Merge pull request #6195 from libgit2/ethomson/zdiff3

merge: support zdiff3 conflict styles

include/git2/checkout.h

@@ -183,6 +183,9 @@ typedef enum {
 	 */
 	GIT_CHECKOUT_DRY_RUN = (1u << 24),
 
+	/** Include common ancestor data in zdiff3 format for conflicts */
+	GIT_CHECKOUT_CONFLICT_STYLE_ZDIFF3 = (1u << 25),
+
 	/**
 	 * THE FOLLOWING OPTIONS ARE NOT YET IMPLEMENTED
 	 */

include/git2/merge.h

@@ -159,7 +159,10 @@ typedef enum {
 	GIT_MERGE_FILE_DIFF_PATIENCE = (1 << 6),
 
 	/** Take extra time to find minimal diff */
-	GIT_MERGE_FILE_DIFF_MINIMAL = (1 << 7)
+	GIT_MERGE_FILE_DIFF_MINIMAL = (1 << 7),
+
+	/** Create zdiff3 ("zealous diff3")-style files */
+	GIT_MERGE_FILE_STYLE_ZDIFF3 = (1 << 8)
 } git_merge_file_flag_t;
 
 #define GIT_MERGE_CONFLICT_MARKER_SIZE	7

src/CMakeLists.txt

@@ -207,7 +207,17 @@ endif()
 # errors for the xdiff sources until we've sorted them out
 if(MSVC)
 	set_source_files_properties(xdiff/xdiffi.c PROPERTIES COMPILE_FLAGS -WX-)
+	set_source_files_properties(xdiff/xemit.c PROPERTIES COMPILE_FLAGS -WX-)
+	set_source_files_properties(xdiff/xhistogram.c PROPERTIES COMPILE_FLAGS -WX-)
+	set_source_files_properties(xdiff/xmerge.c PROPERTIES COMPILE_FLAGS -WX-)
 	set_source_files_properties(xdiff/xutils.c PROPERTIES COMPILE_FLAGS -WX-)
+	set_source_files_properties(xdiff/xpatience.c PROPERTIES COMPILE_FLAGS -WX-)
+else()
+	set_source_files_properties(xdiff/xdiffi.c PROPERTIES COMPILE_FLAGS "-Wno-sign-compare -Wno-unused-parameter")
+	set_source_files_properties(xdiff/xemit.c PROPERTIES COMPILE_FLAGS "-Wno-sign-compare -Wno-unused-parameter")
+	set_source_files_properties(xdiff/xhistogram.c PROPERTIES COMPILE_FLAGS "-Wno-sign-compare")
+	set_source_files_properties(xdiff/xutils.c PROPERTIES COMPILE_FLAGS "-Wno-sign-compare")
+	set_source_files_properties(xdiff/xpatience.c PROPERTIES COMPILE_FLAGS "-Wno-sign-compare")
 endif()
 
 # Determine architecture of the machine

src/blame_git.c

@@ -393,7 +393,7 @@ static void fill_origin_blob(git_blame__origin *o, mmfile_t *file)
 	memset(file, 0, sizeof(*file));
 	if (o->blob) {
 		file->ptr = (char*)git_blob_rawcontent(o->blob);
-		file->size = (size_t)git_blob_rawsize(o->blob);
+		file->size = (long)git_blob_rawsize(o->blob);
 	}
 }
 

src/checkout.c

@@ -2070,6 +2070,9 @@ static int checkout_write_merge(
 	if (data->opts.checkout_strategy & GIT_CHECKOUT_CONFLICT_STYLE_DIFF3)
 		opts.flags |= GIT_MERGE_FILE_STYLE_DIFF3;
 
+	if (data->opts.checkout_strategy & GIT_CHECKOUT_CONFLICT_STYLE_ZDIFF3)
+		opts.flags |= GIT_MERGE_FILE_STYLE_ZDIFF3;
+
 	opts.ancestor_label = data->opts.ancestor_label ?
 		data->opts.ancestor_label : "ancestor";
 	opts.our_label = data->opts.our_label ?
@@ -2493,6 +2496,8 @@ static int checkout_data_init(
 			data->opts.checkout_strategy |= GIT_CHECKOUT_CONFLICT_STYLE_MERGE;
 		else if (strcmp(conflict_style->value, "diff3") == 0)
 			data->opts.checkout_strategy |= GIT_CHECKOUT_CONFLICT_STYLE_DIFF3;
+		else if (strcmp(conflict_style->value, "zdiff3") == 0)
+			data->opts.checkout_strategy |= GIT_CHECKOUT_CONFLICT_STYLE_ZDIFF3;
 		else {
 			git_error_set(GIT_ERROR_CHECKOUT, "unknown style '%s' given for 'merge.conflictstyle'",
 				conflict_style->value);

src/diff_xdiff.c

@@ -218,14 +218,9 @@ static int git_xdiff(git_patch_generated_output *output, git_patch_generated *pa
 	 * updates are needed to xo->params.flags
 	 */
 
-	git_patch_generated_old_data(&info.xd_old_data.ptr, &info.xd_old_data.size, patch);
-	git_patch_generated_new_data(&info.xd_new_data.ptr, &info.xd_new_data.size, patch);
-
-	if (info.xd_old_data.size > GIT_XDIFF_MAX_SIZE ||
-		info.xd_new_data.size > GIT_XDIFF_MAX_SIZE) {
-		git_error_set(GIT_ERROR_INVALID, "files too large for diff");
+	if (git_patch_generated_old_data(&info.xd_old_data.ptr, &info.xd_old_data.size, patch) < 0 ||
+	    git_patch_generated_new_data(&info.xd_new_data.ptr, &info.xd_new_data.size, patch) < 0)
 		return -1;
-	}
 
 	xdl_diff(&info.xd_old_data, &info.xd_new_data,
 		&xo->params, &xo->config, &xo->callback);
@@ -261,5 +256,5 @@ void git_xdiff_init(git_xdiff_output *xo, const git_diff_options *opts)
 	if (flags & GIT_DIFF_IGNORE_BLANK_LINES)
 		xo->params.flags |= XDF_IGNORE_BLANK_LINES;
 
-	xo->callback.outf = git_xdiff_cb;
+	xo->callback.out_line = git_xdiff_cb;
 }

src/merge_file.c

@@ -86,22 +86,30 @@ static int merge_file__xdiff(
 
 	memset(&xmparam, 0x0, sizeof(xmparam_t));
 
+	if (ours->size > LONG_MAX ||
+	    theirs->size > LONG_MAX ||
+	    (ancestor && ancestor->size > LONG_MAX)) {
+		git_error_set(GIT_ERROR_MERGE, "failed to merge files");
+		error = -1;
+		goto done;
+	}
+
 	if (ancestor) {
 		xmparam.ancestor = (options.ancestor_label) ?
 			options.ancestor_label : ancestor->path;
 		ancestor_mmfile.ptr = (char *)ancestor->ptr;
-		ancestor_mmfile.size = ancestor->size;
+		ancestor_mmfile.size = (long)ancestor->size;
 	}
 
 	xmparam.file1 = (options.our_label) ?
 		options.our_label : ours->path;
 	our_mmfile.ptr = (char *)ours->ptr;
-	our_mmfile.size = ours->size;
+	our_mmfile.size = (long)ours->size;
 
 	xmparam.file2 = (options.their_label) ?
 		options.their_label : theirs->path;
 	their_mmfile.ptr = (char *)theirs->ptr;
-	their_mmfile.size = theirs->size;
+	their_mmfile.size = (long)theirs->size;
 
 	if (options.favor == GIT_MERGE_FILE_FAVOR_OURS)
 		xmparam.favor = XDL_MERGE_FAVOR_OURS;
@@ -115,6 +123,8 @@ static int merge_file__xdiff(
 
 	if (options.flags & GIT_MERGE_FILE_STYLE_DIFF3)
 		xmparam.style = XDL_MERGE_DIFF3;
+	if (options.flags & GIT_MERGE_FILE_STYLE_ZDIFF3)
+		xmparam.style = XDL_MERGE_ZEALOUS_DIFF3;
 
 	if (options.flags & GIT_MERGE_FILE_IGNORE_WHITESPACE)
 		xmparam.xpp.flags |= XDF_IGNORE_WHITESPACE;

src/patch_generate.c

@@ -750,18 +750,34 @@ git_diff_driver *git_patch_generated_driver(git_patch_generated *patch)
 	return patch->ofile.driver;
 }
 
-void git_patch_generated_old_data(
-	char **ptr, size_t *len, git_patch_generated *patch)
+int git_patch_generated_old_data(
+	char **ptr, long *len, git_patch_generated *patch)
 {
+	if (patch->ofile.map.len > LONG_MAX ||
+	    patch->ofile.map.len > GIT_XDIFF_MAX_SIZE) {
+		git_error_set(GIT_ERROR_INVALID, "files too large for diff");
+		return -1;
+	}
+
 	*ptr = patch->ofile.map.data;
-	*len = patch->ofile.map.len;
+	*len = (long)patch->ofile.map.len;
+
+	return 0;
 }
 
-void git_patch_generated_new_data(
-	char **ptr, size_t *len, git_patch_generated *patch)
+int git_patch_generated_new_data(
+	char **ptr, long *len, git_patch_generated *patch)
 {
+	if (patch->ofile.map.len > LONG_MAX ||
+	    patch->ofile.map.len > GIT_XDIFF_MAX_SIZE) {
+		git_error_set(GIT_ERROR_INVALID, "files too large for diff");
+		return -1;
+	}
+
 	*ptr = patch->nfile.map.data;
-	*len = patch->nfile.map.len;
+	*len = (long)patch->nfile.map.len;
+
+	return 0;
 }
 
 static int patch_generated_file_cb(

src/patch_generate.h

@@ -39,10 +39,10 @@ typedef struct git_patch_generated git_patch_generated;
 
 extern git_diff_driver *git_patch_generated_driver(git_patch_generated *);
 
-extern void git_patch_generated_old_data(
-	char **, size_t *, git_patch_generated *);
-extern void git_patch_generated_new_data(
-	char **, size_t *, git_patch_generated *);
+extern int git_patch_generated_old_data(
+	char **, long *, git_patch_generated *);
+extern int git_patch_generated_new_data(
+	char **, long *, git_patch_generated *);
 extern int git_patch_generated_from_diff(
 	git_patch **, git_diff *, size_t);
 

src/xdiff/git-xdiff.h

+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+/*
+ * This file provides the necessary indirection between xdiff and
+ * libgit2.  libgit2-specific functionality should live here, so
+ * that git and libgit2 can share a common xdiff implementation.
+ */
+
+#ifndef INCLUDE_git_xdiff_h__
+#define INCLUDE_git_xdiff_h__
+
+#include "regexp.h"
+
+#define xdl_malloc(x) git__malloc(x)
+#define xdl_free(ptr) git__free(ptr)
+#define xdl_realloc(ptr, x) git__realloc(ptr, x)
+
+#define XDL_BUG(msg) GIT_ASSERT(msg)
+
+#define xdl_regex_t git_regexp
+#define xdl_regmatch_t git_regmatch
+
+GIT_INLINE(int) xdl_regexec_buf(
+	const xdl_regex_t *preg, const char *buf, size_t size,
+	size_t nmatch, xdl_regmatch_t pmatch[], int eflags)
+{
+	GIT_UNUSED(preg);
+	GIT_UNUSED(buf);
+	GIT_UNUSED(size);
+	GIT_UNUSED(nmatch);
+	GIT_UNUSED(pmatch);
+	GIT_UNUSED(eflags);
+	GIT_ASSERT("not implemented");
+	return -1;
+}
+
+#endif

src/xdiff/xdiff.h

@@ -23,6 +23,8 @@
 #if !defined(XDIFF_H)
 #define XDIFF_H
 
+#include "git-xdiff.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif /* #ifdef __cplusplus */
@@ -50,16 +52,9 @@ extern "C" {
 
 /* xdemitconf_t.flags */
 #define XDL_EMIT_FUNCNAMES (1 << 0)
+#define XDL_EMIT_NO_HUNK_HDR (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
@@ -73,20 +68,25 @@ extern "C" {
 
 /* merge output styles */
 #define XDL_MERGE_DIFF3 1
+#define XDL_MERGE_ZEALOUS_DIFF3 2
 
 typedef struct s_mmfile {
 	char *ptr;
-	size_t size;
+	long size;
 } mmfile_t;
 
 typedef struct s_mmbuffer {
 	char *ptr;
-	size_t size;
+	long size;
 } mmbuffer_t;
 
 typedef struct s_xpparam {
 	unsigned long flags;
 
+	/* -I<regex> */
+	xdl_regex_t **ignore_regex;
+	size_t ignore_regex_nr;
+
 	/* See Documentation/diff-options.txt. */
 	char **anchors;
 	size_t anchors_nr;
@@ -94,7 +94,11 @@ typedef struct s_xpparam {
 
 typedef struct s_xdemitcb {
 	void *priv;
-	int (*outf)(void *, mmbuffer_t *, int);
+	int (*out_hunk)(void *,
+			long old_begin, long old_nr,
+			long new_begin, long new_nr,
+			const char *func, long funclen);
+	int (*out_line)(void *, mmbuffer_t *, int);
 } xdemitcb_t;
 
 typedef long (*find_func_t)(const char *line, long line_len, char *buffer, long buffer_size, void *priv);
@@ -117,10 +121,6 @@ typedef struct s_bdiffparam {
 } bdiffparam_t;
 
 
-#define xdl_malloc(x) git__malloc(x)
-#define xdl_free(ptr) git__free(ptr)
-#define xdl_realloc(ptr,x) git__realloc(ptr,x)
-
 void *xdl_mmfile_first(mmfile_t *mmf, long *size);
 long xdl_mmfile_size(mmfile_t *mmf);
 

src/xdiff/xemit.c

@@ -31,7 +31,7 @@ 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) {
-	long size, psize = (long)strlen(pre);
+	long size, psize = strlen(pre);
 	char const *rec;
 
 	size = xdl_get_rec(xdf, ri, &rec);
@@ -81,7 +81,7 @@ xdchange_t *xdl_get_hunk(xdchange_t **xscr, xdemitconf_t const *xecfg)
 		} else if (distance < max_ignorable && xch->ignore) {
 			ignored += xch->chg2;
 		} else if (lxch != xchp &&
-			   xch->i1 + ignored - (lxch->i1 + lxch->chg1) > (unsigned long)max_common) {
+			   xch->i1 + ignored - (lxch->i1 + lxch->chg1) > max_common) {
 			break;
 		} else if (!xch->ignore) {
 			lxch = xch;
@@ -97,8 +97,6 @@ xdchange_t *xdl_get_hunk(xdchange_t **xscr, xdemitconf_t const *xecfg)
 
 static long def_ff(const char *rec, long len, char *buf, long sz, void *priv)
 {
-	(void)priv;
-
 	if (len > 0 &&
 			(isalpha((unsigned char)*rec) || /* identifier? */
 			 *rec == '_' || /* also identifier? */
@@ -174,10 +172,12 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 	struct func_line func_line = { 0 };
 
 	for (xch = xscr; xch; xch = xche->next) {
+		xdchange_t *xchp = xch;
 		xche = xdl_get_hunk(&xch, xecfg);
 		if (!xch)
 			break;
 
+pre_context_calculation:
 		s1 = XDL_MAX(xch->i1 - xecfg->ctxlen, 0);
 		s2 = XDL_MAX(xch->i2 - xecfg->ctxlen, 0);
 
@@ -212,8 +212,23 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 			if (fs1 < 0)
 				fs1 = 0;
 			if (fs1 < s1) {
-				s2 -= s1 - fs1;
+				s2 = XDL_MAX(s2 - (s1 - fs1), 0);
 				s1 = fs1;
+
+				/*
+				 * Did we extend context upwards into an
+				 * ignored change?
+				 */
+				while (xchp != xch &&
+				       xchp->i1 + xchp->chg1 <= s1 &&
+				       xchp->i2 + xchp->chg2 <= s2)
+					xchp = xchp->next;
+
+				/* If so, show it after all. */
+				if (xchp != xch) {
+					xch = xchp;
+					goto pre_context_calculation;
+				}
 			}
 		}
 
@@ -234,7 +249,7 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 			if (fe1 < 0)
 				fe1 = xe->xdf1.nrec;
 			if (fe1 > e1) {
-				e2 += fe1 - e1;
+				e2 = XDL_MIN(e2 + (fe1 - e1), xe->xdf2.nrec);
 				e1 = fe1;
 			}
 
@@ -263,7 +278,8 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 				      s1 - 1, funclineprev);
 			funclineprev = s1 - 1;
 		}
-		if (xdl_emit_hunk_hdr(s1 + 1, e1 - s1, s2 + 1, e2 - s2,
+		if (!(xecfg->flags & XDL_EMIT_NO_HUNK_HDR) &&
+		    xdl_emit_hunk_hdr(s1 + 1, e1 - s1, s2 + 1, e2 - s2,
 				      func_line.buf, func_line.len, ecb) < 0)
 			return -1;
 

src/xdiff/xhistogram.c

@@ -42,8 +42,6 @@
  */
 
 #include "xinclude.h"
-#include "xtypes.h"
-#include "xdiff.h"
 
 #define MAX_PTR	UINT_MAX
 #define MAX_CNT	UINT_MAX
@@ -90,27 +88,21 @@ struct region {
 #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)
+static int cmp_recs(xrecord_t *r1, xrecord_t *r2)
 {
-	return r1->ha == r2->ha &&
-		xdl_recmatch(r1->ptr, r1->size, r2->ptr, r2->size,
-			    xpp->flags);
-}
+	return r1->ha == r2->ha;
 
-#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)))
+	(cmp_recs(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, unsigned int line1, unsigned int count1)
+static int scanA(struct histindex *index, int line1, int count1)
 {
-	unsigned int ptr;
-	unsigned int tbl_idx;
+	unsigned int ptr, tbl_idx;
 	unsigned int chain_len;
 	struct record **rec_chain, *rec;
 
@@ -161,10 +153,8 @@ continue_scan:
 	return 0;
 }
 
-static int try_lcs(
-	struct histindex *index, struct region *lcs, unsigned int b_ptr,
-	unsigned int line1, unsigned int count1,
-	unsigned int line2, unsigned int count2)
+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)];
@@ -236,59 +226,33 @@ static int try_lcs(
 	return b_next;
 }
 
-static int find_lcs(
-	struct histindex *index, struct region *lcs,
-	unsigned int line1, unsigned int count1,
-	unsigned int line2, unsigned int count2)
+static int fall_back_to_classic_diff(xpparam_t const *xpp, xdfenv_t *env,
+		int line1, int count1, int line2, int count2)
 {
-	unsigned int b_ptr;
+	xpparam_t xpparam;
 
-	if (scanA(index, line1, count1))
-		return -1;
+	memset(&xpparam, 0, sizeof(xpparam));
+	xpparam.flags = xpp->flags & ~XDF_DIFF_ALGORITHM_MASK;
 
-	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;
+	return xdl_fall_back_diff(env, &xpparam,
+				  line1, count1, line2, count2);
 }
 
-static int fall_back_to_classic_diff(struct histindex *index,
-		int line1, int count1, int line2, int count2)
+static inline void free_index(struct histindex *index)
 {
-	xpparam_t xpp;
-	xpp.flags = index->xpp->flags & ~XDF_DIFF_ALGORITHM_MASK;
-
-	return xdl_fall_back_diff(index->env, &xpp,
-				  line1, count1, line2, count2);
+	xdl_free(index->records);
+	xdl_free(index->line_map);
+	xdl_free(index->next_ptrs);
+	xdl_cha_free(&index->rcha);
 }
 
-static int histogram_diff(
-	xpparam_t const *xpp, xdfenv_t *env,
-	unsigned int line1, unsigned int count1,
-	unsigned int line2, unsigned int count2)
+static int find_lcs(xpparam_t const *xpp, xdfenv_t *env,
+		    struct region *lcs,
+		    int line1, int count1, int line2, int count2)
 {
+	int b_ptr;
+	int sz, ret = -1;
 	struct histindex index;
-	struct region lcs;
-	size_t 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));
 
@@ -302,8 +266,7 @@ static int histogram_diff(
 
 	index.table_bits = xdl_hashbits(count1);
 	sz = index.records_size = 1 << index.table_bits;
-	GIT_ERROR_CHECK_ALLOC_MULTIPLY(&sz, sz, sizeof(struct record *));
-
+	sz *= sizeof(struct record *);
 	if (!(index.records = (struct record **) xdl_malloc(sz)))
 		goto cleanup;
 	memset(index.records, 0, sz);
@@ -327,9 +290,55 @@ static int histogram_diff(
 	index.ptr_shift = line1;
 	index.max_chain_length = 64;
 
+	if (scanA(&index, line1, count1))
+		goto cleanup;
+
+	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);
+
+	if (index.has_common && index.max_chain_length < index.cnt)
+		ret = 1;
+	else
+		ret = 0;
+
+cleanup:
+	free_index(&index);
+	return ret;
+}
+
+static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
+	int line1, int count1, int line2, int count2)
+{
+	struct region lcs;
+	int lcs_found;
+	int result;
+redo:
+	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(&lcs, 0, sizeof(lcs));
-	if (find_lcs(&index, &lcs, line1, count1, line2, count2))
-		result = fall_back_to_classic_diff(&index, line1, count1, line2, count2);
+	lcs_found = find_lcs(xpp, env, &lcs, line1, count1, line2, count2);
+	if (lcs_found < 0)
+		goto out;
+	else if (lcs_found)
+		result = fall_back_to_classic_diff(xpp, env, line1, count1, line2, count2);
 	else {
 		if (lcs.begin1 == 0 && lcs.begin2 == 0) {
 			while (count1--)
@@ -342,21 +351,21 @@ static int histogram_diff(
 						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;
+				goto out;
+			/*
+			 * result = histogram_diff(xpp, env,
+			 *            lcs.end1 + 1, LINE_END(1) - lcs.end1,
+			 *            lcs.end2 + 1, LINE_END(2) - lcs.end2);
+			 * but let's optimize tail recursion ourself:
+			*/
+			count1 = LINE_END(1) - lcs.end1;
+			line1 = lcs.end1 + 1;
+			count2 = LINE_END(2) - lcs.end2;
+			line2 = lcs.end2 + 1;
+			goto redo;
 		}
 	}
-
-cleanup:
-	xdl_free(index.records);
-	xdl_free(index.line_map);
-	xdl_free(index.next_ptrs);
-	xdl_cha_free(&index.rcha);
-
+out:
 	return result;
 }
 

src/xdiff/xinclude.h

@@ -23,17 +23,7 @@
 #if !defined(XINCLUDE_H)
 #define XINCLUDE_H
 
-#include <ctype.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <limits.h>
-
-#ifdef _WIN32
-#else
-#include <unistd.h>
-#endif
-
+#include "git-xdiff.h"
 #include "xmacros.h"
 #include "xdiff.h"
 #include "xtypes.h"
@@ -42,6 +32,5 @@
 #include "xdiffi.h"
 #include "xemit.h"
 
-#include "common.h"
 
 #endif /* #if !defined(XINCLUDE_H) */

src/xdiff/xpatience.c

@@ -20,8 +20,6 @@
  *
  */
 #include "xinclude.h"
-#include "xtypes.h"
-#include "xdiff.h"
 
 /*
  * The basic idea of patience diff is to find lines that are unique in
@@ -78,7 +76,7 @@ struct hashmap {
 
 static int is_anchor(xpparam_t const *xpp, const char *line)
 {
-	unsigned long i;
+	int i;
 	for (i = 0; i < xpp->anchors_nr; i++) {
 		if (!strncmp(line, xpp->anchors[i], strlen(xpp->anchors[i])))
 			return 1;
@@ -92,7 +90,7 @@ static void insert_record(xpparam_t const *xpp, int line, struct hashmap *map,
 {
 	xrecord_t **records = pass == 1 ?
 		map->env->xdf1.recs : map->env->xdf2.recs;
-	xrecord_t *record = records[line - 1], *other;
+	xrecord_t *record = records[line - 1];
 	/*
 	 * After xdl_prepare_env() (or more precisely, due to
 	 * xdl_classify_record()), the "ha" member of the records (AKA lines)
@@ -106,11 +104,7 @@ static void insert_record(xpparam_t const *xpp, int line, struct hashmap *map,
 	int index = (int)((record->ha << 1) % map->alloc);
 
 	while (map->entries[index].line1) {
-		other = map->env->xdf1.recs[map->entries[index].line1 - 1];
-		if (map->entries[index].hash != record->ha ||
-				!xdl_recmatch(record->ptr, record->size,
-					other->ptr, other->size,
-					map->xpp->flags)) {
+		if (map->entries[index].hash != record->ha) {
 			if (++index >= map->alloc)
 				index = 0;
 			continue;
@@ -217,9 +211,6 @@ static struct entry *find_longest_common_sequence(struct hashmap *map)
 	 */
 	int anchor_i = -1;
 
-	if (!sequence)
-		return NULL;
-
 	for (entry = map->first; entry; entry = entry->next) {
 		if (!entry->line2 || entry->line2 == NON_UNIQUE)
 			continue;
@@ -258,8 +249,7 @@ static int match(struct hashmap *map, int line1, int line2)
 {
 	xrecord_t *record1 = map->env->xdf1.recs[line1 - 1];
 	xrecord_t *record2 = map->env->xdf2.recs[line2 - 1];
-	return xdl_recmatch(record1->ptr, record1->size,
-		record2->ptr, record2->size, map->xpp->flags);
+	return record1->ha == record2->ha;
 }
 
 static int patience_diff(mmfile_t *file1, mmfile_t *file2,
@@ -294,9 +284,6 @@ static int walk_common_sequence(struct hashmap *map, struct entry *first,
 
 		/* Recurse */
 		if (next1 > line1 || next2 > line2) {
-			struct hashmap submap;
-
-			memset(&submap, 0, sizeof(submap));
 			if (patience_diff(map->file1, map->file2,
 					map->xpp, map->env,
 					line1, next1 - line1,
@@ -323,6 +310,8 @@ static int fall_back_to_classic_diff(struct hashmap *map,
 		int line1, int count1, int line2, int count2)
 {
 	xpparam_t xpp;
+
+	memset(&xpp, 0, sizeof(xpp));
 	xpp.flags = map->xpp->flags & ~XDF_DIFF_ALGORITHM_MASK;
 
 	return xdl_fall_back_diff(map->env, &xpp,

src/xdiff/xprepare.c

@@ -181,15 +181,11 @@ static int xdl_prepare_ctx(unsigned int pass, mmfile_t *mf, long narec, xpparam_
 	if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *))))
 		goto abort;
 
-	if (XDF_DIFF_ALG(xpp->flags) == XDF_HISTOGRAM_DIFF)
-		hbits = hsize = 0;
-	else {
 	hbits = xdl_hashbits((unsigned int) narec);
 	hsize = 1 << hbits;
 	if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *))))
 		goto abort;
 	memset(rhash, 0, hsize * sizeof(xrecord_t *));
-	}
 
 	nrec = 0;
 	if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {
@@ -208,9 +204,7 @@ static int xdl_prepare_ctx(unsigned int pass, mmfile_t *mf, long narec, xpparam_
 			crec->size = (long) (cur - prev);
 			crec->ha = hav;
 			recs[nrec++] = crec;
-
-			if ((XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF) &&
-			    xdl_classify_record(pass, cf, rhash, hbits, crec) < 0)
+			if (xdl_classify_record(pass, cf, rhash, hbits, crec) < 0)
 				goto abort;
 		}
 	}
@@ -219,10 +213,13 @@ static int xdl_prepare_ctx(unsigned int pass, mmfile_t *mf, long narec, xpparam_
 		goto abort;
 	memset(rchg, 0, (nrec + 2) * sizeof(char));
 
-	if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long))))
+	if ((XDF_DIFF_ALG(xpp->flags) != XDF_PATIENCE_DIFF) &&
+	    (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF)) {
+		if (!(rindex = xdl_malloc((nrec + 1) * sizeof(*rindex))))
 			goto abort;
-	if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long))))
+		if (!(ha = xdl_malloc((nrec + 1) * sizeof(*ha))))
 			goto abort;
+	}
 
 	xdf->nrec = nrec;
 	xdf->recs = recs;
@@ -279,8 +276,7 @@ int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
 	enl1 = xdl_guess_lines(mf1, sample) + 1;
 	enl2 = xdl_guess_lines(mf2, sample) + 1;
 
-	if (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF &&
-	    xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0)
+	if (xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0)
 		return -1;
 
 	if (xdl_prepare_ctx(1, mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
@@ -305,7 +301,6 @@ int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
 		return -1;
 	}
 
-	if (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF)
 	xdl_free_classifier(&cf);
 
 	return 0;

src/xdiff/xutils.c

@@ -23,8 +23,6 @@
 #include "xinclude.h"
 
 
-
-
 long xdl_bogosqrt(long n) {
 	long i;
 
@@ -52,7 +50,7 @@ int xdl_emit_diffrec(char const *rec, long size, char const *pre, long psize,
 		mb[2].size = strlen(mb[2].ptr);
 		i++;
 	}
-	if (ecb->outf(ecb->priv, mb, i) < 0) {
+	if (ecb->out_line(ecb->priv, mb, i) < 0) {
 
 		return -1;
 	}
@@ -342,8 +340,9 @@ int xdl_num_out(char *out, long val) {
 	return str - out;
 }
 
-int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
-		      const char *func, long funclen, xdemitcb_t *ecb) {
+static int xdl_format_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];
@@ -376,7 +375,7 @@ int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
 	nb += 3;
 	if (func && funclen) {
 		buf[nb++] = ' ';
-		if (funclen > (long)(sizeof(buf) - nb - 1))
+		if (funclen > sizeof(buf) - nb - 1)
 			funclen = sizeof(buf) - nb - 1;
 		memcpy(buf + nb, func, funclen);
 		nb += funclen;
@@ -385,9 +384,21 @@ int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
 
 	mb.ptr = buf;
 	mb.size = nb;
-	if (ecb->outf(ecb->priv, &mb, 1) < 0)
+	if (ecb->out_line(ecb->priv, &mb, 1) < 0)
 		return -1;
+	return 0;
+}
 
+int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
+		      const char *func, long funclen,
+		      xdemitcb_t *ecb) {
+	if (!ecb->out_hunk)
+		return xdl_format_hunk_hdr(s1, c1, s2, c2, func, funclen, ecb);
+	if (ecb->out_hunk(ecb->priv,
+			  c1 ? s1 : s1 - 1, c1,
+			  c2 ? s2 : s2 - 1, c2,
+			  func, funclen) < 0)
+		return -1;
 	return 0;
 }
 

tests/merge/conflict_data.h

@@ -36,6 +36,15 @@
 	"this file is changed in branch and master\n" \
 	">>>>>>> 7cb63eed597130ba4abb87b3e544b85021905520\n"
 
+#define CONFLICTING_ZDIFF3_FILE \
+	"<<<<<<< HEAD\n" \
+	"this file is changed in master and branch\n" \
+	"||||||| initial\n" \
+	"this file is a conflict\n" \
+	"=======\n" \
+	"this file is changed in branch and master\n" \
+	">>>>>>> 7cb63eed597130ba4abb87b3e544b85021905520\n"
+
 #define CONFLICTING_UNION_FILE \
 	"this file is changed in master and branch\n" \
 	"this file is changed in branch and master\n"

tests/merge/files.c

@@ -424,3 +424,42 @@ void test_merge_files__crlf_conflict_markers_for_crlf_files(void)
 	cl_assert(memcmp(expected_diff3, result.ptr, expected_len) == 0);
 	git_merge_file_result_free(&result);
 }
+
+void test_merge_files__conflicts_in_zdiff3(void)
+{
+	git_merge_file_input ancestor = GIT_MERGE_FILE_INPUT_INIT,
+		ours = GIT_MERGE_FILE_INPUT_INIT,
+		theirs = GIT_MERGE_FILE_INPUT_INIT;
+	git_merge_file_options opts = GIT_MERGE_FILE_OPTIONS_INIT;
+	git_merge_file_result result = {0};
+
+	const char *expected_zdiff3 =
+		"1,\nfoo,\nbar,\n" \
+		"<<<<<<< file.txt\n" \
+		"||||||| file.txt\n# add more here\n" \
+		"=======\nquux,\nwoot,\n" \
+		">>>>>>> file.txt\nbaz,\n3,\n";
+	size_t expected_zdiff3_len = strlen(expected_zdiff3);
+
+	ancestor.ptr = "1,\n# add more here\n3,\n";
+	ancestor.size = strlen(ancestor.ptr);
+	ancestor.path = "file.txt";
+	ancestor.mode = 0100644;
+
+	ours.ptr = "1,\nfoo,\nbar,\nbaz,\n3,\n";
+	ours.size = strlen(ours.ptr);
+	ours.path = "file.txt";
+	ours.mode = 0100644;
+
+	theirs.ptr = "1,\nfoo,\nbar,\nquux,\nwoot,\nbaz,\n3,\n";
+	theirs.size = strlen(theirs.ptr);
+	theirs.path = "file.txt";
+	theirs.mode = 0100644;
+
+	opts.flags |= GIT_MERGE_FILE_STYLE_ZDIFF3;
+	cl_git_pass(git_merge_file(&result, &ancestor, &ours, &theirs, &opts));
+	cl_assert_equal_i(0, result.automergeable);
+	cl_assert_equal_i(expected_zdiff3_len, result.len);
+	cl_assert(memcmp(expected_zdiff3, result.ptr, expected_zdiff3_len) == 0);
+	git_merge_file_result_free(&result);
+}

tests/merge/workdir/simple.c

@@ -323,6 +323,42 @@ void test_merge_workdir_simple__diff3(void)
 	cl_assert(merge_test_reuc(repo_index, merge_reuc_entries, 3));
 }
 
+void test_merge_workdir_simple__zdiff3(void)
+{
+	git_str conflicting_buf = GIT_STR_INIT;
+
+	struct merge_index_entry merge_index_entries[] = {
+		ADDED_IN_MASTER_INDEX_ENTRY,
+		AUTOMERGEABLE_INDEX_ENTRY,
+		CHANGED_IN_BRANCH_INDEX_ENTRY,
+		CHANGED_IN_MASTER_INDEX_ENTRY,
+
+		{ 0100644, "d427e0b2e138501a3d15cc376077a3631e15bd46", 1, "conflicting.txt" },
+		{ 0100644, "4e886e602529caa9ab11d71f86634bd1b6e0de10", 2, "conflicting.txt" },
+		{ 0100644, "2bd0a343aeef7a2cf0d158478966a6e587ff3863", 3, "conflicting.txt" },
+
+		UNCHANGED_INDEX_ENTRY,
+	};
+
+	struct merge_reuc_entry merge_reuc_entries[] = {
+		AUTOMERGEABLE_REUC_ENTRY,
+		REMOVED_IN_BRANCH_REUC_ENTRY,
+		REMOVED_IN_MASTER_REUC_ENTRY
+	};
+
+	set_core_autocrlf_to(repo, false);
+
+	merge_simple_branch(0, GIT_CHECKOUT_CONFLICT_STYLE_ZDIFF3);
+
+	cl_git_pass(git_futils_readbuffer(&conflicting_buf,
+		TEST_REPO_PATH "/conflicting.txt"));
+	cl_assert_equal_s(CONFLICTING_ZDIFF3_FILE, conflicting_buf.ptr);
+	git_str_dispose(&conflicting_buf);
+
+	cl_assert(merge_test_index(repo_index, merge_index_entries, 8));
+	cl_assert(merge_test_reuc(repo_index, merge_reuc_entries, 3));
+}
+
 void test_merge_workdir_simple__union(void)
 {
 	git_str conflicting_buf = GIT_STR_INIT;
@@ -436,6 +472,48 @@ void test_merge_workdir_simple__diff3_from_config(void)
 	git_config_free(config);
 }
 
+void test_merge_workdir_simple__zdiff3_from_config(void)
+{
+	git_config *config;
+	git_str conflicting_buf = GIT_STR_INIT;
+
+	struct merge_index_entry merge_index_entries[] = {
+		ADDED_IN_MASTER_INDEX_ENTRY,
+		AUTOMERGEABLE_INDEX_ENTRY,
+		CHANGED_IN_BRANCH_INDEX_ENTRY,
+		CHANGED_IN_MASTER_INDEX_ENTRY,
+
+		{ 0100644, "d427e0b2e138501a3d15cc376077a3631e15bd46", 1, "conflicting.txt" },
+		{ 0100644, "4e886e602529caa9ab11d71f86634bd1b6e0de10", 2, "conflicting.txt" },
+		{ 0100644, "2bd0a343aeef7a2cf0d158478966a6e587ff3863", 3, "conflicting.txt" },
+
+		UNCHANGED_INDEX_ENTRY,
+	};
+
+	struct merge_reuc_entry merge_reuc_entries[] = {
+		AUTOMERGEABLE_REUC_ENTRY,
+		REMOVED_IN_BRANCH_REUC_ENTRY,
+		REMOVED_IN_MASTER_REUC_ENTRY
+	};
+
+	cl_git_pass(git_repository_config(&config, repo));
+	cl_git_pass(git_config_set_string(config, "merge.conflictstyle", "zdiff3"));
+
+	set_core_autocrlf_to(repo, false);
+
+	merge_simple_branch(0, 0);
+
+	cl_git_pass(git_futils_readbuffer(&conflicting_buf,
+		TEST_REPO_PATH "/conflicting.txt"));
+	cl_assert(strcmp(conflicting_buf.ptr, CONFLICTING_ZDIFF3_FILE) == 0);
+	git_str_dispose(&conflicting_buf);
+
+	cl_assert(merge_test_index(repo_index, merge_index_entries, 8));
+	cl_assert(merge_test_reuc(repo_index, merge_reuc_entries, 3));
+
+	git_config_free(config);
+}
+
 void test_merge_workdir_simple__merge_overrides_config(void)
 {
 	git_config *config;