sl0ppty: watch what the config was built from, not just what it was called

An included theme that does not reload when you save it is half a
feature, and the half that is missing is the one the file headers in
contrib/themes have been promising all along ("a running session re-reads
it the moment you save"). That was true while a theme was something you
pasted; the moment it became something you include, the watch was on the
wrong file.

So a config now remembers every file it was read from -- itself and
everything it included -- and the watcher watches all of them. Recorded
before each parse rather than after, because a file that is not there yet
is exactly the file worth watching: writing it is the next thing that
will happen, and that is the same reason the watch is on directories
rather than on files. Deduplicated, so a cycle does not fill the list
with two names twice.

The set is rebuilt after every successful load, because it is a property
of the config that just loaded: an include can be added, pointed
somewhere else, or taken out, and the watch has to follow. One inotify
watch per directory, deduplicated by the descriptor inotify hands back
for a directory it is already watching; names are matched against the
whole set rather than against the directory whose watch fired, which
means two directories holding a file of the same name reload for each
other's save. That costs a debounced re-read of a config that has not
changed, and is not worth a second data structure to avoid.

Only the main config's directory is created if missing. An include's is
not: a mistyped path should not leave a directory behind.

tests/test_reload.py drives a real session for this one -- the watcher is
the thing under test and the headless driver has none. It writes a config
that includes a theme, checks the theme applied at startup, then edits
*only the included file* and waits for the session to change colour.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/app.c b/src/app.c
index 48ec42d..9c33601 100644
--- a/src/app.c
+++ b/src/app.c
@@ -57,6 +57,15 @@ bool app_reload_config(char *err, size_t errcap) {
   return true;
 }
 
+/* Which files the config in force was read from. The server watches every one
+ * of them, so a theme that can be included is a theme that reloads when you
+ * save it — asked of the app rather than read from a config the front ends do
+ * not own. */
+size_t app_config_files(const char **out, size_t max) {
+  ensure_config();
+  return config_files(&CFG, out, max);
+}
+
 #define WEIGHT_UNIT 1000
 #define WEIGHT_MIN 150  /* a pane can be squeezed, not squeezed out */
 #define WEIGHT_STEP 120 /* one keyboard nudge */