libbinder: build ParcelFileDescriptor on Trusty

Adds ParcelFileDescriptor.cpp to the Trusty build
which in turn compiles some extra related code from
Parcel.cpp. This code uses fcntl(...O_DUPFD_CLOEXEC...)
to duplicate file descriptors which is not available
on Trusty (or other OSes), so we abstract the relevant
calls to that function in a wrapper in OS.cpp.

Bug: 224644083
Test: m
Test: build on Trusty
Change-Id: I2e0ee517e7c7b55458a6ee6db977985aab4d7c58

1 files changed, 10 insertions, 0 deletions

diff --git a/libs/binder/OS.cpp b/libs/binder/OS.cpp
index 6eb72726f5..cc4a03ba67 100644
--- a/libs/binder/OS.cpp
+++ b/libs/binder/OS.cpp
@@ -48,4 +48,14 @@ status_t getRandomBytes(uint8_t* data, size_t size) {
     return OK;
 }
 
+status_t dupFileDescriptor(int oldFd, int* newFd) {
+    int ret = fcntl(oldFd, F_DUPFD_CLOEXEC, 0);
+    if (ret < 0) {
+        return -errno;
+    }
+
+    *newFd = ret;
+    return OK;
+}
+
 } // namespace android