1 files changed, 128 insertions, 0 deletions
diff --git a/module/zfs/lzjb.c b/module/zfs/lzjb.c
new file mode 100644
index 000000000..7fcde8475
--- /dev/null
+++ b/module/zfs/lzjb.c
@@ -0,0 +1,128 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#pragma ident	"%Z%%M%	%I%	%E% SMI"
+
+/*
+ * We keep our own copy of this algorithm for 2 main reasons:
+ * 	1. If we didn't, anyone modifying common/os/compress.c would
+ *         directly break our on disk format
+ * 	2. Our version of lzjb does not have a number of checks that the
+ *         common/os version needs and uses
+ * In particular, we are adding the "feature" that compress() can
+ * take a destination buffer size and return -1 if the data will not
+ * compress to d_len or less.
+ */
+
+#include <sys/types.h>
+
+#define	MATCH_BITS	6
+#define	MATCH_MIN	3
+#define	MATCH_MAX	((1 << MATCH_BITS) + (MATCH_MIN - 1))
+#define	OFFSET_MASK	((1 << (16 - MATCH_BITS)) - 1)
+#define	LEMPEL_SIZE	256
+
+/*ARGSUSED*/
+size_t
+lzjb_compress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
+{
+	uchar_t *src = s_start;
+	uchar_t *dst = d_start;
+	uchar_t *cpy, *copymap;
+	int copymask = 1 << (NBBY - 1);
+	int mlen, offset;
+	uint16_t *hp;
+	uint16_t lempel[LEMPEL_SIZE];	/* uninitialized; see above */
+
+	while (src < (uchar_t *)s_start + s_len) {
+		if ((copymask <<= 1) == (1 << NBBY)) {
+			if (dst >= (uchar_t *)d_start + d_len - 1 - 2 * NBBY) {
+				if (d_len != s_len)
+					return (s_len);
+				mlen = s_len;
+				for (src = s_start, dst = d_start; mlen; mlen--)
+					*dst++ = *src++;
+				return (s_len);
+			}
+			copymask = 1;
+			copymap = dst;
+			*dst++ = 0;
+		}
+		if (src > (uchar_t *)s_start + s_len - MATCH_MAX) {
+			*dst++ = *src++;
+			continue;
+		}
+		hp = &lempel[((src[0] + 13) ^ (src[1] - 13) ^ src[2]) &
+		    (LEMPEL_SIZE - 1)];
+		offset = (intptr_t)(src - *hp) & OFFSET_MASK;
+		*hp = (uint16_t)(uintptr_t)src;
+		cpy = src - offset;
+		if (cpy >= (uchar_t *)s_start && cpy != src &&
+		    src[0] == cpy[0] && src[1] == cpy[1] && src[2] == cpy[2]) {
+			*copymap |= copymask;
+			for (mlen = MATCH_MIN; mlen < MATCH_MAX; mlen++)
+				if (src[mlen] != cpy[mlen])
+					break;
+			*dst++ = ((mlen - MATCH_MIN) << (NBBY - MATCH_BITS)) |
+			    (offset >> NBBY);
+			*dst++ = (uchar_t)offset;
+			src += mlen;
+		} else {
+			*dst++ = *src++;
+		}
+	}
+	return (dst - (uchar_t *)d_start);
+}
+
+/*ARGSUSED*/
+int
+lzjb_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
+{
+	uchar_t *src = s_start;
+	uchar_t *dst = d_start;
+	uchar_t *d_end = (uchar_t *)d_start + d_len;
+	uchar_t *cpy, copymap;
+	int copymask = 1 << (NBBY - 1);
+
+	while (dst < d_end) {
+		if ((copymask <<= 1) == (1 << NBBY)) {
+			copymask = 1;
+			copymap = *src++;
+		}
+		if (copymap & copymask) {
+			int mlen = (src[0] >> (NBBY - MATCH_BITS)) + MATCH_MIN;
+			int offset = ((src[0] << NBBY) | src[1]) & OFFSET_MASK;
+			src += 2;
+			if ((cpy = dst - offset) < (uchar_t *)d_start)
+				return (-1);
+			while (--mlen >= 0 && dst < d_end)
+				*dst++ = *cpy++;
+		} else {
+			*dst++ = *src++;
+		}
+	}
+	return (0);
+}