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< http://rsync.samba.org/ftp/unpacked/rsync/patches/gzip-rsyncable.diff >
From: Rusty Russell <rusty@rustcorp.com.au>
[NOTE: this patch is for _gzip_! --Wayne]
It's pending for actual gzip inclusion! The maintainer was dug up andeverything: it'll even be on by default.
But here's the old patch,Rusty.--
Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
--- gzip-1.2.4.orig/deflate.c Fri Aug 13 22:35:31 1993
+++ gzip-1.2.4-rsync/deflate.c Sat Dec 30 15:33:25 2000
@@ -121,6 +121,14 @@
#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. */@@ -202,6 +210,8 @@
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@@ -300,6 +310,10 @@
#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;@@ -536,6 +550,8 @@
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; @@ -563,13 +579,46 @@
} } +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@@ -580,7 +629,7 @@
local ulg 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;@@ -609,6 +658,7 @@
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. */@@ -637,9 +687,14 @@
/* 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@@ -715,6 +770,7 @@
*/ lookahead -= prev_length-1; prev_length -= 2;+ RSYNC_ROLL(strstart, prev_length+1);
do { strstart++; INSERT_STRING(strstart, hash_head);@@ -727,24 +783,39 @@
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--; }--- gzip-1.2.4.orig/gzip.c Thu Aug 19 23:39:43 1993
+++ gzip-1.2.4-rsync/gzip.c Fri Dec 29 21:20:54 2000
@@ -239,6 +239,7 @@
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 */
struct option longopts[] = {@@ -268,6 +269,7 @@
{"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 } }; @@ -357,6 +359,7 @@
" -Z --lzw produce output compatible with old compress", " -b --bits maxbits max number of bits per code (implies -Z)", #endif+ " --rsyncable Make rsync-friendly archive",
" file... files to (de)compress. If none given, use standard input.", 0}; char **p = help_msg;@@ -516,6 +519,9 @@
#else recursive = 1; break; #endif+ case 'R':
+ rsync = 1; break;
+
case 'S': #ifdef NO_MULTIPLE_DOTS if (*optarg == '.') optarg++;--- gzip-1.2.4.orig/gzip.h Fri Aug 13 22:35:33 1993
+++ gzip-1.2.4-rsync/gzip.h Sat Dec 30 15:26:56 2000
@@ -131,6 +131,7 @@
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 long bytes_in; /* number of input bytes */ extern long bytes_out; /* number of output bytes */@@ -282,7 +283,7 @@
/* in trees.c */ void ct_init OF((ush *attr, int *method)); int ct_tally OF((int dist, int lc));-ulg flush_block OF((char *buf, ulg stored_len, int eof));
+ulg flush_block OF((char *buf, ulg stored_len, int pad, int eof));
/* in bits.c */ void bi_init OF((file_t zipfile));--- gzip-1.2.4.orig/gzip.texi Thu Aug 19 06:42:50 1993
+++ gzip-1.2.4-rsync/gzip.texi Fri Dec 29 21:20:54 2000
@@ -316,6 +316,14 @@
into the directory and compress all the files it finds there (or decompress them in the case of @code{gunzip}). +@item --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 @samp{@var{suf}} instead of @samp{.gz}. Any suffix can be--- gzip-1.2.4.orig/trees.c Wed Aug 18 03:36:32 1993
+++ gzip-1.2.4-rsync/trees.c Sat Dec 30 15:37:00 2000
@@ -850,9 +850,10 @@
* trees or store, and output the encoded block to the zip file. This function * returns the total compressed length for the file so far. */-ulg flush_block(buf, stored_len, eof)
+ulg 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 */@@ -944,6 +967,10 @@
Assert (input_len == isize, "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 */
} Tracev((stderr,"\ncomprlen %lu(%lu) ", compressed_len>>3, compressed_len-7*eof));
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