diff options
| -rw-r--r-- | Makefile | 7 | ||||
| -rw-r--r-- | delta.h | 6 | ||||
| -rw-r--r-- | diff-delta.c | 333 | ||||
| -rw-r--r-- | patch-delta.c | 88 | ||||
| -rw-r--r-- | test-delta.c | 79 |
5 files changed, 511 insertions, 2 deletions
@@ -36,9 +36,9 @@ install: $(PROG) $(SCRIPTS) $(INSTALL) $(PROG) $(SCRIPTS) $(dest)$(bin) LIB_OBJS=read-cache.o sha1_file.o usage.o object.o commit.o tree.o blob.o \ - tag.o date.o + tag.o date.o diff-delta.o patch-delta.o LIB_FILE=libgit.a -LIB_H=cache.h object.h blob.h tree.h commit.h tag.h +LIB_H=cache.h object.h blob.h tree.h commit.h tag.h delta.h LIB_H += strbuf.h LIB_OBJS += strbuf.o @@ -72,6 +72,9 @@ $(LIB_FILE): $(LIB_OBJS) test-date: test-date.c date.o $(CC) $(CFLAGS) -o $@ test-date.c date.o +test-delta: test-delta.c diff-delta.o patch-delta.o + $(CC) $(CFLAGS) -o $@ $^ + git-%: %.c $(LIB_FILE) $(CC) $(CFLAGS) -o $@ $(filter %.c,$^) $(LIBS) diff --git a/delta.h b/delta.h new file mode 100644 index 000000000..e073dff83 --- /dev/null +++ b/delta.h @@ -0,0 +1,6 @@ +extern void *diff_delta(void *from_buf, unsigned long from_size, + void *to_buf, unsigned long to_size, + unsigned long *delta_size); +extern void *patch_delta(void *src_buf, unsigned long src_size, + void *delta_buf, unsigned long delta_size, + unsigned long *dst_size); diff --git a/diff-delta.c b/diff-delta.c new file mode 100644 index 000000000..480f03cd1 --- /dev/null +++ b/diff-delta.c @@ -0,0 +1,333 @@ +/* + * diff-delta.c: generate a delta between two buffers + * + * Many parts of this file have been lifted from LibXDiff version 0.10. + * http://www.xmailserver.org/xdiff-lib.html + * + * LibXDiff was written by Davide Libenzi <davidel@xmailserver.org> + * Copyright (C) 2003 Davide Libenzi + * + * Many mods for GIT usage by Nicolas Pitre <nico@cam.org>, (C) 2005. + * + * This file is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * Use of this within git automatically means that the LGPL + * licensing gets turned into GPLv2 within this project. + */ + +#include <stdlib.h> +#include "delta.h" + + +/* block size: min = 16, max = 64k, power of 2 */ +#define BLK_SIZE 16 + +#define MIN(a, b) ((a) < (b) ? (a) : (b)) + +#define GR_PRIME 0x9e370001 +#define HASH(v, b) (((unsigned int)(v) * GR_PRIME) >> (32 - (b))) + +/* largest prime smaller than 65536 */ +#define BASE 65521 + +/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */ +#define NMAX 5552 + +#define DO1(buf, i) { s1 += buf[i]; s2 += s1; } +#define DO2(buf, i) DO1(buf, i); DO1(buf, i + 1); +#define DO4(buf, i) DO2(buf, i); DO2(buf, i + 2); +#define DO8(buf, i) DO4(buf, i); DO4(buf, i + 4); +#define DO16(buf) DO8(buf, 0); DO8(buf, 8); + +static unsigned int adler32(unsigned int adler, const unsigned char *buf, int len) +{ + int k; + unsigned int s1 = adler & 0xffff; + unsigned int s2 = adler >> 16; + + while (len > 0) { + k = MIN(len, NMAX); + len -= k; + while (k >= 16) { + DO16(buf); + buf += 16; + k -= 16; + } + if (k != 0) + do { + s1 += *buf++; + s2 += s1; + } while (--k); + s1 %= BASE; + s2 %= BASE; + } + + return (s2 << 16) | s1; +} + +static unsigned int hashbits(unsigned int size) +{ + unsigned int val = 1, bits = 0; + while (val < size && bits < 32) { + val <<= 1; + bits++; + } + return bits ? bits: 1; +} + +typedef struct s_chanode { + struct s_chanode *next; + int icurr; +} chanode_t; + +typedef struct s_chastore { + chanode_t *head, *tail; + int isize, nsize; + chanode_t *ancur; + chanode_t *sncur; + int scurr; +} chastore_t; + +static void cha_init(chastore_t *cha, int isize, int icount) +{ + cha->head = cha->tail = NULL; + cha->isize = isize; + cha->nsize = icount * isize; + cha->ancur = cha->sncur = NULL; + cha->scurr = 0; +} + +static void *cha_alloc(chastore_t *cha) +{ + chanode_t *ancur; + void *data; + + ancur = cha->ancur; + if (!ancur || ancur->icurr == cha->nsize) { + ancur = malloc(sizeof(chanode_t) + cha->nsize); + if (!ancur) + return NULL; + ancur->icurr = 0; + ancur->next = NULL; + if (cha->tail) + cha->tail->next = ancur; + if (!cha->head) + cha->head = ancur; + cha->tail = ancur; + cha->ancur = ancur; + } + + data = (void *)ancur + sizeof(chanode_t) + ancur->icurr; + ancur->icurr += cha->isize; + return data; +} + +static void cha_free(chastore_t *cha) +{ + chanode_t *cur = cha->head; + while (cur) { + chanode_t *tmp = cur; + cur = cur->next; + free(tmp); + } +} + +typedef struct s_bdrecord { + struct s_bdrecord *next; + unsigned int fp; + const unsigned char *ptr; +} bdrecord_t; + +typedef struct s_bdfile { + const unsigned char *data, *top; + chastore_t cha; + unsigned int fphbits; + bdrecord_t **fphash; +} bdfile_t; + +static int delta_prepare(const unsigned char *buf, int bufsize, bdfile_t *bdf) +{ + unsigned int fphbits; + int i, hsize; + const unsigned char *base, *data, *top; + bdrecord_t *brec; + bdrecord_t **fphash; + + fphbits = hashbits(bufsize / BLK_SIZE + 1); + hsize = 1 << fphbits; + fphash = malloc(hsize * sizeof(bdrecord_t *)); + if (!fphash) + return -1; + for (i = 0; i < hsize; i++) + fphash[i] = NULL; + cha_init(&bdf->cha, sizeof(bdrecord_t), hsize / 4 + 1); + + bdf->data = data = base = buf; + bdf->top = top = buf + bufsize; + data += (bufsize / BLK_SIZE) * BLK_SIZE; + if (data == top) + data -= BLK_SIZE; + + for ( ; data >= base; data -= BLK_SIZE) { + brec = cha_alloc(&bdf->cha); + if (!brec) { + cha_free(&bdf->cha); + free(fphash); + return -1; + } + brec->fp = adler32(0, data, MIN(BLK_SIZE, top - data)); + brec->ptr = data; + i = HASH(brec->fp, fphbits); + brec->next = fphash[i]; + fphash[i] = brec; + } + + bdf->fphbits = fphbits; + bdf->fphash = fphash; + + return 0; +} + +static void delta_cleanup(bdfile_t *bdf) +{ + free(bdf->fphash); + cha_free(&bdf->cha); +} + +#define COPYOP_SIZE(o, s) \ + (!!(o & 0xff) + !!(o & 0xff00) + !!(o & 0xff0000) + !!(o & 0xff000000) + \ + !!(s & 0xff) + !!(s & 0xff00) + 1) + +void *diff_delta(void *from_buf, unsigned long from_size, + void *to_buf, unsigned long to_size, + unsigned long *delta_size) +{ + int i, outpos, outsize, inscnt, csize, msize, moff; + unsigned int fp; + const unsigned char *data, *top, *ptr1, *ptr2; + unsigned char *out, *orig; + bdrecord_t *brec; + bdfile_t bdf; + + if (!from_size || !to_size || delta_prepare(from_buf, from_size, &bdf)) + return NULL; + + outpos = 0; + outsize = 8192; + out = malloc(outsize); + if (!out) { + delta_cleanup(&bdf); + return NULL; + } + + data = to_buf; + top = to_buf + to_size; + + /* store reference buffer size */ + orig = out + outpos++; + *orig = i = 0; + do { + if (from_size & 0xff) { + *orig |= (1 << i); + out[outpos++] = from_size; + } + i++; + from_size >>= 8; + } while (from_size); + + /* store target buffer size */ + orig = out + outpos++; + *orig = i = 0; + do { + if (to_size & 0xff) { + *orig |= (1 << i); + out[outpos++] = to_size; + } + i++; + to_size >>= 8; + } while (to_size); + + inscnt = 0; + moff = 0; + while (data < top) { + msize = 0; + fp = adler32(0, data, MIN(top - data, BLK_SIZE)); + i = HASH(fp, bdf.fphbits); + for (brec = bdf.fphash[i]; brec; brec = brec->next) { + if (brec->fp == fp) { + csize = bdf.top - brec->ptr; + if (csize > top - data) + csize = top - data; + for (ptr1 = brec->ptr, ptr2 = data; + csize && *ptr1 == *ptr2; + csize--, ptr1++, ptr2++); + + csize = ptr1 - brec->ptr; + if (csize > msize) { + moff = brec->ptr - bdf.data; + msize = csize; + if (msize >= 0x10000) { + msize = 0x10000; + break; + } + } + } + } + + if (!msize || msize < COPYOP_SIZE(moff, msize)) { + if (!inscnt) + outpos++; + out[outpos++] = *data++; + inscnt++; + if (inscnt == 0x7f) { + out[outpos - inscnt - 1] = inscnt; + inscnt = 0; + } + } else { + if (inscnt) { + out[outpos - inscnt - 1] = inscnt; + inscnt = 0; + } + + data += msize; + orig = out + outpos++; + i = 0x80; + + if (moff & 0xff) { out[outpos++] = moff; i |= 0x01; } + moff >>= 8; + if (moff & 0xff) { out[outpos++] = moff; i |= 0x02; } + moff >>= 8; + if (moff & 0xff) { out[outpos++] = moff; i |= 0x04; } + moff >>= 8; + if (moff & 0xff) { out[outpos++] = moff; i |= 0x08; } + + if (msize & 0xff) { out[outpos++] = msize; i |= 0x10; } + msize >>= 8; + if (msize & 0xff) { out[outpos++] = msize; i |= 0x20; } + + *orig = i; + } + + /* next time around the largest possible output is 1 + 4 + 3 */ + if (outpos > outsize - 8) { + void *tmp = out; + outsize = outsize * 3 / 2; + out = realloc(out, outsize); + if (!out) { + free(tmp); + delta_cleanup(&bdf); + return NULL; + } + } + } + + if (inscnt) + out[outpos - inscnt - 1] = inscnt; + + delta_cleanup(&bdf); + *delta_size = outpos; + return out; +} 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 <nico@cam.org> + * + * 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 <stdlib.h> +#include <string.h> +#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; +} diff --git a/test-delta.c b/test-delta.c new file mode 100644 index 000000000..8751e27c6 --- /dev/null +++ b/test-delta.c @@ -0,0 +1,79 @@ +/* + * test-delta.c: test code to exercise diff-delta.c and patch-delta.c + * + * (C) 2005 Nicolas Pitre <nico@cam.org> + * + * 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 <stdio.h> +#include <unistd.h> +#include <string.h> +#include <fcntl.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/mman.h> +#include "delta.h" + +static const char *usage = + "test-delta (-d|-p) <from_file> <data_file> <out_file>"; + +int main(int argc, char *argv[]) +{ + 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; +} |