Decouple the signalling into a struct IOMuxSignaller

include/ucore/iomux_waker.h

@@ -10,6 +10,11 @@ extern "C" {
 struct IOMuxWaker;
 typedef void (*uc_waker_cb)(struct IOMuxWaker *wk);
 
+/** Usef for signalling an IOMux */
+struct IOMuxSignaller {
+    int fd;
+};
+
 /** These are primitives to wake up an IOMux.
  * An IOMux event loop can be woken up from e.g. an unix signal handler
  * or another thread. The IOMuxWaker itself is not thread safe, it's members
@@ -22,11 +27,11 @@ typedef void (*uc_waker_cb)(struct IOMuxWaker *wk);
  */
 struct IOMuxWaker {
     //private fields
-    int fds[2];
     struct IOMuxFD read_fd;
     uc_waker_cb wake_cb;
 
     //public fields
+    struct IOMuxSignaller signaller;
     struct IOMux *mux;
     void *cookie;
 };
@@ -47,6 +52,8 @@ int uc_iomux_waker_init(struct IOMux *mux, struct IOMuxWaker *wk, uc_waker_cb cb
  *  Care must be taken so the IOMuxWaker is destroyed
  *  without race conditions with a thread that wants to _signal the
  *  waker.
+ *  The embedded IOMuxSignaller of the IOMuxWaker can be used
+ *  by someone else in the uc_iomux_waker_signal() function
  * 
  * @param wk
  * @return 0 on success, errno on failure (Things are seriously
@@ -63,7 +70,7 @@ int uc_iomux_waker_destroy(struct IOMuxWaker *wk);
  * @return 0 on success, errno on failure (Things are seriously
  *         wrong if this fails)
  */
-int uc_iomux_waker_signal(struct IOMuxWaker *wk);
+int uc_iomux_waker_signal(struct IOMuxSignaller *signaller);
 
 #ifdef __cplusplus
 }

src/iomux_waker.c

@@ -6,7 +6,7 @@
 
 static void uc_waker_pipe_cb(struct IOMux *mux, struct IOMuxFD *fd, unsigned int event)
 {
-    char buf[259];
+    char buf[256];
     struct IOMuxWaker *wk;
     int rc;
 
@@ -32,13 +32,13 @@ static void uc_waker_pipe_cb(struct IOMux *mux, struct IOMuxFD *fd, unsigned int
     wk->wake_cb(wk);
 }
 
-static int uc_install_wake_handler(struct IOMuxWaker *wk)
+static int uc_install_wake_handler(struct IOMuxWaker *wk, int rfd)
 {
     struct IOMuxFD *fd = &wk->read_fd;
 
     memset(fd, 0, sizeof *fd);
 
-    fd->fd = wk->fds[0];
+    fd->fd = rfd;
     fd->callback = uc_waker_pipe_cb;
     fd->cookie_ptr = wk;
     fd->what = MUX_EV_READ;
@@ -49,28 +49,30 @@ static int uc_install_wake_handler(struct IOMuxWaker *wk)
 int uc_iomux_waker_init(struct IOMux *mux, struct IOMuxWaker *wk, uc_waker_cb cb)
 {
     int rc;
+    int pfds[2];
 
     assert(wk != NULL);
     assert(cb != NULL);
 
     memset(wk, 0 , sizeof *wk);
 
-    rc = pipe(wk->fds);
+    rc = pipe(pfds);
     if (rc != 0) {
         return errno;
     }
     
     wk->mux = mux;
     wk->wake_cb = cb;
+    wk->signaller.fd = pfds[1];
 
-    if (uc_install_wake_handler(wk) == 0) {
+    if (uc_install_wake_handler(wk, pfds[0]) == 0) {
         return 0;
     } else {
         int saved_errno;
 
         saved_errno = errno;
-        close(wk->fds[0]);
-        close(wk->fds[1]);
+        close(pfds[0]);
+        close(pfds[1]);
 
         return saved_errno;
     }
@@ -82,30 +84,30 @@ int uc_iomux_waker_destroy(struct IOMuxWaker *wk)
 
     assert(wk != NULL);
 
-    close(wk->fds[0]);
-    close(wk->fds[1]);
-
     rc = iomux_unregister_fd(wk->mux, &wk->read_fd);
     assert(rc == 0);
 
+    close(wk->signaller.fd);
+    close(wk->read_fd.fd);
+
     wk->mux = NULL;
     wk->wake_cb = NULL;
-    wk->fds[0] = wk->fds[1] = -1;
+    wk->signaller.fd = -1;
 
     assert(rc == 0);
 
     return rc;
 }
 
-int uc_iomux_waker_signal(struct IOMuxWaker *wk)
+int uc_iomux_waker_signal(struct IOMuxSignaller *signaller)
 {
     int rc;
     static const char x = 'X';
 
-    assert(wk != NULL);
+    assert(signaller != NULL);
 
     do {
-        rc = write(wk->fds[1], &x, 1);
+        rc = write(signaller->fd, &x, 1);
     } while (rc == -1 && errno == EINTR);
 
     //if we would have blocked, the pipe is already