Provide full implementation of epoll_pwait

This patch provides full implementation of epoll_pwait
and exposes it as a public function which is needed
by Node.JS 10.

The implementation is modeled after pselect/select.

Signed-off-by: Waldemar Kozaczuk <[email protected]>
Message-Id: <[email protected]>

Author: wkozaczuk

core/epoll.cc

@@ -12,6 +12,7 @@
 #include <memory>
 #include <stdio.h>
 #include <errno.h>
+#include <signal.h>
 
 #include <osv/file.h>
 #include <osv/poll.h>
@@ -338,6 +339,16 @@ int epoll_wait(int epfd, struct epoll_event *events, int maxevents, int timeout_
     return epo->wait(events, maxevents, timeout_ms);
 }
 
+int epoll_pwait(int epfd, struct epoll_event *events, int maxevents, int timeout_ms,
+            const sigset_t *sigmask)
+{
+    sigset_t origmask;
+    sigprocmask(SIG_SETMASK, sigmask, &origmask);
+    auto ret = epoll_wait(epfd, events, maxevents, timeout_ms);
+    sigprocmask(SIG_SETMASK, &origmask, NULL);
+    return ret;
+}
+
 void epoll_file_closed(epoll_ptr ptr)
 {
     ptr.epoll->del(ptr.key);

linux.cc

@@ -353,18 +353,6 @@ static int pselect6(int nfds, fd_set *readfds, fd_set *writefds,
     return pselect(nfds, readfds, writefds, exceptfds, timeout_ts, NULL);
 }
 
-static int epoll_pwait(int epfd, struct epoll_event *events, int maxevents,
-                       int timeout_ms, void *sig)
-{
-    if(sig) {
-        WARN_ONCE("epoll_pwait(): unimplemented with not-null sigmask\n");
-        errno = ENOSYS;
-        return -1;
-    }
-
-    return epoll_wait(epfd, events, maxevents, timeout_ms);
-}
-
 long syscall(long number, ...)
 {
     // Save FPU state and restore it at the end of this function
@@ -424,7 +412,7 @@ long syscall(long number, ...)
     SYSCALL4(pread64, int, void *, size_t, off_t);
     SYSCALL2(ftruncate, int, off_t);
     SYSCALL1(fsync, int);
-    SYSCALL5(epoll_pwait, int, struct epoll_event *, int, int, void*);
+    SYSCALL5(epoll_pwait, int, struct epoll_event *, int, int, const sigset_t*);
     SYSCALL3(getrandom, char *, size_t, unsigned int);
     SYSCALL2(nanosleep, const struct timespec*, struct timespec *);
     SYSCALL4(fstatat, int, const char *, struct stat *, int);