaSinkPutUint32(ms, dir->ctime);
	metaSinkPutUint32(ms, dir->atime);
	metaSinkPutUint32(ms, dir->mode);

	if(dir->plan9) {
		metaSinkPutc(ms, DirPlan9Entry);	/* plan9 extra info */
		metaSinkPutc(ms, 0);			/* plan9 extra size */
		metaSinkPutc(ms, 12);			/* plan9 extra size */
		metaSinkPutUint64(ms, dir->p9path);
		metaSinkPutUint32(ms, dir->p9version);
	}

	if(dir->qidSpace != 0) {
		metaSinkPutc(ms, DirQidSpaceEntry);
		metaSinkPutc(ms, 0);
		metaSinkPutc(ms, 16);
		metaSinkPutUint64(ms, dir->qidOffset);
		metaSinkPutUint64(ms, dir->qidMax);
	}

	if(dir->gen != 0) {
		metaSinkPutc(ms, DirGenEntry);
		metaSinkPutc(ms, 0);
		metaSinkPutc(ms, 4);
		metaSinkPutUint32(ms, dir->gen);
	}

	metaSinkEOR(ms);
}


void
plan9ToVacDir(VacDir *vd, Dir *dir, ulong entry, uvlong qid)
{
	memset(vd, 0, sizeof(VacDir));

	vd->elem = vtStrDup(dir->name);
	vd->entry = entry;
	vd->qid = qid;
	vd->uid = vtStrDup(dir->uid);
	vd->gid = vtStrDup(dir->gid);
	vd->mid = vtStrDup(dir->muid);
	vd->mtime = dir->mtime;
	vd->mcount = 0;
	vd->ctime = dir->mtime;		/* ctime: not available on plan 9 */
	vd->atime = dir->atime;

	vd->mode = dir->mode & 0777;
	if(dir->mode & DMDIR)
		vd->mode |= ModeDir;
	if(dir->mode & DMAPPEND)
		vd->mode |= ModeAppend;
	if(dir->mode & DMEXCL)
		vd->mode |= ModeExclusive;

	vd->plan9 = 1;
	vd->p9path = dir->qid.path;
	vd->p9version = dir->qid.vers;
}


void
metaSinkEOR(MetaSink *k)
{
	uchar *p;
	int o, n;

	p = k->buf + MetaHeaderSize;
	p += k->nindex * MetaIndexSize;
	o = k->rp-k->buf; 	/* offset from start of block */
	n = k->p-k->rp;		/* size of entry */
	p[0] = o >> 8;
	p[1] = o;
	p[2] = n >> 8;
	p[3] = n;
	k->rp = k->p;
	k->nindex++;
	if(k->nindex == k->maxindex)
		metaSinkFlush(k);
}

void
metaSinkClose(MetaSink *k)
{
	metaSinkFlush(k);
	sinkClose(k->sink);
}

void
metaSinkFree(MetaSink *k)
{
	sinkFree(k->sink);
	vtMemFree(k->buf);
	vtMemFree(k);
}

static void
warn(char *fmt, ...)
{
	va_list arg;

	va_start(arg, fmt);
	fprint(2, "%s: ", argv0);
	vfprint(2, fmt, arg);
	fprint(2, "\n");
	va_end(arg);
}

static void
cleanup(void)
{
	if(oname != nil)
		remove(oname);
}

#define TWID64	((u64int)~(u64int)0)

static u64int
unittoull(char *s)
{
	char *es;
	u64int n;

	if(s == nil)
		return TWID64;
	n = strtoul(s, &es, 0);
	if(*es == 'k' || *es == 'K'){
		n *= 1024;
		es++;
	}else if(*es == 'm' || *es == 'M'){
		n *= 1024*1024;
		es++;
	}else if(*es == 'g' || *es == 'G'){
		n *= 1024*1024*1024;
		es++;
	}
	if(*es != '\0')
		return TWID64;
	return n;
}