kqueue: modernize Struct usage for Ruby 2.5.0dev

Ruby 2.4 deprecates old macros, and it looks like 2.5.0 will
remove RSTRUCT_PTR.

2 files changed, 73 insertions, 43 deletions

diff --git a/ext/sleepy_penguin/extconf.rb b/ext/sleepy_penguin/extconf.rb
index e07f5d2..f11f9c1 100644
--- a/ext/sleepy_penguin/extconf.rb
+++ b/ext/sleepy_penguin/extconf.rb
@@ -34,4 +34,5 @@ have_func('rb_thread_fd_close')
 have_func('rb_update_max_fd')
 have_func('rb_fd_fix_cloexec')
 have_func('rb_io_get_io')
+have_func('rb_struct_size')
 create_makefile('sleepy_penguin_ext')
diff --git a/ext/sleepy_penguin/kqueue.c b/ext/sleepy_penguin/kqueue.c
index d7e8d8e..e6c133f 100644
--- a/ext/sleepy_penguin/kqueue.c
+++ b/ext/sleepy_penguin/kqueue.c
@@ -18,6 +18,9 @@
 #ifndef RARRAY_LENINT
 #  define RARRAY_LENINT(ary) (int)RARRAY_LEN(ary)
 #endif
+#ifndef RARRAY_CONST_PTR
+#  define RARRAY_CONST_PTR(ary) RARRAY_PTR(ary)
+#endif
 #ifndef NUM2SHORT
 #  define NUM2SHORT(n) (short)NUM2INT(n)
 #endif
@@ -233,35 +236,82 @@ static VALUE do_kevent(struct kq_per_thread *kpt)
         return kevent_result(kpt, (int)nevents);
 }
 
-static void event_set(struct kevent *event, VALUE *chg)
+#if defined(HAVE_RB_STRUCT_SIZE) && defined(RSTRUCT_GET)
+static void ev_set_struct(struct kevent *ev, VALUE event)
 {
-        uintptr_t ident = (uintptr_t)NUM2ULONG(chg[0]);
-        short filter = NUM2SHORT(chg[1]);
-        unsigned short flags = NUM2USHORT(chg[2]);
-        unsigned fflags = (unsigned)NUM2UINT(chg[3]);
-        intptr_t data = (intptr_t)NUM2LONG(chg[4]);
-        void *udata = (void *)chg[5];
-
-        EV_SET(event, ident, filter, flags, fflags, data, udata);
+        if (rb_struct_size(event) == INT2NUM(6)) {
+                uintptr_t ident = (uintptr_t)NUM2ULONG(RSTRUCT_GET(event, 0));
+                short filter = NUM2SHORT(RSTRUCT_GET(event, 1));
+                unsigned short flags = NUM2USHORT(RSTRUCT_GET(event, 2));
+                unsigned fflags = (unsigned)NUM2UINT(RSTRUCT_GET(event, 3));
+                intptr_t data = (intptr_t)NUM2LONG(RSTRUCT_GET(event, 4));
+                void *udata = (void *)RSTRUCT_GET(event, 5);
+
+                EV_SET(ev, ident, filter, flags, fflags, data, udata);
+        } else {
+                rb_raise(rb_eTypeError, "unsupported struct in changelist");
+        }
+}
+#elif RBX_STRUCT == 0 && defined(RSTRUCT_LEN) && defined(RSTRUCT_PTR)
+/* legacy MRI */
+static void ev_set_struct(struct kevent *ev, VALUE event)
+{
+        long len = RSTRUCT_LEN(*event);
+        if (len == 6) {
+                const VALUE *ptr = RSTRUCT_PTR(*event);
+                uintptr_t ident = (uintptr_t)NUM2ULONG(ptr[0]);
+                short filter = NUM2SHORT(ptr[1]);
+                unsigned short flags = NUM2USHORT(ptr[2]);
+                unsigned fflags = (unsigned)NUM2UINT(ptr[3]);
+                intptr_t data = (intptr_t)NUM2LONG(ptr[4]);
+                void *udata = (void *)ptr[5];
+
+                EV_SET(event, ident, filter, flags, fflags, data, udata);
+        } else {
+                rb_raise(rb_eTypeError, "unsupported struct in changelist");
+        }
+}
+#else
+static void ev_set_struct(struct kevent *ev, VALUE event)
+{
+        rb_raise(rb_eTypeError, "unsupported struct in changelist");
+}
+#endif
+
+static void ev_set_ary(struct kevent *ev, VALUE event)
+{
+        long len = RARRAY_LEN(event);
+        const VALUE *ptr = RARRAY_CONST_PTR(event);
+
+        if (len == 6) {
+                uintptr_t ident = (uintptr_t)NUM2ULONG(ptr[0]);
+                short filter = NUM2SHORT(ptr[1]);
+                unsigned short flags = NUM2USHORT(ptr[2]);
+                unsigned fflags = (unsigned)NUM2UINT(ptr[3]);
+                intptr_t data = (intptr_t)NUM2LONG(ptr[4]);
+                void *udata = (void *)ptr[5];
+
+                EV_SET(ev, ident, filter, flags, fflags, data, udata);
+                return;
+        }
+        rb_raise(rb_eTypeError,
+                "changelist must be an array of 6-element arrays or structs");
 }
 
 /* sets ptr and len */
-static void unpack_event(VALUE **ptr, VALUE *len, VALUE *event)
+static void unpack_event(struct kevent *ev, VALUE event)
 {
-        switch (TYPE(*event)) {
+        switch (TYPE(event)) {
         case T_STRUCT:
                 if (RBX_STRUCT) {
-                        *event = rb_funcall(*event, rb_intern("to_a"), 0, 0);
+                        event = rb_funcall(event, rb_intern("to_a"), 0, 0);
                         /* fall-through to T_ARRAY */
                 } else {
-                        *len = RSTRUCT_LEN(*event);
-                        *ptr = RSTRUCT_PTR(*event);
+                        ev_set_struct(ev, event);
                         return;
                 }
         case T_ARRAY:
-                *len = RARRAY_LEN(*event);
-                *ptr = RARRAY_PTR(*event);
-                return;
+                ev_set_ary(ev, event);
         default:
                 rb_raise(rb_eTypeError, "unsupported type in changelist");
         }
@@ -269,24 +319,11 @@ static void unpack_event(VALUE **ptr, VALUE *len, VALUE *event)
 
 static void ary2eventlist(struct kevent *events, VALUE changelist)
 {
-        VALUE *chg = RARRAY_PTR(changelist);
+        const VALUE *chg = RARRAY_CONST_PTR(changelist);
         long i = RARRAY_LEN(changelist);
-        VALUE event;
 
-        for (; --i >= 0; chg++) {
-                VALUE clen;
-                VALUE *cptr;
-
-                event = *chg;
-                unpack_event(&cptr, &clen, &event);
-                if (clen != 6)
-                        goto out_list;
-                event_set(events++, cptr);
-        }
-        return;
-out_list:
-        rb_raise(rb_eTypeError,
-                "changelist must be an array of 6-element arrays or structs");
+        for (; --i >= 0; chg++)
+                unpack_event(events++, *chg);
 }
 
 /*
@@ -294,20 +331,12 @@ out_list:
  */
 static void changelist_prepare(struct kevent *events, VALUE changelist)
 {
-        VALUE *cptr;
-        VALUE clen;
-        VALUE event;
-
         switch (TYPE(changelist)) {
         case T_ARRAY:
                 ary2eventlist(events, changelist);
                 return;
-        case T_STRUCT:
-                event = changelist;
-                unpack_event(&cptr, &clen, &event);
-                if (clen != 6)
-                        rb_raise(rb_eTypeError, "event is not a Kevent struct");
-                event_set(events, cptr);
+        case T_STRUCT: /* single event */
+                unpack_event(events, changelist);
                 return;
         default:
                 rb_bug("changelist_prepare not type filtered by sp_kevent");