libbinder_ndk: null ParcelFileDescriptor

-1 <=> nullptr

Bug: 111445392
Test: atest android.binder.cts
Change-Id: I1047ab7f6997672278988ef0079927c1d8a773f5

3 files changed, 73 insertions, 8 deletions

diff --git a/libs/binder/ndk/include_ndk/android/binder_parcel.h b/libs/binder/ndk/include_ndk/android/binder_parcel.h
index b021c23610..3594349021 100644
--- a/libs/binder/ndk/include_ndk/android/binder_parcel.h
+++ b/libs/binder/ndk/include_ndk/android/binder_parcel.h
@@ -347,7 +347,7 @@ binder_status_t AParcel_readStrongBinder(const AParcel* parcel, AIBinder** binde
  * This corresponds to the SDK's android.os.ParcelFileDescriptor.
  *
  * \param parcel the parcel to write to.
- * \param fd the value to write to the parcel.
+ * \param fd the value to write to the parcel (-1 to represent a null ParcelFileDescriptor).
  *
  * \return STATUS_OK on successful write.
  */
@@ -361,7 +361,8 @@ binder_status_t AParcel_writeParcelFileDescriptor(AParcel* parcel, int fd);
  * This corresponds to the SDK's android.os.ParcelFileDescriptor.
  *
  * \param parcel the parcel to read from.
- * \param binder the out parameter for what is read from the parcel.
+ * \param fd the out parameter for what is read from the parcel (or -1 to represent a null
+ * ParcelFileDescriptor)
  *
  * \return STATUS_OK on successful write.
  */
diff --git a/libs/binder/ndk/include_ndk/android/binder_parcel_utils.h b/libs/binder/ndk/include_ndk/android/binder_parcel_utils.h
index 42e2ae5d9e..f99c3a92e2 100644
--- a/libs/binder/ndk/include_ndk/android/binder_parcel_utils.h
+++ b/libs/binder/ndk/include_ndk/android/binder_parcel_utils.h
@@ -202,6 +202,54 @@ static inline binder_status_t AParcel_readRequiredStrongBinder(const AParcel* pa
 }
 
 /**
+ * Convenience method to write a ParcelFileDescriptor where -1 represents a null value.
+ */
+static inline binder_status_t AParcel_writeNullableParcelFileDescriptor(
+        AParcel* parcel, const ScopedFileDescriptor& fd) {
+    return AParcel_writeParcelFileDescriptor(parcel, fd.get());
+}
+
+/**
+ * Convenience method to read a ParcelFileDescriptor where -1 represents a null value.
+ */
+static inline binder_status_t AParcel_readNullableParcelFileDescriptor(const AParcel* parcel,
+                                                                       ScopedFileDescriptor* fd) {
+    int readFd;
+    binder_status_t status = AParcel_readParcelFileDescriptor(parcel, &readFd);
+    if (status == STATUS_OK) {
+        fd->set(readFd);
+    }
+    return status;
+}
+
+/**
+ * Convenience method to write a valid ParcelFileDescriptor.
+ */
+static inline binder_status_t AParcel_writeRequiredParcelFileDescriptor(
+        AParcel* parcel, const ScopedFileDescriptor& fd) {
+    if (fd.get() < 0) {
+        return STATUS_UNEXPECTED_NULL;
+    }
+    return AParcel_writeParcelFileDescriptor(parcel, fd.get());
+}
+
+/**
+ * Convenience method to read a valid ParcelFileDescriptor.
+ */
+static inline binder_status_t AParcel_readRequiredParcelFileDescriptor(const AParcel* parcel,
+                                                                       ScopedFileDescriptor* fd) {
+    int readFd;
+    binder_status_t status = AParcel_readParcelFileDescriptor(parcel, &readFd);
+    if (status == STATUS_OK) {
+        if (readFd < 0) {
+            return STATUS_UNEXPECTED_NULL;
+        }
+        fd->set(readFd);
+    }
+    return status;
+}
+
+/**
  * Allocates a std::string to length and returns the underlying buffer. For use with
  * AParcel_readString. See use below in AParcel_readString(const AParcel*, std::string*).
  */
diff --git a/libs/binder/ndk/parcel.cpp b/libs/binder/ndk/parcel.cpp
index b1a295584a..3c321009f8 100644
--- a/libs/binder/ndk/parcel.cpp
+++ b/libs/binder/ndk/parcel.cpp
@@ -229,23 +229,39 @@ binder_status_t AParcel_readStrongBinder(const AParcel* parcel, AIBinder** binde
 }
 
 binder_status_t AParcel_writeParcelFileDescriptor(AParcel* parcel, int fd) {
-    ParcelFileDescriptor parcelFd((unique_fd(fd)));
+    std::unique_ptr<ParcelFileDescriptor> parcelFd;
 
-    status_t status = parcel->get()->writeParcelable(parcelFd);
+    if (fd < 0) {
+        if (fd != -1) {
+            return STATUS_UNKNOWN_ERROR;
+        }
+        // parcelFd = nullptr
+    } else {  // fd >= 0
+        parcelFd = std::make_unique<ParcelFileDescriptor>(unique_fd(fd));
+    }
+
+    status_t status = parcel->get()->writeNullableParcelable(parcelFd);
 
     // ownership is retained by caller
-    (void)parcelFd.release().release();
+    if (parcelFd != nullptr) {
+        (void)parcelFd->release().release();
+    }
 
     return PruneStatusT(status);
 }
 
 binder_status_t AParcel_readParcelFileDescriptor(const AParcel* parcel, int* fd) {
-    ParcelFileDescriptor parcelFd;
-    // status_t status = parcelFd.readFromParcel(parcel->get());
+    std::unique_ptr<ParcelFileDescriptor> parcelFd;
+
     status_t status = parcel->get()->readParcelable(&parcelFd);
     if (status != STATUS_OK) return PruneStatusT(status);
 
-    *fd = parcelFd.release().release();
+    if (parcelFd) {
+        *fd = parcelFd->release().release();
+    } else {
+        *fd = -1;
+    }
+
     return STATUS_OK;
 }