[Xen-devel] [PATCH 21/28] libxl: ocaml: add wrappers for poll

[Rob Hoes <rob.hoes@xxxxxxxxxx>]

We need this in order to wrap the event API of libxl.

Signed-off-by: Rob Hoes <rob.hoes@xxxxxxxxxx>
---
 tools/ocaml/libs/xl/Makefile     |    2 +-
 tools/ocaml/libs/xl/poll_stubs.c |  128 ++++++++++++++++++++++++++++++++++++++
 tools/ocaml/libs/xl/poll_stubs.h |    6 ++
 3 files changed, 135 insertions(+), 1 deletion(-)
 create mode 100644 tools/ocaml/libs/xl/poll_stubs.c
 create mode 100644 tools/ocaml/libs/xl/poll_stubs.h

diff --git a/tools/ocaml/libs/xl/Makefile b/tools/ocaml/libs/xl/Makefile
index 5a410d2..beca795 100644
--- a/tools/ocaml/libs/xl/Makefile
+++ b/tools/ocaml/libs/xl/Makefile
@@ -15,7 +15,7 @@ OCAMLINCLUDE += -I ../xentoollog
 LIBS_xenlight = $(LDLIBS_libxenlight)
 
 xenlight_OBJS = $(OBJS)
-xenlight_C_OBJS = xenlight_stubs
+xenlight_C_OBJS = xenlight_stubs poll_stubs
 
 OCAML_LIBRARY = xenlight
 
diff --git a/tools/ocaml/libs/xl/poll_stubs.c b/tools/ocaml/libs/xl/poll_stubs.c
new file mode 100644
index 0000000..0cf54b9
--- /dev/null
+++ b/tools/ocaml/libs/xl/poll_stubs.c
@@ -0,0 +1,128 @@
+#include <poll.h>
+#include <caml/alloc.h>
+#include <caml/memory.h>
+#include <caml/signals.h>
+#include <caml/fail.h>
+
+static int list_len(value v)
+{
+       int len = 0;
+       while ( v != Val_emptylist ) {
+               len++;
+               v = Field(v, 1);
+       }
+       return len;
+}
+
+short Poll_val(value event)
+{
+       CAMLparam1(event);
+       short res = -1;
+
+       switch (Int_val(event)) {
+               case 0: res = POLLIN; break;
+               case 1: res = POLLPRI; break;
+               case 2: res = POLLOUT; break;
+               case 3: res = POLLERR; break;
+               case 4: res = POLLHUP; break;
+               case 5: res = POLLNVAL; break;
+       }
+
+       CAMLreturn(res);
+}
+
+short Poll_events_val(value event_list)
+{
+       CAMLparam1(event_list);
+       short events = 0;
+
+       while (event_list != Val_emptylist) {
+               events |= Poll_val(Field(event_list, 0));
+               event_list = Field(event_list, 1);
+       }
+
+       CAMLreturn(events);
+}
+
+value Val_poll(short event)
+{
+       CAMLparam0();
+       CAMLlocal1(res);
+
+       switch (event) {
+               case POLLIN: res = Val_int(0); break;
+               case POLLPRI: res = Val_int(1); break;
+               case POLLOUT: res = Val_int(2); break;
+               case POLLERR: res = Val_int(3); break;
+               case POLLHUP: res = Val_int(4); break;
+               case POLLNVAL: res = Val_int(5); break;
+       }
+
+       CAMLreturn(res);
+}
+
+value add_event(value event_list, short event)
+{
+       CAMLparam1(event_list);
+       CAMLlocal1(new_list);
+
+       new_list = caml_alloc(2, 0);
+       Store_field(new_list, 0, Val_poll(event));
+       Store_field(new_list, 1, event_list);
+
+       CAMLreturn(new_list);
+}
+
+value Val_poll_events(short events)
+{
+       CAMLparam0();
+       CAMLlocal1(event_list);
+
+       event_list = Val_emptylist;
+       if (events & POLLIN)
+               event_list = add_event(event_list, POLLIN);
+       if (events & POLLPRI)
+               event_list = add_event(event_list, POLLPRI);
+       if (events & POLLOUT)
+               event_list = add_event(event_list, POLLOUT);
+       if (events & POLLERR)
+               event_list = add_event(event_list, POLLERR);
+       if (events & POLLHUP)
+               event_list = add_event(event_list, POLLHUP);
+       if (events & POLLNVAL)
+               event_list = add_event(event_list, POLLNVAL);
+
+       CAMLreturn(event_list);
+}
+
+value stub_poll(value fds)
+{
+       CAMLparam1(fds);
+       CAMLlocal2(fd, tmp);
+       int rc, i;
+       const int c_nfds = list_len(fds);
+       struct pollfd c_fds[c_nfds];
+
+       for (i = 0; fds != Val_emptylist; i++) {
+               fd = Field(fds, 0);
+               c_fds[i].fd = Int_val(Field(fd, 0));
+               c_fds[i].events = Poll_events_val(Field(fd, 1));
+               fds = Field(fds, 1);
+       }
+
+       caml_enter_blocking_section();
+       rc = poll(c_fds, c_nfds, -1);
+       caml_leave_blocking_section();
+
+       if (rc > 0) {
+               for (i = c_nfds - 1; i >= 0; i--) {
+                       tmp = caml_alloc(2, 0);
+                       Store_field(tmp, 0, Val_poll_events(c_fds[i].revents));
+                       Store_field(tmp, 1, fds);
+                       fds = tmp;
+               }
+       }
+
+       CAMLreturn(fds);
+}
+
diff --git a/tools/ocaml/libs/xl/poll_stubs.h b/tools/ocaml/libs/xl/poll_stubs.h
new file mode 100644
index 0000000..0b2332d
--- /dev/null
+++ b/tools/ocaml/libs/xl/poll_stubs.h
@@ -0,0 +1,6 @@
+#include <caml/alloc.h>
+
+short Poll_events_val(value event_list);
+value Val_poll_events(short events);
+value stub_poll(value fds);
+
-- 
1.7.10.4


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