1 files changed, 26 insertions, 11 deletions

diff --git a/source/Host/common/MainLoop.cpp b/source/Host/common/MainLoop.cpp
index d0e0d00a3151..6cbb5a842562 100644
--- a/source/Host/common/MainLoop.cpp
+++ b/source/Host/common/MainLoop.cpp
@@ -28,6 +28,8 @@
 #include <sys/event.h>
 #elif defined(LLVM_ON_WIN32)
 #include <winsock2.h>
+#elif defined(__ANDROID__)
+#include <sys/syscall.h>
 #else
 #include <poll.h>
 #endif
@@ -38,10 +40,6 @@
 #define POLL poll
 #endif
 
-#ifdef __ANDROID__
-#define FORCE_PSELECT
-#endif
-
 #if SIGNAL_POLLING_UNSUPPORTED
 #ifdef LLVM_ON_WIN32
 typedef int sigset_t;
@@ -86,7 +84,7 @@ private:
   int num_events = -1;
 
 #else
-#ifdef FORCE_PSELECT
+#ifdef __ANDROID__
   fd_set read_fd_set;
 #else
   std::vector<struct pollfd> read_fds;
@@ -134,7 +132,7 @@ void MainLoop::RunImpl::ProcessEvents() {
 }
 #else
 MainLoop::RunImpl::RunImpl(MainLoop &loop) : loop(loop) {
-#ifndef FORCE_PSELECT
+#ifndef __ANDROID__
   read_fds.reserve(loop.m_read_fds.size());
 #endif
 }
@@ -154,8 +152,14 @@ sigset_t MainLoop::RunImpl::get_sigmask() {
 #endif
 }
 
-#ifdef FORCE_PSELECT
+#ifdef __ANDROID__
 Status MainLoop::RunImpl::Poll() {
+  // ppoll(2) is not supported on older all android versions. Also, older
+  // versions android (API <= 19) implemented pselect in a non-atomic way, as a
+  // combination of pthread_sigmask and select. This is not sufficient for us,
+  // as we rely on the atomicity to correctly implement signal polling, so we
+  // call the underlying syscall ourselves.
+
   FD_ZERO(&read_fd_set);
   int nfds = 0;
   for (const auto &fd : loop.m_read_fds) {
@@ -163,8 +167,19 @@ Status MainLoop::RunImpl::Poll() {
     nfds = std::max(nfds, fd.first + 1);
   }
 
-  sigset_t sigmask = get_sigmask();
-  if (pselect(nfds, &read_fd_set, nullptr, nullptr, nullptr, &sigmask) == -1 &&
+  union {
+    sigset_t set;
+    uint64_t pad;
+  } kernel_sigset;
+  memset(&kernel_sigset, 0, sizeof(kernel_sigset));
+  kernel_sigset.set = get_sigmask();
+
+  struct {
+    void *sigset_ptr;
+    size_t sigset_len;
+  } extra_data = {&kernel_sigset, sizeof(kernel_sigset)};
+  if (syscall(__NR_pselect6, nfds, &read_fd_set, nullptr, nullptr, nullptr,
+              &extra_data) == -1 &&
       errno != EINTR)
     return Status(errno, eErrorTypePOSIX);
 
@@ -193,7 +208,7 @@ Status MainLoop::RunImpl::Poll() {
 #endif
 
 void MainLoop::RunImpl::ProcessEvents() {
-#ifdef FORCE_PSELECT
+#ifdef __ANDROID__
   // Collect first all readable file descriptors into a separate vector and then
   // iterate over it to invoke callbacks. Iterating directly over
   // loop.m_read_fds is not possible because the callbacks can modify the
@@ -206,7 +221,7 @@ void MainLoop::RunImpl::ProcessEvents() {
   for (const auto &handle : fds) {
 #else
   for (const auto &fd : read_fds) {
-    if ((fd.revents & POLLIN) == 0)
+    if ((fd.revents & (POLLIN | POLLHUP)) == 0)
       continue;
     IOObject::WaitableHandle handle = fd.fd;
 #endif