1 files changed, 129 insertions, 7 deletions

diff --git a/merge-recursive.c b/merge-recursive.c
index 4eb62cf64a..3b34401d0b 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -15,6 +15,7 @@
 #include "unpack-trees.h"
 #include "path-list.h"
 #include "xdiff-interface.h"
+#include "attr.h"
 
 static int subtree_merge;
 
@@ -659,6 +660,127 @@ static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 	mm->size = size;
 }
 
+/* Low-level merge functions */
+typedef int (*ll_merge_fn)(mmfile_t *orig,
+			   mmfile_t *src1, const char *name1,
+			   mmfile_t *src2, const char *name2,
+			   mmbuffer_t *result);
+
+static int ll_xdl_merge(mmfile_t *orig,
+			mmfile_t *src1, const char *name1,
+			mmfile_t *src2, const char *name2,
+			mmbuffer_t *result)
+{
+	xpparam_t xpp;
+
+	memset(&xpp, 0, sizeof(xpp));
+	return xdl_merge(orig,
+			 src1, name1,
+			 src2, name2,
+			 &xpp, XDL_MERGE_ZEALOUS,
+			 result);
+}
+
+static int ll_union_merge(mmfile_t *orig,
+			  mmfile_t *src1, const char *name1,
+			  mmfile_t *src2, const char *name2,
+			  mmbuffer_t *result)
+{
+	char *src, *dst;
+	long size;
+	const int marker_size = 7;
+
+	int status = ll_xdl_merge(orig, src1, NULL, src2, NULL, result);
+	if (status <= 0)
+		return status;
+	size = result->size;
+	src = dst = result->ptr;
+	while (size) {
+		char ch;
+		if ((marker_size < size) &&
+		    (*src == '<' || *src == '=' || *src == '>')) {
+			int i;
+			ch = *src;
+			for (i = 0; i < marker_size; i++)
+				if (src[i] != ch)
+					goto not_a_marker;
+			if (src[marker_size] != '\n')
+				goto not_a_marker;
+			src += marker_size + 1;
+			size -= marker_size + 1;
+			continue;
+		}
+	not_a_marker:
+		do {
+			ch = *src++;
+			*dst++ = ch;
+			size--;
+		} while (ch != '\n' && size);
+	}
+	result->size = dst - result->ptr;
+	return 0;
+}
+
+static int ll_binary_merge(mmfile_t *orig,
+			   mmfile_t *src1, const char *name1,
+			   mmfile_t *src2, const char *name2,
+			   mmbuffer_t *result)
+{
+	/*
+	 * The tentative merge result is "ours" for the final round,
+	 * or common ancestor for an internal merge.  Still return
+	 * "conflicted merge" status.
+	 */
+	mmfile_t *stolen = index_only ? orig : src1;
+
+	result->ptr = stolen->ptr;
+	result->size = stolen->size;
+	stolen->ptr = NULL;
+	return 1;
+}
+
+static struct {
+	const char *name;
+	ll_merge_fn fn;
+} ll_merge_fns[] = {
+	{ "text", ll_xdl_merge },
+	{ "binary", ll_binary_merge },
+	{ "union", ll_union_merge },
+	{ NULL, NULL },
+};
+
+static ll_merge_fn find_ll_merge_fn(void *merge_attr)
+{
+	const char *name;
+	int i;
+
+	if (ATTR_TRUE(merge_attr) || ATTR_UNSET(merge_attr))
+		return ll_xdl_merge;
+	else if (ATTR_FALSE(merge_attr))
+		return ll_binary_merge;
+
+	/* Otherwise merge_attr may name the merge function */
+	name = merge_attr;
+	for (i = 0; ll_merge_fns[i].name; i++)
+		if (!strcmp(ll_merge_fns[i].name, name))
+			return ll_merge_fns[i].fn;
+
+	/* default to the 3-way */
+	return ll_xdl_merge;
+}
+
+static void *git_path_check_merge(const char *path)
+{
+	static struct git_attr_check attr_merge_check;
+
+	if (!attr_merge_check.attr)
+		attr_merge_check.attr = git_attr("merge", 5);
+
+	if (git_checkattr(path, 1, &attr_merge_check))
+		return ATTR__UNSET;
+	return attr_merge_check.value;
+}
+
 static int ll_merge(mmbuffer_t *result_buf,
 		    struct diff_filespec *o,
 		    struct diff_filespec *a,
@@ -667,9 +789,10 @@ static int ll_merge(mmbuffer_t *result_buf,
 		    const char *branch2)
 {
 	mmfile_t orig, src1, src2;
-	xpparam_t xpp;
 	char *name1, *name2;
 	int merge_status;
+	void *merge_attr;
+	ll_merge_fn fn;
 
 	name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 	name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
@@ -678,12 +801,11 @@ static int ll_merge(mmbuffer_t *result_buf,
 	fill_mm(a->sha1, &src1);
 	fill_mm(b->sha1, &src2);
 
-	memset(&xpp, 0, sizeof(xpp));
-	merge_status = xdl_merge(&orig,
-				 &src1, name1,
-				 &src2, name2,
-				 &xpp, XDL_MERGE_ZEALOUS,
-				 result_buf);
+	merge_attr = git_path_check_merge(a->path);
+	fn = find_ll_merge_fn(merge_attr);
+
+	merge_status = fn(&orig, &src1, name1, &src2, name2, result_buf);
+
 	free(name1);
 	free(name2);
 	free(orig.ptr);