Mercurial > hg
view mercurial/bdiff.c @ 1691:e70e1ed66093
Removed executable bit from patchbomb extension.
author | Thomas Arendsen Hein <thomas@intevation.de> |
---|---|
date | Fri, 03 Feb 2006 11:43:49 +0100 |
parents | 8e80eefb3de6 |
children | 5afd459db177 |
line wrap: on
line source
/* bdiff.c - efficient binary diff extension for Mercurial Copyright 2005 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> #ifdef __hpux #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> #include <arpa/inet.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 h, i; const char *p, *b = a; struct line *l; /* count the lines */ i = 1; /* extra line for sentinel */ for (p = a; p < a + len; p++) if (*p == '\n' || p == a + len - 1) i++; *lr = l = 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++) { h = *p + rol32(h, 7); /* a simple hash from GNU diff */ if (*p == '\n' || p == a + len - 1) { 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; struct pos *h; /* build a hash table of the next highest power of 2 */ while (buckets < bn + 1) buckets *= 2; h = malloc(buckets * sizeof(struct pos)); buckets = buckets - 1; if (!h) return 0; /* 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 = calloc(bn, sizeof(struct pos)); /* we can't have more matches than lines in the shorter file */ l.head = l.base = 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 = an; l.head->b1 = 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) { PyObject *sa, *sb, *result = NULL; struct line *al, *bl; struct hunklist l = {NULL, NULL}; struct hunk *h; char encode[12], *rb; int an, bn, len = 0, la = 0, lb = 0; if (!PyArg_ParseTuple(args, "SS:bdiff", &sa, &sb)) return NULL; an = splitlines(PyString_AsString(sa), PyString_Size(sa), &al); bn = splitlines(PyString_AsString(sb), PyString_Size(sb), &bl); if (!al || !bl) goto nomem; l = diff(al, an, bl, bn); if (!l.head) goto nomem; /* calculate length of output */ 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); }