trailers: introduce struct new_trailer_item

This will provide a place to store the current state of the
--where, --if-exists and --if-missing options.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/interpret-trailers.c

@@ -16,17 +16,50 @@ static const char * const git_interpret_trailers_usage[] = {
 	NULL
 };
 
+static void new_trailers_clear(struct list_head *trailers)
+{
+	struct list_head *pos, *tmp;
+	struct new_trailer_item *item;
+
+	list_for_each_safe(pos, tmp, trailers) {
+		item = list_entry(pos, struct new_trailer_item, list);
+		list_del(pos);
+		free(item);
+	}
+}
+
+static int option_parse_trailer(const struct option *opt,
+				   const char *arg, int unset)
+{
+	struct list_head *trailers = opt->value;
+	struct new_trailer_item *item;
+
+	if (unset) {
+		new_trailers_clear(trailers);
+		return 0;
+	}
+
+	if (!arg)
+		return -1;
+
+	item = xmalloc(sizeof(*item));
+	item->text = arg;
+	list_add_tail(&item->list, trailers);
+	return 0;
+}
+
 int cmd_interpret_trailers(int argc, const char **argv, const char *prefix)
 {
 	int in_place = 0;
 	int trim_empty = 0;
-	struct string_list trailers = STRING_LIST_INIT_NODUP;
+	LIST_HEAD(trailers);
 
 	struct option options[] = {
 		OPT_BOOL(0, "in-place", &in_place, N_("edit files in place")),
 		OPT_BOOL(0, "trim-empty", &trim_empty, N_("trim empty trailers")),
-		OPT_STRING_LIST(0, "trailer", &trailers, N_("trailer"),
-				N_("trailer(s) to add")),
+
+		OPT_CALLBACK(0, "trailer", &trailers, N_("trailer"),
+				N_("trailer(s) to add"), option_parse_trailer),
 		OPT_END()
 	};
 
@@ -43,7 +76,7 @@ int cmd_interpret_trailers(int argc, const char **argv, const char *prefix)
 		process_trailers(NULL, in_place, trim_empty, &trailers);
 	}
 
-	string_list_clear(&trailers, 0);
+	new_trailers_clear(&trailers);
 
 	return 0;
 }

trailer.c

@@ -669,9 +669,8 @@ static void add_arg_item(struct list_head *arg_head, char *tok, char *val,
 }
 
 static void process_command_line_args(struct list_head *arg_head,
-				      struct string_list *trailers)
+				      struct list_head *new_trailer_head)
 {
-	struct string_list_item *tr;
 	struct arg_item *item;
 	struct strbuf tok = STRBUF_INIT;
 	struct strbuf val = STRBUF_INIT;
@@ -695,17 +694,20 @@ static void process_command_line_args(struct list_head *arg_head,
 	}
 
 	/* Add an arg item for each trailer on the command line */
-	for_each_string_list_item(tr, trailers) {
-		int separator_pos = find_separator(tr->string, cl_separators);
+	list_for_each(pos, new_trailer_head) {
+		struct new_trailer_item *tr =
+			list_entry(pos, struct new_trailer_item, list);
+		int separator_pos = find_separator(tr->text, cl_separators);
+
 		if (separator_pos == 0) {
 			struct strbuf sb = STRBUF_INIT;
-			strbuf_addstr(&sb, tr->string);
+			strbuf_addstr(&sb, tr->text);
 			strbuf_trim(&sb);
 			error(_("empty trailer token in trailer '%.*s'"),
 			      (int) sb.len, sb.buf);
 			strbuf_release(&sb);
 		} else {
-			parse_trailer(&tok, &val, &conf, tr->string,
+			parse_trailer(&tok, &val, &conf, tr->text,
 				      separator_pos);
 			add_arg_item(arg_head,
 				     strbuf_detach(&tok, NULL),
@@ -969,7 +971,8 @@ static FILE *create_in_place_tempfile(const char *file)
 	return outfile;
 }
 
-void process_trailers(const char *file, int in_place, int trim_empty, struct string_list *trailers)
+void process_trailers(const char *file, int in_place, int trim_empty,
+		      struct list_head *new_trailer_head)
 {
 	LIST_HEAD(head);
 	LIST_HEAD(arg_head);
@@ -987,7 +990,7 @@ void process_trailers(const char *file, int in_place, int trim_empty, struct str
 	/* Print the lines before the trailers */
 	trailer_end = process_input_file(outfile, sb.buf, &head);
 
-	process_command_line_args(&arg_head, trailers);
+	process_command_line_args(&arg_head, new_trailer_head);
 
 	process_trailers_lists(&head, &arg_head);
 

trailer.h

@@ -1,6 +1,8 @@
 #ifndef TRAILER_H
 #define TRAILER_H
 
+#include "list.h"
+
 enum trailer_where {
 	WHERE_END,
 	WHERE_AFTER,
@@ -44,8 +46,18 @@ struct trailer_info {
 	size_t trailer_nr;
 };
 
+/*
+ * A list that represents newly-added trailers, such as those provided
+ * with the --trailer command line option of git-interpret-trailers.
+ */
+struct new_trailer_item {
+	struct list_head list;
+
+	const char *text;
+};
+
 void process_trailers(const char *file, int in_place, int trim_empty,
-		      struct string_list *trailers);
+		      struct list_head *new_trailer_head);
 
 void trailer_info_get(struct trailer_info *info, const char *str);