Merge branch 'lt/diffgen' into next

* lt/diffgen:
  built-in diff: minimum tweaks
  builtin-diff: \No newline at end of file.
  Use a *real* built-in diff generator

Makefile

@@ -188,6 +188,7 @@ PYMODULES = \
 	gitMergeCommon.py
 
 LIB_FILE=libgit.a
+XDIFF_LIB=xdiff/lib.a
 
 LIB_H = \
 	blob.h cache.h commit.h csum-file.h delta.h \
@@ -209,7 +210,7 @@ LIB_OBJS = \
 	fetch-clone.o revision.o pager.o \
 	$(DIFF_OBJS)
 
-LIBS = $(LIB_FILE)
+LIBS = $(LIB_FILE) $(XDIFF_LIB)
 LIBS += -lz
 
 #
@@ -544,12 +545,18 @@ init-db.o: init-db.c
 		-DDEFAULT_GIT_TEMPLATE_DIR='"$(template_dir_SQ)"' $*.c
 
 $(LIB_OBJS): $(LIB_H)
-$(patsubst git-%$X,%.o,$(PROGRAMS)): $(LIB_H)
+$(patsubst git-%$X,%.o,$(PROGRAMS)): $(LIBS)
 $(DIFF_OBJS): diffcore.h
 
 $(LIB_FILE): $(LIB_OBJS)
 	$(AR) rcs $@ $(LIB_OBJS)
 
+XDIFF_OBJS=xdiff/xdiffi.o xdiff/xprepare.o xdiff/xutils.o xdiff/xemit.o
+
+$(XDIFF_LIB): $(XDIFF_OBJS)
+	$(AR) rcs $@ $(XDIFF_OBJS)
+
+
 doc:
 	$(MAKE) -C Documentation all
 

diff.c

@@ -8,6 +8,7 @@
 #include "quote.h"
 #include "diff.h"
 #include "diffcore.h"
+#include "xdiff/xdiff.h"
 
 static const char *diff_opts = "-pu";
 
@@ -178,6 +179,70 @@ static void emit_rewrite_diff(const char *name_a,
 		copy_file('+', temp[1].name);
 }
 
+static int fill_mmfile(mmfile_t *mf, const char *file)
+{
+	int fd = open(file, O_RDONLY);
+	struct stat st;
+	char *buf;
+	unsigned long size;
+
+	mf->ptr = NULL;
+	mf->size = 0;
+	if (fd < 0)
+		return 0;
+	fstat(fd, &st);
+	size = st.st_size;
+	buf = xmalloc(size);
+	mf->ptr = buf;
+	mf->size = size;
+	while (size) {
+		int retval = read(fd, buf, size);
+		if (retval < 0) {
+			if (errno == EINTR || errno == EAGAIN)
+				continue;
+			break;
+		}
+		if (!retval)
+			break;
+		buf += retval;
+		size -= retval;
+	}
+	mf->size -= size;
+	close(fd);
+	return 0;
+}
+
+struct emit_callback {
+	const char **label_path;
+};
+
+static int fn_out(void *priv, mmbuffer_t *mb, int nbuf)
+{
+	int i;
+	struct emit_callback *ecbdata = priv;
+
+	if (ecbdata->label_path[0]) {
+		printf("--- %s\n", ecbdata->label_path[0]);
+		printf("+++ %s\n", ecbdata->label_path[1]);
+		ecbdata->label_path[0] = ecbdata->label_path[1] = NULL;
+	}
+	for (i = 0; i < nbuf; i++)
+		if (!fwrite(mb[i].ptr, mb[i].size, 1, stdout))
+			return -1;
+	return 0;
+}
+
+#define FIRST_FEW_BYTES 8000
+static int mmfile_is_binary(mmfile_t *mf)
+{
+	long sz = mf->size;
+	if (FIRST_FEW_BYTES < sz)
+		sz = FIRST_FEW_BYTES;
+	if (memchr(mf->ptr, 0, sz))
+		return 1;
+	return 0;
+}
+
 static const char *builtin_diff(const char *name_a,
 			 const char *name_b,
 			 struct diff_tempfile *temp,
@@ -186,6 +251,7 @@ static const char *builtin_diff(const char *name_a,
 			 const char **args)
 {
 	int i, next_at, cmd_size;
+	mmfile_t mf1, mf2;
 	const char *const diff_cmd = "diff -L%s -L%s";
 	const char *const diff_arg  = "-- %s %s||:"; /* "||:" is to return 0 */
 	const char *input_name_sq[2];
@@ -255,12 +321,44 @@ static const char *builtin_diff(const char *name_a,
 		}
 	}
 
-	/* This is disgusting */
-	*args++ = "sh";
-	*args++ = "-c";
-	*args++ = cmd;
-	*args = NULL;
-	return "/bin/sh";
+	/* Un-quote the paths */
+	if (label_path[0][0] != '/')
+		label_path[0] = quote_two("a/", name_a);
+	if (label_path[1][0] != '/')
+		label_path[1] = quote_two("b/", name_b);
+
+	if (fill_mmfile(&mf1, temp[0].name) < 0 ||
+	    fill_mmfile(&mf2, temp[1].name) < 0)
+		die("unable to read files to diff");
+
+	if (mmfile_is_binary(&mf1) || mmfile_is_binary(&mf2))
+		printf("Binary files %s and %s differ\n",
+		       label_path[0], label_path[1]);
+	else {
+		/* Crazy xdl interfaces.. */
+		const char *diffopts = getenv("GIT_DIFF_OPTS");
+		xpparam_t xpp;
+		xdemitconf_t xecfg;
+		xdemitcb_t ecb;
+		struct emit_callback ecbdata;
+
+		ecbdata.label_path = label_path;
+		xpp.flags = XDF_NEED_MINIMAL;
+		xecfg.ctxlen = 3;
+		if (!diffopts)
+			;
+		else if (!strncmp(diffopts, "--unified=", 10))
+			xecfg.ctxlen = strtoul(diffopts + 10, NULL, 10);
+		else if (!strncmp(diffopts, "-u", 2))
+			xecfg.ctxlen = strtoul(diffopts + 2, NULL, 10);
+		ecb.outf = fn_out;
+		ecb.priv = &ecbdata;
+		xdl_diff(&mf1, &mf2, &xpp, &xecfg, &ecb);
+	}
+
+	free(mf1.ptr);
+	free(mf2.ptr);
+	return NULL;
 }
 
 struct diff_filespec *alloc_filespec(const char *path)

t/t4001-diff-rename.sh

@@ -49,7 +49,7 @@ rename from path0
 rename to path1
 --- a/path0
 +++ b/path1
-@@ -8,7 +8,7 @@ Line 7
+@@ -8,7 +8,7 @@
  Line 8
  Line 9
  Line 10

xdiff/xdiff.h

@@ -0,0 +1,91 @@
+/*
+ *  LibXDiff by Davide Libenzi ( File Differential Library )
+ *  Copyright (C) 2003  Davide Libenzi
+ *
+ *  This library 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.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+
+#if !defined(XDIFF_H)
+#define XDIFF_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* #ifdef __cplusplus */
+
+
+#define XDF_NEED_MINIMAL (1 << 1)
+
+#define XDL_PATCH_NORMAL '-'
+#define XDL_PATCH_REVERSE '+'
+#define XDL_PATCH_MODEMASK ((1 << 8) - 1)
+#define XDL_PATCH_IGNOREBSPACE (1 << 8)
+
+#define XDL_MMB_READONLY (1 << 0)
+
+#define XDL_MMF_ATOMIC (1 << 0)
+
+#define XDL_BDOP_INS 1
+#define XDL_BDOP_CPY 2
+#define XDL_BDOP_INSB 3
+
+
+typedef struct s_mmfile {
+	char *ptr;
+	long size;
+} mmfile_t;
+
+typedef struct s_mmbuffer {
+	char *ptr;
+	long size;
+} mmbuffer_t;
+
+typedef struct s_xpparam {
+	unsigned long flags;
+} xpparam_t;
+
+typedef struct s_xdemitcb {
+	void *priv;
+	int (*outf)(void *, mmbuffer_t *, int);
+} xdemitcb_t;
+
+typedef struct s_xdemitconf {
+	long ctxlen;
+} xdemitconf_t;
+
+typedef struct s_bdiffparam {
+	long bsize;
+} bdiffparam_t;
+
+
+#define xdl_malloc(x) malloc(x)
+#define xdl_free(ptr) free(ptr)
+#define xdl_realloc(ptr,x) realloc(ptr,x)
+
+void *xdl_mmfile_first(mmfile_t *mmf, long *size);
+void *xdl_mmfile_next(mmfile_t *mmf, long *size);
+long xdl_mmfile_size(mmfile_t *mmf);
+
+int xdl_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
+	     xdemitconf_t const *xecfg, xdemitcb_t *ecb);
+
+#ifdef __cplusplus
+}
+#endif /* #ifdef __cplusplus */
+
+#endif /* #if !defined(XDIFF_H) */
+

xdiff/xdiffi.c

@@ -0,0 +1,469 @@
+/*
+ *  LibXDiff by Davide Libenzi ( File Differential Library )
+ *  Copyright (C) 2003	Davide Libenzi
+ *
+ *  This library 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.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+
+#include "xinclude.h"
+
+
+
+#define XDL_MAX_COST_MIN 256
+#define XDL_HEUR_MIN_COST 256
+#define XDL_LINE_MAX (long)((1UL << (8 * sizeof(long) - 1)) - 1)
+#define XDL_SNAKE_CNT 20
+#define XDL_K_HEUR 4
+
+
+
+typedef struct s_xdpsplit {
+	long i1, i2;
+	int min_lo, min_hi;
+} xdpsplit_t;
+
+
+
+
+static long xdl_split(unsigned long const *ha1, long off1, long lim1,
+		      unsigned long const *ha2, long off2, long lim2,
+		      long *kvdf, long *kvdb, int need_min, xdpsplit_t *spl,
+		      xdalgoenv_t *xenv);
+static xdchange_t *xdl_add_change(xdchange_t *xscr, long i1, long i2, long chg1, long chg2);
+
+
+
+
+/*
+ * See "An O(ND) Difference Algorithm and its Variations", by Eugene Myers.
+ * Basically considers a "box" (off1, off2, lim1, lim2) and scan from both
+ * the forward diagonal starting from (off1, off2) and the backward diagonal
+ * starting from (lim1, lim2). If the K values on the same diagonal crosses
+ * returns the furthest point of reach. We might end up having to expensive
+ * cases using this algorithm is full, so a little bit of heuristic is needed
+ * to cut the search and to return a suboptimal point.
+ */
+static long xdl_split(unsigned long const *ha1, long off1, long lim1,
+		      unsigned long const *ha2, long off2, long lim2,
+		      long *kvdf, long *kvdb, int need_min, xdpsplit_t *spl,
+		      xdalgoenv_t *xenv) {
+	long dmin = off1 - lim2, dmax = lim1 - off2;
+	long fmid = off1 - off2, bmid = lim1 - lim2;
+	long odd = (fmid - bmid) & 1;
+	long fmin = fmid, fmax = fmid;
+	long bmin = bmid, bmax = bmid;
+	long ec, d, i1, i2, prev1, best, dd, v, k;
+
+	/*
+	 * Set initial diagonal values for both forward and backward path.
+	 */
+	kvdf[fmid] = off1;
+	kvdb[bmid] = lim1;
+
+	for (ec = 1;; ec++) {
+		int got_snake = 0;
+
+		/*
+		 * We need to extent the diagonal "domain" by one. If the next
+		 * values exits the box boundaries we need to change it in the
+		 * opposite direction because (max - min) must be a power of two.
+		 * Also we initialize the extenal K value to -1 so that we can
+		 * avoid extra conditions check inside the core loop.
+		 */
+		if (fmin > dmin)
+			kvdf[--fmin - 1] = -1;
+		else
+			++fmin;
+		if (fmax < dmax)
+			kvdf[++fmax + 1] = -1;
+		else
+			--fmax;
+
+		for (d = fmax; d >= fmin; d -= 2) {
+			if (kvdf[d - 1] >= kvdf[d + 1])
+				i1 = kvdf[d - 1] + 1;
+			else
+				i1 = kvdf[d + 1];
+			prev1 = i1;
+			i2 = i1 - d;
+			for (; i1 < lim1 && i2 < lim2 && ha1[i1] == ha2[i2]; i1++, i2++);
+			if (i1 - prev1 > xenv->snake_cnt)
+				got_snake = 1;
+			kvdf[d] = i1;
+			if (odd && bmin <= d && d <= bmax && kvdb[d] <= i1) {
+				spl->i1 = i1;
+				spl->i2 = i2;
+				spl->min_lo = spl->min_hi = 1;
+				return ec;
+			}
+		}
+
+		/*
+		 * We need to extent the diagonal "domain" by one. If the next
+		 * values exits the box boundaries we need to change it in the
+		 * opposite direction because (max - min) must be a power of two.
+		 * Also we initialize the extenal K value to -1 so that we can
+		 * avoid extra conditions check inside the core loop.
+		 */
+		if (bmin > dmin)
+			kvdb[--bmin - 1] = XDL_LINE_MAX;
+		else
+			++bmin;
+		if (bmax < dmax)
+			kvdb[++bmax + 1] = XDL_LINE_MAX;
+		else
+			--bmax;
+
+		for (d = bmax; d >= bmin; d -= 2) {
+			if (kvdb[d - 1] < kvdb[d + 1])
+				i1 = kvdb[d - 1];
+			else
+				i1 = kvdb[d + 1] - 1;
+			prev1 = i1;
+			i2 = i1 - d;
+			for (; i1 > off1 && i2 > off2 && ha1[i1 - 1] == ha2[i2 - 1]; i1--, i2--);
+			if (prev1 - i1 > xenv->snake_cnt)
+				got_snake = 1;
+			kvdb[d] = i1;
+			if (!odd && fmin <= d && d <= fmax && i1 <= kvdf[d]) {
+				spl->i1 = i1;
+				spl->i2 = i2;
+				spl->min_lo = spl->min_hi = 1;
+				return ec;
+			}
+		}
+
+		if (need_min)
+			continue;
+
+		/*
+		 * If the edit cost is above the heuristic trigger and if
+		 * we got a good snake, we sample current diagonals to see
+		 * if some of the, have reached an "interesting" path. Our
+		 * measure is a function of the distance from the diagonal
+		 * corner (i1 + i2) penalized with the distance from the
+		 * mid diagonal itself. If this value is above the current
+		 * edit cost times a magic factor (XDL_K_HEUR) we consider
+		 * it interesting.
+		 */
+		if (got_snake && ec > xenv->heur_min) {
+			for (best = 0, d = fmax; d >= fmin; d -= 2) {
+				dd = d > fmid ? d - fmid: fmid - d;
+				i1 = kvdf[d];
+				i2 = i1 - d;
+				v = (i1 - off1) + (i2 - off2) - dd;
+
+				if (v > XDL_K_HEUR * ec && v > best &&
+				    off1 + xenv->snake_cnt <= i1 && i1 < lim1 &&
+				    off2 + xenv->snake_cnt <= i2 && i2 < lim2) {
+					for (k = 1; ha1[i1 - k] == ha2[i2 - k]; k++)
+						if (k == xenv->snake_cnt) {
+							best = v;
+							spl->i1 = i1;
+							spl->i2 = i2;
+							break;
+						}
+				}
+			}
+			if (best > 0) {
+				spl->min_lo = 1;
+				spl->min_hi = 0;
+				return ec;
+			}
+
+			for (best = 0, d = bmax; d >= bmin; d -= 2) {
+				dd = d > bmid ? d - bmid: bmid - d;
+				i1 = kvdb[d];
+				i2 = i1 - d;
+				v = (lim1 - i1) + (lim2 - i2) - dd;
+
+				if (v > XDL_K_HEUR * ec && v > best &&
+				    off1 < i1 && i1 <= lim1 - xenv->snake_cnt &&
+				    off2 < i2 && i2 <= lim2 - xenv->snake_cnt) {
+					for (k = 0; ha1[i1 + k] == ha2[i2 + k]; k++)
+						if (k == xenv->snake_cnt - 1) {
+							best = v;
+							spl->i1 = i1;
+							spl->i2 = i2;
+							break;
+						}
+				}
+			}
+			if (best > 0) {
+				spl->min_lo = 0;
+				spl->min_hi = 1;
+				return ec;
+			}
+		}
+
+		/*
+		 * Enough is enough. We spent too much time here and now we collect
+		 * the furthest reaching path using the (i1 + i2) measure.
+		 */
+		if (ec >= xenv->mxcost) {
+			long fbest, fbest1, bbest, bbest1;
+
+			fbest = -1;
+			for (d = fmax; d >= fmin; d -= 2) {
+				i1 = XDL_MIN(kvdf[d], lim1);
+				i2 = i1 - d;
+				if (lim2 < i2)
+					i1 = lim2 + d, i2 = lim2;
+				if (fbest < i1 + i2) {
+					fbest = i1 + i2;
+					fbest1 = i1;
+				}
+			}
+
+			bbest = XDL_LINE_MAX;
+			for (d = bmax; d >= bmin; d -= 2) {
+				i1 = XDL_MAX(off1, kvdb[d]);
+				i2 = i1 - d;
+				if (i2 < off2)
+					i1 = off2 + d, i2 = off2;
+				if (i1 + i2 < bbest) {
+					bbest = i1 + i2;
+					bbest1 = i1;
+				}
+			}
+
+			if ((lim1 + lim2) - bbest < fbest - (off1 + off2)) {
+				spl->i1 = fbest1;
+				spl->i2 = fbest - fbest1;
+				spl->min_lo = 1;
+				spl->min_hi = 0;
+			} else {
+				spl->i1 = bbest1;
+				spl->i2 = bbest - bbest1;
+				spl->min_lo = 0;
+				spl->min_hi = 1;
+			}
+			return ec;
+		}
+	}
+
+	return -1;
+}
+
+
+/*
+ * Rule: "Divide et Impera". Recursively split the box in sub-boxes by calling
+ * the box splitting function. Note that the real job (marking changed lines)
+ * is done in the two boundary reaching checks.
+ */
+int xdl_recs_cmp(diffdata_t *dd1, long off1, long lim1,
+		 diffdata_t *dd2, long off2, long lim2,
+		 long *kvdf, long *kvdb, int need_min, xdalgoenv_t *xenv) {
+	unsigned long const *ha1 = dd1->ha, *ha2 = dd2->ha;
+
+	/*
+	 * Shrink the box by walking through each diagonal snake (SW and NE).
+	 */
+	for (; off1 < lim1 && off2 < lim2 && ha1[off1] == ha2[off2]; off1++, off2++);
+	for (; off1 < lim1 && off2 < lim2 && ha1[lim1 - 1] == ha2[lim2 - 1]; lim1--, lim2--);
+
+	/*
+	 * If one dimension is empty, then all records on the other one must
+	 * be obviously changed.
+	 */
+	if (off1 == lim1) {
+		char *rchg2 = dd2->rchg;
+		long *rindex2 = dd2->rindex;
+
+		for (; off2 < lim2; off2++)
+			rchg2[rindex2[off2]] = 1;
+	} else if (off2 == lim2) {
+		char *rchg1 = dd1->rchg;
+		long *rindex1 = dd1->rindex;
+
+		for (; off1 < lim1; off1++)
+			rchg1[rindex1[off1]] = 1;
+	} else {
+		long ec;
+		xdpsplit_t spl;
+
+		/*
+		 * Divide ...
+		 */
+		if ((ec = xdl_split(ha1, off1, lim1, ha2, off2, lim2, kvdf, kvdb,
+				    need_min, &spl, xenv)) < 0) {
+
+			return -1;
+		}
+
+		/*
+		 * ... et Impera.
+		 */
+		if (xdl_recs_cmp(dd1, off1, spl.i1, dd2, off2, spl.i2,
+				 kvdf, kvdb, spl.min_lo, xenv) < 0 ||
+		    xdl_recs_cmp(dd1, spl.i1, lim1, dd2, spl.i2, lim2,
+				 kvdf, kvdb, spl.min_hi, xenv) < 0) {
+
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+
+int xdl_do_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
+		xdfenv_t *xe) {
+	long ndiags;
+	long *kvd, *kvdf, *kvdb;
+	xdalgoenv_t xenv;
+	diffdata_t dd1, dd2;
+
+	if (xdl_prepare_env(mf1, mf2, xpp, xe) < 0) {
+
+		return -1;
+	}
+
+	/*
+	 * Allocate and setup K vectors to be used by the differential algorithm.
+	 * One is to store the forward path and one to store the backward path.
+	 */
+	ndiags = xe->xdf1.nreff + xe->xdf2.nreff + 3;
+	if (!(kvd = (long *) xdl_malloc((2 * ndiags + 2) * sizeof(long)))) {
+
+		xdl_free_env(xe);
+		return -1;
+	}
+	kvdf = kvd;
+	kvdb = kvdf + ndiags;
+	kvdf += xe->xdf2.nreff + 1;
+	kvdb += xe->xdf2.nreff + 1;
+
+	/*
+	 * Classical integer square root approximation using shifts.
+	 */
+	xenv.mxcost = 1;
+	for (; ndiags; ndiags >>= 2)
+		xenv.mxcost <<= 1;
+	if (xenv.mxcost < XDL_MAX_COST_MIN)
+		xenv.mxcost = XDL_MAX_COST_MIN;
+	xenv.snake_cnt = XDL_SNAKE_CNT;
+	xenv.heur_min = XDL_HEUR_MIN_COST;
+
+	dd1.nrec = xe->xdf1.nreff;
+	dd1.ha = xe->xdf1.ha;
+	dd1.rchg = xe->xdf1.rchg;
+	dd1.rindex = xe->xdf1.rindex;
+	dd2.nrec = xe->xdf2.nreff;
+	dd2.ha = xe->xdf2.ha;
+	dd2.rchg = xe->xdf2.rchg;
+	dd2.rindex = xe->xdf2.rindex;
+
+	if (xdl_recs_cmp(&dd1, 0, dd1.nrec, &dd2, 0, dd2.nrec,
+			 kvdf, kvdb, (xpp->flags & XDF_NEED_MINIMAL) != 0, &xenv) < 0) {
+
+		xdl_free(kvd);
+		xdl_free_env(xe);
+		return -1;
+	}
+
+	xdl_free(kvd);
+
+	return 0;
+}
+
+
+static xdchange_t *xdl_add_change(xdchange_t *xscr, long i1, long i2, long chg1, long chg2) {
+	xdchange_t *xch;
+
+	if (!(xch = (xdchange_t *) xdl_malloc(sizeof(xdchange_t))))
+		return NULL;
+
+	xch->next = xscr;
+	xch->i1 = i1;
+	xch->i2 = i2;
+	xch->chg1 = chg1;
+	xch->chg2 = chg2;
+
+	return xch;
+}
+
+
+int xdl_build_script(xdfenv_t *xe, xdchange_t **xscr) {
+	xdchange_t *cscr = NULL, *xch;
+	char *rchg1 = xe->xdf1.rchg, *rchg2 = xe->xdf2.rchg;
+	long i1, i2, l1, l2;
+
+	/*
+	 * Trivial. Collects "groups" of changes and creates an edit script.
+	 */
+	for (i1 = xe->xdf1.nrec, i2 = xe->xdf2.nrec; i1 >= 0 || i2 >= 0; i1--, i2--)
+		if (rchg1[i1 - 1] || rchg2[i2 - 1]) {
+			for (l1 = i1; rchg1[i1 - 1]; i1--);
+			for (l2 = i2; rchg2[i2 - 1]; i2--);
+
+			if (!(xch = xdl_add_change(cscr, i1, i2, l1 - i1, l2 - i2))) {
+				xdl_free_script(cscr);
+				return -1;
+			}
+			cscr = xch;
+		}
+
+	*xscr = cscr;
+
+	return 0;
+}
+
+
+void xdl_free_script(xdchange_t *xscr) {
+	xdchange_t *xch;
+
+	while ((xch = xscr) != NULL) {
+		xscr = xscr->next;
+		xdl_free(xch);
+	}
+}
+
+
+int xdl_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
+	     xdemitconf_t const *xecfg, xdemitcb_t *ecb) {
+	xdchange_t *xscr;
+	xdfenv_t xe;
+
+	if (xdl_do_diff(mf1, mf2, xpp, &xe) < 0) {
+
+		return -1;
+	}
+
+	if (xdl_build_script(&xe, &xscr) < 0) {
+
+		xdl_free_env(&xe);
+		return -1;
+	}
+
+	if (xscr) {
+		if (xdl_emit_diff(&xe, xscr, ecb, xecfg) < 0) {
+
+			xdl_free_script(xscr);
+			xdl_free_env(&xe);
+			return -1;
+		}
+
+		xdl_free_script(xscr);
+	}
+
+	xdl_free_env(&xe);
+
+	return 0;
+}
+

xdiff/xdiffi.h

@@ -0,0 +1,60 @@
+/*
+ *  LibXDiff by Davide Libenzi ( File Differential Library )
+ *  Copyright (C) 2003  Davide Libenzi
+ *
+ *  This library 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.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+
+#if !defined(XDIFFI_H)
+#define XDIFFI_H
+
+
+typedef struct s_diffdata {
+	long nrec;
+	unsigned long const *ha;
+	long *rindex;
+	char *rchg;
+} diffdata_t;
+
+typedef struct s_xdalgoenv {
+	long mxcost;
+	long snake_cnt;
+	long heur_min;
+} xdalgoenv_t;
+
+typedef struct s_xdchange {
+	struct s_xdchange *next;
+	long i1, i2;
+	long chg1, chg2;
+} xdchange_t;
+
+
+
+int xdl_recs_cmp(diffdata_t *dd1, long off1, long lim1,
+		 diffdata_t *dd2, long off2, long lim2,
+		 long *kvdf, long *kvdb, int need_min, xdalgoenv_t *xenv);
+int xdl_do_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
+		xdfenv_t *xe);
+int xdl_build_script(xdfenv_t *xe, xdchange_t **xscr);
+void xdl_free_script(xdchange_t *xscr);
+int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
+		  xdemitconf_t const *xecfg);
+
+
+#endif /* #if !defined(XDIFFI_H) */
+

xdiff/xemit.c

@@ -0,0 +1,141 @@
+/*
+ *  LibXDiff by Davide Libenzi ( File Differential Library )
+ *  Copyright (C) 2003	Davide Libenzi
+ *
+ *  This library 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.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+
+#include "xinclude.h"
+
+
+
+
+static long xdl_get_rec(xdfile_t *xdf, long ri, char const **rec);
+static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *ecb);
+static xdchange_t *xdl_get_hunk(xdchange_t *xscr, xdemitconf_t const *xecfg);
+
+
+
+
+static long xdl_get_rec(xdfile_t *xdf, long ri, char const **rec) {
+
+	*rec = xdf->recs[ri]->ptr;
+
+	return xdf->recs[ri]->size;
+}
+
+
+static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *ecb) {
+	long size, psize = strlen(pre);
+	char const *rec;
+
+	size = xdl_get_rec(xdf, ri, &rec);
+	if (xdl_emit_diffrec(rec, size, pre, psize, ecb) < 0) {
+
+		return -1;
+	}
+
+	return 0;
+}
+
+
+/*
+ * Starting at the passed change atom, find the latest change atom to be included
+ * inside the differential hunk according to the specified configuration.
+ */
+static xdchange_t *xdl_get_hunk(xdchange_t *xscr, xdemitconf_t const *xecfg) {
+	xdchange_t *xch, *xchp;
+
+	for (xchp = xscr, xch = xscr->next; xch; xchp = xch, xch = xch->next)
+		if (xch->i1 - (xchp->i1 + xchp->chg1) > 2 * xecfg->ctxlen)
+			break;
+
+	return xchp;
+}
+
+
+int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
+		  xdemitconf_t const *xecfg) {
+	long s1, s2, e1, e2, lctx;
+	xdchange_t *xch, *xche;
+
+	for (xch = xche = xscr; xch; xch = xche->next) {
+		xche = xdl_get_hunk(xch, xecfg);
+
+		s1 = XDL_MAX(xch->i1 - xecfg->ctxlen, 0);
+		s2 = XDL_MAX(xch->i2 - xecfg->ctxlen, 0);
+
+		lctx = xecfg->ctxlen;
+		lctx = XDL_MIN(lctx, xe->xdf1.nrec - (xche->i1 + xche->chg1));
+		lctx = XDL_MIN(lctx, xe->xdf2.nrec - (xche->i2 + xche->chg2));
+
+		e1 = xche->i1 + xche->chg1 + lctx;
+		e2 = xche->i2 + xche->chg2 + lctx;
+
+		/*
+		 * Emit current hunk header.
+		 */
+		if (xdl_emit_hunk_hdr(s1 + 1, e1 - s1, s2 + 1, e2 - s2, ecb) < 0)
+			return -1;
+
+		/*
+		 * Emit pre-context.
+		 */
+		for (; s1 < xch->i1; s1++)
+			if (xdl_emit_record(&xe->xdf1, s1, " ", ecb) < 0)
+				return -1;
+
+		for (s1 = xch->i1, s2 = xch->i2;; xch = xch->next) {
+			/*
+			 * Merge previous with current change atom.
+			 */
+			for (; s1 < xch->i1 && s2 < xch->i2; s1++, s2++)
+				if (xdl_emit_record(&xe->xdf1, s1, " ", ecb) < 0)
+					return -1;
+
+			/*
+			 * Removes lines from the first file.
+			 */
+			for (s1 = xch->i1; s1 < xch->i1 + xch->chg1; s1++)
+				if (xdl_emit_record(&xe->xdf1, s1, "-", ecb) < 0)
+					return -1;
+
+			/*
+			 * Adds lines from the second file.
+			 */
+			for (s2 = xch->i2; s2 < xch->i2 + xch->chg2; s2++)
+				if (xdl_emit_record(&xe->xdf2, s2, "+", ecb) < 0)
+					return -1;
+
+			if (xch == xche)
+				break;
+			s1 = xch->i1 + xch->chg1;
+			s2 = xch->i2 + xch->chg2;
+		}
+
+		/*
+		 * Emit post-context.
+		 */
+		for (s1 = xche->i1 + xche->chg1; s1 < e1; s1++)
+			if (xdl_emit_record(&xe->xdf1, s1, " ", ecb) < 0)
+				return -1;
+	}
+
+	return 0;
+}
+

xdiff/xemit.h

@@ -0,0 +1,34 @@
+/*
+ *  LibXDiff by Davide Libenzi ( File Differential Library )
+ *  Copyright (C) 2003  Davide Libenzi
+ *
+ *  This library 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.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+
+#if !defined(XEMIT_H)
+#define XEMIT_H
+
+
+
+int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
+		  xdemitconf_t const *xecfg);
+
+
+
+#endif /* #if !defined(XEMIT_H) */
+

xdiff/xinclude.h

@@ -0,0 +1,42 @@
+/*
+ *  LibXDiff by Davide Libenzi ( File Differential Library )
+ *  Copyright (C) 2003  Davide Libenzi
+ *
+ *  This library 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.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+
+#if !defined(XINCLUDE_H)
+#define XINCLUDE_H
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <limits.h>
+
+#include "xmacros.h"
+#include "xdiff.h"
+#include "xtypes.h"
+#include "xutils.h"
+#include "xprepare.h"
+#include "xdiffi.h"
+#include "xemit.h"
+
+
+#endif /* #if !defined(XINCLUDE_H) */
+

xdiff/xmacros.h

@@ -0,0 +1,53 @@
+/*
+ *  LibXDiff by Davide Libenzi ( File Differential Library )
+ *  Copyright (C) 2003  Davide Libenzi
+ *
+ *  This library 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.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+
+#if !defined(XMACROS_H)
+#define XMACROS_H
+
+
+#define GR_PRIME 0x9e370001UL
+
+
+#define XDL_MIN(a, b) ((a) < (b) ? (a): (b))
+#define XDL_MAX(a, b) ((a) > (b) ? (a): (b))
+#define XDL_ABS(v) ((v) >= 0 ? (v): -(v))
+#define XDL_ISDIGIT(c) ((c) >= '0' && (c) <= '9')
+#define XDL_HASHLONG(v, b) (((unsigned long)(v) * GR_PRIME) >> ((CHAR_BIT * sizeof(unsigned long)) - (b)))
+#define XDL_PTRFREE(p) do { if (p) { xdl_free(p); (p) = NULL; } } while (0)
+#define XDL_LE32_PUT(p, v) \
+do { \
+	unsigned char *__p = (unsigned char *) (p); \
+	*__p++ = (unsigned char) (v); \
+	*__p++ = (unsigned char) ((v) >> 8); \
+	*__p++ = (unsigned char) ((v) >> 16); \
+	*__p = (unsigned char) ((v) >> 24); \
+} while (0)
+#define XDL_LE32_GET(p, v) \
+do { \
+	unsigned char const *__p = (unsigned char const *) (p); \
+	(v) = (unsigned long) __p[0] | ((unsigned long) __p[1]) << 8 | \
+		((unsigned long) __p[2]) << 16 | ((unsigned long) __p[3]) << 24; \
+} while (0)
+
+
+#endif /* #if !defined(XMACROS_H) */
+

xdiff/xprepare.c

@@ -0,0 +1,436 @@
+/*
+ *  LibXDiff by Davide Libenzi ( File Differential Library )
+ *  Copyright (C) 2003  Davide Libenzi
+ *
+ *  This library 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.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+
+#include "xinclude.h"
+
+
+
+#define XDL_KPDIS_RUN 4
+
+
+
+typedef struct s_xdlclass {
+	struct s_xdlclass *next;
+	unsigned long ha;
+	char const *line;
+	long size;
+	long idx;
+} xdlclass_t;
+
+typedef struct s_xdlclassifier {
+	unsigned int hbits;
+	long hsize;
+	xdlclass_t **rchash;
+	chastore_t ncha;
+	long count;
+} xdlclassifier_t;
+
+
+
+
+static int xdl_init_classifier(xdlclassifier_t *cf, long size);
+static void xdl_free_classifier(xdlclassifier_t *cf);
+static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned int hbits,
+			       xrecord_t *rec);
+static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
+			   xdlclassifier_t *cf, xdfile_t *xdf);
+static void xdl_free_ctx(xdfile_t *xdf);
+static int xdl_clean_mmatch(char const *dis, long i, long s, long e);
+static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2);
+static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2);
+static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2);
+
+
+
+
+static int xdl_init_classifier(xdlclassifier_t *cf, long size) {
+	long i;
+
+	cf->hbits = xdl_hashbits((unsigned int) size);
+	cf->hsize = 1 << cf->hbits;
+
+	if (xdl_cha_init(&cf->ncha, sizeof(xdlclass_t), size / 4 + 1) < 0) {
+
+		return -1;
+	}
+	if (!(cf->rchash = (xdlclass_t **) xdl_malloc(cf->hsize * sizeof(xdlclass_t *)))) {
+
+		xdl_cha_free(&cf->ncha);
+		return -1;
+	}
+	for (i = 0; i < cf->hsize; i++)
+		cf->rchash[i] = NULL;
+
+	cf->count = 0;
+
+	return 0;
+}
+
+
+static void xdl_free_classifier(xdlclassifier_t *cf) {
+
+	xdl_free(cf->rchash);
+	xdl_cha_free(&cf->ncha);
+}
+
+
+static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned int hbits,
+			       xrecord_t *rec) {
+	long hi;
+	char const *line;
+	xdlclass_t *rcrec;
+
+	line = rec->ptr;
+	hi = (long) XDL_HASHLONG(rec->ha, cf->hbits);
+	for (rcrec = cf->rchash[hi]; rcrec; rcrec = rcrec->next)
+		if (rcrec->ha == rec->ha && rcrec->size == rec->size &&
+		    !memcmp(line, rcrec->line, rec->size))
+			break;
+
+	if (!rcrec) {
+		if (!(rcrec = xdl_cha_alloc(&cf->ncha))) {
+
+			return -1;
+		}
+		rcrec->idx = cf->count++;
+		rcrec->line = line;
+		rcrec->size = rec->size;
+		rcrec->ha = rec->ha;
+		rcrec->next = cf->rchash[hi];
+		cf->rchash[hi] = rcrec;
+	}
+
+	rec->ha = (unsigned long) rcrec->idx;
+
+	hi = (long) XDL_HASHLONG(rec->ha, hbits);
+	rec->next = rhash[hi];
+	rhash[hi] = rec;
+
+	return 0;
+}
+
+
+static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
+			   xdlclassifier_t *cf, xdfile_t *xdf) {
+	unsigned int hbits;
+	long i, nrec, hsize, bsize;
+	unsigned long hav;
+	char const *blk, *cur, *top, *prev;
+	xrecord_t *crec;
+	xrecord_t **recs, **rrecs;
+	xrecord_t **rhash;
+	unsigned long *ha;
+	char *rchg;
+	long *rindex;
+
+	if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0) {
+
+		return -1;
+	}
+	if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *)))) {
+
+		xdl_cha_free(&xdf->rcha);
+		return -1;
+	}
+
+	hbits = xdl_hashbits((unsigned int) narec);
+	hsize = 1 << hbits;
+	if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *)))) {
+
+		xdl_free(recs);
+		xdl_cha_free(&xdf->rcha);
+		return -1;
+	}
+	for (i = 0; i < hsize; i++)
+		rhash[i] = NULL;
+
+	nrec = 0;
+	if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {
+		for (top = blk + bsize;;) {
+			if (cur >= top) {
+				if (!(cur = blk = xdl_mmfile_next(mf, &bsize)))
+					break;
+				top = blk + bsize;
+			}
+			prev = cur;
+			hav = xdl_hash_record(&cur, top);
+			if (nrec >= narec) {
+				narec *= 2;
+				if (!(rrecs = (xrecord_t **) xdl_realloc(recs, narec * sizeof(xrecord_t *)))) {
+
+					xdl_free(rhash);
+					xdl_free(recs);
+					xdl_cha_free(&xdf->rcha);
+					return -1;
+				}
+				recs = rrecs;
+			}
+			if (!(crec = xdl_cha_alloc(&xdf->rcha))) {
+
+				xdl_free(rhash);
+				xdl_free(recs);
+				xdl_cha_free(&xdf->rcha);
+				return -1;
+			}
+			crec->ptr = prev;
+			crec->size = (long) (cur - prev);
+			crec->ha = hav;
+			recs[nrec++] = crec;
+
+			if (xdl_classify_record(cf, rhash, hbits, crec) < 0) {
+
+				xdl_free(rhash);
+				xdl_free(recs);
+				xdl_cha_free(&xdf->rcha);
+				return -1;
+			}
+		}
+	}
+
+	if (!(rchg = (char *) xdl_malloc((nrec + 2) * sizeof(char)))) {
+
+		xdl_free(rhash);
+		xdl_free(recs);
+		xdl_cha_free(&xdf->rcha);
+		return -1;
+	}
+	memset(rchg, 0, (nrec + 2) * sizeof(char));
+
+	if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long)))) {
+
+		xdl_free(rchg);
+		xdl_free(rhash);
+		xdl_free(recs);
+		xdl_cha_free(&xdf->rcha);
+		return -1;
+	}
+	if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long)))) {
+
+		xdl_free(rindex);
+		xdl_free(rchg);
+		xdl_free(rhash);
+		xdl_free(recs);
+		xdl_cha_free(&xdf->rcha);
+		return -1;
+	}
+
+	xdf->nrec = nrec;
+	xdf->recs = recs;
+	xdf->hbits = hbits;
+	xdf->rhash = rhash;
+	xdf->rchg = rchg + 1;
+	xdf->rindex = rindex;
+	xdf->nreff = 0;
+	xdf->ha = ha;
+	xdf->dstart = 0;
+	xdf->dend = nrec - 1;
+
+	return 0;
+}
+
+
+static void xdl_free_ctx(xdfile_t *xdf) {
+
+	xdl_free(xdf->rhash);
+	xdl_free(xdf->rindex);
+	xdl_free(xdf->rchg - 1);
+	xdl_free(xdf->ha);
+	xdl_free(xdf->recs);
+	xdl_cha_free(&xdf->rcha);
+}
+
+
+int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
+		    xdfenv_t *xe) {
+	long enl1, enl2;
+	xdlclassifier_t cf;
+
+	enl1 = xdl_guess_lines(mf1) + 1;
+	enl2 = xdl_guess_lines(mf2) + 1;
+
+	if (xdl_init_classifier(&cf, enl1 + enl2 + 1) < 0) {
+
+		return -1;
+	}
+
+	if (xdl_prepare_ctx(mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
+
+		xdl_free_classifier(&cf);
+		return -1;
+	}
+	if (xdl_prepare_ctx(mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
+
+		xdl_free_ctx(&xe->xdf1);
+		xdl_free_classifier(&cf);
+		return -1;
+	}
+
+	xdl_free_classifier(&cf);
+
+	if (xdl_optimize_ctxs(&xe->xdf1, &xe->xdf2) < 0) {
+
+		xdl_free_ctx(&xe->xdf2);
+		xdl_free_ctx(&xe->xdf1);
+		return -1;
+	}
+
+	return 0;
+}
+
+
+void xdl_free_env(xdfenv_t *xe) {
+
+	xdl_free_ctx(&xe->xdf2);
+	xdl_free_ctx(&xe->xdf1);
+}
+
+
+static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
+	long r, rdis, rpdis;
+
+	for (r = 1, rdis = 0, rpdis = 1; (i - r) >= s; r++) {
+		if (!dis[i - r])
+			rdis++;
+		else if (dis[i - r] == 2)
+			rpdis++;
+		else
+			break;
+	}
+	for (r = 1; (i + r) <= e; r++) {
+		if (!dis[i + r])
+			rdis++;
+		else if (dis[i + r] == 2)
+			rpdis++;
+		else
+			break;
+	}
+
+	return rpdis * XDL_KPDIS_RUN < (rpdis + rdis);
+}
+
+
+/*
+ * Try to reduce the problem complexity, discard records that have no
+ * matches on the other file. Also, lines that have multiple matches
+ * might be potentially discarded if they happear in a run of discardable.
+ */
+static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2) {
+	long i, rhi, nreff;
+	unsigned long hav;
+	xrecord_t **recs;
+	xrecord_t *rec;
+	char *dis, *dis1, *dis2;
+
+	if (!(dis = (char *) xdl_malloc((xdf1->nrec + xdf2->nrec + 2) * sizeof(char)))) {
+
+		return -1;
+	}
+	memset(dis, 0, (xdf1->nrec + xdf2->nrec + 2) * sizeof(char));
+	dis1 = dis;
+	dis2 = dis1 + xdf1->nrec + 1;
+
+	for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
+		hav = (*recs)->ha;
+		rhi = (long) XDL_HASHLONG(hav, xdf2->hbits);
+		for (rec = xdf2->rhash[rhi]; rec; rec = rec->next)
+			if (rec->ha == hav && ++dis1[i] == 2)
+				break;
+	}
+
+	for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
+		hav = (*recs)->ha;
+		rhi = (long) XDL_HASHLONG(hav, xdf1->hbits);
+		for (rec = xdf1->rhash[rhi]; rec; rec = rec->next)
+			if (rec->ha == hav && ++dis2[i] == 2)
+				break;
+	}
+
+	for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
+	     i <= xdf1->dend; i++, recs++) {
+		if (dis1[i] == 1 ||
+		    (dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {
+			xdf1->rindex[nreff] = i;
+			xdf1->ha[nreff] = (*recs)->ha;
+			nreff++;
+		} else
+			xdf1->rchg[i] = 1;
+	}
+	xdf1->nreff = nreff;
+
+	for (nreff = 0, i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];
+	     i <= xdf2->dend; i++, recs++) {
+		if (dis2[i] == 1 ||
+		    (dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {
+			xdf2->rindex[nreff] = i;
+			xdf2->ha[nreff] = (*recs)->ha;
+			nreff++;
+		} else
+			xdf2->rchg[i] = 1;
+	}
+	xdf2->nreff = nreff;
+
+	xdl_free(dis);
+
+	return 0;
+}
+
+
+/*
+ * Early trim initial and terminal matching records.
+ */
+static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2) {
+	long i, lim;
+	xrecord_t **recs1, **recs2;
+
+	recs1 = xdf1->recs;
+	recs2 = xdf2->recs;
+	for (i = 0, lim = XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;
+	     i++, recs1++, recs2++)
+		if ((*recs1)->ha != (*recs2)->ha)
+			break;
+
+	xdf1->dstart = xdf2->dstart = i;
+
+	recs1 = xdf1->recs + xdf1->nrec - 1;
+	recs2 = xdf2->recs + xdf2->nrec - 1;
+	for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)
+		if ((*recs1)->ha != (*recs2)->ha)
+			break;
+
+	xdf1->dend = xdf1->nrec - i - 1;
+	xdf2->dend = xdf2->nrec - i - 1;
+
+	return 0;
+}
+
+
+static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2) {
+
+	if (xdl_trim_ends(xdf1, xdf2) < 0 ||
+	    xdl_cleanup_records(xdf1, xdf2) < 0) {
+
+		return -1;
+	}
+
+	return 0;
+}
+

xdiff/xprepare.h

@@ -0,0 +1,35 @@
+/*
+ *  LibXDiff by Davide Libenzi ( File Differential Library )
+ *  Copyright (C) 2003  Davide Libenzi
+ *
+ *  This library 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.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+
+#if !defined(XPREPARE_H)
+#define XPREPARE_H
+
+
+
+int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
+		    xdfenv_t *xe);
+void xdl_free_env(xdfenv_t *xe);
+
+
+
+#endif /* #if !defined(XPREPARE_H) */
+

xdiff/xtypes.h

@@ -0,0 +1,68 @@
+/*
+ *  LibXDiff by Davide Libenzi ( File Differential Library )
+ *  Copyright (C) 2003  Davide Libenzi
+ *
+ *  This library 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.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+
+#if !defined(XTYPES_H)
+#define XTYPES_H
+
+
+
+typedef struct s_chanode {
+	struct s_chanode *next;
+	long icurr;
+} chanode_t;
+
+typedef struct s_chastore {
+	chanode_t *head, *tail;
+	long isize, nsize;
+	chanode_t *ancur;
+	chanode_t *sncur;
+	long scurr;
+} chastore_t;
+
+typedef struct s_xrecord {
+	struct s_xrecord *next;
+	char const *ptr;
+	long size;
+	unsigned long ha;
+} xrecord_t;
+
+typedef struct s_xdfile {
+	chastore_t rcha;
+	long nrec;
+	unsigned int hbits;
+	xrecord_t **rhash;
+	long dstart, dend;
+	xrecord_t **recs;
+	char *rchg;
+	long *rindex;
+	long nreff;
+	unsigned long *ha;
+} xdfile_t;
+
+typedef struct s_xdfenv {
+	xdfile_t xdf1, xdf2;
+} xdfenv_t;
+
+
+
+#endif /* #if !defined(XTYPES_H) */
+

xdiff/xutils.c

@@ -0,0 +1,277 @@
+/*
+ *  LibXDiff by Davide Libenzi ( File Differential Library )
+ *  Copyright (C) 2003	Davide Libenzi
+ *
+ *  This library 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.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+
+#include "xinclude.h"
+
+
+
+#define XDL_GUESS_NLINES 256
+
+
+
+
+int xdl_emit_diffrec(char const *rec, long size, char const *pre, long psize,
+		     xdemitcb_t *ecb) {
+	mmbuffer_t mb[3];
+	int i;
+
+	mb[0].ptr = (char *) pre;
+	mb[0].size = psize;
+	mb[1].ptr = (char *) rec;
+	mb[1].size = size;
+	i = 2;
+
+	if (!size || rec[size-1] != '\n') {
+		mb[2].ptr = "\n\\ No newline at end of file\n";
+		mb[2].size = strlen(mb[2].ptr);
+		i = 3;
+	}
+
+	if (ecb->outf(ecb->priv, mb, i) < 0) {
+
+		return -1;
+	}
+
+	return 0;
+}
+
+void *xdl_mmfile_first(mmfile_t *mmf, long *size)
+{
+	*size = mmf->size;
+	return mmf->ptr;
+}
+
+
+void *xdl_mmfile_next(mmfile_t *mmf, long *size)
+{
+	return NULL;
+}
+
+
+long xdl_mmfile_size(mmfile_t *mmf)
+{
+	return mmf->size;
+}
+
+
+int xdl_cha_init(chastore_t *cha, long isize, long icount) {
+
+	cha->head = cha->tail = NULL;
+	cha->isize = isize;
+	cha->nsize = icount * isize;
+	cha->ancur = cha->sncur = NULL;
+	cha->scurr = 0;
+
+	return 0;
+}
+
+
+void xdl_cha_free(chastore_t *cha) {
+	chanode_t *cur, *tmp;
+
+	for (cur = cha->head; (tmp = cur) != NULL;) {
+		cur = cur->next;
+		xdl_free(tmp);
+	}
+}
+
+
+void *xdl_cha_alloc(chastore_t *cha) {
+	chanode_t *ancur;
+	void *data;
+
+	if (!(ancur = cha->ancur) || ancur->icurr == cha->nsize) {
+		if (!(ancur = (chanode_t *) xdl_malloc(sizeof(chanode_t) + cha->nsize))) {
+
+			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 = (char *) ancur + sizeof(chanode_t) + ancur->icurr;
+	ancur->icurr += cha->isize;
+
+	return data;
+}
+
+
+void *xdl_cha_first(chastore_t *cha) {
+	chanode_t *sncur;
+
+	if (!(cha->sncur = sncur = cha->head))
+		return NULL;
+
+	cha->scurr = 0;
+
+	return (char *) sncur + sizeof(chanode_t) + cha->scurr;
+}
+
+
+void *xdl_cha_next(chastore_t *cha) {
+	chanode_t *sncur;
+
+	if (!(sncur = cha->sncur))
+		return NULL;
+	cha->scurr += cha->isize;
+	if (cha->scurr == sncur->icurr) {
+		if (!(sncur = cha->sncur = sncur->next))
+			return NULL;
+		cha->scurr = 0;
+	}
+
+	return (char *) sncur + sizeof(chanode_t) + cha->scurr;
+}
+
+
+long xdl_guess_lines(mmfile_t *mf) {
+	long nl = 0, size, tsize = 0;
+	char const *data, *cur, *top;
+
+	if ((cur = data = xdl_mmfile_first(mf, &size)) != NULL) {
+		for (top = data + size; nl < XDL_GUESS_NLINES;) {
+			if (cur >= top) {
+				tsize += (long) (cur - data);
+				if (!(cur = data = xdl_mmfile_next(mf, &size)))
+					break;
+				top = data + size;
+			}
+			nl++;
+			if (!(cur = memchr(cur, '\n', top - cur)))
+				cur = top;
+			else
+				cur++;
+		}
+		tsize += (long) (cur - data);
+	}
+
+	if (nl && tsize)
+		nl = xdl_mmfile_size(mf) / (tsize / nl);
+
+	return nl + 1;
+}
+
+
+unsigned long xdl_hash_record(char const **data, char const *top) {
+	unsigned long ha = 5381;
+	char const *ptr = *data;
+
+	for (; ptr < top && *ptr != '\n'; ptr++) {
+		ha += (ha << 5);
+		ha ^= (unsigned long) *ptr;
+	}
+	*data = ptr < top ? ptr + 1: ptr;
+
+	return ha;
+}
+
+
+unsigned int xdl_hashbits(unsigned int size) {
+	unsigned int val = 1, bits = 0;
+
+	for (; val < size && bits < CHAR_BIT * sizeof(unsigned int); val <<= 1, bits++);
+	return bits ? bits: 1;
+}
+
+
+int xdl_num_out(char *out, long val) {
+	char *ptr, *str = out;
+	char buf[32];
+
+	ptr = buf + sizeof(buf) - 1;
+	*ptr = '\0';
+	if (val < 0) {
+		*--ptr = '-';
+		val = -val;
+	}
+	for (; val && ptr > buf; val /= 10)
+		*--ptr = "0123456789"[val % 10];
+	if (*ptr)
+		for (; *ptr; ptr++, str++)
+			*str = *ptr;
+	else
+		*str++ = '0';
+	*str = '\0';
+
+	return str - out;
+}
+
+
+long xdl_atol(char const *str, char const **next) {
+	long val, base;
+	char const *top;
+
+	for (top = str; XDL_ISDIGIT(*top); top++);
+	if (next)
+		*next = top;
+	for (val = 0, base = 1, top--; top >= str; top--, base *= 10)
+		val += base * (long)(*top - '0');
+	return val;
+}
+
+
+int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2, xdemitcb_t *ecb) {
+	int nb = 0;
+	mmbuffer_t mb;
+	char buf[128];
+
+	memcpy(buf, "@@ -", 4);
+	nb += 4;
+
+	nb += xdl_num_out(buf + nb, c1 ? s1: 0);
+
+	if (c1 != 1) {
+		memcpy(buf + nb, ",", 1);
+		nb += 1;
+
+		nb += xdl_num_out(buf + nb, c1);
+	}
+
+	memcpy(buf + nb, " +", 2);
+	nb += 2;
+
+	nb += xdl_num_out(buf + nb, c2 ? s2: 0);
+
+	if (c2 != 1) {
+		memcpy(buf + nb, ",", 1);
+		nb += 1;
+
+		nb += xdl_num_out(buf + nb, c2);
+	}
+
+	memcpy(buf + nb, " @@\n", 4);
+	nb += 4;
+
+	mb.ptr = buf;
+	mb.size = nb;
+	if (ecb->outf(ecb->priv, &mb, 1) < 0)
+		return -1;
+
+	return 0;
+}
+

xdiff/xutils.h

@@ -0,0 +1,44 @@
+/*
+ *  LibXDiff by Davide Libenzi ( File Differential Library )
+ *  Copyright (C) 2003  Davide Libenzi
+ *
+ *  This library 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.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+
+#if !defined(XUTILS_H)
+#define XUTILS_H
+
+
+int xdl_emit_diffrec(char const *rec, long size, char const *pre, long psize,
+		     xdemitcb_t *ecb);
+int xdl_cha_init(chastore_t *cha, long isize, long icount);
+void xdl_cha_free(chastore_t *cha);
+void *xdl_cha_alloc(chastore_t *cha);
+void *xdl_cha_first(chastore_t *cha);
+void *xdl_cha_next(chastore_t *cha);
+long xdl_guess_lines(mmfile_t *mf);
+unsigned long xdl_hash_record(char const **data, char const *top);
+unsigned int xdl_hashbits(unsigned int size);
+int xdl_num_out(char *out, long val);
+long xdl_atol(char const *str, char const **next);
+int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2, xdemitcb_t *ecb);
+
+
+
+#endif /* #if !defined(XUTILS_H) */
+