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.

5 files changed, 155 insertions, 85 deletions

diff --git a/lib/directory.cc b/lib/directory.cc
index 16492c0d..946be4f4 100644
--- a/lib/directory.cc
+++ b/lib/directory.cc
@@ -33,12 +33,12 @@ _create_filenames_for_terms_with_prefix (void *ctx,
 					 notmuch_database_t *notmuch,
 					 const char *prefix)
 {
-    notmuch_filenames_t *filenames;
+    notmuch_filename_list_t *filename_list;
     Xapian::TermIterator i, end;
     int prefix_len = strlen (prefix);
 
-    filenames = _notmuch_filenames_create (ctx);
-    if (unlikely (filenames == NULL))
+    filename_list = _notmuch_filename_list_create (ctx);
+    if (unlikely (filename_list == NULL))
 	return NULL;
 
     end = notmuch->xapian_db->allterms_end (prefix);
@@ -47,13 +47,11 @@ _create_filenames_for_terms_with_prefix (void *ctx,
     {
 	std::string term = *i;
 
-	_notmuch_filenames_add_filename (filenames, term.c_str () +
-					 prefix_len);
+	_notmuch_filename_list_add_filename (filename_list, term.c_str () +
+					     prefix_len);
     }
 
-    _notmuch_filenames_move_to_first (filenames);
-
-    return filenames;
+    return _notmuch_filenames_create (ctx, filename_list);
 }
 
 struct _notmuch_directory {
diff --git a/lib/filenames.c b/lib/filenames.c
index cff9e830..50e14354 100644
--- a/lib/filenames.c
+++ b/lib/filenames.c
@@ -20,55 +20,67 @@
 
 #include "notmuch-private.h"
 
-typedef struct _notmuch_filenames_node {
-    char *filename;
-    struct _notmuch_filenames_node *next;
-} notmuch_filenames_node_t;
-
 struct _notmuch_filenames {
-    notmuch_filenames_node_t *head;
-    notmuch_filenames_node_t **tail;
-    notmuch_filenames_node_t *iterator;
+    notmuch_filename_node_t *iterator;
 };
 
-/* Create a new notmuch_filenames_t object, with 'ctx' as its
+/* Create a new notmuch_filename_list_t object, with 'ctx' as its
  * talloc owner.
  *
  * This function can return NULL in case of out-of-memory.
  */
-notmuch_filenames_t *
-_notmuch_filenames_create (const void *ctx)
+notmuch_filename_list_t *
+_notmuch_filename_list_create (const void *ctx)
 {
-    notmuch_filenames_t *filenames;
+    notmuch_filename_list_t *list;
 
-    filenames = talloc (ctx, notmuch_filenames_t);
-    if (unlikely (filenames == NULL))
+    list = talloc (ctx, notmuch_filename_list_t);
+    if (unlikely (list == NULL))
 	return NULL;
 
-    filenames->head = NULL;
-    filenames->tail = &filenames->head;
-
-    filenames->iterator = NULL;
+    list->head = NULL;
+    list->tail = &list->head;
 
-    return filenames;
+    return list;
 }
 
-/* Append a single 'node' to the end of 'filenames'.
- */
 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)
 {
     /* Create and initialize new node. */
-    notmuch_filenames_node_t *node = talloc (filenames,
-					     notmuch_filenames_node_t);
+    notmuch_filename_node_t *node = talloc (list,
+					    notmuch_filename_node_t);
 
     node->filename = talloc_strdup (node, filename);
     node->next = NULL;
 
     /* Append the node to the list. */
-    *(filenames->tail) = node;
-    filenames->tail = &node->next;
+    *(list->tail) = node;
+    list->tail = &node->next;
+}
+
+void
+_notmuch_filename_list_destroy (notmuch_filename_list_t *list)
+{
+    talloc_free (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)
+{
+    notmuch_filenames_t *filenames;
+
+    filenames = talloc (ctx, notmuch_filenames_t);
+    if (unlikely (filenames == NULL))
+	return NULL;
+
+    filenames->iterator = list->head;
+
+    return filenames;
 }
 
 notmuch_bool_t
@@ -90,12 +102,6 @@ notmuch_filenames_get (notmuch_filenames_t *filenames)
 }
 
 void
-_notmuch_filenames_move_to_first (notmuch_filenames_t *filenames)
-{
-    filenames->iterator = filenames->head;
-}
-
-void
 notmuch_filenames_move_to_next (notmuch_filenames_t *filenames)
 {
     if (filenames->iterator == NULL)
diff --git a/lib/message.cc b/lib/message.cc
index bc9cd259..83e05191 100644
--- a/lib/message.cc
+++ b/lib/message.cc
@@ -32,7 +32,7 @@ struct _notmuch_message {
     char *message_id;
     char *thread_id;
     char *in_reply_to;
-    char *filename;
+    notmuch_filename_list_t *filename_list;
     char *author;
     notmuch_message_file_t *message_file;
     notmuch_message_list_t *replies;
@@ -101,7 +101,7 @@ _notmuch_message_create_for_document (const void *talloc_owner,
     message->message_id = NULL;
     message->thread_id = NULL;
     message->in_reply_to = NULL;
-    message->filename = NULL;
+    message->filename_list = NULL;
     message->message_file = NULL;
     message->author = NULL;
 
@@ -432,9 +432,9 @@ _notmuch_message_add_filename (notmuch_message_t *message,
     void *local = talloc_new (message);
     char *direntry;
 
-    if (message->filename) {
-	talloc_free (message->filename);
-	message->filename = NULL;
+    if (message->filename_list) {
+	_notmuch_filename_list_destroy (message->filename_list);
+	message->filename_list = NULL;
     }
 
     if (filename == NULL)
@@ -465,28 +465,23 @@ _notmuch_message_clear_data (notmuch_message_t *message)
     message->doc.set_data ("");
 }
 
-const char *
-notmuch_message_get_filename (notmuch_message_t *message)
+static void
+_notmuch_message_ensure_filename_list (notmuch_message_t *message)
 {
     const char *prefix = _find_prefix ("file-direntry");
     int prefix_len = strlen (prefix);
     Xapian::TermIterator i;
-    char *colon, *direntry = NULL;
-    const char *db_path, *directory, *basename;
-    unsigned int directory_id;
-    void *local = talloc_new (message);
 
-    if (message->filename)
-	return message->filename;
+    if (message->filename_list)
+	return;
+
+    message->filename_list = _notmuch_filename_list_create (message);
 
     i = message->doc.termlist_begin ();
     i.skip_to (prefix);
 
-    if (i != message->doc.termlist_end ())
-	direntry = talloc_strdup (local, (*i).c_str ());
-
     if (i == message->doc.termlist_end () ||
-	strncmp (direntry, prefix, prefix_len))
+	strncmp ((*i).c_str (), prefix, prefix_len))
     {
 	/* A message document created by an old version of notmuch
 	 * (prior to rename support) will have the filename in the
@@ -501,39 +496,77 @@ notmuch_message_get_filename (notmuch_message_t *message)
 	if (data == NULL)
 	    INTERNAL_ERROR ("message with no filename");
 
-	message->filename = talloc_strdup (message, data);
+	_notmuch_filename_list_add_filename (message->filename_list, data);
 
-	return message->filename;
+	return;
     }
 
-    direntry += prefix_len;
+    for (; i != message->doc.termlist_end (); i++) {
+	void *local = talloc_new (message);
+	const char *db_path, *directory, *basename, *filename;
+	char *colon, *direntry = NULL;
+	unsigned int directory_id;
 
-    directory_id = strtol (direntry, &colon, 10);
+	/* Terminate loop at first term without desired prefix. */
+	if (strncmp ((*i).c_str (), prefix, prefix_len))
+	    break;
 
-    if (colon == NULL || *colon != ':')
-	INTERNAL_ERROR ("malformed direntry");
+	direntry = talloc_strdup (local, (*i).c_str ());
 
-    basename = colon + 1;
+	direntry += prefix_len;
 
-    *colon = '\0';
+	directory_id = strtol (direntry, &colon, 10);
 
-    db_path = notmuch_database_get_path (message->notmuch);
+	if (colon == NULL || *colon != ':')
+	    INTERNAL_ERROR ("malformed direntry");
 
-    directory = _notmuch_database_get_directory_path (local,
-						      message->notmuch,
-						      directory_id);
+	basename = colon + 1;
 
-    if (strlen (directory))
-	message->filename = talloc_asprintf (message, "%s/%s/%s",
-					     db_path, directory, basename);
-    else
-	message->filename = talloc_asprintf (message, "%s/%s",
-					     db_path, basename);
-    talloc_free ((void *) directory);
+	*colon = '\0';
 
-    talloc_free (local);
+	db_path = notmuch_database_get_path (message->notmuch);
+
+	directory = _notmuch_database_get_directory_path (local,
+							  message->notmuch,
+							  directory_id);
+
+	if (strlen (directory))
+	    filename = talloc_asprintf (message, "%s/%s/%s",
+					db_path, directory, basename);
+	else
+	    filename = talloc_asprintf (message, "%s/%s",
+					db_path, basename);
+
+	_notmuch_filename_list_add_filename (message->filename_list,
+					     filename);
+
+	talloc_free (local);
+    }
+}
+
+const char *
+notmuch_message_get_filename (notmuch_message_t *message)
+{
+    _notmuch_message_ensure_filename_list (message);
+
+    if (message->filename_list == NULL)
+	return NULL;
+
+    if (message->filename_list->head == NULL ||
+	message->filename_list->head->filename == NULL)
+    {
+	INTERNAL_ERROR ("message with no filename");
+    }
+
+    return message->filename_list->head->filename;
+}
+
+notmuch_filenames_t *
+notmuch_message_get_filenames (notmuch_message_t *message)
+{
+    _notmuch_message_ensure_filename_list (message);
 
-    return message->filename;
+    return _notmuch_filenames_create (message, message->filename_list);
 }
 
 notmuch_bool_t
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
 
diff --git a/lib/notmuch.h b/lib/notmuch.h
index b15f1249..413b5709 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -772,11 +772,24 @@ notmuch_message_get_replies (notmuch_message_t *message);
  * Note: If this message corresponds to multiple files in the mail
  * store, (that is, multiple files contain identical message IDs),
  * this function will arbitrarily return a single one of those
- * filenames.
+ * filenames. See notmuch_message_get_filenames for returning the
+ * complete list of filenames.
  */
 const char *
 notmuch_message_get_filename (notmuch_message_t *message);
 
+/* Get all filenames for the email corresponding to 'message'.
+ *
+ * Returns a notmuch_filenames_t iterator listing all the filenames
+ * associated with 'message'. These files may not have identical
+ * content, but each will have the identical Message-ID.
+ *
+ * Each filename in the iterator is an absolute filename, (the initial
+ * component will match notmuch_database_get_path() ).
+ */
+notmuch_filenames_t *
+notmuch_message_get_filenames (notmuch_message_t *message);
+
 /* Message flags */
 typedef enum _notmuch_message_flag {
     NOTMUCH_MESSAGE_FLAG_MATCH