[PATCH v14 01/11] trailer: add data structures and basic functions

@@ -888,6 +888,7 @@ LIB_OBJS += submodule-config.o
 LIB_OBJS += symlinks.o
 LIB_OBJS += tag.o
 LIB_OBJS += trace.o
+LIB_OBJS += trailer.o
 LIB_OBJS += transport.o
 LIB_OBJS += transport-helper.o
 LIB_OBJS += tree-diff.o

@@ -0,0 +1,64 @@
+#include "cache.h"
+/*
+ * Copyright (c) 2013, 2014 Christian Couder <chriscool@tuxfamily.org>
+ */
+
+enum action_where { WHERE_END, WHERE_AFTER, WHERE_BEFORE, WHERE_START };
+enum action_if_exists { EXISTS_ADD_IF_DIFFERENT_NEIGHBOR, EXISTS_ADD_IF_DIFFERENT,
+			EXISTS_ADD, EXISTS_REPLACE, EXISTS_DO_NOTHING };
+enum action_if_missing { MISSING_ADD, MISSING_DO_NOTHING };
+
+struct conf_info {
+	char *name;
+	char *key;
+	char *command;
+	enum action_where where;
+	enum action_if_exists if_exists;
+	enum action_if_missing if_missing;
+};
+
+static struct conf_info default_conf_info;
+
+struct trailer_item {
+	struct trailer_item *previous;
+	struct trailer_item *next;
+	const char *token;
+	const char *value;
+	struct conf_info conf;
+};
+
+static struct trailer_item *first_conf_item;
+
+static char *separators = ":";
+
+static int after_or_end(enum action_where where)
+{
+	return (where == WHERE_AFTER) || (where == WHERE_END);
+}
+
+/* Get the length of buf from its beginning until its last alphanumeric character */
+static size_t alnum_len(const char *buf, size_t len)
+{
+	while (len > 0 && !isalnum(buf[len - 1]))
+		len--;
+	return len;
+}
+
+static int same_token(struct trailer_item *a, struct trailer_item *b)
+{
+	size_t a_alnum_len = alnum_len(a->token, strlen(a->token));
+	size_t b_alnum_len = alnum_len(b->token, strlen(b->token));
+	size_t min_alnum_len = (a_alnum_len > b_alnum_len) ? b_alnum_len : a_alnum_len;
+
+	return !strncasecmp(a->token, b->token, min_alnum_len);
+}
+
+static int same_value(struct trailer_item *a, struct trailer_item *b)
+{
+	return !strcasecmp(a->value, b->value);
+}
+
+static int same_trailer(struct trailer_item *a, struct trailer_item *b)
+{
+	return same_token(a, b) && same_value(a, b);
+}