From a310d4349467d78266f38d29e500c77b96ee5bef Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Thu, 19 May 2005 10:27:14 -0400 Subject: [PATCH] Deltification library work by Nicolas Pitre. This patch adds the basic library functions to create and replay delta information. Also included is a test-delta utility to validate the code. diff-delta was based on LibXDiff written by Davide Libenzi Signed-off-by: Nicolas Pitre Signed-off-by: Davide Libenzi Signed-off-by: Linus Torvalds --- patch-delta.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 patch-delta.c (limited to 'patch-delta.c') diff --git a/patch-delta.c b/patch-delta.c new file mode 100644 index 000000000..a8d75ee1c --- /dev/null +++ b/patch-delta.c @@ -0,0 +1,88 @@ +/* + * patch-delta.c: + * recreate a buffer from a source and the delta produced by diff-delta.c + * + * (C) 2005 Nicolas Pitre + * + * This code is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include +#include +#include "delta.h" + +void *patch_delta(void *src_buf, unsigned long src_size, + void *delta_buf, unsigned long delta_size, + unsigned long *dst_size) +{ + const unsigned char *data, *top; + unsigned char *dst_buf, *out, cmd; + unsigned long size; + int i; + + /* the smallest delta size possible is 6 bytes */ + if (delta_size < 6) + return NULL; + + data = delta_buf; + top = delta_buf + delta_size; + + /* make sure the orig file size matches what we expect */ + size = i = 0; + cmd = *data++; + while (cmd) { + if (cmd & 1) + size |= *data++ << i; + i += 8; + cmd >>= 1; + } + if (size != src_size) + return NULL; + + /* now the result size */ + size = i = 0; + cmd = *data++; + while (cmd) { + if (cmd & 1) + size |= *data++ << i; + i += 8; + cmd >>= 1; + } + dst_buf = malloc(size); + if (!dst_buf) + return NULL; + + out = dst_buf; + while (data < top) { + cmd = *data++; + if (cmd & 0x80) { + unsigned long cp_off = 0, cp_size = 0; + const unsigned char *buf; + if (cmd & 0x01) cp_off = *data++; + if (cmd & 0x02) cp_off |= (*data++ << 8); + if (cmd & 0x04) cp_off |= (*data++ << 16); + if (cmd & 0x08) cp_off |= (*data++ << 24); + if (cmd & 0x10) cp_size = *data++; + if (cmd & 0x20) cp_size |= (*data++ << 8); + if (cp_size == 0) cp_size = 0x10000; + buf = (cmd & 0x40) ? dst_buf : src_buf; + memcpy(out, buf + cp_off, cp_size); + out += cp_size; + } else { + memcpy(out, data, cmd); + out += cmd; + data += cmd; + } + } + + /* sanity check */ + if (data != top || out - dst_buf != size) { + free(dst_buf); + return NULL; + } + + *dst_size = size; + return dst_buf; +} -- cgit v1.2.1