libbinder: FdTrigger encapsulate poll

So we can use this in other places.

Bug: 185167543
Test: binderRpcTest
Change-Id: Ie8012b1c8dcea035bc8d0f14af2bd2ddbb197d89

1 files changed, 21 insertions, 0 deletions

diff --git a/libs/binder/RpcSession.cpp b/libs/binder/RpcSession.cpp
index 4efa6bb1a9..ea82f36400 100644
--- a/libs/binder/RpcSession.cpp
+++ b/libs/binder/RpcSession.cpp
@@ -19,10 +19,12 @@
 #include <binder/RpcSession.h>
 
 #include <inttypes.h>
+#include <poll.h>
 #include <unistd.h>
 
 #include <string_view>
 
+#include <android-base/macros.h>
 #include <binder/Parcel.h>
 #include <binder/RpcServer.h>
 #include <binder/Stability.h>
@@ -123,6 +125,25 @@ void RpcSession::FdTrigger::trigger() {
     mWrite.reset();
 }
 
+bool RpcSession::FdTrigger::triggerablePollRead(base::borrowed_fd fd) {
+    while (true) {
+        pollfd pfd[]{{.fd = fd.get(), .events = POLLIN, .revents = 0},
+                     {.fd = mRead.get(), .events = POLLHUP, .revents = 0}};
+        int ret = TEMP_FAILURE_RETRY(poll(pfd, arraysize(pfd), -1));
+        if (ret < 0) {
+            ALOGE("Could not poll: %s", strerror(errno));
+            continue;
+        }
+        if (ret == 0) {
+            continue;
+        }
+        if (pfd[1].revents & POLLHUP) {
+            return false;
+        }
+        return true;
+    }
+}
+
 status_t RpcSession::readId() {
     {
         std::lock_guard<std::mutex> _l(mMutex);