Add support for file descriptors and vectors thereof

We use ScopedFd from nativehelper to manage the lifetime.

Test: Passes AIDL unit and integration tests. Full build completes and
      runs.
Bug: 25242023
Signed-off-by: Casey Dahlin <sadmac@google.com>

Change-Id: I22c87ed1cb3bd4bf667b372ea4a2e9fcd4dd986a
diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index 03348da..9496821 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -980,12 +980,20 @@
         return -errno;
     }
     status_t err = writeFileDescriptor(dupFd, true /*takeOwnership*/);
-    if (err) {
+    if (err != OK) {
         close(dupFd);
     }
     return err;
 }
 
+status_t Parcel::writeUniqueFileDescriptor(const ScopedFd& fd) {
+    return writeDupFileDescriptor(fd.get());
+}
+
+status_t Parcel::writeUniqueFileDescriptorVector(const std::vector<ScopedFd>& val) {
+    return writeTypedVector(val, &Parcel::writeUniqueFileDescriptor);
+}
+
 status_t Parcel::writeBlob(size_t len, bool mutableCopy, WritableBlob* outBlob)
 {
     if (len > INT32_MAX) {
@@ -1601,16 +1609,36 @@
 int Parcel::readFileDescriptor() const
 {
     const flat_binder_object* flat = readObject(true);
-    if (flat) {
-        switch (flat->type) {
-            case BINDER_TYPE_FD:
-                //ALOGI("Returning file descriptor %ld from parcel %p", flat->handle, this);
-                return flat->handle;
-        }
+
+    if (flat && flat->type == BINDER_TYPE_FD) {
+        return flat->handle;
     }
+
     return BAD_TYPE;
 }
 
+status_t Parcel::readUniqueFileDescriptor(ScopedFd* val) const
+{
+    int got = readFileDescriptor();
+
+    if (got == BAD_TYPE) {
+        return BAD_TYPE;
+    }
+
+    val->reset(dup(got));
+
+    if (val->get() < 0) {
+        return BAD_VALUE;
+    }
+
+    return OK;
+}
+
+
+status_t Parcel::readUniqueFileDescriptorVector(std::vector<ScopedFd>* val) const {
+    return readTypedVector(val, &Parcel::readUniqueFileDescriptor);
+}
+
 status_t Parcel::readBlob(size_t len, ReadableBlob* outBlob) const
 {
     int32_t blobType;