SharedMemory API changes
Hides getFd & getFileDescriptor due to lifecycle concenrs.
Adds ASharedMemory_dupFromJava to allow sharing a shared
memory region between Java & Native as safe as possible.
Mis-use results in an FD leak instead of double-close.
Bug: 64394076
Test: SharedMemory CTS tests
Change-Id: I01a5eb978fc4e99559a79baac75754c32f13bdc4
diff --git a/api/current.txt b/api/current.txt
index 8d2e9c8..c5fe76b 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -31066,7 +31066,6 @@
ctor public MemoryFile(java.lang.String, int) throws java.io.IOException;
method public deprecated synchronized boolean allowPurging(boolean) throws java.io.IOException;
method public void close();
- method public java.io.FileDescriptor getFileDescriptor() throws java.io.IOException;
method public java.io.InputStream getInputStream();
method public java.io.OutputStream getOutputStream();
method public deprecated boolean isPurgingAllowed();
@@ -31498,8 +31497,6 @@
method public void close();
method public static android.os.SharedMemory create(java.lang.String, int) throws android.system.ErrnoException;
method public int describeContents();
- method public int getFd();
- method public java.io.FileDescriptor getFileDescriptor();
method public int getSize();
method public java.nio.ByteBuffer map(int, int, int) throws android.system.ErrnoException;
method public java.nio.ByteBuffer mapReadOnly() throws android.system.ErrnoException;
diff --git a/api/system-current.txt b/api/system-current.txt
index e2754fd..60e4960 100644
--- a/api/system-current.txt
+++ b/api/system-current.txt
@@ -33911,7 +33911,6 @@
ctor public MemoryFile(java.lang.String, int) throws java.io.IOException;
method public deprecated synchronized boolean allowPurging(boolean) throws java.io.IOException;
method public void close();
- method public java.io.FileDescriptor getFileDescriptor() throws java.io.IOException;
method public java.io.InputStream getInputStream();
method public java.io.OutputStream getOutputStream();
method public deprecated boolean isPurgingAllowed();
@@ -34372,8 +34371,6 @@
method public void close();
method public static android.os.SharedMemory create(java.lang.String, int) throws android.system.ErrnoException;
method public int describeContents();
- method public int getFd();
- method public java.io.FileDescriptor getFileDescriptor();
method public int getSize();
method public java.nio.ByteBuffer map(int, int, int) throws android.system.ErrnoException;
method public java.nio.ByteBuffer mapReadOnly() throws android.system.ErrnoException;
diff --git a/api/test-current.txt b/api/test-current.txt
index fcb404e..70addad 100644
--- a/api/test-current.txt
+++ b/api/test-current.txt
@@ -31223,7 +31223,6 @@
ctor public MemoryFile(java.lang.String, int) throws java.io.IOException;
method public deprecated synchronized boolean allowPurging(boolean) throws java.io.IOException;
method public void close();
- method public java.io.FileDescriptor getFileDescriptor() throws java.io.IOException;
method public java.io.InputStream getInputStream();
method public java.io.OutputStream getOutputStream();
method public deprecated boolean isPurgingAllowed();
@@ -31656,8 +31655,6 @@
method public void close();
method public static android.os.SharedMemory create(java.lang.String, int) throws android.system.ErrnoException;
method public int describeContents();
- method public int getFd();
- method public java.io.FileDescriptor getFileDescriptor();
method public int getSize();
method public java.nio.ByteBuffer map(int, int, int) throws android.system.ErrnoException;
method public java.nio.ByteBuffer mapReadOnly() throws android.system.ErrnoException;
diff --git a/core/java/android/os/MemoryFile.java b/core/java/android/os/MemoryFile.java
index 9294c44..ff3258f 100644
--- a/core/java/android/os/MemoryFile.java
+++ b/core/java/android/os/MemoryFile.java
@@ -219,6 +219,8 @@
* The returned file descriptor is not duplicated.
*
* @throws IOException If the memory file has been closed.
+ *
+ * @hide
*/
public FileDescriptor getFileDescriptor() throws IOException {
return mSharedMemory.getFileDescriptor();
diff --git a/core/java/android/os/SharedMemory.java b/core/java/android/os/SharedMemory.java
index 459aeb0..e6c7a17 100644
--- a/core/java/android/os/SharedMemory.java
+++ b/core/java/android/os/SharedMemory.java
@@ -60,7 +60,8 @@
}
mMemoryRegistration = new MemoryRegistration(mSize);
- mCleaner = Cleaner.create(this, new Closer(mFileDescriptor, mMemoryRegistration));
+ mCleaner = Cleaner.create(mFileDescriptor,
+ new Closer(mFileDescriptor, mMemoryRegistration));
}
/**
@@ -138,6 +139,8 @@
* This FileDescriptor is interoperable with the ASharedMemory NDK APIs.
*
* @return Returns the FileDescriptor associated with this object.
+ *
+ * @hide Exists only for MemoryFile interop
*/
public @NonNull FileDescriptor getFileDescriptor() {
return mFileDescriptor;
@@ -150,6 +153,8 @@
* This fd is interoperable with the ASharedMemory NDK APIs.
*
* @return Returns the native fd associated with this object, or -1 if it is already closed.
+ *
+ * @hide Exposed for native ASharedMemory_dupFromJava()
*/
public int getFd() {
return mFileDescriptor.getInt$();
diff --git a/native/android/libandroid.map.txt b/native/android/libandroid.map.txt
index c82a1f6..bbd2783 100644
--- a/native/android/libandroid.map.txt
+++ b/native/android/libandroid.map.txt
@@ -198,6 +198,7 @@
ASharedMemory_create; # introduced=26
ASharedMemory_getSize; # introduced=26
ASharedMemory_setProt; # introduced=26
+ ASharedMemory_dupFromJava; # introduced=27
AStorageManager_delete;
AStorageManager_getMountedObbPath;
AStorageManager_isObbMounted;
diff --git a/native/android/sharedmem.cpp b/native/android/sharedmem.cpp
index 9d029dfa..757aaec 100644
--- a/native/android/sharedmem.cpp
+++ b/native/android/sharedmem.cpp
@@ -14,10 +14,36 @@
* limitations under the License.
*/
+#include <jni.h>
+
#include <android/sharedmem.h>
+#include <android/sharedmem_jni.h>
#include <cutils/ashmem.h>
+#include <log/log.h>
#include <utils/Errors.h>
+#include <mutex>
+#include <unistd.h>
+
+static struct {
+ jclass clazz;
+ jmethodID getFd;
+} sSharedMemory;
+
+static void jniInit(JNIEnv* env) {
+ static std::once_flag sJniInitialized;
+ std::call_once(sJniInitialized, [](JNIEnv* env) {
+ jclass clazz = env->FindClass("android/os/SharedMemory");
+ LOG_ALWAYS_FATAL_IF(clazz == nullptr, "Failed to find android.os.SharedMemory");
+ sSharedMemory.clazz = (jclass) env->NewGlobalRef(clazz);
+ LOG_ALWAYS_FATAL_IF(sSharedMemory.clazz == nullptr,
+ "Failed to create global ref of android.os.SharedMemory");
+ sSharedMemory.getFd = env->GetMethodID(sSharedMemory.clazz, "getFd", "()I");
+ LOG_ALWAYS_FATAL_IF(sSharedMemory.getFd == nullptr,
+ "Failed to find method SharedMemory#getFd()");
+ }, env);
+}
+
int ASharedMemory_create(const char *name, size_t size) {
if (size == 0) {
return android::BAD_VALUE;
@@ -32,3 +58,20 @@
int ASharedMemory_setProt(int fd, int prot) {
return ashmem_set_prot_region(fd, prot);
}
+
+int ASharedMemory_dupFromJava(JNIEnv* env, jobject javaSharedMemory) {
+ if (env == nullptr || javaSharedMemory == nullptr) {
+ return -1;
+ }
+ jniInit(env);
+ if (!env->IsInstanceOf(javaSharedMemory, sSharedMemory.clazz)) {
+ ALOGW("ASharedMemory_dupFromJava called with object "
+ "that's not an instanceof android.os.SharedMemory");
+ return -1;
+ }
+ int fd = env->CallIntMethod(javaSharedMemory, sSharedMemory.getFd);
+ if (fd != -1) {
+ fd = dup(fd);
+ }
+ return fd;
+}
