sl0ppty: saving the config reloads it

The reload existed but you had to ask for it, which is the wrong shape for the
thing it is mostly used for: changing a colour and looking at the result. The
server now watches the config and re-reads it when it changes.

It watches the config's *directory* and filters by name, rather than watching
the file. Editors overwhelmingly save by writing a temporary file and renaming
it over the target, which swaps the inode out from under a watch on the file
itself — it fires once and then never again, which is worse than not watching
at all because it looks like it works. The test writes in place *and* renames
over, because only the second one would have caught that.

Reloading goes through the same call the command does, so it keeps the
fail-open behaviour: a file that does not parse leaves the running config alone
and says so in a toast. That matters more here than it did for the command,
because a file caught halfway through a save is a normal thing for a watcher to
see rather than an operator mistake — and there is a test for it, and for the
recovery once the file is valid again.

Turning it off is a command-line flag rather than a setting, because a setting
would be circular: you would have to reload the config to stop it reloading the
config. --no-reload only stops the *watching*; asking explicitly still works,
which is the distinction the flag name is trying to make.

The test is a live one because inotify lives in the server's poll loop and the
headless driver has no server. It polls for the colour it expects rather than
sleeping a guess, so the passing cases cost milliseconds; the two cases that
assert nothing happened are the only ones that wait, because proving a negative
has to.

1 files changed, 5 insertions, 3 deletions

diff --git a/src/main.c b/src/main.c
index 94621c1..f898746 100644
--- a/src/main.c
+++ b/src/main.c
@@ -36,7 +36,7 @@ static void term_size(uint16_t *cols, uint16_t *rows) {
 }
 
 static void usage(void) {
-  fputs("usage: sl0ppty [-s NAME] [--layout FILE] [ls | cmd LINE | -- CMD...]\n",
+  fputs("usage: sl0ppty [-s NAME] [--layout FILE] [--no-reload]\n                [ls | cmd LINE | -- CMD...]\n",
         stderr);
 }
 
@@ -47,6 +47,7 @@ int main(int argc, char **argv) {
   const char *name = "main";
   const char *cmd_line = NULL;
   const char *layout = NULL;
+  bool watch = true;
   bool list = false;
   const char *cmd_argv[64];
   int cmd_n = 0;
@@ -58,6 +59,7 @@ int main(int argc, char **argv) {
     else if (strcmp(a, "--server") == 0) server = true;
     else if (strcmp(a, "-s") == 0 && i + 1 < argc) name = argv[++i];
     else if (strcmp(a, "--layout") == 0 && i + 1 < argc) layout = argv[++i];
+    else if (strcmp(a, "--no-reload") == 0) watch = false;
     else if (strcmp(a, "ls") == 0) list = true;
     else if (strcmp(a, "cmd") == 0 && i + 1 < argc) cmd_line = argv[++i];
     else if (strcmp(a, "--cols") == 0 && i + 1 < argc) cols = (uint16_t)atoi(argv[++i]);
@@ -107,11 +109,11 @@ int main(int argc, char **argv) {
   if (headless) return run_headless(cmd_argv, cols, rows, idle_ms, script, layout);
 
   if (isatty(STDOUT_FILENO)) term_size(&cols, &rows);
-  if (server) return server_run(name, cmd_argv, cols, rows, layout);
+  if (server) return server_run(name, cmd_argv, cols, rows, layout, watch);
 
   /* attach, creating the session if nobody is home */
   int fd = server_connect(name);
-  if (fd < 0) fd = server_spawn(name, cmd_argv, cols, rows, layout);
+  if (fd < 0) fd = server_spawn(name, cmd_argv, cols, rows, layout, watch);
   if (fd < 0) {
     fprintf(stderr, "sl0ppty: cannot start session %s\n", name);
     return 1;