Import xdiff library from git

This is the initial import of the xdiff code (LGPL) from
core git as of rev f349b562086e2b7595d8a977d2734ab2ef9e71ef

CMakeLists.txt

@@ -97,9 +97,9 @@ FILE(GLOB SRC_H include/git2/*.h)
 # On Windows use specific platform sources
 IF (WIN32 AND NOT CYGWIN)
 	ADD_DEFINITIONS(-DWIN32 -D_DEBUG)
-	FILE(GLOB SRC src/*.c src/transports/*.c src/win32/*.c)
+	FILE(GLOB SRC src/*.c src/transports/*.c src/xdiff/*.c src/win32/*.c)
 ELSE()
-	FILE(GLOB SRC src/*.c src/transports/*.c src/unix/*.c)
+	FILE(GLOB SRC src/*.c src/transports/*.c src/xdiff/*.c src/unix/*.c)
 ENDIF ()
 
 # Compile and link libgit2

src/xdiff/xdiff.h

+/*
+ *  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 XDF_IGNORE_WHITESPACE (1 << 2)
+#define XDF_IGNORE_WHITESPACE_CHANGE (1 << 3)
+#define XDF_IGNORE_WHITESPACE_AT_EOL (1 << 4)
+#define XDF_PATIENCE_DIFF (1 << 5)
+#define XDF_HISTOGRAM_DIFF (1 << 6)
+#define XDF_WHITESPACE_FLAGS (XDF_IGNORE_WHITESPACE | XDF_IGNORE_WHITESPACE_CHANGE | XDF_IGNORE_WHITESPACE_AT_EOL)
+
+#define XDL_PATCH_NORMAL '-'
+#define XDL_PATCH_REVERSE '+'
+#define XDL_PATCH_MODEMASK ((1 << 8) - 1)
+#define XDL_PATCH_IGNOREBSPACE (1 << 8)
+
+#define XDL_EMIT_FUNCNAMES (1 << 0)
+#define XDL_EMIT_COMMON (1 << 1)
+#define XDL_EMIT_FUNCCONTEXT (1 << 2)
+
+#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
+
+/* merge simplification levels */
+#define XDL_MERGE_MINIMAL 0
+#define XDL_MERGE_EAGER 1
+#define XDL_MERGE_ZEALOUS 2
+#define XDL_MERGE_ZEALOUS_ALNUM 3
+
+/* merge favor modes */
+#define XDL_MERGE_FAVOR_OURS 1
+#define XDL_MERGE_FAVOR_THEIRS 2
+#define XDL_MERGE_FAVOR_UNION 3
+
+/* merge output styles */
+#define XDL_MERGE_DIFF3 1
+
+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 long (*find_func_t)(const char *line, long line_len, char *buffer, long buffer_size, void *priv);
+
+typedef struct s_xdemitconf {
+	long ctxlen;
+	long interhunkctxlen;
+	unsigned long flags;
+	find_func_t find_func;
+	void *find_func_priv;
+	void (*emit_func)();
+} 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);
+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);
+
+typedef struct s_xmparam {
+	xpparam_t xpp;
+	int marker_size;
+	int level;
+	int favor;
+	int style;
+	const char *ancestor;	/* label for orig */
+	const char *file1;	/* label for mf1 */
+	const char *file2;	/* label for mf2 */
+} xmparam_t;
+
+#define DEFAULT_CONFLICT_MARKER_SIZE 7
+
+int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t *mf2,
+		xmparam_t const *xmp, mmbuffer_t *result);
+
+#ifdef __cplusplus
+}
+#endif /* #ifdef __cplusplus */
+
+#endif /* #if !defined(XDIFF_H) */

src/xdiff/xdiffi.h

+/*
+ *  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_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags);
+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);
+int xdl_do_patience_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
+		xdfenv_t *env);
+int xdl_do_histogram_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
+		xdfenv_t *env);
+
+#endif /* #if !defined(XDIFFI_H) */

src/xdiff/xemit.c

+/*
+ *  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 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.
+ */
+xdchange_t *xdl_get_hunk(xdchange_t *xscr, xdemitconf_t const *xecfg) {
+	xdchange_t *xch, *xchp;
+	long max_common = 2 * xecfg->ctxlen + xecfg->interhunkctxlen;
+
+	for (xchp = xscr, xch = xscr->next; xch; xchp = xch, xch = xch->next)
+		if (xch->i1 - (xchp->i1 + xchp->chg1) > max_common)
+			break;
+
+	return xchp;
+}
+
+
+static long def_ff(const char *rec, long len, char *buf, long sz, void *priv)
+{
+	if (len > 0 &&
+			(isalpha((unsigned char)*rec) || /* identifier? */
+			 *rec == '_' ||	/* also identifier? */
+			 *rec == '$')) { /* identifiers from VMS and other esoterico */
+		if (len > sz)
+			len = sz;
+		while (0 < len && isspace((unsigned char)rec[len - 1]))
+			len--;
+		memcpy(buf, rec, len);
+		return len;
+	}
+	return -1;
+}
+
+static int xdl_emit_common(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
+                           xdemitconf_t const *xecfg) {
+	xdfile_t *xdf = &xe->xdf2;
+	const char *rchg = xdf->rchg;
+	long ix;
+
+	for (ix = 0; ix < xdf->nrec; ix++) {
+		if (rchg[ix])
+			continue;
+		if (xdl_emit_record(xdf, ix, "", ecb))
+			return -1;
+	}
+	return 0;
+}
+
+struct func_line {
+	long len;
+	char buf[80];
+};
+
+static long get_func_line(xdfenv_t *xe, xdemitconf_t const *xecfg,
+			  struct func_line *func_line, long start, long limit)
+{
+	find_func_t ff = xecfg->find_func ? xecfg->find_func : def_ff;
+	long l, size, step = (start > limit) ? -1 : 1;
+	char *buf, dummy[1];
+
+	buf = func_line ? func_line->buf : dummy;
+	size = func_line ? sizeof(func_line->buf) : sizeof(dummy);
+
+	for (l = start; l != limit && 0 <= l && l < xe->xdf1.nrec; l += step) {
+		const char *rec;
+		long reclen = xdl_get_rec(&xe->xdf1, l, &rec);
+		long len = ff(rec, reclen, buf, size, xecfg->find_func_priv);
+		if (len >= 0) {
+			if (func_line)
+				func_line->len = len;
+			return l;
+		}
+	}
+	return -1;
+}
+
+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;
+	long funclineprev = -1;
+	struct func_line func_line = { 0 };
+
+	if (xecfg->flags & XDL_EMIT_COMMON)
+		return xdl_emit_common(xe, xscr, ecb, xecfg);
+
+	for (xch = 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);
+
+		if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
+			long fs1 = get_func_line(xe, xecfg, NULL, xch->i1, -1);
+			if (fs1 < 0)
+				fs1 = 0;
+			if (fs1 < s1) {
+				s2 -= s1 - fs1;
+				s1 = fs1;
+			}
+		}
+
+ again:
+		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;
+
+		if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
+			long fe1 = get_func_line(xe, xecfg, NULL,
+						 xche->i1 + xche->chg1,
+						 xe->xdf1.nrec);
+			if (fe1 < 0)
+				fe1 = xe->xdf1.nrec;
+			if (fe1 > e1) {
+				e2 += fe1 - e1;
+				e1 = fe1;
+			}
+
+			/*
+			 * Overlap with next change?  Then include it
+			 * in the current hunk and start over to find
+			 * its new end.
+			 */
+			if (xche->next) {
+				long l = xche->next->i1;
+				if (l <= e1 ||
+				    get_func_line(xe, xecfg, NULL, l, e1) < 0) {
+					xche = xche->next;
+					goto again;
+				}
+			}
+		}
+
+		/*
+		 * Emit current hunk header.
+		 */
+
+		if (xecfg->flags & XDL_EMIT_FUNCNAMES) {
+			get_func_line(xe, xecfg, &func_line,
+				      s1 - 1, funclineprev);
+			funclineprev = s1 - 1;
+		}
+		if (xdl_emit_hunk_hdr(s1 + 1, e1 - s1, s2 + 1, e2 - s2,
+				      func_line.buf, func_line.len, ecb) < 0)
+			return -1;
+
+		/*
+		 * Emit pre-context.
+		 */
+		for (; s2 < xch->i2; s2++)
+			if (xdl_emit_record(&xe->xdf2, s2, " ", 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->xdf2, s2, " ", 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 (s2 = xche->i2 + xche->chg2; s2 < e2; s2++)
+			if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
+				return -1;
+	}
+
+	return 0;
+}

src/xdiff/xemit.h

+/*
+ *  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
+
+
+typedef int (*emit_func_t)(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
+			   xdemitconf_t const *xecfg);
+
+xdchange_t *xdl_get_hunk(xdchange_t *xscr, xdemitconf_t const *xecfg);
+int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
+		  xdemitconf_t const *xecfg);
+
+
+
+#endif /* #if !defined(XEMIT_H) */

src/xdiff/xhistogram.c

+/*
+ * Copyright (C) 2010, Google Inc.
+ * and other copyright owners as documented in JGit's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "xinclude.h"
+#include "xtypes.h"
+#include "xdiff.h"
+
+#define MAX_PTR	UINT_MAX
+#define MAX_CNT	UINT_MAX
+
+#define LINE_END(n) (line##n + count##n - 1)
+#define LINE_END_PTR(n) (*line##n + *count##n - 1)
+
+struct histindex {
+	struct record {
+		unsigned int ptr, cnt;
+		struct record *next;
+	} **records, /* an ocurrence */
+	  **line_map; /* map of line to record chain */
+	chastore_t rcha;
+	unsigned int *next_ptrs;
+	unsigned int table_bits,
+		     records_size,
+		     line_map_size;
+
+	unsigned int max_chain_length,
+		     key_shift,
+		     ptr_shift;
+
+	unsigned int cnt,
+		     has_common;
+
+	xdfenv_t *env;
+	xpparam_t const *xpp;
+};
+
+struct region {
+	unsigned int begin1, end1;
+	unsigned int begin2, end2;
+};
+
+#define LINE_MAP(i, a) (i->line_map[(a) - i->ptr_shift])
+
+#define NEXT_PTR(index, ptr) \
+	(index->next_ptrs[(ptr) - index->ptr_shift])
+
+#define CNT(index, ptr) \
+	((LINE_MAP(index, ptr))->cnt)
+
+#define REC(env, s, l) \
+	(env->xdf##s.recs[l - 1])
+
+static int cmp_recs(xpparam_t const *xpp,
+	xrecord_t *r1, xrecord_t *r2)
+{
+	return r1->ha == r2->ha &&
+		xdl_recmatch(r1->ptr, r1->size, r2->ptr, r2->size,
+			    xpp->flags);
+}
+
+#define CMP_ENV(xpp, env, s1, l1, s2, l2) \
+	(cmp_recs(xpp, REC(env, s1, l1), REC(env, s2, l2)))
+
+#define CMP(i, s1, l1, s2, l2) \
+	(cmp_recs(i->xpp, REC(i->env, s1, l1), REC(i->env, s2, l2)))
+
+#define TABLE_HASH(index, side, line) \
+	XDL_HASHLONG((REC(index->env, side, line))->ha, index->table_bits)
+
+static int scanA(struct histindex *index, int line1, int count1)
+{
+	unsigned int ptr, tbl_idx;
+	unsigned int chain_len;
+	struct record **rec_chain, *rec;
+
+	for (ptr = LINE_END(1); line1 <= ptr; ptr--) {
+		tbl_idx = TABLE_HASH(index, 1, ptr);
+		rec_chain = index->records + tbl_idx;
+		rec = *rec_chain;
+
+		chain_len = 0;
+		while (rec) {
+			if (CMP(index, 1, rec->ptr, 1, ptr)) {
+				/*
+				 * ptr is identical to another element. Insert
+				 * it onto the front of the existing element
+				 * chain.
+				 */
+				NEXT_PTR(index, ptr) = rec->ptr;
+				rec->ptr = ptr;
+				/* cap rec->cnt at MAX_CNT */
+				rec->cnt = XDL_MIN(MAX_CNT, rec->cnt + 1);
+				LINE_MAP(index, ptr) = rec;
+				goto continue_scan;
+			}
+
+			rec = rec->next;
+			chain_len++;
+		}
+
+		if (chain_len == index->max_chain_length)
+			return -1;
+
+		/*
+		 * This is the first time we have ever seen this particular
+		 * element in the sequence. Construct a new chain for it.
+		 */
+		if (!(rec = xdl_cha_alloc(&index->rcha)))
+			return -1;
+		rec->ptr = ptr;
+		rec->cnt = 1;
+		rec->next = *rec_chain;
+		*rec_chain = rec;
+		LINE_MAP(index, ptr) = rec;
+
+continue_scan:
+		; /* no op */
+	}
+
+	return 0;
+}
+
+static int try_lcs(struct histindex *index, struct region *lcs, int b_ptr,
+	int line1, int count1, int line2, int count2)
+{
+	unsigned int b_next = b_ptr + 1;
+	struct record *rec = index->records[TABLE_HASH(index, 2, b_ptr)];
+	unsigned int as, ae, bs, be, np, rc;
+	int should_break;
+
+	for (; rec; rec = rec->next) {
+		if (rec->cnt > index->cnt) {
+			if (!index->has_common)
+				index->has_common = CMP(index, 1, rec->ptr, 2, b_ptr);
+			continue;
+		}
+
+		as = rec->ptr;
+		if (!CMP(index, 1, as, 2, b_ptr))
+			continue;
+
+		index->has_common = 1;
+		for (;;) {
+			should_break = 0;
+			np = NEXT_PTR(index, as);
+			bs = b_ptr;
+			ae = as;
+			be = bs;
+			rc = rec->cnt;
+
+			while (line1 < as && line2 < bs
+				&& CMP(index, 1, as - 1, 2, bs - 1)) {
+				as--;
+				bs--;
+				if (1 < rc)
+					rc = XDL_MIN(rc, CNT(index, as));
+			}
+			while (ae < LINE_END(1) && be < LINE_END(2)
+				&& CMP(index, 1, ae + 1, 2, be + 1)) {
+				ae++;
+				be++;
+				if (1 < rc)
+					rc = XDL_MIN(rc, CNT(index, ae));
+			}
+
+			if (b_next <= be)
+				b_next = be + 1;
+			if (lcs->end1 - lcs->begin1 < ae - as || rc < index->cnt) {
+				lcs->begin1 = as;
+				lcs->begin2 = bs;
+				lcs->end1 = ae;
+				lcs->end2 = be;
+				index->cnt = rc;
+			}
+
+			if (np == 0)
+				break;
+
+			while (np <= ae) {
+				np = NEXT_PTR(index, np);
+				if (np == 0) {
+					should_break = 1;
+					break;
+				}
+			}
+
+			if (should_break)
+				break;
+
+			as = np;
+		}
+	}
+	return b_next;
+}
+
+static int find_lcs(struct histindex *index, struct region *lcs,
+	int line1, int count1, int line2, int count2) {
+	int b_ptr;
+
+	if (scanA(index, line1, count1))
+		return -1;
+
+	index->cnt = index->max_chain_length + 1;
+
+	for (b_ptr = line2; b_ptr <= LINE_END(2); )
+		b_ptr = try_lcs(index, lcs, b_ptr, line1, count1, line2, count2);
+
+	return index->has_common && index->max_chain_length < index->cnt;
+}
+
+static int fall_back_to_classic_diff(struct histindex *index,
+		int line1, int count1, int line2, int count2)
+{
+	xpparam_t xpp;
+	xpp.flags = index->xpp->flags & ~XDF_HISTOGRAM_DIFF;
+
+	return xdl_fall_back_diff(index->env, &xpp,
+				  line1, count1, line2, count2);
+}
+
+static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
+	int line1, int count1, int line2, int count2)
+{
+	struct histindex index;
+	struct region lcs;
+	int sz;
+	int result = -1;
+
+	if (count1 <= 0 && count2 <= 0)
+		return 0;
+
+	if (LINE_END(1) >= MAX_PTR)
+		return -1;
+
+	if (!count1) {
+		while(count2--)
+			env->xdf2.rchg[line2++ - 1] = 1;
+		return 0;
+	} else if (!count2) {
+		while(count1--)
+			env->xdf1.rchg[line1++ - 1] = 1;
+		return 0;
+	}
+
+	memset(&index, 0, sizeof(index));
+
+	index.env = env;
+	index.xpp = xpp;
+
+	index.records = NULL;
+	index.line_map = NULL;
+	/* in case of early xdl_cha_free() */
+	index.rcha.head = NULL;
+
+	index.table_bits = xdl_hashbits(count1);
+	sz = index.records_size = 1 << index.table_bits;
+	sz *= sizeof(struct record *);
+	if (!(index.records = (struct record **) xdl_malloc(sz)))
+		goto cleanup;
+	memset(index.records, 0, sz);
+
+	sz = index.line_map_size = count1;
+	sz *= sizeof(struct record *);
+	if (!(index.line_map = (struct record **) xdl_malloc(sz)))
+		goto cleanup;
+	memset(index.line_map, 0, sz);
+
+	sz = index.line_map_size;
+	sz *= sizeof(unsigned int);
+	if (!(index.next_ptrs = (unsigned int *) xdl_malloc(sz)))
+		goto cleanup;
+	memset(index.next_ptrs, 0, sz);
+
+	/* lines / 4 + 1 comes from xprepare.c:xdl_prepare_ctx() */
+	if (xdl_cha_init(&index.rcha, sizeof(struct record), count1 / 4 + 1) < 0)
+		goto cleanup;
+
+	index.ptr_shift = line1;
+	index.max_chain_length = 64;
+
+	memset(&lcs, 0, sizeof(lcs));
+	if (find_lcs(&index, &lcs, line1, count1, line2, count2))
+		result = fall_back_to_classic_diff(&index, line1, count1, line2, count2);
+	else {
+		if (lcs.begin1 == 0 && lcs.begin2 == 0) {
+			while (count1--)
+				env->xdf1.rchg[line1++ - 1] = 1;
+			while (count2--)
+				env->xdf2.rchg[line2++ - 1] = 1;
+			result = 0;
+		} else {
+			result = histogram_diff(xpp, env,
+						line1, lcs.begin1 - line1,
+						line2, lcs.begin2 - line2);
+			if (result)
+				goto cleanup;
+			result = histogram_diff(xpp, env,
+						lcs.end1 + 1, LINE_END(1) - lcs.end1,
+						lcs.end2 + 1, LINE_END(2) - lcs.end2);
+			if (result)
+				goto cleanup;
+		}
+	}
+
+cleanup:
+	xdl_free(index.records);
+	xdl_free(index.line_map);
+	xdl_free(index.next_ptrs);
+	xdl_cha_free(&index.rcha);
+
+	return result;
+}
+
+int xdl_do_histogram_diff(mmfile_t *file1, mmfile_t *file2,
+	xpparam_t const *xpp, xdfenv_t *env)
+{
+	if (xdl_prepare_env(file1, file2, xpp, env) < 0)
+		return -1;
+
+	return histogram_diff(xpp, env,
+		env->xdf1.dstart + 1, env->xdf1.dend - env->xdf1.dstart + 1,
+		env->xdf2.dstart + 1, env->xdf2.dend - env->xdf2.dstart + 1);
+}

src/xdiff/xinclude.h

+/*
+ *  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 <ctype.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) */

src/xdiff/xmacros.h

+/*
+ *  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 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_ISSPACE(c) (isspace((unsigned char)(c)))
+#define XDL_ADDBITS(v,b)	((v) + ((v) >> (b)))
+#define XDL_MASKBITS(b)		((1UL << (b)) - 1)
+#define XDL_HASHLONG(v,b)	(XDL_ADDBITS((unsigned long)(v), b) & XDL_MASKBITS(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) */

src/xdiff/xprepare.h

+/*
+ *  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) */

src/xdiff/xtypes.h

+/*
+ *  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) */

src/xdiff/xutils.c

+/*
+ *  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"
+
+
+
+
+long xdl_bogosqrt(long n) {
+	long i;
+
+	/*
+	 * Classical integer square root approximation using shifts.
+	 */
+	for (i = 1; n > 0; n >>= 2)
+		i <<= 1;
+
+	return i;
+}
+
+
+int xdl_emit_diffrec(char const *rec, long size, char const *pre, long psize,
+		     xdemitcb_t *ecb) {
+	int i = 2;
+	mmbuffer_t mb[3];
+
+	mb[0].ptr = (char *) pre;
+	mb[0].size = psize;
+	mb[1].ptr = (char *) rec;
+	mb[1].size = size;
+	if (size > 0 && rec[size - 1] != '\n') {
+		mb[2].ptr = (char *) "\n\\ No newline at end of file\n";
+		mb[2].size = strlen(mb[2].ptr);
+		i++;
+	}
+	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;
+}
+
+
+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 sample) {
+	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 < sample && cur < top; ) {
+			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;
+}
+
+int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags)
+{
+	int i1, i2;
+
+	if (s1 == s2 && !memcmp(l1, l2, s1))
+		return 1;
+	if (!(flags & XDF_WHITESPACE_FLAGS))
+		return 0;
+
+	i1 = 0;
+	i2 = 0;
+
+	/*
+	 * -w matches everything that matches with -b, and -b in turn
+	 * matches everything that matches with --ignore-space-at-eol.
+	 *
+	 * Each flavor of ignoring needs different logic to skip whitespaces
+	 * while we have both sides to compare.
+	 */
+	if (flags & XDF_IGNORE_WHITESPACE) {
+		goto skip_ws;
+		while (i1 < s1 && i2 < s2) {
+			if (l1[i1++] != l2[i2++])
+				return 0;
+		skip_ws:
+			while (i1 < s1 && XDL_ISSPACE(l1[i1]))
+				i1++;
+			while (i2 < s2 && XDL_ISSPACE(l2[i2]))
+				i2++;
+		}
+	} else if (flags & XDF_IGNORE_WHITESPACE_CHANGE) {
+		while (i1 < s1 && i2 < s2) {
+			if (XDL_ISSPACE(l1[i1]) && XDL_ISSPACE(l2[i2])) {
+				/* Skip matching spaces and try again */
+				while (i1 < s1 && XDL_ISSPACE(l1[i1]))
+					i1++;
+				while (i2 < s2 && XDL_ISSPACE(l2[i2]))
+					i2++;
+				continue;
+			}
+			if (l1[i1++] != l2[i2++])
+				return 0;
+		}
+	} else if (flags & XDF_IGNORE_WHITESPACE_AT_EOL) {
+		while (i1 < s1 && i2 < s2 && l1[i1++] == l2[i2++])
+			; /* keep going */
+	}
+
+	/*
+	 * After running out of one side, the remaining side must have
+	 * nothing but whitespace for the lines to match.  Note that
+	 * ignore-whitespace-at-eol case may break out of the loop
+	 * while there still are characters remaining on both lines.
+	 */
+	if (i1 < s1) {
+		while (i1 < s1 && XDL_ISSPACE(l1[i1]))
+			i1++;
+		if (s1 != i1)
+			return 0;
+	}
+	if (i2 < s2) {
+		while (i2 < s2 && XDL_ISSPACE(l2[i2]))
+			i2++;
+		return (s2 == i2);
+	}
+	return 1;
+}
+
+static unsigned long xdl_hash_record_with_whitespace(char const **data,
+		char const *top, long flags) {
+	unsigned long ha = 5381;
+	char const *ptr = *data;
+
+	for (; ptr < top && *ptr != '\n'; ptr++) {
+		if (XDL_ISSPACE(*ptr)) {
+			const char *ptr2 = ptr;
+			int at_eol;
+			while (ptr + 1 < top && XDL_ISSPACE(ptr[1])
+					&& ptr[1] != '\n')
+				ptr++;
+			at_eol = (top <= ptr + 1 || ptr[1] == '\n');
+			if (flags & XDF_IGNORE_WHITESPACE)
+				; /* already handled */
+			else if (flags & XDF_IGNORE_WHITESPACE_CHANGE
+				 && !at_eol) {
+				ha += (ha << 5);
+				ha ^= (unsigned long) ' ';
+			}
+			else if (flags & XDF_IGNORE_WHITESPACE_AT_EOL
+				 && !at_eol) {
+				while (ptr2 != ptr + 1) {
+					ha += (ha << 5);
+					ha ^= (unsigned long) *ptr2;
+					ptr2++;
+				}
+			}
+			continue;
+		}
+		ha += (ha << 5);
+		ha ^= (unsigned long) *ptr;
+	}
+	*data = ptr < top ? ptr + 1: ptr;
+
+	return ha;
+}
+
+
+unsigned long xdl_hash_record(char const **data, char const *top, long flags) {
+	unsigned long ha = 5381;
+	char const *ptr = *data;
+
+	if (flags & XDF_WHITESPACE_FLAGS)
+		return xdl_hash_record_with_whitespace(data, top, flags);
+
+	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,
+		      const char *func, long funclen, 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: s1 - 1);
+
+	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: s2 - 1);
+
+	if (c2 != 1) {
+		memcpy(buf + nb, ",", 1);
+		nb += 1;
+
+		nb += xdl_num_out(buf + nb, c2);
+	}
+
+	memcpy(buf + nb, " @@", 3);
+	nb += 3;
+	if (func && funclen) {
+		buf[nb++] = ' ';
+		if (funclen > sizeof(buf) - nb - 1)
+			funclen = sizeof(buf) - nb - 1;
+		memcpy(buf + nb, func, funclen);
+		nb += funclen;
+	}
+	buf[nb++] = '\n';
+
+	mb.ptr = buf;
+	mb.size = nb;
+	if (ecb->outf(ecb->priv, &mb, 1) < 0)
+		return -1;
+
+	return 0;
+}
+
+int xdl_fall_back_diff(xdfenv_t *diff_env, xpparam_t const *xpp,
+		int line1, int count1, int line2, int count2)
+{
+	/*
+	 * This probably does not work outside Git, since
+	 * we have a very simple mmfile structure.
+	 *
+	 * Note: ideally, we would reuse the prepared environment, but
+	 * the libxdiff interface does not (yet) allow for diffing only
+	 * ranges of lines instead of the whole files.
+	 */
+	mmfile_t subfile1, subfile2;
+	xdfenv_t env;
+
+	subfile1.ptr = (char *)diff_env->xdf1.recs[line1 - 1]->ptr;
+	subfile1.size = diff_env->xdf1.recs[line1 + count1 - 2]->ptr +
+		diff_env->xdf1.recs[line1 + count1 - 2]->size - subfile1.ptr;
+	subfile2.ptr = (char *)diff_env->xdf2.recs[line2 - 1]->ptr;
+	subfile2.size = diff_env->xdf2.recs[line2 + count2 - 2]->ptr +
+		diff_env->xdf2.recs[line2 + count2 - 2]->size - subfile2.ptr;
+	if (xdl_do_diff(&subfile1, &subfile2, xpp, &env) < 0)
+		return -1;
+
+	memcpy(diff_env->xdf1.rchg + line1 - 1, env.xdf1.rchg, count1);
+	memcpy(diff_env->xdf2.rchg + line2 - 1, env.xdf2.rchg, count2);
+
+	xdl_free_env(&env);
+
+	return 0;
+}

src/xdiff/xutils.h

+/*
+ *  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
+
+
+
+long xdl_bogosqrt(long n);
+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, long sample);
+int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags);
+unsigned long xdl_hash_record(char const **data, char const *top, long flags);
+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,
+		      const char *func, long funclen, xdemitcb_t *ecb);
+int xdl_fall_back_diff(xdfenv_t *diff_env, xpparam_t const *xpp,
+		       int line1, int count1, int line2, int count2);
+
+
+
+#endif /* #if !defined(XUTILS_H) */