Allow to compress on-the-wire data using two algorithms:

- HOLE - it simply turns all-zero blocks into few bytes header;
	it is extremely fast, so it is turned on by default;
	it is mostly intended to speed up initial synchronization
	where we expect many zeros;
- LZF - very fast algorithm by Marc Alexander Lehmann, which shows
	very decent compression ratio and has BSD license.

MFC after:	2 weeks

1 files changed, 211 insertions, 0 deletions

diff --git a/sbin/hastd/lzf.h b/sbin/hastd/lzf.h
new file mode 100644
index 0000000..92fdd0f
--- /dev/null
+++ b/sbin/hastd/lzf.h
@@ -0,0 +1,211 @@
+/*
+ * Copyright (c) 2000-2008 Marc Alexander Lehmann <schmorp@schmorp.de>
+ * 
+ * Redistribution and use in source and binary forms, with or without modifica-
+ * tion, are permitted provided that the following conditions are met:
+ * 
+ *   1.  Redistributions of source code must retain the above copyright notice,
+ *       this list of conditions and the following disclaimer.
+ * 
+ *   2.  Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
+ * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
+ * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
+ * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
+ * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * the GNU General Public License ("GPL") version 2 or any later version,
+ * in which case the provisions of the GPL are applicable instead of
+ * the above. If you wish to allow the use of your version of this file
+ * only under the terms of the GPL and not to allow others to use your
+ * version of this file under the BSD license, indicate your decision
+ * by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL. If you do not delete the
+ * provisions above, a recipient may use your version of this file under
+ * either the BSD or the GPL.
+ */
+
+#ifndef LZF_H
+#define LZF_H
+
+/***********************************************************************
+**
+**	lzf -- an extremely fast/free compression/decompression-method
+**	http://liblzf.plan9.de/
+**
+**	This algorithm is believed to be patent-free.
+**
+***********************************************************************/
+
+#define LZF_VERSION 0x0105 /* 1.5, API version */
+
+/*
+ * Compress in_len bytes stored at the memory block starting at
+ * in_data and write the result to out_data, up to a maximum length
+ * of out_len bytes.
+ *
+ * If the output buffer is not large enough or any error occurs return 0,
+ * otherwise return the number of bytes used, which might be considerably
+ * more than in_len (but less than 104% of the original size), so it
+ * makes sense to always use out_len == in_len - 1), to ensure _some_
+ * compression, and store the data uncompressed otherwise (with a flag, of
+ * course.
+ *
+ * lzf_compress might use different algorithms on different systems and
+ * even different runs, thus might result in different compressed strings
+ * depending on the phase of the moon or similar factors. However, all
+ * these strings are architecture-independent and will result in the
+ * original data when decompressed using lzf_decompress.
+ *
+ * The buffers must not be overlapping.
+ *
+ * If the option LZF_STATE_ARG is enabled, an extra argument must be
+ * supplied which is not reflected in this header file. Refer to lzfP.h
+ * and lzf_c.c.
+ *
+ */
+unsigned int 
+lzf_compress (const void *const in_data,  unsigned int in_len,
+              void             *out_data, unsigned int out_len);
+
+/*
+ * Decompress data compressed with some version of the lzf_compress
+ * function and stored at location in_data and length in_len. The result
+ * will be stored at out_data up to a maximum of out_len characters.
+ *
+ * If the output buffer is not large enough to hold the decompressed
+ * data, a 0 is returned and errno is set to E2BIG. Otherwise the number
+ * of decompressed bytes (i.e. the original length of the data) is
+ * returned.
+ *
+ * If an error in the compressed data is detected, a zero is returned and
+ * errno is set to EINVAL.
+ *
+ * This function is very fast, about as fast as a copying loop.
+ */
+unsigned int 
+lzf_decompress (const void *const in_data,  unsigned int in_len,
+                void             *out_data, unsigned int out_len);
+
+/*
+ * Size of hashtable is (1 << HLOG) * sizeof (char *)
+ * decompression is independent of the hash table size
+ * the difference between 15 and 14 is very small
+ * for small blocks (and 14 is usually a bit faster).
+ * For a low-memory/faster configuration, use HLOG == 13;
+ * For best compression, use 15 or 16 (or more, up to 23).
+ */
+#ifndef HLOG
+# define HLOG 16
+#endif
+
+/*
+ * Sacrifice very little compression quality in favour of compression speed.
+ * This gives almost the same compression as the default code, and is
+ * (very roughly) 15% faster. This is the preferred mode of operation.
+ */
+#ifndef VERY_FAST
+# define VERY_FAST 1
+#endif
+
+/*
+ * Sacrifice some more compression quality in favour of compression speed.
+ * (roughly 1-2% worse compression for large blocks and
+ * 9-10% for small, redundant, blocks and >>20% better speed in both cases)
+ * In short: when in need for speed, enable this for binary data,
+ * possibly disable this for text data.
+ */
+#ifndef ULTRA_FAST
+# define ULTRA_FAST 0
+#endif
+
+/*
+ * Unconditionally aligning does not cost very much, so do it if unsure
+ */
+#ifndef STRICT_ALIGN
+# define STRICT_ALIGN !(defined(__i386) || defined (__amd64))
+#endif
+
+/*
+ * You may choose to pre-set the hash table (might be faster on some
+ * modern cpus and large (>>64k) blocks, and also makes compression
+ * deterministic/repeatable when the configuration otherwise is the same).
+ */
+#ifndef INIT_HTAB
+# define INIT_HTAB 1
+#endif
+
+/*
+ * Avoid assigning values to errno variable? for some embedding purposes
+ * (linux kernel for example), this is neccessary. NOTE: this breaks
+ * the documentation in lzf.h.
+ */
+#ifndef AVOID_ERRNO
+# define AVOID_ERRNO 0
+#endif
+
+/*
+ * Wether to pass the LZF_STATE variable as argument, or allocate it
+ * on the stack. For small-stack environments, define this to 1.
+ * NOTE: this breaks the prototype in lzf.h.
+ */
+#ifndef LZF_STATE_ARG
+# define LZF_STATE_ARG 0
+#endif
+
+/*
+ * Wether to add extra checks for input validity in lzf_decompress
+ * and return EINVAL if the input stream has been corrupted. This
+ * only shields against overflowing the input buffer and will not
+ * detect most corrupted streams.
+ * This check is not normally noticable on modern hardware
+ * (<1% slowdown), but might slow down older cpus considerably.
+ */
+#ifndef CHECK_INPUT
+# define CHECK_INPUT 1
+#endif
+
+/*****************************************************************************/
+/* nothing should be changed below */
+
+typedef unsigned char u8;
+
+typedef const u8 *LZF_STATE[1 << (HLOG)];
+
+#if !STRICT_ALIGN
+/* for unaligned accesses we need a 16 bit datatype. */
+# include <limits.h>
+# if USHRT_MAX == 65535
+    typedef unsigned short u16;
+# elif UINT_MAX == 65535
+    typedef unsigned int u16;
+# else
+#  undef STRICT_ALIGN
+#  define STRICT_ALIGN 1
+# endif
+#endif
+
+#if ULTRA_FAST
+# if defined(VERY_FAST)
+#  undef VERY_FAST
+# endif
+#endif
+
+#if INIT_HTAB
+# ifdef __cplusplus
+#  include <cstring>
+# else
+#  include <string.h>
+# endif
+#endif
+
+#endif