API change -- Remove first ctx argument and add event mask to callback

There really does not exist a good reason for us sending a `uev_ctx_t *`
pointer as the first argument to event callbacks.  If the callback needs
to reference the context, it can find the ctx pointer in the `uev_t *w`.

This patch removes the first argument from all callbacks and also fixes
a slight bug in that the event loop never returned the actual event that
triggered the callback!

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

README.md

@@ -61,15 +61,16 @@ details, see [this article][4] at [lwn.net](http://lwn.net).
 API
 ---
 
-Here is the interface to [libuEv].  It handles three different types of
-events: I/O (files, sockets, message queues, etc.), timers, and signals.
+The C interface to [libuEv] is very simple.  It handles three different
+types of events: I/O (files, sockets, message queues, etc.), timers, and
+signals.  With a slight caveat on signals
 
 ```C
     /* Callback example, arg is passed from watcher's *_init()
      * w->fd holds the file descriptor, events is set by libuEv
      * to indicate if any of UEV_READ and/or UEV_WRITE is ready.
      */
-    void callback       (uev_ctx_t *ctx, uev_t *w, void *arg, int events);
+    void callback       (uev_t *w, void *arg, int events);
 
     /* Event loop functions, notice use of flags! */
     int uev_init        (uev_ctx_t *ctx);
@@ -111,10 +112,10 @@ file descriptor to monitor, and an event callback function, by calling
 the event type's `_init()` function with the `uev_ctx_t` context.
 
 ```C
-    void cleanup_exit(uev_ctx_t *ctx, uev_t *w, void *arg, int events)
+    void cleanup_exit(uev_t *w, void *arg, int events)
     {
         /* Graceful exit, with optional cleanup ... */
-        uev_exit(ctx);
+        uev_exit(w->ctx);
     }
     
     uev_t termw;
@@ -186,7 +187,7 @@ struct js_event {
 	uint8_t  number;	/* axis/button number */
 } e;
 
-static void joystick_cb(uev_ctx_t *ctx, uev_t *w, void *arg, int events)
+static void joystick_cb(uev_t *w, void *arg, int events)
 {
 	read (w->fd, &e, sizeof(e));
 

examples/joystick.c

@@ -40,7 +40,7 @@ struct js_event {
 	uint8_t  number;	/* axis/button number */
 } e;
 
-static void joystick_cb(uev_ctx_t *UNUSED(ctx), uev_t *w, void *UNUSED(arg), int UNUSED(events))
+static void joystick_cb(uev_t *w, void *UNUSED(arg), int UNUSED(events))
 {
 	if (read (w->fd, &e, sizeof(e)) < 0)
 		errx(errno, "Failed reading joystick event");

examples/signal.c

@@ -69,13 +69,13 @@ static int callback(arg_t *arg, int event, void *foo)
         return 42;
 }
 
-static void sigsegv_cb(uev_ctx_t *UNUSED(ctx), uev_t *UNUSED(w), void *UNUSED(arg), int UNUSED(events))
+static void sigsegv_cb(uev_t *UNUSED(w), void *UNUSED(arg), int UNUSED(events))
 {
 	warnx("PID %d caused segfault.", getpid());
 	exit(-1);
 }
 
-static void sigchld_cb(uev_ctx_t *UNUSED(ctx), uev_t *UNUSED(w), void *UNUSED(arg), int UNUSED(events))
+static void sigchld_cb(uev_t *UNUSED(w), void *UNUSED(arg), int UNUSED(events))
 {
         pid_t pid = waitpid(-1, NULL, WNOHANG);
 
@@ -83,7 +83,7 @@ static void sigchld_cb(uev_ctx_t *UNUSED(ctx), uev_t *UNUSED(w), void *UNUSED(ar
                 warnx("PID %d exited, bye.", pid);
 }
 
-static void work_cb(uev_ctx_t *UNUSED(ctx), uev_t *UNUSED(w), void *arg, int UNUSED(events))
+static void work_cb(uev_t *UNUSED(w), void *arg, int UNUSED(events))
 {
 	int    status = 0;
         pid_t  pid;
@@ -102,15 +102,17 @@ static void work_cb(uev_ctx_t *UNUSED(ctx), uev_t *UNUSED(w), void *arg, int UNU
 	if (WIFEXITED(status))
 		printf("Child exited normally => %d\n", WEXITSTATUS(status));
 	else if (WCOREDUMP(status))
-		printf("Child crashed!\n");
+		printf("Child crashed! %s\n", DO_SEGFAULT
+		       ? "As expected, everything is OK."
+		       : "This should not happen!");
 	else
 		printf("Child did not exit normally!\n");
 }
 
-static void exit_cb(uev_ctx_t *ctx, uev_t *UNUSED(w), void *UNUSED(arg), int UNUSED(events))
+static void exit_cb(uev_t *w, void *UNUSED(arg), int UNUSED(events))
 {
         printf("Process deadline reached, exiting!\n");
-	uev_exit(ctx);
+	uev_exit(w->ctx);
 }
 
 int main(void)
@@ -120,6 +122,8 @@ int main(void)
 
 	/* Initialize libuEv */
 	uev_init(&ctx);
+
+	/* Setup callbacks */
 	uev_signal_init(&ctx, &sigsegv_watcher, sigsegv_cb, NULL, SIGSEGV);
 	uev_signal_init(&ctx, &sigchld_watcher, sigchld_cb, NULL, SIGCHLD);
 	uev_timer_init(&ctx, &timeout_watcher, work_cb, &arg, 400, 0);

examples/test.c

@@ -40,33 +40,33 @@ static int in, out;
 static int period = 0;
 static uev_t *watchdog;
 
-static void lifetime_cb(uev_ctx_t *ctx, uev_t UNUSED(*w), void *arg, int UNUSED(events))
+static void lifetime_cb(uev_t *w, void *arg, int UNUSED(events))
 {
 	fprintf(stderr, "\nLifetime exceeded, program completed successfully! (arg:%p)\n", arg);
-	uev_exit(ctx);
+	uev_exit(w->ctx);
 }
 
 /* The pipe watchdog, if it triggers we haven't received data in time. */
-static void timeout_cb(uev_ctx_t *ctx, uev_t *UNUSED(w), void *arg, int UNUSED(events))
+static void timeout_cb(uev_t *w, void *arg, int UNUSED(events))
 {
 	watchdog = NULL;
 	fprintf(stderr, "\nTimeout exceeded %p\n", arg);
 
 	// uev_timer_stop(w); <-- No need to stop timers with period=0 :)
-	uev_exit(ctx);
+	uev_exit(w->ctx);
 }
 
-static void periodic_task(uev_ctx_t UNUSED(*ctx), uev_t UNUSED(*w), void UNUSED(*arg), int UNUSED(events))
+static void periodic_task(uev_t UNUSED(*w), void UNUSED(*arg), int UNUSED(events))
 {
 	fprintf(stderr, "|");
 }
 
-static void signal_cb(uev_ctx_t *UNUSED(ctx), uev_t *w, void *UNUSED(arg), int UNUSED(events))
+static void signal_cb(uev_t *w, void *UNUSED(arg), int UNUSED(events))
 {
 	fprintf(stderr, w->signo == SIGINT ? "^Cv" : "^\v");
 }
 
-static void pipe_read_cb(uev_ctx_t *UNUSED(ctx), uev_t UNUSED(*w), void UNUSED(*arg), int UNUSED(events))
+static void pipe_read_cb(uev_t UNUSED(*w), void UNUSED(*arg), int UNUSED(events))
 {
 	int cnt;
 	char msg[50];
@@ -80,7 +80,7 @@ static void pipe_read_cb(uev_ctx_t *UNUSED(ctx), uev_t UNUSED(*w), void UNUSED(*
 	fprintf(stderr, "%.*s.%d ", cnt, msg, cnt);
 }
 
-static void pipe_write_cb(uev_ctx_t UNUSED(*ctx), uev_t *w, void *arg, int UNUSED(events))
+static void pipe_write_cb(uev_t *w, void *arg, int UNUSED(events))
 {
 	my_t *my  = arg;
 	char *msg = "TESTING";

uev.c

@@ -297,7 +297,7 @@ int uev_run(uev_ctx_t *ctx, int flags)
 			}
 
 			if (w->cb)
-				w->cb((struct uev *)ctx, w, w->arg);
+				w->cb(w, w->arg, events[i].events & UEV_EVENT_MASK);
 
 			if (UEV_TIMER_TYPE == w->type) {
 				if (!w->timeout)

uev.h

@@ -38,6 +38,7 @@
 #define UEV_NONE        0
 #define UEV_READ        EPOLLIN
 #define UEV_WRITE       EPOLLOUT
+#define UEV_EVENT_MASK  (UEV_READ | UEV_WRITE)
 
 /* Run flags */
 #define UEV_ONCE        1
@@ -73,7 +74,7 @@ typedef struct uev {
 	int             events;
 
 	/* Watcher callback with optional argument */
-	void          (*cb)(struct uev *, struct uev *, void *);
+	void          (*cb)(struct uev *, void *, int);
 	void           *arg;
 
 	/* Timer watchers, time in milliseconds */
@@ -85,7 +86,7 @@ typedef struct uev {
 } uev_t;
 
 /* Generic callback for watchers */
-typedef void (uev_cb_t)(uev_ctx_t *ctx, uev_t *w, void *arg, int events);
+typedef void (uev_cb_t)(uev_t *w, void *arg, int events);
 
 /* Private methods, do not use directly! */
 int uev_watcher_init   (uev_ctx_t *ctx, uev_t *w, uev_type_t type, uev_cb_t *cb, void *arg, int fd, int events);