# HG changeset patch
# User jbe
# Date 1496587246 -7200
# Node ID 48ffca6443d99b774f9f27573926fbb0ff572020
# Parent  37aaca00941cd944ee4615def4bc41835eab2cc1
Added moonbridge_io.signalsocket(...) and moonbridge_io.getpid() functions; poll returns true on signal interruption (instead of nil)

diff -r 37aaca00941c -r 48ffca6443d9 moonbridge_io.c
--- a/moonbridge_io.c	Sun Jun 04 13:49:12 2017 +0200
+++ b/moonbridge_io.c	Sun Jun 04 16:40:46 2017 +0200
@@ -55,11 +55,16 @@
     moonbr_io_return_prepared_errmsg(); \
   } while (0)
 
+static int moonbr_io_signalfds[2];
+#define moonbr_io_signalfd_read moonbr_io_signalfds[0]
+#define moonbr_io_signalfd_write moonbr_io_signalfds[1]
+
 #define MOONBR_IO_HANDLE_MT_REGKEY "moonbridge_io_handle"
 #define MOONBR_IO_HANDLE_PUBLIC_MT_REGKEY "moonbridge_io_handle_public"
 #define MOONBR_IO_LISTENER_MT_REGKEY "moonbridge_io_listener"
 #define MOONBR_IO_CHILD_MT_REGKEY "moonbridge_io_child"
 #define MOONBR_IO_CHILD_PT_REGKEY "moonbridge_io_child_pt"
+#define MOONBR_IO_SIGNALSOCKET_REGKEY "moonbridge_io_signalsocket"
 
 #ifdef MOONBR_IO_USE_TLS
 
@@ -1607,6 +1612,44 @@
 
 moonbr_io_yield_wrapper(moonbr_io_wait_yield, moonbr_io_wait_call);
 
+static void moonbr_io_signalhandler(int sig) {
+  int errno2 = errno;
+  char buf[1] = {sig};
+  write(moonbr_io_signalfd_write, buf, 1);
+  errno = errno2;
+}
+
+static int moonbr_io_signalsocket(lua_State *L) {
+  int i, argc, sig;
+  if (moonbr_io_signalfd_read < 0) {
+    if (socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, moonbr_io_signalfds)) {
+      luaL_error(L, "Could not create socket pair for signal queueing");
+    }
+  }
+  argc = lua_gettop(L);
+  for (i=1; i<=argc; i++) {
+    sig = luaL_checkinteger(L, i);
+    errno = 0;
+    signal(sig, moonbr_io_signalhandler);
+    if (errno) luaL_error(L, "Could not install signal handler (invalid signal number?)");
+  }
+  lua_settop(L, 0);
+  lua_getfield(L, LUA_REGISTRYINDEX, MOONBR_IO_SIGNALSOCKET_REGKEY);
+  if (lua_isnil(L, -1)) {
+    int fd = dup(moonbr_io_signalfd_read);  /* TODO: determine how mooonbr_io_pushhandle acts in case of error */
+    if (fd < 0) luaL_error(L, "Error in dup() system call");
+    moonbr_io_pushhandle(L, fd);
+    lua_pushvalue(L, -1);
+    lua_setfield(L, LUA_REGISTRYINDEX, MOONBR_IO_SIGNALSOCKET_REGKEY);
+  }
+  return 1;
+}
+
+static int moonbr_io_getpid(lua_State *L) {
+  lua_pushinteger(L, getpid());
+  return 1;
+}
+
 #ifdef MOONBR_IO_USE_TLS
 
 #define moonbr_io_poll_tls() \
@@ -1724,9 +1767,8 @@
   }
   if (status == -1) {
     if (errno == EINTR) {
-      lua_pushnil(L);
-      lua_pushliteral(L, "Signal received while polling file descriptors");
-      return 2;
+      lua_pushboolean(L, 1);
+      return 1;
     } else {
       moonbr_io_prepare_errmsg();
       return luaL_error(L, "Unexpected error during \"select\" system call: %s", errmsg);
@@ -1957,6 +1999,8 @@
   {"locallisten", moonbr_io_locallisten},
   {"tcplisten", moonbr_io_tcplisten},
   {"exec", moonbr_io_exec},
+  {"signalsocket", moonbr_io_signalsocket},
+  {"getpid", moonbr_io_getpid},
   {"poll", moonbr_io_poll},
   {"timeref", moonbr_io_timeref},
 #ifdef MOONBR_IO_USE_TLS
@@ -1977,6 +2021,8 @@
 int luaopen_moonbridge_io(lua_State *L) {
 
   signal(SIGPIPE, SIG_IGN);  /* generate I/O errors instead of signal 13 */
+  moonbr_io_signalfd_read = -1;
+  moonbr_io_signalfd_write = -1;
 
   lua_newtable(L);  // module
 
diff -r 37aaca00941c -r 48ffca6443d9 reference.txt
--- a/reference.txt	Sun Jun 04 13:49:12 2017 +0200
+++ b/reference.txt	Sun Jun 04 16:40:46 2017 +0200
@@ -386,9 +386,19 @@
 nil, it is treated as being empty.
 
 Returns true when at least one file descriptor or handle is ready for reading
-or writing respectively. Returns false (plus a notice as second return value)
-in case of timeout. Returns nil (plus a notice as second return value) if a
-signal was received during waiting.
+or writing respectively, or if a signal has been received during waiting.
+Returns false (plus a notice as second return value) in case of timeout.
+
+
+### moonbridge_io.signalsocket(signal, ...)
+
+This function installs a signal handler for the signals with the numbers passed
+as arguments and returns a socket which receives a byte for each received
+signal.
+
+Subsequent calls of this function can extend the set of signals but will always
+return the same socket. If the socket is closed, it is no longer possible to
+detect signals until the process is terminated.
 
 
 ### moonbridge_io.tcpconnect(hostname, port)