some distros have been carrying an --rsyncable patch for quite some time (the
Fedora version is below). could this possibly be merged into mainline ?
-mike
diff -up gzip-1.3.13/deflate.c.rsync gzip-1.3.13/deflate.c
--- gzip-1.3.13/deflate.c.rsync 2009-09-26 20:43:28.000000000 +0200
+++ gzip-1.3.13/deflate.c 2009-12-01 16:14:24.656387546 +0100
@@ -131,6 +131,14 @@
#endif
/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
+#ifndef RSYNC_WIN
+# define RSYNC_WIN 4096
+#endif
+/* Size of rsync window, must be< MAX_DIST */
+
+#define RSYNC_SUM_MATCH(sum) ((sum) % RSYNC_WIN == 0)
+/* Whether window sum matches magic value */
+
/*
===========================================================================
* Local data used by the "longest match" routines.
*/
@@ -212,6 +220,8 @@ local int compr_level;
unsigned near good_match;
/* Use a faster search when the previous match is longer than this */
+local ulg rsync_sum; /* rolling sum of rsync window */
+local ulg rsync_chunk_end; /* next rsync sequence point */
/* Values for max_lazy_match, good_match and max_chain_length, depending on
* the desired pack level (0..9). The values given below have been tuned to
@@ -310,6 +320,10 @@ void lm_init (pack_level, flags)
#endif
/* prev will be initialized on the fly */
+ /* rsync params */
+ rsync_chunk_end = 0xFFFFFFFFUL;
+ rsync_sum = 0;
+
/* Set the default configuration parameters:
*/
max_lazy_match = configuration_table[pack_level].max_lazy;
@@ -546,6 +560,8 @@ local void fill_window()
memcpy((char*)window, (char*)window+WSIZE, (unsigned)WSIZE);
match_start -= WSIZE;
strstart -= WSIZE; /* we now have strstart>= MAX_DIST: */
+ if (rsync_chunk_end != 0xFFFFFFFFUL)
+ rsync_chunk_end -= WSIZE;
block_start -= (long) WSIZE;
@@ -573,13 +589,46 @@ local void fill_window()
}
}
+local void rsync_roll(start, num)
+ unsigned start;
+ unsigned num;
+{
+ unsigned i;
+
+ if (start< RSYNC_WIN) {
+ /* before window fills. */
+ for (i = start; i< RSYNC_WIN; i++) {
+ if (i == start + num) return;
+ rsync_sum += (ulg)window[i];
+ }
+ num -= (RSYNC_WIN - start);
+ start = RSYNC_WIN;
+ }
+
+ /* buffer after window full */
+ for (i = start; i< start+num; i++) {
+ /* New character in */
+ rsync_sum += (ulg)window[i];
+ /* Old character out */
+ rsync_sum -= (ulg)window[i - RSYNC_WIN];
+ if (rsync_chunk_end == 0xFFFFFFFFUL&& RSYNC_SUM_MATCH(rsync_sum))
+ rsync_chunk_end = i;
+ }
+}
+
+/*
===========================================================================
+ * Set rsync_chunk_end if window sum matches magic value.
+ */
+#define RSYNC_ROLL(s, n) \
+ do { if (rsync) rsync_roll((s), (n)); } while(0)
+
/*
===========================================================================
* Flush the current block, with given end-of-file flag.
* IN assertion: strstart is set to the end of the current match.
*/
#define FLUSH_BLOCK(eof) \
flush_block(block_start>= 0L ? (char*)&window[(unsigned)block_start] : \
- (char*)NULL, (long)strstart - block_start, (eof))
+ (char*)NULL, (long)strstart - block_start, flush-1, (eof))
/*
===========================================================================
* Processes a new input file and return its compressed length. This
@@ -590,7 +639,7 @@ local void fill_window()
local off_t deflate_fast()
{
IPos hash_head; /* head of the hash chain */
- int flush; /* set if current block must be flushed */
+ int flush; /* set if current block must be flushed, 2=>and padded */
unsigned match_length = 0; /* length of best match */
prev_length = MIN_MATCH-1;
@@ -620,6 +669,7 @@ local off_t deflate_fast()
lookahead -= match_length;
+ RSYNC_ROLL(strstart, match_length);
/* Insert new strings in the hash table only if the match length
* is not too large. This saves time but degrades compression.
*/
@@ -648,9 +698,14 @@ local off_t deflate_fast()
/* No match, output a literal byte */
Tracevv((stderr,"%c",window[strstart]));
flush = ct_tally (0, window[strstart]);
+ RSYNC_ROLL(strstart, 1);
lookahead--;
strstart++;
}
+ if (rsync&& strstart> rsync_chunk_end) {
+ rsync_chunk_end = 0xFFFFFFFFUL;
+ flush = 2;
+ }
if (flush) FLUSH_BLOCK(0), block_start = strstart;
/* Make sure that we always have enough lookahead, except
@@ -724,6 +779,7 @@ off_t deflate()
*/
lookahead -= prev_length-1;
prev_length -= 2;
+ RSYNC_ROLL(strstart, prev_length+1);
do {
strstart++;
INSERT_STRING(strstart, hash_head);
@@ -736,24 +792,40 @@ off_t deflate()
match_available = 0;
match_length = MIN_MATCH-1;
strstart++;
- if (flush) FLUSH_BLOCK(0), block_start = strstart;
+ if (rsync&& strstart> rsync_chunk_end) {
+ rsync_chunk_end = 0xFFFFFFFFUL;
+ flush = 2;
+ }
+ if (flush) FLUSH_BLOCK(0), block_start = strstart;
} else if (match_available) {
/* If there was no match at the previous position, output a
* single literal. If there was a match but the current match
* is longer, truncate the previous match to a single literal.
*/
Tracevv((stderr,"%c",window[strstart-1]));
- if (ct_tally (0, window[strstart-1])) {
- FLUSH_BLOCK(0), block_start = strstart;
+ flush = ct_tally (0, window[strstart-1]);
+ if (rsync&& strstart> rsync_chunk_end) {
+ rsync_chunk_end = 0xFFFFFFFFUL;
+ flush = 2;
}
+ if (flush) FLUSH_BLOCK(0), block_start = strstart;
+ RSYNC_ROLL(strstart, 1);
strstart++;
lookahead--;
} else {
/* There is no previous match to compare with, wait for
* the next step to decide.
*/
+ if (rsync&& strstart> rsync_chunk_end) {
+ /* Reset huffman tree */
+ rsync_chunk_end = 0xFFFFFFFFUL;
+ flush = 2;
+ FLUSH_BLOCK(0), block_start = strstart;
+ }
+
match_available = 1;
+ RSYNC_ROLL(strstart, 1);
strstart++;
lookahead--;
}
diff -up gzip-1.3.13/doc/gzip.texi.rsync gzip-1.3.13/doc/gzip.texi
--- gzip-1.3.13/doc/gzip.texi.rsync 2009-09-28 11:08:16.000000000 +0200
+++ gzip-1.3.13/doc/gzip.texi 2009-12-01 16:14:24.664394713 +0100
@@ -353,6 +353,14 @@ specified on the command line are direct
into the directory and compress all the files it finds there (or
decompress them in the case of @command{gunzip}).
address@hidden --rsyncable
+While compressing, synchronize the output occasionally based on the
+input. This reduces compression by about 1 percent most cases, but
+means that the @code{rsync} program can take advantage of similarities
+in the uncompressed input when syncronizing two files compressed with
+this flag. @code{gunzip} cannot tell the difference between a
+compressed file created with this option, and one created without it.
+
@item --suffix @var{suf}
@itemx -S @var{suf}
Use suffix @var{suf} instead of @samp{.gz}. Any suffix can be
diff -up gzip-1.3.13/gzip.c.rsync gzip-1.3.13/gzip.c
--- gzip-1.3.13/gzip.c.rsync 2009-09-26 20:56:02.000000000 +0200
+++ gzip-1.3.13/gzip.c 2009-12-01 16:18:17.121387126 +0100
@@ -229,6 +229,7 @@ int ofd; /* output fil
unsigned insize; /* valid bytes in inbuf */
unsigned inptr; /* index of next byte to be processed in inbuf */
unsigned outcnt; /* bytes in output buffer */
+int rsync = 0; /* make ryncable chunks */
static int handled_sig[] =
{
@@ -282,6 +283,7 @@ struct option longopts[] =
{"best", 0, 0, '9'}, /* compress better */
{"lzw", 0, 0, 'Z'}, /* make output compatible with old compress */
{"bits", 1, 0, 'b'}, /* max number of bits per code (implies -Z) */
+ {"rsyncable", 0, 0, 'R'}, /* make rsync-friendly archive */
{ 0, 0, 0, 0 }
};
@@ -363,6 +365,7 @@ local void help()
" -Z, --lzw produce output compatible with old compress",
" -b, --bits=BITS max number of bits per code (implies -Z)",
#endif
+ " --rsyncable Make rsync-friendly archive",
"",
"With no FILE, or when FILE is -, read standard input.",
"",
@@ -493,6 +496,9 @@ int main (argc, argv)
recursive = 1;
#endif
break;
+
+ case 'R':
+ rsync = 1; break;
case 'S':
#ifdef NO_MULTIPLE_DOTS
if (*optarg == '.') optarg++;
diff -up gzip-1.3.13/gzip.h.rsync gzip-1.3.13/gzip.h
--- gzip-1.3.13/gzip.h.rsync 2009-09-26 20:43:28.000000000 +0200
+++ gzip-1.3.13/gzip.h 2009-12-01 16:14:24.664394713 +0100
@@ -158,6 +158,7 @@ EXTERN(uch, window); /* Sliding
extern unsigned insize; /* valid bytes in inbuf */
extern unsigned inptr; /* index of next byte to be processed in inbuf */
extern unsigned outcnt; /* bytes in output buffer */
+extern int rsync; /* deflate into rsyncable chunks */
extern off_t bytes_in; /* number of input bytes */
extern off_t bytes_out; /* number of output bytes */
@@ -306,7 +307,7 @@ off_t deflate OF((void));
/* in trees.c */
void ct_init OF((ush *attr, int *method));
int ct_tally OF((int dist, int lc));
-off_t flush_block OF((char *buf, ulg stored_len, int eof));
+off_t flush_block OF((char *buf, ulg stored_len, int pad, int eof));
/* in bits.c */
void bi_init OF((file_t zipfile));
diff -up gzip-1.3.13/trees.c.rsync gzip-1.3.13/trees.c
--- gzip-1.3.13/trees.c.rsync 2009-09-26 20:43:28.000000000 +0200
+++ gzip-1.3.13/trees.c 2009-12-01 16:14:24.655388257 +0100
@@ -856,9 +856,10 @@ local void send_all_trees(lcodes, dcodes
* trees or store, and output the encoded block to the zip file. This function
* returns the total compressed length for the file so far.
*/
-off_t flush_block(buf, stored_len, eof)
+off_t flush_block(buf, stored_len, pad, eof)
char *buf; /* input block, or NULL if too old */
ulg stored_len; /* length of input block */
+ int pad; /* pad output to byte boundary */
int eof; /* true if this is the last block for a file */
{
ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
@@ -951,6 +952,10 @@ off_t flush_block(buf, stored_len, eof)
Assert (input_len == bytes_in, "bad input size");
bi_windup();
compressed_len += 7; /* align on byte boundary */
+ } else if (pad&& (compressed_len % 8) != 0) {
+ send_bits((STORED_BLOCK<<1)+eof, 3); /* send block type */
+ compressed_len = (compressed_len + 3 + 7)& ~7L;
+ copy_block(buf, 0, 1); /* with header */
}
return compressed_len>> 3;