A new configuration key 'database.exclude' is used to determine
which directories user wants not to be scanned for new mails.

---

Notes (from 2011-09-13):

1) Currently the comments for newly created configuration file are not
updated, so for not this is 'undocumented feature'. Should there be an
empty configuration line as a placeholder ... ?

2) Whenever some already existing directory is added to the exclude list
and the parent directory timestamp has not changed, notmuch new will not
notice the directory has gone (as it still is there), user needs to 'touch'
the parent directory before next 'notmuch new' no make notmuch notice.

2012-01-26: could notmuch track mtime of the configuration file and if
that changes, ignore mail directory timestamps ?

3) count_files() function is not touched. The functionality there has fallen
behind of add_files_recursive (maildir+tmp check and following symlinks).
The question there should it be updated, or attempted to merge with
add_files (as the comment says). count_files() is only called at the beginning
when database is not yet initialised.
---
 notmuch-client.h |    3 +++
 notmuch-config.c |   13 +++++++++++++
 notmuch-new.c    |   22 ++++++++++++++++++++--
 3 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/notmuch-client.h b/notmuch-client.h
index e0eb594..78460fc 100644
--- a/notmuch-client.h
+++ b/notmuch-client.h
@@ -219,6 +219,9 @@ void
 notmuch_config_set_database_path (notmuch_config_t *config,
 				  const char *database_path);
 
+const char **
+notmuch_config_get_database_exclude (notmuch_config_t *config,
+				     size_t *length);
 const char *
 notmuch_config_get_user_name (notmuch_config_t *config);
 
diff --git a/notmuch-config.c b/notmuch-config.c
index a124e34..e236114 100644
--- a/notmuch-config.c
+++ b/notmuch-config.c
@@ -99,6 +99,8 @@ struct _notmuch_config {
     GKeyFile *key_file;
 
     char *database_path;
+    const char **database_exclude;
+    size_t database_exclude_length;
     char *user_name;
     char *user_primary_email;
     const char **user_other_email;
@@ -258,6 +260,8 @@ notmuch_config_open (void *ctx,
     config->key_file = g_key_file_new ();
 
     config->database_path = NULL;
+    config->database_exclude = NULL;
+    config->database_exclude_length = 0;
     config->user_name = NULL;
     config->user_primary_email = NULL;
     config->user_other_email = NULL;
@@ -537,6 +541,15 @@ notmuch_config_set_database_path (notmuch_config_t *config,
     config->database_path = NULL;
 }
 
+const char **
+notmuch_config_get_database_exclude (notmuch_config_t *config,
+				     size_t *length)
+{
+    return _config_get_list (config, "database", "exclude",
+			     &(config->database_exclude),
+			     &(config->database_exclude_length), length);
+}
+
 const char *
 notmuch_config_get_user_name (notmuch_config_t *config)
 {
diff --git a/notmuch-new.c b/notmuch-new.c
index a569a54..d607f5b 100644
--- a/notmuch-new.c
+++ b/notmuch-new.c
@@ -39,6 +39,8 @@ typedef struct {
     int verbose;
     const char **new_tags;
     size_t new_tags_length;
+    const char **database_exclude;
+    size_t database_exclude_length;
 
     int total_files;
     int processed_files;
@@ -300,6 +302,8 @@ add_files_recursive (notmuch_database_t *notmuch,
     is_maildir = _entries_resemble_maildir (fs_entries, num_fs_entries);
 
     for (i = 0; i < num_fs_entries; i++) {
+	size_t j;
+
 	if (interrupted)
 	    break;
 
@@ -323,8 +327,6 @@ add_files_recursive (notmuch_database_t *notmuch,
 	 * Also ignore the .notmuch directory and any "tmp" directory
 	 * that appears within a maildir.
 	 */
-	/* XXX: Eventually we'll want more sophistication to let the
-	 * user specify files to be ignored. */
 	if (strcmp (entry->d_name, ".") == 0 ||
 	    strcmp (entry->d_name, "..") == 0 ||
 	    (is_maildir && strcmp (entry->d_name, "tmp") == 0) ||
@@ -332,6 +334,12 @@ add_files_recursive (notmuch_database_t *notmuch,
 	{
 	    continue;
 	}
+	/* Ignore user-specified directories */
+	for (j = 0; j < state->database_exclude_length; j++)
+	    if (strcmp(entry->d_name, state->database_exclude[j]) == 0)
+		break;
+	if (j < state->database_exclude_length)
+	    continue;
 
 	next = talloc_asprintf (notmuch, "%s/%s", path, entry->d_name);
 	status = add_files_recursive (notmuch, next, state);
@@ -364,11 +372,20 @@ add_files_recursive (notmuch_database_t *notmuch,
     /* Pass 2: Scan for new files, removed files, and removed directories. */
     for (i = 0; i < num_fs_entries; i++)
     {
+	size_t j;
+
 	if (interrupted)
 	    break;
 
         entry = fs_entries[i];
 
+	/* Ignore user-specified files & directories */
+	for (j = 0; j < state->database_exclude_length; j++)
+	    if (strcmp(entry->d_name, state->database_exclude[j]) == 0)
+		break;
+	if (j < state->database_exclude_length)
+	    continue;
+
 	/* Check if we've walked past any names in db_files or
 	 * db_subdirs. If so, these have been deleted. */
 	while (notmuch_filenames_valid (db_files) &&
@@ -837,6 +854,7 @@ notmuch_new_command (void *ctx, int argc, char *argv[])
 	return 1;
 
     add_files_state.new_tags = notmuch_config_get_new_tags (config, &add_files_state.new_tags_length);
+    add_files_state.database_exclude = notmuch_config_get_database_exclude (config, &add_files_state.database_exclude_length);
     add_files_state.synchronize_flags = notmuch_config_get_maildir_synchronize_flags (config);
     db_path = notmuch_config_get_database_path (config);
 
-- 
1.7.6.4