|
|
/*
|
|
|
bdiff.c - efficient binary diff extension for Mercurial
|
|
|
|
|
|
Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>
|
|
|
|
|
|
This software may be used and distributed according to the terms of
|
|
|
the GNU General Public License, incorporated herein by reference.
|
|
|
|
|
|
Based roughly on Python difflib
|
|
|
*/
|
|
|
|
|
|
#include <Python.h>
|
|
|
#include <stdlib.h>
|
|
|
#include <string.h>
|
|
|
|
|
|
#if defined __hpux || defined __SUNPRO_C || defined _AIX
|
|
|
# define inline
|
|
|
#endif
|
|
|
|
|
|
#ifdef _WIN32
|
|
|
#ifdef _MSC_VER
|
|
|
#define inline __inline
|
|
|
typedef unsigned long uint32_t;
|
|
|
#else
|
|
|
#include <stdint.h>
|
|
|
#endif
|
|
|
static uint32_t htonl(uint32_t x)
|
|
|
{
|
|
|
return ((x & 0x000000ffUL) << 24) |
|
|
|
((x & 0x0000ff00UL) << 8) |
|
|
|
((x & 0x00ff0000UL) >> 8) |
|
|
|
((x & 0xff000000UL) >> 24);
|
|
|
}
|
|
|
#else
|
|
|
#include <sys/types.h>
|
|
|
#ifdef __BEOS__
|
|
|
#include <ByteOrder.h>
|
|
|
#else
|
|
|
#include <arpa/inet.h>
|
|
|
#endif
|
|
|
#include <inttypes.h>
|
|
|
#endif
|
|
|
|
|
|
struct line {
|
|
|
int h, len, n, e;
|
|
|
const char *l;
|
|
|
};
|
|
|
|
|
|
struct pos {
|
|
|
int pos, len;
|
|
|
};
|
|
|
|
|
|
struct hunk {
|
|
|
int a1, a2, b1, b2;
|
|
|
};
|
|
|
|
|
|
struct hunklist {
|
|
|
struct hunk *base, *head;
|
|
|
};
|
|
|
|
|
|
static inline uint32_t rol32(uint32_t word, unsigned int shift)
|
|
|
{
|
|
|
return (word << shift) | (word >> (32 - shift));
|
|
|
}
|
|
|
|
|
|
int splitlines(const char *a, int len, struct line **lr)
|
|
|
{
|
|
|
int g, h, i;
|
|
|
const char *p, *b = a;
|
|
|
const char * const plast = a + len - 1;
|
|
|
struct line *l;
|
|
|
|
|
|
/* count the lines */
|
|
|
i = 1; /* extra line for sentinel */
|
|
|
for (p = a; p < a + len; p++)
|
|
|
if (*p == '\n' || p == plast)
|
|
|
i++;
|
|
|
|
|
|
*lr = l = (struct line *)malloc(sizeof(struct line) * i);
|
|
|
if (!l)
|
|
|
return -1;
|
|
|
|
|
|
/* build the line array and calculate hashes */
|
|
|
h = 0;
|
|
|
for (p = a; p < a + len; p++) {
|
|
|
/*
|
|
|
* a simple hash from GNU diff, with better collision
|
|
|
* resistance from hashpjw. this slows down common
|
|
|
* case by 10%, but speeds up worst case by 100x.
|
|
|
*/
|
|
|
h = *p + rol32(h, 7);
|
|
|
if ((g = h & 0xf0000000)) {
|
|
|
h ^= g >> 24;
|
|
|
h ^= g;
|
|
|
}
|
|
|
if (*p == '\n' || p == plast) {
|
|
|
l->len = p - b + 1;
|
|
|
l->h = h * l->len;
|
|
|
l->l = b;
|
|
|
l->n = -1;
|
|
|
l++;
|
|
|
b = p + 1;
|
|
|
h = 0;
|
|
|
}
|
|
|
}
|
|
|
|
|
|
/* set up a sentinel */
|
|
|
l->h = l->len = 0;
|
|
|
l->l = a + len;
|
|
|
return i - 1;
|
|
|
}
|
|
|
|
|
|
int inline cmp(struct line *a, struct line *b)
|
|
|
{
|
|
|
return a->h != b->h || a->len != b->len || memcmp(a->l, b->l, a->len);
|
|
|
}
|
|
|
|
|
|
static int equatelines(struct line *a, int an, struct line *b, int bn)
|
|
|
{
|
|
|
int i, j, buckets = 1, t;
|
|
|
int scale = 32;
|
|
|
struct pos *h;
|
|
|
|
|
|
/* build a hash table of the next highest power of 2 */
|
|
|
while (buckets < bn + 1)
|
|
|
buckets *= 2;
|
|
|
|
|
|
/* try to allocate a large hash table to avoid collisions */
|
|
|
do {
|
|
|
scale /= 2;
|
|
|
h = (struct pos *)malloc(scale * buckets * sizeof(struct pos));
|
|
|
} while (!h && scale != 1);
|
|
|
|
|
|
if (!h)
|
|
|
return 0;
|
|
|
|
|
|
buckets = buckets * scale - 1;
|
|
|
|
|
|
/* clear the hash table */
|
|
|
for (i = 0; i <= buckets; i++) {
|
|
|
h[i].pos = -1;
|
|
|
h[i].len = 0;
|
|
|
}
|
|
|
|
|
|
/* add lines to the hash table chains */
|
|
|
for (i = bn - 1; i >= 0; i--) {
|
|
|
/* find the equivalence class */
|
|
|
for (j = b[i].h & buckets; h[j].pos != -1;
|
|
|
j = (j + 1) & buckets)
|
|
|
if (!cmp(b + i, b + h[j].pos))
|
|
|
break;
|
|
|
|
|
|
/* add to the head of the equivalence class */
|
|
|
b[i].n = h[j].pos;
|
|
|
b[i].e = j;
|
|
|
h[j].pos = i;
|
|
|
h[j].len++; /* keep track of popularity */
|
|
|
}
|
|
|
|
|
|
/* compute popularity threshold */
|
|
|
t = (bn >= 200) ? bn / 100 : bn + 1;
|
|
|
|
|
|
/* match items in a to their equivalence class in b */
|
|
|
for (i = 0; i < an; i++) {
|
|
|
/* find the equivalence class */
|
|
|
for (j = a[i].h & buckets; h[j].pos != -1;
|
|
|
j = (j + 1) & buckets)
|
|
|
if (!cmp(a + i, b + h[j].pos))
|
|
|
break;
|
|
|
|
|
|
a[i].e = j; /* use equivalence class for quick compare */
|
|
|
if (h[j].len <= t)
|
|
|
a[i].n = h[j].pos; /* point to head of match list */
|
|
|
else
|
|
|
a[i].n = -1; /* too popular */
|
|
|
}
|
|
|
|
|
|
/* discard hash tables */
|
|
|
free(h);
|
|
|
return 1;
|
|
|
}
|
|
|
|
|
|
static int longest_match(struct line *a, struct line *b, struct pos *pos,
|
|
|
int a1, int a2, int b1, int b2, int *omi, int *omj)
|
|
|
{
|
|
|
int mi = a1, mj = b1, mk = 0, mb = 0, i, j, k;
|
|
|
|
|
|
for (i = a1; i < a2; i++) {
|
|
|
/* skip things before the current block */
|
|
|
for (j = a[i].n; j != -1 && j < b1; j = b[j].n)
|
|
|
;
|
|
|
|
|
|
/* loop through all lines match a[i] in b */
|
|
|
for (; j != -1 && j < b2; j = b[j].n) {
|
|
|
/* does this extend an earlier match? */
|
|
|
if (i > a1 && j > b1 && pos[j - 1].pos == i - 1)
|
|
|
k = pos[j - 1].len + 1;
|
|
|
else
|
|
|
k = 1;
|
|
|
pos[j].pos = i;
|
|
|
pos[j].len = k;
|
|
|
|
|
|
/* best match so far? */
|
|
|
if (k > mk) {
|
|
|
mi = i;
|
|
|
mj = j;
|
|
|
mk = k;
|
|
|
}
|
|
|
}
|
|
|
}
|
|
|
|
|
|
if (mk) {
|
|
|
mi = mi - mk + 1;
|
|
|
mj = mj - mk + 1;
|
|
|
}
|
|
|
|
|
|
/* expand match to include neighboring popular lines */
|
|
|
while (mi - mb > a1 && mj - mb > b1 &&
|
|
|
a[mi - mb - 1].e == b[mj - mb - 1].e)
|
|
|
mb++;
|
|
|
while (mi + mk < a2 && mj + mk < b2 &&
|
|
|
a[mi + mk].e == b[mj + mk].e)
|
|
|
mk++;
|
|
|
|
|
|
*omi = mi - mb;
|
|
|
*omj = mj - mb;
|
|
|
return mk + mb;
|
|
|
}
|
|
|
|
|
|
static void recurse(struct line *a, struct line *b, struct pos *pos,
|
|
|
int a1, int a2, int b1, int b2, struct hunklist *l)
|
|
|
{
|
|
|
int i, j, k;
|
|
|
|
|
|
/* find the longest match in this chunk */
|
|
|
k = longest_match(a, b, pos, a1, a2, b1, b2, &i, &j);
|
|
|
if (!k)
|
|
|
return;
|
|
|
|
|
|
/* and recurse on the remaining chunks on either side */
|
|
|
recurse(a, b, pos, a1, i, b1, j, l);
|
|
|
l->head->a1 = i;
|
|
|
l->head->a2 = i + k;
|
|
|
l->head->b1 = j;
|
|
|
l->head->b2 = j + k;
|
|
|
l->head++;
|
|
|
recurse(a, b, pos, i + k, a2, j + k, b2, l);
|
|
|
}
|
|
|
|
|
|
static struct hunklist diff(struct line *a, int an, struct line *b, int bn)
|
|
|
{
|
|
|
struct hunklist l;
|
|
|
struct pos *pos;
|
|
|
int t;
|
|
|
|
|
|
/* allocate and fill arrays */
|
|
|
t = equatelines(a, an, b, bn);
|
|
|
pos = (struct pos *)calloc(bn, sizeof(struct pos));
|
|
|
/* we can't have more matches than lines in the shorter file */
|
|
|
l.head = l.base = (struct hunk *)malloc(sizeof(struct hunk) *
|
|
|
((an<bn ? an:bn) + 1));
|
|
|
|
|
|
if (pos && l.base && t) {
|
|
|
/* generate the matching block list */
|
|
|
recurse(a, b, pos, 0, an, 0, bn, &l);
|
|
|
l.head->a1 = l.head->a2 = an;
|
|
|
l.head->b1 = l.head->b2 = bn;
|
|
|
l.head++;
|
|
|
}
|
|
|
|
|
|
free(pos);
|
|
|
return l;
|
|
|
}
|
|
|
|
|
|
static PyObject *blocks(PyObject *self, PyObject *args)
|
|
|
{
|
|
|
PyObject *sa, *sb, *rl = NULL, *m;
|
|
|
struct line *a, *b;
|
|
|
struct hunklist l = {NULL, NULL};
|
|
|
struct hunk *h;
|
|
|
int an, bn, pos = 0;
|
|
|
|
|
|
if (!PyArg_ParseTuple(args, "SS:bdiff", &sa, &sb))
|
|
|
return NULL;
|
|
|
|
|
|
an = splitlines(PyString_AsString(sa), PyString_Size(sa), &a);
|
|
|
bn = splitlines(PyString_AsString(sb), PyString_Size(sb), &b);
|
|
|
if (!a || !b)
|
|
|
goto nomem;
|
|
|
|
|
|
l = diff(a, an, b, bn);
|
|
|
rl = PyList_New(l.head - l.base);
|
|
|
if (!l.head || !rl)
|
|
|
goto nomem;
|
|
|
|
|
|
for (h = l.base; h != l.head; h++) {
|
|
|
m = Py_BuildValue("iiii", h->a1, h->a2, h->b1, h->b2);
|
|
|
PyList_SetItem(rl, pos, m);
|
|
|
pos++;
|
|
|
}
|
|
|
|
|
|
nomem:
|
|
|
free(a);
|
|
|
free(b);
|
|
|
free(l.base);
|
|
|
return rl ? rl : PyErr_NoMemory();
|
|
|
}
|
|
|
|
|
|
static PyObject *bdiff(PyObject *self, PyObject *args)
|
|
|
{
|
|
|
char *sa, *sb;
|
|
|
PyObject *result = NULL;
|
|
|
struct line *al, *bl;
|
|
|
struct hunklist l = {NULL, NULL};
|
|
|
struct hunk *h;
|
|
|
char encode[12], *rb;
|
|
|
int an, bn, len = 0, la, lb;
|
|
|
|
|
|
if (!PyArg_ParseTuple(args, "s#s#:bdiff", &sa, &la, &sb, &lb))
|
|
|
return NULL;
|
|
|
|
|
|
an = splitlines(sa, la, &al);
|
|
|
bn = splitlines(sb, lb, &bl);
|
|
|
if (!al || !bl)
|
|
|
goto nomem;
|
|
|
|
|
|
l = diff(al, an, bl, bn);
|
|
|
if (!l.head)
|
|
|
goto nomem;
|
|
|
|
|
|
/* calculate length of output */
|
|
|
la = lb = 0;
|
|
|
for (h = l.base; h != l.head; h++) {
|
|
|
if (h->a1 != la || h->b1 != lb)
|
|
|
len += 12 + bl[h->b1].l - bl[lb].l;
|
|
|
la = h->a2;
|
|
|
lb = h->b2;
|
|
|
}
|
|
|
|
|
|
result = PyString_FromStringAndSize(NULL, len);
|
|
|
if (!result)
|
|
|
goto nomem;
|
|
|
|
|
|
/* build binary patch */
|
|
|
rb = PyString_AsString(result);
|
|
|
la = lb = 0;
|
|
|
|
|
|
for (h = l.base; h != l.head; h++) {
|
|
|
if (h->a1 != la || h->b1 != lb) {
|
|
|
len = bl[h->b1].l - bl[lb].l;
|
|
|
*(uint32_t *)(encode) = htonl(al[la].l - al->l);
|
|
|
*(uint32_t *)(encode + 4) = htonl(al[h->a1].l - al->l);
|
|
|
*(uint32_t *)(encode + 8) = htonl(len);
|
|
|
memcpy(rb, encode, 12);
|
|
|
memcpy(rb + 12, bl[lb].l, len);
|
|
|
rb += 12 + len;
|
|
|
}
|
|
|
la = h->a2;
|
|
|
lb = h->b2;
|
|
|
}
|
|
|
|
|
|
nomem:
|
|
|
free(al);
|
|
|
free(bl);
|
|
|
free(l.base);
|
|
|
return result ? result : PyErr_NoMemory();
|
|
|
}
|
|
|
|
|
|
static char mdiff_doc[] = "Efficient binary diff.";
|
|
|
|
|
|
static PyMethodDef methods[] = {
|
|
|
{"bdiff", bdiff, METH_VARARGS, "calculate a binary diff\n"},
|
|
|
{"blocks", blocks, METH_VARARGS, "find a list of matching lines\n"},
|
|
|
{NULL, NULL}
|
|
|
};
|
|
|
|
|
|
PyMODINIT_FUNC initbdiff(void)
|
|
|
{
|
|
|
Py_InitModule3("bdiff", methods, mdiff_doc);
|
|
|
}
|
|
|
|
|
|
|