lib: Add new, public notmuch_message_get_filenames

This augments the existing notmuch_message_get_filename by allowing
the caller access to all filenames in the case of multiple files for a
single message.

To support this, we split the iterator (notmuch_filenames_t) away from
the list storage (notmuch_filename_list_t) where previously these were
a single object (notmuch_filenames_t). Then, whenever the user asks
for a file or filename, the message object lazily creates a complete
notmuch_filename_list_t and then:

	For notmuch_message_get_filename, returns the first filename
	in the list.

	For notmuch_message_get_filenames, creates and returns a new
	iterator for the filename list.

1 files changed, 25 insertions, 5 deletions

diff --git a/lib/notmuch-private.h b/lib/notmuch-private.h
index 6a9d5ddd..37ccbb31 100644
--- a/lib/notmuch-private.h
+++ b/lib/notmuch-private.h
@@ -450,15 +450,35 @@ _notmuch_tags_prepare_iterator (notmuch_tags_t *tags);
 
 /* filenames.c */
 
-notmuch_filenames_t *
-_notmuch_filenames_create (const void *ctx);
+typedef struct _notmuch_filename_node {
+    char *filename;
+    struct _notmuch_filename_node *next;
+} notmuch_filename_node_t;
+
+typedef struct _notmuch_filename_list {
+    notmuch_filename_node_t *head;
+    notmuch_filename_node_t **tail;
+} notmuch_filename_list_t;
 
+notmuch_filename_list_t *
+_notmuch_filename_list_create (const void *ctx);
+
+/* Add 'filename' to 'list'.
+ *
+ * The list will create its own talloced copy of 'filename'.
+ */
 void
-_notmuch_filenames_add_filename (notmuch_filenames_t *filenames,
-				 const char *filename);
+_notmuch_filename_list_add_filename (notmuch_filename_list_t *list,
+				     const char *filename);
 
 void
-_notmuch_filenames_move_to_first (notmuch_filenames_t *filenames);
+_notmuch_filename_list_destroy (notmuch_filename_list_t *list);
+
+/* The notmuch_filenames_t is an iterator object for a
+ * notmuch_filename_list_t */
+notmuch_filenames_t *
+_notmuch_filenames_create (const void *ctx,
+			   notmuch_filename_list_t *list);
 
 #pragma GCC visibility pop