Initial stab at Venti.

src/cmd/venti/clump.c

@@ -0,0 +1,200 @@
+#include "stdinc.h"
+#include "dat.h"
+#include "fns.h"
+#include "whack.h"
+
+/*
+ * writes a lump to disk
+ * returns the address in amap of the clump
+ */
+int
+storeclump(Index *ix, ZBlock *zb, u8int *sc, int type, u32int creator, IAddr *ia)
+{
+	ZBlock *cb;
+	Clump cl;
+	u64int a;
+	u8int bh[VtScoreSize];
+	int size, dsize;
+
+if(0)print("storeclump %08x %p\n", mainindex->arenas[0], &cl);
+	size = zb->len;
+	if(size > VtMaxLumpSize){
+		seterr(EStrange, "lump too large");
+		return -1;
+	}
+	if(vttypevalid(type) < 0){
+		seterr(EStrange, "invalid lump type");
+		return -1;
+	}
+
+	if(1){
+		scoremem(bh, zb->data, size);
+		if(scorecmp(sc, bh) != 0){
+			seterr(ECorrupt, "storing clump: corrupted; expected=%V got=%V, size=%d", sc, bh, size);
+			return -1;
+		}
+	}
+
+	cb = alloczblock(size + ClumpSize, 0);
+	if(cb == nil)
+		return -1;
+
+	cl.info.type = type;
+	cl.info.uncsize = size;
+	cl.creator = creator;
+	cl.time = now();
+	scorecp(cl.info.score, sc);
+
+if(0)print("whackblock %08x %p\n", mainindex->arenas[0], &cl);
+	dsize = whackblock(&cb->data[ClumpSize], zb->data, size);
+if(0)print("whackedblock %08x %p\n", mainindex->arenas[0], &cl);
+	if(dsize > 0 && dsize < size){
+		cl.encoding = ClumpECompress;
+	}else{
+		cl.encoding = ClumpENone;
+		dsize = size;
+		memmove(&cb->data[ClumpSize], zb->data, size);
+	}
+	cl.info.size = dsize;
+
+	a = writeiclump(ix, &cl, cb->data);
+
+	freezblock(cb);
+	if(a == 0)
+		return -1;
+
+	qlock(&stats.lock);
+	stats.clumpwrites++;
+	stats.clumpbwrites += size;
+	stats.clumpbcomp += dsize;
+	qunlock(&stats.lock);
+
+	ia->addr = a;
+	ia->type = type;
+	ia->size = size;
+	ia->blocks = (dsize + ClumpSize + (1 << ABlockLog) - 1) >> ABlockLog;
+
+	return 0;
+}
+
+u32int
+clumpmagic(Arena *arena, u64int aa)
+{
+	u8int buf[U32Size];
+
+	if(readarena(arena, aa, buf, U32Size) < 0)
+		return TWID32;
+	return unpackmagic(buf);
+}
+
+/*
+ * fetch a block based at addr.
+ * score is filled in with the block's score.
+ * blocks is roughly the length of the clump on disk;
+ * if zero, the length is unknown.
+ */
+ZBlock*
+loadclump(Arena *arena, u64int aa, int blocks, Clump *cl, u8int *score, int verify)
+{
+	Unwhack uw;
+	ZBlock *zb, *cb;
+	u8int bh[VtScoreSize], *buf;
+	u32int n;
+	int nunc;
+
+	qlock(&stats.lock);
+	stats.clumpreads++;
+	qunlock(&stats.lock);
+
+	if(blocks <= 0)
+		blocks = 1;
+
+	cb = alloczblock(blocks << ABlockLog, 0);
+	if(cb == nil)
+		return nil;
+	n = readarena(arena, aa, cb->data, blocks << ABlockLog);
+	if(n < ClumpSize){
+		if(n != 0)
+			seterr(ECorrupt, "loadclump read less than a header");
+		freezblock(cb);
+		return nil;
+	}
+	if(unpackclump(cl, cb->data) < 0){
+		freezblock(cb);
+		return nil;
+	}
+	n -= ClumpSize;
+	if(n < cl->info.size){
+		freezblock(cb);
+		n = cl->info.size;
+		cb = alloczblock(n, 0);
+		if(cb == nil)
+			return nil;
+		if(readarena(arena, aa + ClumpSize, cb->data, n) != n){
+			seterr(ECorrupt, "loadclump read too little data");
+			freezblock(cb);
+			return nil;
+		}
+		buf = cb->data;
+	}else
+		buf = cb->data + ClumpSize;
+
+	scorecp(score, cl->info.score);
+
+	zb = alloczblock(cl->info.uncsize, 0);
+	if(zb == nil){
+		freezblock(cb);
+		return nil;
+	}
+	switch(cl->encoding){
+	case ClumpECompress:
+		unwhackinit(&uw);
+		nunc = unwhack(&uw, zb->data, cl->info.uncsize, buf, cl->info.size);
+		if(nunc != cl->info.uncsize){
+			if(nunc < 0)
+				seterr(ECorrupt, "decompression failed: %s", uw.err);
+			else
+				seterr(ECorrupt, "decompression gave partial block: %d/%d\n", nunc, cl->info.uncsize);
+			freezblock(cb);
+			freezblock(zb);
+			return nil;
+		}
+		break;
+	case ClumpENone:
+		if(cl->info.size != cl->info.uncsize){
+			seterr(ECorrupt, "loading clump: bad uncompressed size for uncompressed block");
+			freezblock(cb);
+			freezblock(zb);
+			return nil;
+		}
+		memmove(zb->data, buf, cl->info.uncsize);
+		break;
+	default:
+		seterr(ECorrupt, "unknown encoding in loadlump");
+		freezblock(cb);
+		freezblock(zb);
+		return nil;
+	}
+	freezblock(cb);
+
+	if(verify){
+		scoremem(bh, zb->data, cl->info.uncsize);
+		if(scorecmp(cl->info.score, bh) != 0){
+			seterr(ECorrupt, "loading clump: corrupted; expected=%V got=%V", cl->info.score, bh);
+			freezblock(zb);
+			return nil;
+		}
+		if(vttypevalid(cl->info.type) < 0){
+			seterr(ECorrupt, "loading lump: invalid lump type %d", cl->info.type);
+			freezblock(zb);
+			return nil;
+		}
+	}
+
+	qlock(&stats.lock);
+	stats.clumpbreads += cl->info.size;
+	stats.clumpbuncomp += cl->info.uncsize;
+	qunlock(&stats.lock);
+
+	return zb;
+}