Adding upstream version 1:2.39.2.upstream/1%2.39.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1659 insertions, 0 deletions

diff --git a/combine-diff.c b/combine-diff.c
new file mode 100644
index 0000000..b0ece95
--- /dev/null
+++ b/combine-diff.c
@@ -0,0 +1,1659 @@
+#include "cache.h"
+#include "object-store.h"
+#include "commit.h"
+#include "blob.h"
+#include "diff.h"
+#include "diffcore.h"
+#include "quote.h"
+#include "xdiff-interface.h"
+#include "xdiff/xmacros.h"
+#include "log-tree.h"
+#include "refs.h"
+#include "userdiff.h"
+#include "oid-array.h"
+#include "revision.h"
+
+static int compare_paths(const struct combine_diff_path *one,
+			  const struct diff_filespec *two)
+{
+	if (!S_ISDIR(one->mode) && !S_ISDIR(two->mode))
+		return strcmp(one->path, two->path);
+
+	return base_name_compare(one->path, strlen(one->path), one->mode,
+				 two->path, strlen(two->path), two->mode);
+}
+
+static int filename_changed(char status)
+{
+	return status == 'R' || status == 'C';
+}
+
+static struct combine_diff_path *intersect_paths(
+	struct combine_diff_path *curr,
+	int n,
+	int num_parent,
+	int combined_all_paths)
+{
+	struct diff_queue_struct *q = &diff_queued_diff;
+	struct combine_diff_path *p, **tail = &curr;
+	int i, j, cmp;
+
+	if (!n) {
+		for (i = 0; i < q->nr; i++) {
+			int len;
+			const char *path;
+			if (diff_unmodified_pair(q->queue[i]))
+				continue;
+			path = q->queue[i]->two->path;
+			len = strlen(path);
+			p = xmalloc(combine_diff_path_size(num_parent, len));
+			p->path = (char *) &(p->parent[num_parent]);
+			memcpy(p->path, path, len);
+			p->path[len] = 0;
+			p->next = NULL;
+			memset(p->parent, 0,
+			       sizeof(p->parent[0]) * num_parent);
+
+			oidcpy(&p->oid, &q->queue[i]->two->oid);
+			p->mode = q->queue[i]->two->mode;
+			oidcpy(&p->parent[n].oid, &q->queue[i]->one->oid);
+			p->parent[n].mode = q->queue[i]->one->mode;
+			p->parent[n].status = q->queue[i]->status;
+
+			if (combined_all_paths &&
+			    filename_changed(p->parent[n].status)) {
+				strbuf_init(&p->parent[n].path, 0);
+				strbuf_addstr(&p->parent[n].path,
+					      q->queue[i]->one->path);
+			}
+			*tail = p;
+			tail = &p->next;
+		}
+		return curr;
+	}
+
+	/*
+	 * paths in curr (linked list) and q->queue[] (array) are
+	 * both sorted in the tree order.
+	 */
+	i = 0;
+	while ((p = *tail) != NULL) {
+		cmp = ((i >= q->nr)
+		       ? -1 : compare_paths(p, q->queue[i]->two));
+
+		if (cmp < 0) {
+			/* p->path not in q->queue[]; drop it */
+			*tail = p->next;
+			for (j = 0; j < num_parent; j++)
+				if (combined_all_paths &&
+				    filename_changed(p->parent[j].status))
+					strbuf_release(&p->parent[j].path);
+			free(p);
+			continue;
+		}
+
+		if (cmp > 0) {
+			/* q->queue[i] not in p->path; skip it */
+			i++;
+			continue;
+		}
+
+		oidcpy(&p->parent[n].oid, &q->queue[i]->one->oid);
+		p->parent[n].mode = q->queue[i]->one->mode;
+		p->parent[n].status = q->queue[i]->status;
+		if (combined_all_paths &&
+		    filename_changed(p->parent[n].status))
+			strbuf_addstr(&p->parent[n].path,
+				      q->queue[i]->one->path);
+
+		tail = &p->next;
+		i++;
+	}
+	return curr;
+}
+
+/* Lines lost from parent */
+struct lline {
+	struct lline *next, *prev;
+	int len;
+	unsigned long parent_map;
+	char line[FLEX_ARRAY];
+};
+
+/* Lines lost from current parent (before coalescing) */
+struct plost {
+	struct lline *lost_head, *lost_tail;
+	int len;
+};
+
+/* Lines surviving in the merge result */
+struct sline {
+	/* Accumulated and coalesced lost lines */
+	struct lline *lost;
+	int lenlost;
+	struct plost plost;
+	char *bol;
+	int len;
+	/* bit 0 up to (N-1) are on if the parent has this line (i.e.
+	 * we did not change it).
+	 * bit N is used for "interesting" lines, including context.
+	 * bit (N+1) is used for "do not show deletion before this".
+	 */
+	unsigned long flag;
+	unsigned long *p_lno;
+};
+
+static int match_string_spaces(const char *line1, int len1,
+			       const char *line2, int len2,
+			       long flags)
+{
+	if (flags & XDF_WHITESPACE_FLAGS) {
+		for (; len1 > 0 && XDL_ISSPACE(line1[len1 - 1]); len1--);
+		for (; len2 > 0 && XDL_ISSPACE(line2[len2 - 1]); len2--);
+	}
+
+	if (!(flags & (XDF_IGNORE_WHITESPACE | XDF_IGNORE_WHITESPACE_CHANGE)))
+		return (len1 == len2 && !memcmp(line1, line2, len1));
+
+	while (len1 > 0 && len2 > 0) {
+		len1--;
+		len2--;
+		if (XDL_ISSPACE(line1[len1]) || XDL_ISSPACE(line2[len2])) {
+			if ((flags & XDF_IGNORE_WHITESPACE_CHANGE) &&
+			    (!XDL_ISSPACE(line1[len1]) || !XDL_ISSPACE(line2[len2])))
+				return 0;
+
+			for (; len1 > 0 && XDL_ISSPACE(line1[len1]); len1--);
+			for (; len2 > 0 && XDL_ISSPACE(line2[len2]); len2--);
+		}
+		if (line1[len1] != line2[len2])
+			return 0;
+	}
+
+	if (flags & XDF_IGNORE_WHITESPACE) {
+		/* Consume remaining spaces */
+		for (; len1 > 0 && XDL_ISSPACE(line1[len1 - 1]); len1--);
+		for (; len2 > 0 && XDL_ISSPACE(line2[len2 - 1]); len2--);
+	}
+
+	/* We matched full line1 and line2 */
+	if (!len1 && !len2)
+		return 1;
+
+	return 0;
+}
+
+enum coalesce_direction { MATCH, BASE, NEW };
+
+/* Coalesce new lines into base by finding LCS */
+static struct lline *coalesce_lines(struct lline *base, int *lenbase,
+				    struct lline *newline, int lennew,
+				    unsigned long parent, long flags)
+{
+	int **lcs;
+	enum coalesce_direction **directions;
+	struct lline *baseend, *newend = NULL;
+	int i, j, origbaselen = *lenbase;
+
+	if (!newline)
+		return base;
+
+	if (!base) {
+		*lenbase = lennew;
+		return newline;
+	}
+
+	/*
+	 * Coalesce new lines into base by finding the LCS
+	 * - Create the table to run dynamic programming
+	 * - Compute the LCS
+	 * - Then reverse read the direction structure:
+	 *   - If we have MATCH, assign parent to base flag, and consume
+	 *   both baseend and newend
+	 *   - Else if we have BASE, consume baseend
+	 *   - Else if we have NEW, insert newend lline into base and
+	 *   consume newend
+	 */
+	CALLOC_ARRAY(lcs, st_add(origbaselen, 1));
+	CALLOC_ARRAY(directions, st_add(origbaselen, 1));
+	for (i = 0; i < origbaselen + 1; i++) {
+		CALLOC_ARRAY(lcs[i], st_add(lennew, 1));
+		CALLOC_ARRAY(directions[i], st_add(lennew, 1));
+		directions[i][0] = BASE;
+	}
+	for (j = 1; j < lennew + 1; j++)
+		directions[0][j] = NEW;
+
+	for (i = 1, baseend = base; i < origbaselen + 1; i++) {
+		for (j = 1, newend = newline; j < lennew + 1; j++) {
+			if (match_string_spaces(baseend->line, baseend->len,
+						newend->line, newend->len, flags)) {
+				lcs[i][j] = lcs[i - 1][j - 1] + 1;
+				directions[i][j] = MATCH;
+			} else if (lcs[i][j - 1] >= lcs[i - 1][j]) {
+				lcs[i][j] = lcs[i][j - 1];
+				directions[i][j] = NEW;
+			} else {
+				lcs[i][j] = lcs[i - 1][j];
+				directions[i][j] = BASE;
+			}
+			if (newend->next)
+				newend = newend->next;
+		}
+		if (baseend->next)
+			baseend = baseend->next;
+	}
+
+	for (i = 0; i < origbaselen + 1; i++)
+		free(lcs[i]);
+	free(lcs);
+
+	/* At this point, baseend and newend point to the end of each lists */
+	i--;
+	j--;
+	while (i != 0 || j != 0) {
+		if (directions[i][j] == MATCH) {
+			baseend->parent_map |= 1<<parent;
+			baseend = baseend->prev;
+			newend = newend->prev;
+			i--;
+			j--;
+		} else if (directions[i][j] == NEW) {
+			struct lline *lline;
+
+			lline = newend;
+			/* Remove lline from new list and update newend */
+			if (lline->prev)
+				lline->prev->next = lline->next;
+			else
+				newline = lline->next;
+			if (lline->next)
+				lline->next->prev = lline->prev;
+
+			newend = lline->prev;
+			j--;
+
+			/* Add lline to base list */
+			if (baseend) {
+				lline->next = baseend->next;
+				lline->prev = baseend;
+				if (lline->prev)
+					lline->prev->next = lline;
+			}
+			else {
+				lline->next = base;
+				base = lline;
+			}
+			(*lenbase)++;
+
+			if (lline->next)
+				lline->next->prev = lline;
+
+		} else {
+			baseend = baseend->prev;
+			i--;
+		}
+	}
+
+	newend = newline;
+	while (newend) {
+		struct lline *lline = newend;
+		newend = newend->next;
+		free(lline);
+	}
+
+	for (i = 0; i < origbaselen + 1; i++)
+		free(directions[i]);
+	free(directions);
+
+	return base;
+}
+
+static char *grab_blob(struct repository *r,
+		       const struct object_id *oid, unsigned int mode,
+		       unsigned long *size, struct userdiff_driver *textconv,
+		       const char *path)
+{
+	char *blob;
+	enum object_type type;
+
+	if (S_ISGITLINK(mode)) {
+		struct strbuf buf = STRBUF_INIT;
+		strbuf_addf(&buf, "Subproject commit %s\n", oid_to_hex(oid));
+		*size = buf.len;
+		blob = strbuf_detach(&buf, NULL);
+	} else if (is_null_oid(oid)) {
+		/* deleted blob */
+		*size = 0;
+		return xcalloc(1, 1);
+	} else if (textconv) {
+		struct diff_filespec *df = alloc_filespec(path);
+		fill_filespec(df, oid, 1, mode);
+		*size = fill_textconv(r, textconv, df, &blob);
+		free_filespec(df);
+	} else {
+		blob = read_object_file(oid, &type, size);
+		if (type != OBJ_BLOB)
+			die("object '%s' is not a blob!", oid_to_hex(oid));
+	}
+	return blob;
+}
+
+static void append_lost(struct sline *sline, int n, const char *line, int len)
+{
+	struct lline *lline;
+	unsigned long this_mask = (1UL<<n);
+	if (line[len-1] == '\n')
+		len--;
+
+	FLEX_ALLOC_MEM(lline, line, line, len);
+	lline->len = len;
+	lline->next = NULL;
+	lline->prev = sline->plost.lost_tail;
+	if (lline->prev)
+		lline->prev->next = lline;
+	else
+		sline->plost.lost_head = lline;
+	sline->plost.lost_tail = lline;
+	sline->plost.len++;
+	lline->parent_map = this_mask;
+}
+
+struct combine_diff_state {
+	unsigned int lno;
+	int ob, on, nb, nn;
+	unsigned long nmask;
+	int num_parent;
+	int n;
+	struct sline *sline;
+	struct sline *lost_bucket;
+};
+
+static void consume_hunk(void *state_,
+			 long ob, long on,
+			 long nb, long nn,
+			 const char *funcline, long funclen)
+{
+	struct combine_diff_state *state = state_;
+
+	state->ob = ob;
+	state->on = on;
+	state->nb = nb;
+	state->nn = nn;
+	state->lno = state->nb;
+	if (state->nn == 0) {
+		/* @@ -X,Y +N,0 @@ removed Y lines
+		 * that would have come *after* line N
+		 * in the result.  Our lost buckets hang
+		 * to the line after the removed lines,
+		 *
+		 * Note that this is correct even when N == 0,
+		 * in which case the hunk removes the first
+		 * line in the file.
+		 */
+		state->lost_bucket = &state->sline[state->nb];
+		if (!state->nb)
+			state->nb = 1;
+	} else {
+		state->lost_bucket = &state->sline[state->nb-1];
+	}
+	if (!state->sline[state->nb-1].p_lno)
+		CALLOC_ARRAY(state->sline[state->nb - 1].p_lno,
+			     state->num_parent);
+	state->sline[state->nb-1].p_lno[state->n] = state->ob;
+}
+
+static int consume_line(void *state_, char *line, unsigned long len)
+{
+	struct combine_diff_state *state = state_;
+	if (!state->lost_bucket)
+		return 0; /* not in any hunk yet */
+	switch (line[0]) {
+	case '-':
+		append_lost(state->lost_bucket, state->n, line+1, len-1);
+		break;
+	case '+':
+		state->sline[state->lno-1].flag |= state->nmask;
+		state->lno++;
+		break;
+	}
+	return 0;
+}
+
+static void combine_diff(struct repository *r,
+			 const struct object_id *parent, unsigned int mode,
+			 mmfile_t *result_file,
+			 struct sline *sline, unsigned int cnt, int n,
+			 int num_parent, int result_deleted,
+			 struct userdiff_driver *textconv,
+			 const char *path, long flags)
+{
+	unsigned int p_lno, lno;
+	unsigned long nmask = (1UL << n);
+	xpparam_t xpp;
+	xdemitconf_t xecfg;
+	mmfile_t parent_file;
+	struct combine_diff_state state;
+	unsigned long sz;
+
+	if (result_deleted)
+		return; /* result deleted */
+
+	parent_file.ptr = grab_blob(r, parent, mode, &sz, textconv, path);
+	parent_file.size = sz;
+	memset(&xpp, 0, sizeof(xpp));
+	xpp.flags = flags;
+	memset(&xecfg, 0, sizeof(xecfg));
+	memset(&state, 0, sizeof(state));
+	state.nmask = nmask;
+	state.sline = sline;
+	state.lno = 1;
+	state.num_parent = num_parent;
+	state.n = n;
+
+	if (xdi_diff_outf(&parent_file, result_file, consume_hunk,
+			  consume_line, &state, &xpp, &xecfg))
+		die("unable to generate combined diff for %s",
+		    oid_to_hex(parent));
+	free(parent_file.ptr);
+
+	/* Assign line numbers for this parent.
+	 *
+	 * sline[lno].p_lno[n] records the first line number
+	 * (counting from 1) for parent N if the final hunk display
+	 * started by showing sline[lno] (possibly showing the lost
+	 * lines attached to it first).
+	 */
+	for (lno = 0,  p_lno = 1; lno <= cnt; lno++) {
+		struct lline *ll;
+		sline[lno].p_lno[n] = p_lno;
+
+		/* Coalesce new lines */
+		if (sline[lno].plost.lost_head) {
+			struct sline *sl = &sline[lno];
+			sl->lost = coalesce_lines(sl->lost, &sl->lenlost,
+						  sl->plost.lost_head,
+						  sl->plost.len, n, flags);
+			sl->plost.lost_head = sl->plost.lost_tail = NULL;
+			sl->plost.len = 0;
+		}
+
+		/* How many lines would this sline advance the p_lno? */
+		ll = sline[lno].lost;
+		while (ll) {
+			if (ll->parent_map & nmask)
+				p_lno++; /* '-' means parent had it */
+			ll = ll->next;
+		}
+		if (lno < cnt && !(sline[lno].flag & nmask))
+			p_lno++; /* no '+' means parent had it */
+	}
+	sline[lno].p_lno[n] = p_lno; /* trailer */
+}
+
+static unsigned long context = 3;
+static char combine_marker = '@';
+
+static int interesting(struct sline *sline, unsigned long all_mask)
+{
+	/* If some parents lost lines here, or if we have added to
+	 * some parent, it is interesting.
+	 */
+	return ((sline->flag & all_mask) || sline->lost);
+}
+
+static unsigned long adjust_hunk_tail(struct sline *sline,
+				      unsigned long all_mask,
+				      unsigned long hunk_begin,
+				      unsigned long i)
+{
+	/* i points at the first uninteresting line.  If the last line
+	 * of the hunk was interesting only because it has some
+	 * deletion, then it is not all that interesting for the
+	 * purpose of giving trailing context lines.  This is because
+	 * we output '-' line and then unmodified sline[i-1] itself in
+	 * that case which gives us one extra context line.
+	 */
+	if ((hunk_begin + 1 <= i) && !(sline[i-1].flag & all_mask))
+		i--;
+	return i;
+}
+
+static unsigned long find_next(struct sline *sline,
+			       unsigned long mark,
+			       unsigned long i,
+			       unsigned long cnt,
+			       int look_for_uninteresting)
+{
+	/* We have examined up to i-1 and are about to look at i.
+	 * Find next interesting or uninteresting line.  Here,
+	 * "interesting" does not mean interesting(), but marked by
+	 * the give_context() function below (i.e. it includes context
+	 * lines that are not interesting to interesting() function
+	 * that are surrounded by interesting() ones.
+	 */
+	while (i <= cnt)
+		if (look_for_uninteresting
+		    ? !(sline[i].flag & mark)
+		    : (sline[i].flag & mark))
+			return i;
+		else
+			i++;
+	return i;
+}
+
+static int give_context(struct sline *sline, unsigned long cnt, int num_parent)
+{
+	unsigned long all_mask = (1UL<<num_parent) - 1;
+	unsigned long mark = (1UL<<num_parent);
+	unsigned long no_pre_delete = (2UL<<num_parent);
+	unsigned long i;
+
+	/* Two groups of interesting lines may have a short gap of
+	 * uninteresting lines.  Connect such groups to give them a
+	 * bit of context.
+	 *
+	 * We first start from what the interesting() function says,
+	 * and mark them with "mark", and paint context lines with the
+	 * mark.  So interesting() would still say false for such context
+	 * lines but they are treated as "interesting" in the end.
+	 */
+	i = find_next(sline, mark, 0, cnt, 0);
+	if (cnt < i)
+		return 0;
+
+	while (i <= cnt) {
+		unsigned long j = (context < i) ? (i - context) : 0;
+		unsigned long k;
+
+		/* Paint a few lines before the first interesting line. */
+		while (j < i) {
+			if (!(sline[j].flag & mark))
+				sline[j].flag |= no_pre_delete;
+			sline[j++].flag |= mark;
+		}
+
+	again:
+		/* we know up to i is to be included.  where does the
+		 * next uninteresting one start?
+		 */
+		j = find_next(sline, mark, i, cnt, 1);
+		if (cnt < j)
+			break; /* the rest are all interesting */
+
+		/* lookahead context lines */
+		k = find_next(sline, mark, j, cnt, 0);
+		j = adjust_hunk_tail(sline, all_mask, i, j);
+
+		if (k < j + context) {
+			/* k is interesting and [j,k) are not, but
+			 * paint them interesting because the gap is small.
+			 */
+			while (j < k)
+				sline[j++].flag |= mark;
+			i = k;
+			goto again;
+		}
+
+		/* j is the first uninteresting line and there is
+		 * no overlap beyond it within context lines.  Paint
+		 * the trailing edge a bit.
+		 */
+		i = k;
+		k = (j + context < cnt+1) ? j + context : cnt+1;
+		while (j < k)
+			sline[j++].flag |= mark;
+	}
+	return 1;
+}
+
+static int make_hunks(struct sline *sline, unsigned long cnt,
+		       int num_parent, int dense)
+{
+	unsigned long all_mask = (1UL<<num_parent) - 1;
+	unsigned long mark = (1UL<<num_parent);
+	unsigned long i;
+	int has_interesting = 0;
+
+	for (i = 0; i <= cnt; i++) {
+		if (interesting(&sline[i], all_mask))
+			sline[i].flag |= mark;
+		else
+			sline[i].flag &= ~mark;
+	}
+	if (!dense)
+		return give_context(sline, cnt, num_parent);
+
+	/* Look at each hunk, and if we have changes from only one
+	 * parent, or the changes are the same from all but one
+	 * parent, mark that uninteresting.
+	 */
+	i = 0;
+	while (i <= cnt) {
+		unsigned long j, hunk_begin, hunk_end;
+		unsigned long same_diff;
+		while (i <= cnt && !(sline[i].flag & mark))
+			i++;
+		if (cnt < i)
+			break; /* No more interesting hunks */
+		hunk_begin = i;
+		for (j = i + 1; j <= cnt; j++) {
+			if (!(sline[j].flag & mark)) {
+				/* Look beyond the end to see if there
+				 * is an interesting line after this
+				 * hunk within context span.
+				 */
+				unsigned long la; /* lookahead */
+				int contin = 0;
+				la = adjust_hunk_tail(sline, all_mask,
+						     hunk_begin, j);
+				la = (la + context < cnt + 1) ?
+					(la + context) : cnt + 1;
+				while (la && j <= --la) {
+					if (sline[la].flag & mark) {
+						contin = 1;
+						break;
+					}
+				}
+				if (!contin)
+					break;
+				j = la;
+			}
+		}
+		hunk_end = j;
+
+		/* [i..hunk_end) are interesting.  Now is it really
+		 * interesting?  We check if there are only two versions
+		 * and the result matches one of them.  That is, we look
+		 * at:
+		 *   (+) line, which records lines added to which parents;
+		 *       this line appears in the result.
+		 *   (-) line, which records from what parents the line
+		 *       was removed; this line does not appear in the result.
+		 * then check the set of parents the result has difference
+		 * from, from all lines.  If there are lines that has
+		 * different set of parents that the result has differences
+		 * from, that means we have more than two versions.
+		 *
+		 * Even when we have only two versions, if the result does
+		 * not match any of the parents, the it should be considered
+		 * interesting.  In such a case, we would have all '+' line.
+		 * After passing the above "two versions" test, that would
+		 * appear as "the same set of parents" to be "all parents".
+		 */
+		same_diff = 0;
+		has_interesting = 0;
+		for (j = i; j < hunk_end && !has_interesting; j++) {
+			unsigned long this_diff = sline[j].flag & all_mask;
+			struct lline *ll = sline[j].lost;
+			if (this_diff) {
+				/* This has some changes.  Is it the
+				 * same as others?
+				 */
+				if (!same_diff)
+					same_diff = this_diff;
+				else if (same_diff != this_diff) {
+					has_interesting = 1;
+					break;
+				}
+			}
+			while (ll && !has_interesting) {
+				/* Lost this line from these parents;
+				 * who are they?  Are they the same?
+				 */
+				this_diff = ll->parent_map;
+				if (!same_diff)
+					same_diff = this_diff;
+				else if (same_diff != this_diff) {
+					has_interesting = 1;
+				}
+				ll = ll->next;
+			}
+		}
+
+		if (!has_interesting && same_diff != all_mask) {
+			/* This hunk is not that interesting after all */
+			for (j = hunk_begin; j < hunk_end; j++)
+				sline[j].flag &= ~mark;
+		}
+		i = hunk_end;
+	}
+
+	has_interesting = give_context(sline, cnt, num_parent);
+	return has_interesting;
+}
+
+static void show_parent_lno(struct sline *sline, unsigned long l0, unsigned long l1, int n, unsigned long null_context)
+{
+	l0 = sline[l0].p_lno[n];
+	l1 = sline[l1].p_lno[n];
+	printf(" -%lu,%lu", l0, l1-l0-null_context);
+}
+
+static int hunk_comment_line(const char *bol)
+{
+	int ch;
+
+	if (!bol)
+		return 0;
+	ch = *bol & 0xff;
+	return (isalpha(ch) || ch == '_' || ch == '$');
+}
+
+static void show_line_to_eol(const char *line, int len, const char *reset)
+{
+	int saw_cr_at_eol = 0;
+	if (len < 0)
+		len = strlen(line);
+	saw_cr_at_eol = (len && line[len-1] == '\r');
+
+	printf("%.*s%s%s\n", len - saw_cr_at_eol, line,
+	       reset,
+	       saw_cr_at_eol ? "\r" : "");
+}
+
+static void dump_sline(struct sline *sline, const char *line_prefix,
+		       unsigned long cnt, int num_parent,
+		       int use_color, int result_deleted)
+{
+	unsigned long mark = (1UL<<num_parent);
+	unsigned long no_pre_delete = (2UL<<num_parent);
+	int i;
+	unsigned long lno = 0;
+	const char *c_frag = diff_get_color(use_color, DIFF_FRAGINFO);
+	const char *c_func = diff_get_color(use_color, DIFF_FUNCINFO);
+	const char *c_new = diff_get_color(use_color, DIFF_FILE_NEW);
+	const char *c_old = diff_get_color(use_color, DIFF_FILE_OLD);
+	const char *c_context = diff_get_color(use_color, DIFF_CONTEXT);
+	const char *c_reset = diff_get_color(use_color, DIFF_RESET);
+
+	if (result_deleted)
+		return; /* result deleted */
+
+	while (1) {
+		unsigned long hunk_end;
+		unsigned long rlines;
+		const char *hunk_comment = NULL;
+		unsigned long null_context = 0;
+
+		while (lno <= cnt && !(sline[lno].flag & mark)) {
+			if (hunk_comment_line(sline[lno].bol))
+				hunk_comment = sline[lno].bol;
+			lno++;
+		}
+		if (cnt < lno)
+			break;
+		else {
+			for (hunk_end = lno + 1; hunk_end <= cnt; hunk_end++)
+				if (!(sline[hunk_end].flag & mark))
+					break;
+		}
+		rlines = hunk_end - lno;
+		if (cnt < hunk_end)
+			rlines--; /* pointing at the last delete hunk */
+
+		if (!context) {
+			/*
+			 * Even when running with --unified=0, all
+			 * lines in the hunk needs to be processed in
+			 * the loop below in order to show the
+			 * deletion recorded in lost_head.  However,
+			 * we do not want to show the resulting line
+			 * with all blank context markers in such a
+			 * case.  Compensate.
+			 */
+			unsigned long j;
+			for (j = lno; j < hunk_end; j++)
+				if (!(sline[j].flag & (mark-1)))
+					null_context++;
+			rlines -= null_context;
+		}
+
+		printf("%s%s", line_prefix, c_frag);
+		for (i = 0; i <= num_parent; i++) putchar(combine_marker);
+		for (i = 0; i < num_parent; i++)
+			show_parent_lno(sline, lno, hunk_end, i, null_context);
+		printf(" +%lu,%lu ", lno+1, rlines);
+		for (i = 0; i <= num_parent; i++) putchar(combine_marker);
+
+		if (hunk_comment) {
+			int comment_end = 0;
+			for (i = 0; i < 40; i++) {
+				int ch = hunk_comment[i] & 0xff;
+				if (!ch || ch == '\n')
+					break;
+				if (!isspace(ch))
+				    comment_end = i;
+			}
+			if (comment_end)
+				printf("%s%s %s%s", c_reset,
+						    c_context, c_reset,
+						    c_func);
+			for (i = 0; i < comment_end; i++)
+				putchar(hunk_comment[i]);
+		}
+
+		printf("%s\n", c_reset);
+		while (lno < hunk_end) {
+			struct lline *ll;
+			int j;
+			unsigned long p_mask;
+			struct sline *sl = &sline[lno++];
+			ll = (sl->flag & no_pre_delete) ? NULL : sl->lost;
+			while (ll) {
+				printf("%s%s", line_prefix, c_old);
+				for (j = 0; j < num_parent; j++) {
+					if (ll->parent_map & (1UL<<j))
+						putchar('-');
+					else
+						putchar(' ');
+				}
+				show_line_to_eol(ll->line, -1, c_reset);
+				ll = ll->next;
+			}
+			if (cnt < lno)
+				break;
+			p_mask = 1;
+			fputs(line_prefix, stdout);
+			if (!(sl->flag & (mark-1))) {
+				/*
+				 * This sline was here to hang the
+				 * lost lines in front of it.
+				 */
+				if (!context)
+					continue;
+				fputs(c_context, stdout);
+			}
+			else
+				fputs(c_new, stdout);
+			for (j = 0; j < num_parent; j++) {
+				if (p_mask & sl->flag)
+					putchar('+');
+				else
+					putchar(' ');
+				p_mask <<= 1;
+			}
+			show_line_to_eol(sl->bol, sl->len, c_reset);
+		}
+	}
+}
+
+static void reuse_combine_diff(struct sline *sline, unsigned long cnt,
+			       int i, int j)
+{
+	/* We have already examined parent j and we know parent i
+	 * and parent j are the same, so reuse the combined result
+	 * of parent j for parent i.
+	 */
+	unsigned long lno, imask, jmask;
+	imask = (1UL<<i);
+	jmask = (1UL<<j);
+
+	for (lno = 0; lno <= cnt; lno++) {
+		struct lline *ll = sline->lost;
+		sline->p_lno[i] = sline->p_lno[j];
+		while (ll) {
+			if (ll->parent_map & jmask)
+				ll->parent_map |= imask;
+			ll = ll->next;
+		}
+		if (sline->flag & jmask)
+			sline->flag |= imask;
+		sline++;
+	}
+	/* the overall size of the file (sline[cnt]) */
+	sline->p_lno[i] = sline->p_lno[j];
+}
+
+static void dump_quoted_path(const char *head,
+			     const char *prefix,
+			     const char *path,
+			     const char *line_prefix,
+			     const char *c_meta, const char *c_reset)
+{
+	static struct strbuf buf = STRBUF_INIT;
+
+	strbuf_reset(&buf);
+	strbuf_addstr(&buf, line_prefix);
+	strbuf_addstr(&buf, c_meta);
+	strbuf_addstr(&buf, head);
+	quote_two_c_style(&buf, prefix, path, 0);
+	strbuf_addstr(&buf, c_reset);
+	puts(buf.buf);
+}
+
+static void show_combined_header(struct combine_diff_path *elem,
+				 int num_parent,
+				 struct rev_info *rev,
+				 const char *line_prefix,
+				 int mode_differs,
+				 int show_file_header)
+{
+	struct diff_options *opt = &rev->diffopt;
+	int abbrev = opt->flags.full_index ? the_hash_algo->hexsz : DEFAULT_ABBREV;
+	const char *a_prefix = opt->a_prefix ? opt->a_prefix : "a/";
+	const char *b_prefix = opt->b_prefix ? opt->b_prefix : "b/";
+	const char *c_meta = diff_get_color_opt(opt, DIFF_METAINFO);
+	const char *c_reset = diff_get_color_opt(opt, DIFF_RESET);
+	const char *abb;
+	int added = 0;
+	int deleted = 0;
+	int i;
+	int dense = rev->dense_combined_merges;
+
+	if (rev->loginfo && !rev->no_commit_id)
+		show_log(rev);
+
+	dump_quoted_path(dense ? "diff --cc " : "diff --combined ",
+			 "", elem->path, line_prefix, c_meta, c_reset);
+	printf("%s%sindex ", line_prefix, c_meta);
+	for (i = 0; i < num_parent; i++) {
+		abb = find_unique_abbrev(&elem->parent[i].oid,
+					 abbrev);
+		printf("%s%s", i ? "," : "", abb);
+	}
+	abb = find_unique_abbrev(&elem->oid, abbrev);
+	printf("..%s%s\n", abb, c_reset);
+
+	if (mode_differs) {
+		deleted = !elem->mode;
+
+		/* We say it was added if nobody had it */
+		added = !deleted;
+		for (i = 0; added && i < num_parent; i++)
+			if (elem->parent[i].status !=
+			    DIFF_STATUS_ADDED)
+				added = 0;
+		if (added)
+			printf("%s%snew file mode %06o",
+			       line_prefix, c_meta, elem->mode);
+		else {
+			if (deleted)
+				printf("%s%sdeleted file ",
+				       line_prefix, c_meta);
+			printf("mode ");
+			for (i = 0; i < num_parent; i++) {
+				printf("%s%06o", i ? "," : "",
+				       elem->parent[i].mode);
+			}
+			if (elem->mode)
+				printf("..%06o", elem->mode);
+		}
+		printf("%s\n", c_reset);
+	}
+
+	if (!show_file_header)
+		return;
+
+	if (rev->combined_all_paths) {
+		for (i = 0; i < num_parent; i++) {
+			char *path = filename_changed(elem->parent[i].status)
+				? elem->parent[i].path.buf : elem->path;
+			if (elem->parent[i].status == DIFF_STATUS_ADDED)
+				dump_quoted_path("--- ", "", "/dev/null",
+						 line_prefix, c_meta, c_reset);
+			else
+				dump_quoted_path("--- ", a_prefix, path,
+						 line_prefix, c_meta, c_reset);
+		}
+	} else {
+		if (added)
+			dump_quoted_path("--- ", "", "/dev/null",
+					 line_prefix, c_meta, c_reset);
+		else
+			dump_quoted_path("--- ", a_prefix, elem->path,
+					 line_prefix, c_meta, c_reset);
+	}
+	if (deleted)
+		dump_quoted_path("+++ ", "", "/dev/null",
+				 line_prefix, c_meta, c_reset);
+	else
+		dump_quoted_path("+++ ", b_prefix, elem->path,
+				 line_prefix, c_meta, c_reset);
+}
+
+static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
+			    int working_tree_file,
+			    struct rev_info *rev)
+{
+	struct diff_options *opt = &rev->diffopt;
+	unsigned long result_size, cnt, lno;
+	int result_deleted = 0;
+	char *result, *cp;
+	struct sline *sline; /* survived lines */
+	int mode_differs = 0;
+	int i, show_hunks;
+	mmfile_t result_file;
+	struct userdiff_driver *userdiff;
+	struct userdiff_driver *textconv = NULL;
+	int is_binary;
+	const char *line_prefix = diff_line_prefix(opt);
+
+	context = opt->context;
+	userdiff = userdiff_find_by_path(opt->repo->index, elem->path);
+	if (!userdiff)
+		userdiff = userdiff_find_by_name("default");
+	if (opt->flags.allow_textconv)
+		textconv = userdiff_get_textconv(opt->repo, userdiff);
+
+	/* Read the result of merge first */
+	if (!working_tree_file)
+		result = grab_blob(opt->repo, &elem->oid, elem->mode, &result_size,
+				   textconv, elem->path);
+	else {
+		/* Used by diff-tree to read from the working tree */
+		struct stat st;
+		int fd = -1;
+
+		if (lstat(elem->path, &st) < 0)
+			goto deleted_file;
+
+		if (S_ISLNK(st.st_mode)) {
+			struct strbuf buf = STRBUF_INIT;
+
+			if (strbuf_readlink(&buf, elem->path, st.st_size) < 0) {
+				error_errno("readlink(%s)", elem->path);
+				return;
+			}
+			result_size = buf.len;
+			result = strbuf_detach(&buf, NULL);
+			elem->mode = canon_mode(st.st_mode);
+		} else if (S_ISDIR(st.st_mode)) {
+			struct object_id oid;
+			if (resolve_gitlink_ref(elem->path, "HEAD", &oid) < 0)
+				result = grab_blob(opt->repo, &elem->oid,
+						   elem->mode, &result_size,
+						   NULL, NULL);
+			else
+				result = grab_blob(opt->repo, &oid, elem->mode,
+						   &result_size, NULL, NULL);
+		} else if (textconv) {
+			struct diff_filespec *df = alloc_filespec(elem->path);
+			fill_filespec(df, null_oid(), 0, st.st_mode);
+			result_size = fill_textconv(opt->repo, textconv, df, &result);
+			free_filespec(df);
+		} else if (0 <= (fd = open(elem->path, O_RDONLY))) {
+			size_t len = xsize_t(st.st_size);
+			ssize_t done;
+			int is_file, i;
+
+			elem->mode = canon_mode(st.st_mode);
+			/* if symlinks don't work, assume symlink if all parents
+			 * are symlinks
+			 */
+			is_file = has_symlinks;
+			for (i = 0; !is_file && i < num_parent; i++)
+				is_file = !S_ISLNK(elem->parent[i].mode);
+			if (!is_file)
+				elem->mode = canon_mode(S_IFLNK);
+
+			result_size = len;
+			result = xmallocz(len);
+
+			done = read_in_full(fd, result, len);
+			if (done < 0)
+				die_errno("read error '%s'", elem->path);
+			else if (done < len)
+				die("early EOF '%s'", elem->path);
+
+			/* If not a fake symlink, apply filters, e.g. autocrlf */
+			if (is_file) {
+				struct strbuf buf = STRBUF_INIT;
+
+				if (convert_to_git(rev->diffopt.repo->index,
+						   elem->path, result, len, &buf, global_conv_flags_eol)) {
+					free(result);
+					result = strbuf_detach(&buf, &len);
+					result_size = len;
+				}
+			}
+		}
+		else {
+		deleted_file:
+			result_deleted = 1;
+			result_size = 0;
+			elem->mode = 0;
+			result = xcalloc(1, 1);
+		}
+
+		if (0 <= fd)
+			close(fd);
+	}
+
+	for (i = 0; i < num_parent; i++) {
+		if (elem->parent[i].mode != elem->mode) {
+			mode_differs = 1;
+			break;
+		}
+	}
+
+	if (textconv)
+		is_binary = 0;
+	else if (userdiff->binary != -1)
+		is_binary = userdiff->binary;
+	else {
+		is_binary = buffer_is_binary(result, result_size);
+		for (i = 0; !is_binary && i < num_parent; i++) {
+			char *buf;
+			unsigned long size;
+			buf = grab_blob(opt->repo,
+					&elem->parent[i].oid,
+					elem->parent[i].mode,
+					&size, NULL, NULL);
+			if (buffer_is_binary(buf, size))
+				is_binary = 1;
+			free(buf);
+		}
+	}
+	if (is_binary) {
+		show_combined_header(elem, num_parent, rev,
+				     line_prefix, mode_differs, 0);
+		printf("Binary files differ\n");
+		free(result);
+		return;
+	}
+
+	for (cnt = 0, cp = result; cp < result + result_size; cp++) {
+		if (*cp == '\n')
+			cnt++;
+	}
+	if (result_size && result[result_size-1] != '\n')
+		cnt++; /* incomplete line */
+
+	CALLOC_ARRAY(sline, st_add(cnt, 2));
+	sline[0].bol = result;
+	for (lno = 0, cp = result; cp < result + result_size; cp++) {
+		if (*cp == '\n') {
+			sline[lno].len = cp - sline[lno].bol;
+			lno++;
+			if (lno < cnt)
+				sline[lno].bol = cp + 1;
+		}
+	}
+	if (result_size && result[result_size-1] != '\n')
+		sline[cnt-1].len = result_size - (sline[cnt-1].bol - result);
+
+	result_file.ptr = result;
+	result_file.size = result_size;
+
+	/* Even p_lno[cnt+1] is valid -- that is for the end line number
+	 * for deletion hunk at the end.
+	 */
+	CALLOC_ARRAY(sline[0].p_lno, st_mult(st_add(cnt, 2), num_parent));
+	for (lno = 0; lno <= cnt; lno++)
+		sline[lno+1].p_lno = sline[lno].p_lno + num_parent;
+
+	for (i = 0; i < num_parent; i++) {
+		int j;
+		for (j = 0; j < i; j++) {
+			if (oideq(&elem->parent[i].oid,
+				  &elem->parent[j].oid)) {
+				reuse_combine_diff(sline, cnt, i, j);
+				break;
+			}
+		}
+		if (i <= j)
+			combine_diff(opt->repo,
+				     &elem->parent[i].oid,
+				     elem->parent[i].mode,
+				     &result_file, sline,
+				     cnt, i, num_parent, result_deleted,
+				     textconv, elem->path, opt->xdl_opts);
+	}
+
+	show_hunks = make_hunks(sline, cnt, num_parent, rev->dense_combined_merges);
+
+	if (show_hunks || mode_differs || working_tree_file) {
+		show_combined_header(elem, num_parent, rev,
+				     line_prefix, mode_differs, 1);
+		dump_sline(sline, line_prefix, cnt, num_parent,
+			   opt->use_color, result_deleted);
+	}
+	free(result);
+
+	for (lno = 0; lno < cnt; lno++) {
+		if (sline[lno].lost) {
+			struct lline *ll = sline[lno].lost;
+			while (ll) {
+				struct lline *tmp = ll;
+				ll = ll->next;
+				free(tmp);
+			}
+		}
+	}
+	free(sline[0].p_lno);
+	free(sline);
+}
+
+static void show_raw_diff(struct combine_diff_path *p, int num_parent, struct rev_info *rev)
+{
+	struct diff_options *opt = &rev->diffopt;
+	int line_termination, inter_name_termination, i;
+	const char *line_prefix = diff_line_prefix(opt);
+
+	line_termination = opt->line_termination;
+	inter_name_termination = '\t';
+	if (!line_termination)
+		inter_name_termination = 0;
+
+	if (rev->loginfo && !rev->no_commit_id)
+		show_log(rev);
+
+
+	if (opt->output_format & DIFF_FORMAT_RAW) {
+		printf("%s", line_prefix);
+
+		/* As many colons as there are parents */
+		for (i = 0; i < num_parent; i++)
+			putchar(':');
+
+		/* Show the modes */
+		for (i = 0; i < num_parent; i++)
+			printf("%06o ", p->parent[i].mode);
+		printf("%06o", p->mode);
+
+		/* Show sha1's */
+		for (i = 0; i < num_parent; i++)
+			printf(" %s", diff_aligned_abbrev(&p->parent[i].oid,
+							  opt->abbrev));
+		printf(" %s ", diff_aligned_abbrev(&p->oid, opt->abbrev));
+	}
+
+	if (opt->output_format & (DIFF_FORMAT_RAW | DIFF_FORMAT_NAME_STATUS)) {
+		for (i = 0; i < num_parent; i++)
+			putchar(p->parent[i].status);
+		putchar(inter_name_termination);
+	}
+
+	for (i = 0; i < num_parent; i++)
+		if (rev->combined_all_paths) {
+			if (filename_changed(p->parent[i].status))
+				write_name_quoted(p->parent[i].path.buf, stdout,
+						  inter_name_termination);
+			else
+				write_name_quoted(p->path, stdout,
+						  inter_name_termination);
+		}
+	write_name_quoted(p->path, stdout, line_termination);
+}
+
+/*
+ * The result (p->elem) is from the working tree and their
+ * parents are typically from multiple stages during a merge
+ * (i.e. diff-files) or the state in HEAD and in the index
+ * (i.e. diff-index).
+ */
+void show_combined_diff(struct combine_diff_path *p,
+		       int num_parent,
+		       struct rev_info *rev)
+{
+	struct diff_options *opt = &rev->diffopt;
+
+	if (opt->output_format & (DIFF_FORMAT_RAW |
+				  DIFF_FORMAT_NAME |
+				  DIFF_FORMAT_NAME_STATUS))
+		show_raw_diff(p, num_parent, rev);
+	else if (opt->output_format & DIFF_FORMAT_PATCH)
+		show_patch_diff(p, num_parent, 1, rev);
+}
+
+static void free_combined_pair(struct diff_filepair *pair)
+{
+	free(pair->two);
+	free(pair);
+}
+
+/*
+ * A combine_diff_path expresses N parents on the LHS against 1 merge
+ * result. Synthesize a diff_filepair that has N entries on the "one"
+ * side and 1 entry on the "two" side.
+ *
+ * In the future, we might want to add more data to combine_diff_path
+ * so that we can fill fields we are ignoring (most notably, size) here,
+ * but currently nobody uses it, so this should suffice for now.
+ */
+static struct diff_filepair *combined_pair(struct combine_diff_path *p,
+					   int num_parent)
+{
+	int i;
+	struct diff_filepair *pair;
+	struct diff_filespec *pool;
+
+	pair = xmalloc(sizeof(*pair));
+	CALLOC_ARRAY(pool, st_add(num_parent, 1));
+	pair->one = pool + 1;
+	pair->two = pool;
+
+	for (i = 0; i < num_parent; i++) {
+		pair->one[i].path = p->path;
+		pair->one[i].mode = p->parent[i].mode;
+		oidcpy(&pair->one[i].oid, &p->parent[i].oid);
+		pair->one[i].oid_valid = !is_null_oid(&p->parent[i].oid);
+		pair->one[i].has_more_entries = 1;
+	}
+	pair->one[num_parent - 1].has_more_entries = 0;
+
+	pair->two->path = p->path;
+	pair->two->mode = p->mode;
+	oidcpy(&pair->two->oid, &p->oid);
+	pair->two->oid_valid = !is_null_oid(&p->oid);
+	return pair;
+}
+
+static void handle_combined_callback(struct diff_options *opt,
+				     struct combine_diff_path *paths,
+				     int num_parent,
+				     int num_paths)
+{
+	struct combine_diff_path *p;
+	struct diff_queue_struct q;
+	int i;
+
+	CALLOC_ARRAY(q.queue, num_paths);
+	q.alloc = num_paths;
+	q.nr = num_paths;
+	for (i = 0, p = paths; p; p = p->next)
+		q.queue[i++] = combined_pair(p, num_parent);
+	opt->format_callback(&q, opt, opt->format_callback_data);
+	for (i = 0; i < num_paths; i++)
+		free_combined_pair(q.queue[i]);
+	free(q.queue);
+}
+
+static const char *path_path(void *obj)
+{
+	struct combine_diff_path *path = (struct combine_diff_path *)obj;
+
+	return path->path;
+}
+
+/*
+ * Diff stat formats which we always compute solely against the first parent.
+ */
+#define STAT_FORMAT_MASK (DIFF_FORMAT_NUMSTAT \
+			  | DIFF_FORMAT_SHORTSTAT \
+			  | DIFF_FORMAT_SUMMARY \
+			  | DIFF_FORMAT_DIRSTAT \
+			  | DIFF_FORMAT_DIFFSTAT)
+
+/* find set of paths that every parent touches */
+static struct combine_diff_path *find_paths_generic(const struct object_id *oid,
+	const struct oid_array *parents,
+	struct diff_options *opt,
+	int combined_all_paths)
+{
+	struct combine_diff_path *paths = NULL;
+	int i, num_parent = parents->nr;
+
+	int output_format = opt->output_format;
+	const char *orderfile = opt->orderfile;
+
+	opt->output_format = DIFF_FORMAT_NO_OUTPUT;
+	/* tell diff_tree to emit paths in sorted (=tree) order */
+	opt->orderfile = NULL;
+
+	/* D(A,P1...Pn) = D(A,P1) ^ ... ^ D(A,Pn)  (wrt paths) */
+	for (i = 0; i < num_parent; i++) {
+		/*
+		 * show stat against the first parent even when doing
+		 * combined diff.
+		 */
+		int stat_opt = output_format & STAT_FORMAT_MASK;
+		if (i == 0 && stat_opt)
+			opt->output_format = stat_opt;
+		else
+			opt->output_format = DIFF_FORMAT_NO_OUTPUT;
+		diff_tree_oid(&parents->oid[i], oid, "", opt);
+		diffcore_std(opt);
+		paths = intersect_paths(paths, i, num_parent,
+					combined_all_paths);
+
+		/* if showing diff, show it in requested order */
+		if (opt->output_format != DIFF_FORMAT_NO_OUTPUT &&
+		    orderfile) {
+			diffcore_order(orderfile);
+		}
+
+		diff_flush(opt);
+	}
+
+	opt->output_format = output_format;
+	opt->orderfile = orderfile;
+	return paths;
+}
+
+
+/*
+ * find set of paths that everybody touches, assuming diff is run without
+ * rename/copy detection, etc, comparing all trees simultaneously (= faster).
+ */
+static struct combine_diff_path *find_paths_multitree(
+	const struct object_id *oid, const struct oid_array *parents,
+	struct diff_options *opt)
+{
+	int i, nparent = parents->nr;
+	const struct object_id **parents_oid;
+	struct combine_diff_path paths_head;
+	struct strbuf base;
+
+	ALLOC_ARRAY(parents_oid, nparent);
+	for (i = 0; i < nparent; i++)
+		parents_oid[i] = &parents->oid[i];
+
+	/* fake list head, so worker can assume it is non-NULL */
+	paths_head.next = NULL;
+
+	strbuf_init(&base, PATH_MAX);
+	diff_tree_paths(&paths_head, oid, parents_oid, nparent, &base, opt);
+
+	strbuf_release(&base);
+	free(parents_oid);
+	return paths_head.next;
+}
+
+static int match_objfind(struct combine_diff_path *path,
+			 int num_parent,
+			 const struct oidset *set)
+{
+	int i;
+	if (oidset_contains(set, &path->oid))
+		return 1;
+	for (i = 0; i < num_parent; i++) {
+		if (oidset_contains(set, &path->parent[i].oid))
+			return 1;
+	}
+	return 0;
+}
+
+static struct combine_diff_path *combined_objfind(struct diff_options *opt,
+						  struct combine_diff_path *paths,
+						  int num_parent)
+{
+	struct combine_diff_path *ret = NULL, **tail = &ret;
+	struct combine_diff_path *p = paths;
+
+	while (p) {
+		struct combine_diff_path *next = p->next;
+
+		if (match_objfind(p, num_parent, opt->objfind)) {
+			p->next = NULL;
+			*tail = p;
+			tail = &p->next;
+		} else {
+			free(p);
+		}
+		p = next;
+	}
+
+	return ret;
+}
+
+void diff_tree_combined(const struct object_id *oid,
+			const struct oid_array *parents,
+			struct rev_info *rev)
+{
+	struct diff_options *opt = &rev->diffopt;
+	struct diff_options diffopts;
+	struct combine_diff_path *p, *paths;
+	int i, num_paths, needsep, show_log_first, num_parent = parents->nr;
+	int need_generic_pathscan;
+
+	if (opt->ignore_regex_nr)
+		die("combined diff and '%s' cannot be used together",
+		    "--ignore-matching-lines");
+	if (opt->close_file)
+		die("combined diff and '%s' cannot be used together",
+		    "--output");
+
+	/* nothing to do, if no parents */
+	if (!num_parent)
+		return;
+
+	show_log_first = !!rev->loginfo && !rev->no_commit_id;
+	needsep = 0;
+	if (show_log_first) {
+		show_log(rev);
+
+		if (rev->verbose_header && opt->output_format &&
+		    opt->output_format != DIFF_FORMAT_NO_OUTPUT &&
+		    !commit_format_is_empty(rev->commit_format))
+			printf("%s%c", diff_line_prefix(opt),
+			       opt->line_termination);
+	}
+
+	diffopts = *opt;
+	copy_pathspec(&diffopts.pathspec, &opt->pathspec);
+	diffopts.flags.recursive = 1;
+	diffopts.flags.allow_external = 0;
+
+	/* find set of paths that everybody touches
+	 *
+	 * NOTE
+	 *
+	 * Diffcore transformations are bound to diff_filespec and logic
+	 * comparing two entries - i.e. they do not apply directly to combine
+	 * diff.
+	 *
+	 * If some of such transformations is requested - we launch generic
+	 * path scanning, which works significantly slower compared to
+	 * simultaneous all-trees-in-one-go scan in find_paths_multitree().
+	 *
+	 * TODO some of the filters could be ported to work on
+	 * combine_diff_paths - i.e. all functionality that skips paths, so in
+	 * theory, we could end up having only multitree path scanning.
+	 *
+	 * NOTE please keep this semantically in sync with diffcore_std()
+	 */
+	need_generic_pathscan = opt->skip_stat_unmatch	||
+			opt->flags.follow_renames	||
+			opt->break_opt != -1	||
+			opt->detect_rename	||
+			(opt->pickaxe_opts &
+			 (DIFF_PICKAXE_KINDS_MASK & ~DIFF_PICKAXE_KIND_OBJFIND)) ||
+			opt->filter;
+
+	if (need_generic_pathscan) {
+		/*
+		 * NOTE generic case also handles --stat, as it computes
+		 * diff(sha1,parent_i) for all i to do the job, specifically
+		 * for parent0.
+		 */
+		paths = find_paths_generic(oid, parents, &diffopts,
+					   rev->combined_all_paths);
+	}
+	else {
+		int stat_opt;
+		paths = find_paths_multitree(oid, parents, &diffopts);
+
+		if (opt->pickaxe_opts & DIFF_PICKAXE_KIND_OBJFIND)
+			paths = combined_objfind(opt, paths, num_parent);
+
+		/*
+		 * show stat against the first parent even
+		 * when doing combined diff.
+		 */
+		stat_opt = opt->output_format & STAT_FORMAT_MASK;
+		if (stat_opt) {
+			diffopts.output_format = stat_opt;
+
+			diff_tree_oid(&parents->oid[0], oid, "", &diffopts);
+			diffcore_std(&diffopts);
+			if (opt->orderfile)
+				diffcore_order(opt->orderfile);
+			diff_flush(&diffopts);
+		}
+	}
+
+	/* find out number of surviving paths */
+	for (num_paths = 0, p = paths; p; p = p->next)
+		num_paths++;
+
+	/* order paths according to diffcore_order */
+	if (opt->orderfile && num_paths) {
+		struct obj_order *o;
+
+		ALLOC_ARRAY(o, num_paths);
+		for (i = 0, p = paths; p; p = p->next, i++)
+			o[i].obj = p;
+		order_objects(opt->orderfile, path_path, o, num_paths);
+		for (i = 0; i < num_paths - 1; i++) {
+			p = o[i].obj;
+			p->next = o[i+1].obj;
+		}
+
+		p = o[num_paths-1].obj;
+		p->next = NULL;
+		paths = o[0].obj;
+		free(o);
+	}
+
+
+	if (num_paths) {
+		if (opt->output_format & (DIFF_FORMAT_RAW |
+					  DIFF_FORMAT_NAME |
+					  DIFF_FORMAT_NAME_STATUS)) {
+			for (p = paths; p; p = p->next)
+				show_raw_diff(p, num_parent, rev);
+			needsep = 1;
+		}
+		else if (opt->output_format & STAT_FORMAT_MASK)
+			needsep = 1;
+		else if (opt->output_format & DIFF_FORMAT_CALLBACK)
+			handle_combined_callback(opt, paths, num_parent, num_paths);
+
+		if (opt->output_format & DIFF_FORMAT_PATCH) {
+			if (needsep)
+				printf("%s%c", diff_line_prefix(opt),
+				       opt->line_termination);
+			for (p = paths; p; p = p->next)
+				show_patch_diff(p, num_parent, 0, rev);
+		}
+	}
+
+	/* Clean things up */
+	while (paths) {
+		struct combine_diff_path *tmp = paths;
+		paths = paths->next;
+		for (i = 0; i < num_parent; i++)
+			if (rev->combined_all_paths &&
+			    filename_changed(tmp->parent[i].status))
+				strbuf_release(&tmp->parent[i].path);
+		free(tmp);
+	}
+
+	clear_pathspec(&diffopts.pathspec);
+}
+
+void diff_tree_combined_merge(const struct commit *commit,
+			      struct rev_info *rev)
+{
+	struct commit_list *parent = get_saved_parents(rev, commit);
+	struct oid_array parents = OID_ARRAY_INIT;
+
+	while (parent) {
+		oid_array_append(&parents, &parent->item->object.oid);
+		parent = parent->next;
+	}
+	diff_tree_combined(&commit->object.oid, &parents, rev);
+	oid_array_clear(&parents);
+}