rerere: honor conflict-marker-size attribute

Signed-off-by: Junio C Hamano <gitster@pobox.com>

ll-merge.c

@@ -380,3 +380,18 @@ int ll_merge(mmbuffer_t *result_buf,
 			  ours, our_label, theirs, their_label,
 			  virtual_ancestor, marker_size);
 }
+
+int ll_merge_marker_size(const char *path)
+{
+	static struct git_attr_check check;
+	int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
+
+	if (!check.attr)
+		check.attr = git_attr("conflict-marker-size");
+	if (!git_checkattr(path, 1, &check) && check.value) {
+		marker_size = atoi(check.value);
+		if (marker_size <= 0)
+			marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
+	}
+	return marker_size;
+}

ll-merge.h

@@ -12,4 +12,6 @@ int ll_merge(mmbuffer_t *result_buf,
 	     mmfile_t *theirs, const char *their_label,
 	     int virtual_ancestor);
 
+int ll_merge_marker_size(const char *path);
+
 #endif

rerere.c

@@ -5,6 +5,7 @@
 #include "dir.h"
 #include "resolve-undo.h"
 #include "ll-merge.h"
+#include "attr.h"
 
 /* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
 static int rerere_enabled = -1;
@@ -221,7 +222,7 @@ static int handle_file(const char *path, unsigned char *sha1, const char *output
 {
 	int hunk_no = 0;
 	struct rerere_io_file io;
-	int marker_size = 7;
+	int marker_size = ll_merge_marker_size(path);
 
 	memset(&io, 0, sizeof(io));
 	io.io.getline = rerere_file_getline;
@@ -288,7 +289,7 @@ static int handle_cache(const char *path, unsigned char *sha1, const char *outpu
 	struct cache_entry *ce;
 	int pos, len, i, hunk_no;
 	struct rerere_io_mem io;
-	int marker_size = 7;
+	int marker_size = ll_merge_marker_size(path);
 
 	/*
 	 * Reproduce the conflicted merge in-core