libbinder_ndk: read/write parcelable array

Bug: 111445392
Test: atest android.binder.cts
Change-Id: Ib7e7634b32611e26e6bd7e359ab4d9e9764e1cbc
diff --git a/libs/binder/ndk/include_ndk/android/binder_parcel.h b/libs/binder/ndk/include_ndk/android/binder_parcel.h
index 866af70..7296d87 100644
--- a/libs/binder/ndk/include_ndk/android/binder_parcel.h
+++ b/libs/binder/ndk/include_ndk/android/binder_parcel.h
@@ -151,6 +151,48 @@
 typedef const char* (*AParcel_stringArrayElementGetter)(const void* arrayData, size_t index,
                                                         size_t* outLength);
 
+/**
+ * This is called to allocate an array of size 'length'. If length is -1, then a 'null' array (or
+ * equivalent) should be created.
+ *
+ * See also AParcel_readParcelableArray
+ *
+ * \param arrayData some external representation of an array
+ * \param length the length to allocate this array to
+ *
+ * \return true if allocation succeeded. If length is -1, a true return here means that a 'null'
+ * value (or equivalent) was successfully stored.
+ */
+typedef bool (*AParcel_parcelableArrayAllocator)(void* arrayData, int32_t length);
+
+/**
+ * This is called to parcel the underlying data from an arrayData object at index.
+ *
+ * See also AParcel_writeParcelableArray
+ *
+ * \param parcel parcel to write the parcelable to
+ * \param arrayData some external representation of an array of parcelables (a user-defined type).
+ * \param index the index of the value to be retrieved.
+ *
+ * \return status (usually returned from other parceling functions). STATUS_OK for success.
+ */
+typedef binder_status_t (*AParcel_writeParcelableElement)(AParcel* parcel, const void* arrayData,
+                                                          size_t index);
+
+/**
+ * This is called to set an underlying value in an arrayData object at index.
+ *
+ * See also AParcel_readParcelableArray
+ *
+ * \param parcel parcel to read the parcelable from
+ * \param arrayData some external representation of an array of parcelables (a user-defined type).
+ * \param index the index of the value to be set.
+ *
+ * \return status (usually returned from other parceling functions). STATUS_OK for success.
+ */
+typedef binder_status_t (*AParcel_readParcelableElement)(const AParcel* parcel, void* arrayData,
+                                                         size_t index);
+
 // @START-PRIMITIVE-VECTOR-GETTERS
 /**
  * This is called to get the underlying data from an arrayData object.
@@ -497,6 +539,40 @@
                                         AParcel_stringArrayElementAllocator elementAllocator)
         __INTRODUCED_IN(29);
 
+/**
+ * Writes an array of parcelables (user-defined types) to the next location in a non-null parcel.
+ *
+ * \param parcel the parcel to write to.
+ * \param arrayData an array of size 'length' (or null if length is -1, may be null if length is 0).
+ * \param length the length of arrayData or -1 if this represents a null array.
+ * \param elementWriter function to be called for every array index to write the user-defined type
+ * at that location.
+ *
+ * \return STATUS_OK on successful write.
+ */
+binder_status_t AParcel_writeParcelableArray(AParcel* parcel, const void* arrayData, int32_t length,
+                                             AParcel_writeParcelableElement elementWriter)
+        __INTRODUCED_IN(29);
+
+/**
+ * Reads an array of parcelables (user-defined types) from the next location in a non-null parcel.
+ *
+ * First, allocator will be called with the length of the array. If the allocation succeeds and the
+ * length is greater than zero, elementReader will be called for every index to read the
+ * corresponding parcelable.
+ *
+ * \param parcel the parcel to read from.
+ * \param arrayData some external representation of an array.
+ * \param allocator the callback that will be called to allocate the array.
+ * \param elementReader the callback that will be called to fill out individual elements.
+ *
+ * \return STATUS_OK on successful read.
+ */
+binder_status_t AParcel_readParcelableArray(const AParcel* parcel, void* arrayData,
+                                            AParcel_parcelableArrayAllocator allocator,
+                                            AParcel_readParcelableElement elementReader)
+        __INTRODUCED_IN(29);
+
 // @START-PRIMITIVE-READ-WRITE
 /**
  * Writes int32_t value to the next location in a non-null parcel.
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 f99c3a9..53d6e95 100644
--- a/libs/binder/ndk/include_ndk/android/binder_parcel_utils.h
+++ b/libs/binder/ndk/include_ndk/android/binder_parcel_utils.h
@@ -420,6 +420,46 @@
             AParcel_nullableStdVectorStringElementAllocator);
 }
 
+/**
+ * Writes a parcelable object of type P inside a std::vector<P> at index 'index' to 'parcel'.
+ */
+template <typename P>
+binder_status_t AParcel_writeStdVectorParcelableElement(AParcel* parcel, const void* vectorData,
+                                                        size_t index) {
+    const std::vector<P>* vector = static_cast<const std::vector<P>*>(vectorData);
+    return vector->at(index).writeToParcel(parcel);
+}
+
+/**
+ * Reads a parcelable object of type P inside a std::vector<P> at index 'index' from 'parcel'.
+ */
+template <typename P>
+binder_status_t AParcel_readStdVectorParcelableElement(const AParcel* parcel, void* vectorData,
+                                                       size_t index) {
+    std::vector<P>* vector = static_cast<std::vector<P>*>(vectorData);
+    return vector->at(index).readFromParcel(parcel);
+}
+
+/**
+ * Convenience API for writing a std::vector<P>
+ */
+template <typename P>
+static inline binder_status_t AParcel_writeVector(AParcel* parcel, const std::vector<P>& vec) {
+    const void* vectorData = static_cast<const void*>(&vec);
+    return AParcel_writeParcelableArray(parcel, vectorData, vec.size(),
+                                        AParcel_writeStdVectorParcelableElement<P>);
+}
+
+/**
+ * Convenience API for reading a std::vector<P>
+ */
+template <typename P>
+static inline binder_status_t AParcel_readVector(const AParcel* parcel, std::vector<P>* vec) {
+    void* vectorData = static_cast<void*>(vec);
+    return AParcel_readParcelableArray(parcel, vectorData, AParcel_stdVectorExternalAllocator<P>,
+                                       AParcel_readStdVectorParcelableElement<P>);
+}
+
 // @START
 /**
  * Writes a vector of int32_t to the next location in a non-null parcel.
diff --git a/libs/binder/ndk/libbinder_ndk.map.txt b/libs/binder/ndk/libbinder_ndk.map.txt
index 4328b6e..ee7132f 100644
--- a/libs/binder/ndk/libbinder_ndk.map.txt
+++ b/libs/binder/ndk/libbinder_ndk.map.txt
@@ -40,6 +40,7 @@
     AParcel_readInt32Array;
     AParcel_readInt64;
     AParcel_readInt64Array;
+    AParcel_readParcelableArray;
     AParcel_readParcelFileDescriptor;
     AParcel_readStatusHeader;
     AParcel_readString;
@@ -64,6 +65,7 @@
     AParcel_writeInt32Array;
     AParcel_writeInt64;
     AParcel_writeInt64Array;
+    AParcel_writeParcelableArray;
     AParcel_writeParcelFileDescriptor;
     AParcel_writeStatusHeader;
     AParcel_writeString;
diff --git a/libs/binder/ndk/parcel.cpp b/libs/binder/ndk/parcel.cpp
index 2d68559..3976855 100644
--- a/libs/binder/ndk/parcel.cpp
+++ b/libs/binder/ndk/parcel.cpp
@@ -377,11 +377,11 @@
     if (length <= 0) return STATUS_OK;
 
     for (size_t i = 0; i < length; i++) {
-        size_t length = 0;
-        const char* str = getter(arrayData, i, &length);
-        if (str == nullptr && length != -1) return STATUS_BAD_VALUE;
+        size_t elementLength = 0;
+        const char* str = getter(arrayData, i, &elementLength);
+        if (str == nullptr && elementLength != -1) return STATUS_BAD_VALUE;
 
-        binder_status_t status = AParcel_writeString(parcel, str, length);
+        binder_status_t status = AParcel_writeString(parcel, str, elementLength);
         if (status != STATUS_OK) return status;
     }
 
@@ -433,6 +433,45 @@
     return STATUS_OK;
 }
 
+binder_status_t AParcel_writeParcelableArray(AParcel* parcel, const void* arrayData, int32_t length,
+                                             AParcel_writeParcelableElement elementWriter) {
+    // we have no clue if arrayData represents a null object or not, we can only infer from length
+    bool arrayIsNull = length < 0;
+    binder_status_t status = WriteAndValidateArraySize(parcel, arrayIsNull, length);
+    if (status != STATUS_OK) return status;
+    if (length <= 0) return STATUS_OK;
+
+    for (size_t i = 0; i < length; i++) {
+        binder_status_t status = elementWriter(parcel, arrayData, i);
+        if (status != STATUS_OK) return status;
+    }
+
+    return STATUS_OK;
+}
+
+binder_status_t AParcel_readParcelableArray(const AParcel* parcel, void* arrayData,
+                                            AParcel_parcelableArrayAllocator allocator,
+                                            AParcel_readParcelableElement elementReader) {
+    const Parcel* rawParcel = parcel->get();
+
+    int32_t length;
+    status_t status = rawParcel->readInt32(&length);
+
+    if (status != STATUS_OK) return PruneStatusT(status);
+    if (length < -1) return STATUS_BAD_VALUE;
+
+    if (!allocator(arrayData, length)) return STATUS_NO_MEMORY;
+
+    if (length == -1) return STATUS_OK;  // null array
+
+    for (size_t i = 0; i < length; i++) {
+        binder_status_t status = elementReader(parcel, arrayData, i);
+        if (status != STATUS_OK) return status;
+    }
+
+    return STATUS_OK;
+}
+
 // See gen_parcel_helper.py. These auto-generated read/write methods use the same types for
 // libbinder and this library.
 // @START