Add shared diff-handling functions

This adds a standard interface for tree diffing.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

cgit.h

@@ -19,6 +19,7 @@
 
 
 typedef void (*configfn)(const char *name, const char *value);
+typedef void (*filepair_fn)(struct diff_filepair *pair);
 
 struct cacheitem {
 	char *name;
@@ -116,6 +117,10 @@ extern int chk_positive(int result, char *msg);
 extern int hextoint(char c);
 
 extern void *cgit_free_commitinfo(struct commitinfo *info);
+extern void cgit_diff_tree(const unsigned char *old_sha1,
+			   const unsigned char *new_sha1,
+			   filepair_fn fn);
+extern void cgit_diff_commit(struct commit *commit, filepair_fn fn);
 
 extern char *fmt(const char *format,...);
 

shared.c

@@ -195,3 +195,46 @@ int hextoint(char c)
 		return -1;
 }
 
+void cgit_diff_tree_cb(struct diff_queue_struct *q,
+		       struct diff_options *options, void *data)
+{
+	int i;
+
+	for (i = 0; i < q->nr; i++) {
+		if (q->queue[i]->status == 'U')
+			continue;
+		((filepair_fn)data)(q->queue[i]);
+	}
+}
+
+void cgit_diff_tree(const unsigned char *old_sha1,
+		    const unsigned char *new_sha1,
+		    filepair_fn fn)
+{
+	struct diff_options opt;
+	int ret;
+
+	diff_setup(&opt);
+	opt.output_format = DIFF_FORMAT_CALLBACK;
+	opt.detect_rename = 1;
+	opt.recursive = 1;
+	opt.format_callback = cgit_diff_tree_cb;
+	opt.format_callback_data = fn;
+	diff_setup_done(&opt);
+
+	if (old_sha1)
+		ret = diff_tree_sha1(old_sha1, new_sha1, "", &opt);
+	else
+		ret = diff_root_tree_sha1(new_sha1, "", &opt);
+	diffcore_std(&opt);
+	diff_flush(&opt);
+}
+
+void cgit_diff_commit(struct commit *commit, filepair_fn fn)
+{
+	unsigned char *old_sha1 = NULL;
+
+	if (commit->parents)
+		old_sha1 = commit->parents->item->object.sha1;
+	cgit_diff_tree(old_sha1, commit->object.sha1, fn);
+}