linux: fix epoll_pwait() sigmask size calculation

Revisit the fix from commit b705b53.  The problem with using sigset_t
and _NSIG is that the size of sigset_t and the value of _NSIG depend
on what headers libuv picks up first, <signal.h> or <asm/signal.h>.
With the former, sizeof(sigset_t) = 128; with the latter, it's 8.

Simply sidestep the issue by calculating the signal mask as a 64 bits
integer, without using sigset_t or _NSIG.

PR-URL: https://github.com/libuv/libuv/pull/83
Reviewed-By: Saúl Ibarra Corretgé <saghul@gmail.com>

Makefile.am

@@ -159,6 +159,7 @@ test_run_tests_SOURCES = test/blackhole-server.c \
                          test/test-loop-close.c \
                          test/test-loop-stop.c \
                          test/test-loop-time.c \
+                         test/test-loop-configure.c \
                          test/test-multiple-listen.c \
                          test/test-mutexes.c \
                          test/test-osx-select.c \

src/unix/linux-core.c

@@ -33,7 +33,6 @@
 #include <sys/prctl.h>
 #include <sys/sysinfo.h>
 #include <unistd.h>
-#include <signal.h>
 #include <fcntl.h>
 #include <time.h>
 
@@ -142,8 +141,7 @@ void uv__io_poll(uv_loop_t* loop, int timeout) {
   struct uv__epoll_event e;
   QUEUE* q;
   uv__io_t* w;
-  sigset_t* pset;
-  sigset_t set;
+  uint64_t sigmask;
   uint64_t base;
   uint64_t diff;
   int nevents;
@@ -194,24 +192,21 @@ void uv__io_poll(uv_loop_t* loop, int timeout) {
     w->events = w->pevents;
   }
 
-  pset = NULL;
-  if (loop->flags & UV_LOOP_BLOCK_SIGPROF) {
-    pset = &set;
-    sigemptyset(pset);
-    sigaddset(pset, SIGPROF);
-  }
+  sigmask = 0;
+  if (loop->flags & UV_LOOP_BLOCK_SIGPROF)
+    sigmask |= 1 << (SIGPROF - 1);
 
   assert(timeout >= -1);
   base = loop->time;
   count = 48; /* Benchmarks suggest this gives the best throughput. */
 
   for (;;) {
-    if (no_epoll_wait || pset != NULL) {
+    if (no_epoll_wait || sigmask) {
       nfds = uv__epoll_pwait(loop->backend_fd,
                              events,
                              ARRAY_SIZE(events),
                              timeout,
-                             pset);
+                             sigmask);
     } else {
       nfds = uv__epoll_wait(loop->backend_fd,
                             events,

src/unix/linux-syscalls.c

@@ -321,15 +321,15 @@ int uv__epoll_pwait(int epfd,
                     struct uv__epoll_event* events,
                     int nevents,
                     int timeout,
-                    const sigset_t* sigmask) {
+                    uint64_t sigmask) {
 #if defined(__NR_epoll_pwait)
   return syscall(__NR_epoll_pwait,
                  epfd,
                  events,
                  nevents,
                  timeout,
-                 sigmask,
-                 _NSIG / 8);
+                 &sigmask,
+                 sizeof(sigmask));
 #else
   return errno = ENOSYS, -1;
 #endif

src/unix/linux-syscalls.h

@@ -131,7 +131,7 @@ int uv__epoll_pwait(int epfd,
                     struct uv__epoll_event* events,
                     int nevents,
                     int timeout,
-                    const sigset_t* sigmask);
+                    uint64_t sigmask);
 int uv__eventfd2(unsigned int count, int flags);
 int uv__inotify_init(void);
 int uv__inotify_init1(int flags);

test/test-list.h

@@ -29,6 +29,7 @@ TEST_DECLARE   (loop_close)
 TEST_DECLARE   (loop_stop)
 TEST_DECLARE   (loop_update_time)
 TEST_DECLARE   (loop_backend_timeout)
+TEST_DECLARE   (loop_configure)
 TEST_DECLARE   (default_loop_close)
 TEST_DECLARE   (barrier_1)
 TEST_DECLARE   (barrier_2)
@@ -313,6 +314,7 @@ TASK_LIST_START
   TEST_ENTRY  (loop_stop)
   TEST_ENTRY  (loop_update_time)
   TEST_ENTRY  (loop_backend_timeout)
+  TEST_ENTRY  (loop_configure)
   TEST_ENTRY  (default_loop_close)
   TEST_ENTRY  (barrier_1)
   TEST_ENTRY  (barrier_2)

test/test-loop-configure.c

@@ -0,0 +1,38 @@
+/* Copyright (c) 2014, Ben Noordhuis <info@bnoordhuis.nl>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "uv.h"
+#include "task.h"
+
+static void timer_cb(uv_timer_t* handle) {
+  uv_close((uv_handle_t*) handle, NULL);
+}
+
+
+TEST_IMPL(loop_configure) {
+  uv_timer_t timer_handle;
+  uv_loop_t loop;
+  ASSERT(0 == uv_loop_init(&loop));
+#ifdef _WIN32
+  ASSERT(UV_ENOSYS == uv_loop_configure(&loop, UV_LOOP_BLOCK_SIGNAL, 0));
+#else
+  ASSERT(0 == uv_loop_configure(&loop, UV_LOOP_BLOCK_SIGNAL, SIGPROF));
+#endif
+  ASSERT(0 == uv_timer_init(&loop, &timer_handle));
+  ASSERT(0 == uv_timer_start(&timer_handle, timer_cb, 10, 0));
+  ASSERT(0 == uv_run(&loop, UV_RUN_DEFAULT));
+  ASSERT(0 == uv_loop_close(&loop));
+  return 0;
+}

uv.gyp

@@ -315,6 +315,7 @@
         'test/test-loop-close.c',
         'test/test-loop-stop.c',
         'test/test-loop-time.c',
+        'test/test-loop-configure.c',
         'test/test-walk-handles.c',
         'test/test-watcher-cross-stop.c',
         'test/test-multiple-listen.c',