[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 <nico@cam.org> Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Nicolas Pitre
Linus Torvalds
parent
21949255d1
commit
a310d43494
7
Makefile
7
Makefile
@ -36,9 +36,9 @@ install: $(PROG) $(SCRIPTS)
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$(INSTALL) $(PROG) $(SCRIPTS) $(dest)$(bin)
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LIB_OBJS=read-cache.o sha1_file.o usage.o object.o commit.o tree.o blob.o \
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tag.o date.o
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tag.o date.o diff-delta.o patch-delta.o
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LIB_FILE=libgit.a
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LIB_H=cache.h object.h blob.h tree.h commit.h tag.h
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LIB_H=cache.h object.h blob.h tree.h commit.h tag.h delta.h
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LIB_H += strbuf.h
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LIB_OBJS += strbuf.o
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@ -72,6 +72,9 @@ $(LIB_FILE): $(LIB_OBJS)
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test-date: test-date.c date.o
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$(CC) $(CFLAGS) -o $@ test-date.c date.o
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test-delta: test-delta.c diff-delta.o patch-delta.o
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$(CC) $(CFLAGS) -o $@ $^
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git-%: %.c $(LIB_FILE)
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$(CC) $(CFLAGS) -o $@ $(filter %.c,$^) $(LIBS)
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6
delta.h
Normal file
6
delta.h
Normal file
@ -0,0 +1,6 @@
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extern void *diff_delta(void *from_buf, unsigned long from_size,
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void *to_buf, unsigned long to_size,
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unsigned long *delta_size);
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extern void *patch_delta(void *src_buf, unsigned long src_size,
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void *delta_buf, unsigned long delta_size,
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unsigned long *dst_size);
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333
diff-delta.c
Normal file
333
diff-delta.c
Normal file
@ -0,0 +1,333 @@
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/*
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* diff-delta.c: generate a delta between two buffers
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*
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* Many parts of this file have been lifted from LibXDiff version 0.10.
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* http://www.xmailserver.org/xdiff-lib.html
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*
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* LibXDiff was written by Davide Libenzi <davidel@xmailserver.org>
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* Copyright (C) 2003 Davide Libenzi
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*
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* Many mods for GIT usage by Nicolas Pitre <nico@cam.org>, (C) 2005.
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*
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* This file is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Use of this within git automatically means that the LGPL
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* licensing gets turned into GPLv2 within this project.
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*/
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#include <stdlib.h>
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#include "delta.h"
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/* block size: min = 16, max = 64k, power of 2 */
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#define BLK_SIZE 16
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#define MIN(a, b) ((a) < (b) ? (a) : (b))
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#define GR_PRIME 0x9e370001
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#define HASH(v, b) (((unsigned int)(v) * GR_PRIME) >> (32 - (b)))
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/* largest prime smaller than 65536 */
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#define BASE 65521
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/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
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#define NMAX 5552
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#define DO1(buf, i) { s1 += buf[i]; s2 += s1; }
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#define DO2(buf, i) DO1(buf, i); DO1(buf, i + 1);
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#define DO4(buf, i) DO2(buf, i); DO2(buf, i + 2);
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#define DO8(buf, i) DO4(buf, i); DO4(buf, i + 4);
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#define DO16(buf) DO8(buf, 0); DO8(buf, 8);
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static unsigned int adler32(unsigned int adler, const unsigned char *buf, int len)
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{
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int k;
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unsigned int s1 = adler & 0xffff;
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unsigned int s2 = adler >> 16;
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while (len > 0) {
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k = MIN(len, NMAX);
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len -= k;
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while (k >= 16) {
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DO16(buf);
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buf += 16;
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k -= 16;
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}
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if (k != 0)
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do {
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s1 += *buf++;
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s2 += s1;
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} while (--k);
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s1 %= BASE;
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s2 %= BASE;
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}
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return (s2 << 16) | s1;
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}
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static unsigned int hashbits(unsigned int size)
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{
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unsigned int val = 1, bits = 0;
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while (val < size && bits < 32) {
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val <<= 1;
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bits++;
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}
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return bits ? bits: 1;
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}
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typedef struct s_chanode {
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struct s_chanode *next;
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int icurr;
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} chanode_t;
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typedef struct s_chastore {
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chanode_t *head, *tail;
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int isize, nsize;
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chanode_t *ancur;
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chanode_t *sncur;
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int scurr;
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} chastore_t;
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static void cha_init(chastore_t *cha, int isize, int icount)
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{
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cha->head = cha->tail = NULL;
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cha->isize = isize;
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cha->nsize = icount * isize;
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cha->ancur = cha->sncur = NULL;
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cha->scurr = 0;
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}
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static void *cha_alloc(chastore_t *cha)
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{
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chanode_t *ancur;
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void *data;
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ancur = cha->ancur;
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if (!ancur || ancur->icurr == cha->nsize) {
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ancur = malloc(sizeof(chanode_t) + cha->nsize);
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if (!ancur)
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return NULL;
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ancur->icurr = 0;
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ancur->next = NULL;
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if (cha->tail)
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cha->tail->next = ancur;
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if (!cha->head)
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cha->head = ancur;
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cha->tail = ancur;
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cha->ancur = ancur;
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}
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data = (void *)ancur + sizeof(chanode_t) + ancur->icurr;
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ancur->icurr += cha->isize;
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return data;
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}
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static void cha_free(chastore_t *cha)
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{
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chanode_t *cur = cha->head;
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while (cur) {
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chanode_t *tmp = cur;
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cur = cur->next;
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free(tmp);
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}
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}
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typedef struct s_bdrecord {
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struct s_bdrecord *next;
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unsigned int fp;
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const unsigned char *ptr;
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} bdrecord_t;
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typedef struct s_bdfile {
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const unsigned char *data, *top;
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chastore_t cha;
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unsigned int fphbits;
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bdrecord_t **fphash;
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} bdfile_t;
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static int delta_prepare(const unsigned char *buf, int bufsize, bdfile_t *bdf)
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{
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unsigned int fphbits;
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int i, hsize;
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const unsigned char *base, *data, *top;
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bdrecord_t *brec;
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bdrecord_t **fphash;
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fphbits = hashbits(bufsize / BLK_SIZE + 1);
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hsize = 1 << fphbits;
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fphash = malloc(hsize * sizeof(bdrecord_t *));
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if (!fphash)
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return -1;
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for (i = 0; i < hsize; i++)
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fphash[i] = NULL;
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cha_init(&bdf->cha, sizeof(bdrecord_t), hsize / 4 + 1);
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bdf->data = data = base = buf;
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bdf->top = top = buf + bufsize;
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data += (bufsize / BLK_SIZE) * BLK_SIZE;
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if (data == top)
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data -= BLK_SIZE;
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for ( ; data >= base; data -= BLK_SIZE) {
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brec = cha_alloc(&bdf->cha);
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if (!brec) {
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cha_free(&bdf->cha);
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free(fphash);
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return -1;
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}
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brec->fp = adler32(0, data, MIN(BLK_SIZE, top - data));
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brec->ptr = data;
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i = HASH(brec->fp, fphbits);
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brec->next = fphash[i];
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fphash[i] = brec;
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}
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bdf->fphbits = fphbits;
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bdf->fphash = fphash;
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return 0;
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}
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static void delta_cleanup(bdfile_t *bdf)
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{
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free(bdf->fphash);
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cha_free(&bdf->cha);
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}
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#define COPYOP_SIZE(o, s) \
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(!!(o & 0xff) + !!(o & 0xff00) + !!(o & 0xff0000) + !!(o & 0xff000000) + \
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!!(s & 0xff) + !!(s & 0xff00) + 1)
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void *diff_delta(void *from_buf, unsigned long from_size,
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void *to_buf, unsigned long to_size,
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unsigned long *delta_size)
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{
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int i, outpos, outsize, inscnt, csize, msize, moff;
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unsigned int fp;
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const unsigned char *data, *top, *ptr1, *ptr2;
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unsigned char *out, *orig;
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bdrecord_t *brec;
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bdfile_t bdf;
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if (!from_size || !to_size || delta_prepare(from_buf, from_size, &bdf))
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return NULL;
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outpos = 0;
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outsize = 8192;
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out = malloc(outsize);
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if (!out) {
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delta_cleanup(&bdf);
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return NULL;
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}
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data = to_buf;
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top = to_buf + to_size;
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/* store reference buffer size */
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orig = out + outpos++;
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*orig = i = 0;
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do {
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if (from_size & 0xff) {
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*orig |= (1 << i);
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out[outpos++] = from_size;
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}
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i++;
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from_size >>= 8;
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} while (from_size);
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/* store target buffer size */
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orig = out + outpos++;
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*orig = i = 0;
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do {
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if (to_size & 0xff) {
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*orig |= (1 << i);
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out[outpos++] = to_size;
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}
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i++;
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to_size >>= 8;
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} while (to_size);
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inscnt = 0;
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moff = 0;
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while (data < top) {
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msize = 0;
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fp = adler32(0, data, MIN(top - data, BLK_SIZE));
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i = HASH(fp, bdf.fphbits);
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for (brec = bdf.fphash[i]; brec; brec = brec->next) {
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if (brec->fp == fp) {
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csize = bdf.top - brec->ptr;
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if (csize > top - data)
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csize = top - data;
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for (ptr1 = brec->ptr, ptr2 = data;
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csize && *ptr1 == *ptr2;
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csize--, ptr1++, ptr2++);
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csize = ptr1 - brec->ptr;
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if (csize > msize) {
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moff = brec->ptr - bdf.data;
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msize = csize;
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if (msize >= 0x10000) {
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msize = 0x10000;
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break;
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}
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}
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}
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}
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if (!msize || msize < COPYOP_SIZE(moff, msize)) {
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if (!inscnt)
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outpos++;
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out[outpos++] = *data++;
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inscnt++;
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if (inscnt == 0x7f) {
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out[outpos - inscnt - 1] = inscnt;
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inscnt = 0;
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}
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} else {
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if (inscnt) {
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out[outpos - inscnt - 1] = inscnt;
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inscnt = 0;
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}
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data += msize;
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orig = out + outpos++;
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i = 0x80;
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if (moff & 0xff) { out[outpos++] = moff; i |= 0x01; }
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moff >>= 8;
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if (moff & 0xff) { out[outpos++] = moff; i |= 0x02; }
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moff >>= 8;
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if (moff & 0xff) { out[outpos++] = moff; i |= 0x04; }
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moff >>= 8;
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if (moff & 0xff) { out[outpos++] = moff; i |= 0x08; }
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if (msize & 0xff) { out[outpos++] = msize; i |= 0x10; }
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msize >>= 8;
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if (msize & 0xff) { out[outpos++] = msize; i |= 0x20; }
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*orig = i;
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}
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/* next time around the largest possible output is 1 + 4 + 3 */
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if (outpos > outsize - 8) {
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void *tmp = out;
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outsize = outsize * 3 / 2;
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out = realloc(out, outsize);
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if (!out) {
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free(tmp);
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delta_cleanup(&bdf);
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return NULL;
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}
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}
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}
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if (inscnt)
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out[outpos - inscnt - 1] = inscnt;
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delta_cleanup(&bdf);
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*delta_size = outpos;
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return out;
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}
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88
patch-delta.c
Normal file
88
patch-delta.c
Normal file
@ -0,0 +1,88 @@
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/*
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* patch-delta.c:
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* recreate a buffer from a source and the delta produced by diff-delta.c
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*
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* (C) 2005 Nicolas Pitre <nico@cam.org>
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*
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* This code is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <stdlib.h>
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#include <string.h>
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#include "delta.h"
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void *patch_delta(void *src_buf, unsigned long src_size,
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void *delta_buf, unsigned long delta_size,
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unsigned long *dst_size)
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{
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const unsigned char *data, *top;
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unsigned char *dst_buf, *out, cmd;
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unsigned long size;
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int i;
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/* the smallest delta size possible is 6 bytes */
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if (delta_size < 6)
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return NULL;
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data = delta_buf;
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top = delta_buf + delta_size;
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/* make sure the orig file size matches what we expect */
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size = i = 0;
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cmd = *data++;
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while (cmd) {
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if (cmd & 1)
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size |= *data++ << i;
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i += 8;
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cmd >>= 1;
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}
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if (size != src_size)
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return NULL;
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/* now the result size */
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size = i = 0;
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cmd = *data++;
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while (cmd) {
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if (cmd & 1)
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size |= *data++ << i;
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i += 8;
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cmd >>= 1;
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}
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dst_buf = malloc(size);
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if (!dst_buf)
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return NULL;
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out = dst_buf;
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while (data < top) {
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cmd = *data++;
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if (cmd & 0x80) {
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unsigned long cp_off = 0, cp_size = 0;
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const unsigned char *buf;
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if (cmd & 0x01) cp_off = *data++;
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if (cmd & 0x02) cp_off |= (*data++ << 8);
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if (cmd & 0x04) cp_off |= (*data++ << 16);
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if (cmd & 0x08) cp_off |= (*data++ << 24);
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if (cmd & 0x10) cp_size = *data++;
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if (cmd & 0x20) cp_size |= (*data++ << 8);
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if (cp_size == 0) cp_size = 0x10000;
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buf = (cmd & 0x40) ? dst_buf : src_buf;
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memcpy(out, buf + cp_off, cp_size);
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out += cp_size;
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} else {
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memcpy(out, data, cmd);
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out += cmd;
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data += cmd;
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}
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}
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/* sanity check */
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if (data != top || out - dst_buf != size) {
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free(dst_buf);
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return NULL;
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}
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*dst_size = size;
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return dst_buf;
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}
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79
test-delta.c
Normal file
79
test-delta.c
Normal file
@ -0,0 +1,79 @@
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/*
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* test-delta.c: test code to exercise diff-delta.c and patch-delta.c
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*
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* (C) 2005 Nicolas Pitre <nico@cam.org>
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*
|
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* 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.
|
||||
*/
|
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#include <stdio.h>
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#include <unistd.h>
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#include <string.h>
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#include <fcntl.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/mman.h>
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#include "delta.h"
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static const char *usage =
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"test-delta (-d|-p) <from_file> <data_file> <out_file>";
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int main(int argc, char *argv[])
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{
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int fd;
|
||||
struct stat st;
|
||||
void *from_buf, *data_buf, *out_buf;
|
||||
unsigned long from_size, data_size, out_size;
|
||||
|
||||
if (argc != 5 || (strcmp(argv[1], "-d") && strcmp(argv[1], "-p"))) {
|
||||
fprintf(stderr, "Usage: %s\n", usage);
|
||||
return 1;
|
||||
}
|
||||
|
||||
fd = open(argv[2], O_RDONLY);
|
||||
if (fd < 0 || fstat(fd, &st)) {
|
||||
perror(argv[2]);
|
||||
return 1;
|
||||
}
|
||||
from_size = st.st_size;
|
||||
from_buf = mmap(NULL, from_size, PROT_READ, MAP_PRIVATE, fd, 0);
|
||||
if (from_buf == MAP_FAILED) {
|
||||
perror(argv[2]);
|
||||
return 1;
|
||||
}
|
||||
close(fd);
|
||||
|
||||
fd = open(argv[3], O_RDONLY);
|
||||
if (fd < 0 || fstat(fd, &st)) {
|
||||
perror(argv[3]);
|
||||
return 1;
|
||||
}
|
||||
data_size = st.st_size;
|
||||
data_buf = mmap(NULL, data_size, PROT_READ, MAP_PRIVATE, fd, 0);
|
||||
if (data_buf == MAP_FAILED) {
|
||||
perror(argv[3]);
|
||||
return 1;
|
||||
}
|
||||
close(fd);
|
||||
|
||||
if (argv[1][1] == 'd')
|
||||
out_buf = diff_delta(from_buf, from_size,
|
||||
data_buf, data_size, &out_size);
|
||||
else
|
||||
out_buf = patch_delta(from_buf, from_size,
|
||||
data_buf, data_size, &out_size);
|
||||
if (!out_buf) {
|
||||
fprintf(stderr, "delta operation failed (returned NULL)\n");
|
||||
return 1;
|
||||
}
|
||||
|
||||
fd = open (argv[4], O_WRONLY|O_CREAT|O_TRUNC, 0666);
|
||||
if (fd < 0 || write(fd, out_buf, out_size) != out_size) {
|
||||
perror(argv[4]);
|
||||
return 1;
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user