libbinder_ndk: AParcel_(get|set)DataPosition
This allows you do the following:
- a = getPosition
- writeInt32(0)
- b = getPosition
- write data of unknown size
- c = getPosition
- setPosition(a)
- write(c - b)
This allows to skip reading the data of unknown size.
Bug: 118395170
Test: atest android.binder.cts
Change-Id: Id8033705331c6a48327c240ad33bd2d5f9fc190c
diff --git a/libs/binder/ndk/include_ndk/android/binder_parcel.h b/libs/binder/ndk/include_ndk/android/binder_parcel.h
index 3594349..866af70 100644
--- a/libs/binder/ndk/include_ndk/android/binder_parcel.h
+++ b/libs/binder/ndk/include_ndk/android/binder_parcel.h
@@ -54,6 +54,31 @@
void AParcel_delete(AParcel* parcel) __INTRODUCED_IN(29);
/**
+ * Sets the position within the parcel.
+ *
+ * \param parcel The parcel of which to set the position.
+ * \param position Position of the parcel to set. This must be a value returned by
+ * AParcel_getDataPosition. Positions are constant for a given parcel between processes.
+ *
+ * \return STATUS_OK on success. If position is negative, then STATUS_BAD_VALUE will be returned.
+ */
+binder_status_t AParcel_setDataPosition(const AParcel* parcel, int32_t position)
+ __INTRODUCED_IN(29);
+
+/**
+ * Gets the current position within the parcel.
+ *
+ * \param parcel The parcel of which to get the position.
+ *
+ * \return The size of the parcel. This will always be greater than 0. The values returned by this
+ * function before and after calling various reads and writes are not defined. Only the delta
+ * between two positions between a specific sequence of calls is defined. For instance, if position
+ * is X, writeBool is called, and then position is Y, readBool can be called from position X will
+ * return the same value, and then position will be Y.
+ */
+int32_t AParcel_getDataPosition(const AParcel* parcel) __INTRODUCED_IN(29);
+
+/**
* This is called to allocate a buffer for a C-style string (null-terminated). The returned buffer
* should be at least length bytes. This includes space for a null terminator. For a string, length
* will always be strictly less than or equal to the maximum size that can be held in a size_t and
diff --git a/libs/binder/ndk/libbinder_ndk.map.txt b/libs/binder/ndk/libbinder_ndk.map.txt
index 41df90b..4328b6e 100644
--- a/libs/binder/ndk/libbinder_ndk.map.txt
+++ b/libs/binder/ndk/libbinder_ndk.map.txt
@@ -25,6 +25,7 @@
AIBinder_Weak_new;
AIBinder_Weak_promote;
AParcel_delete;
+ AParcel_getDataPosition;
AParcel_readBool;
AParcel_readBoolArray;
AParcel_readByte;
@@ -48,6 +49,7 @@
AParcel_readUint32Array;
AParcel_readUint64;
AParcel_readUint64Array;
+ AParcel_setDataPosition;
AParcel_writeBool;
AParcel_writeBoolArray;
AParcel_writeByte;
diff --git a/libs/binder/ndk/parcel.cpp b/libs/binder/ndk/parcel.cpp
index 3c32100..2d68559 100644
--- a/libs/binder/ndk/parcel.cpp
+++ b/libs/binder/ndk/parcel.cpp
@@ -212,6 +212,19 @@
delete parcel;
}
+binder_status_t AParcel_setDataPosition(const AParcel* parcel, int32_t position) {
+ if (position < 0) {
+ return STATUS_BAD_VALUE;
+ }
+
+ parcel->get()->setDataPosition(position);
+ return STATUS_OK;
+}
+
+int32_t AParcel_getDataPosition(const AParcel* parcel) {
+ return parcel->get()->dataPosition();
+}
+
binder_status_t AParcel_writeStrongBinder(AParcel* parcel, AIBinder* binder) {
sp<IBinder> writeBinder = binder != nullptr ? binder->getBinder() : nullptr;
return parcel->get()->writeStrongBinder(writeBinder);