c0a7e690bf
Add native Parcel methods analogous to the Java versions.
Currently, these don't do much, but upcoming StrictMode work changes
the RPC calling conventions in some cases, so it's important that
everybody uses these consistently, rather than having a lot of code
trying to parse RPC responses out of Parcels themselves.
As a summary, the current convention that Java Binder services use is
to prepend the reply Parcel with an int32 signaling the exception
status:
0: no exception
-1: Security exception
-2: Bad Parcelable
-3: ...
-4: ...
-5: ...
... followed by Parceled String if the exception code is non-zero.
With an upcoming change, it'll be the case that a response Parcel can,
non-exceptionally return rich data in the header, and also return data
to the caller. The important thing to note in this new case is that
the first int32 in the reply parcel *will not be zero*, so anybody
manually checking for it with reply.readInt32() will get false
negative failures.
Short summary: If you're calling into a Java service and manually
checking the exception status with reply.readInt32(), change it to
reply.readExceptionCode().
Change-Id: I23f9a0e53a8cfbbd9759242cfde16723641afe04
61 lines
2.1 KiB
C++
61 lines
2.1 KiB
C++
/*
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* Copyright (C) 2006 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <unistd.h>
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#include <android_runtime/ActivityManager.h>
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#include <binder/IBinder.h>
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#include <binder/IServiceManager.h>
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#include <binder/Parcel.h>
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#include <utils/String8.h>
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namespace android {
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const uint32_t OPEN_CONTENT_URI_TRANSACTION = IBinder::FIRST_CALL_TRANSACTION + 4;
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// Perform ContentProvider.openFile() on the given URI, returning
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// the resulting native file descriptor. Returns < 0 on error.
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int openContentProviderFile(const String16& uri)
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{
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int fd = -1;
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sp<IServiceManager> sm = defaultServiceManager();
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sp<IBinder> am = sm->getService(String16("activity"));
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if (am != NULL) {
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Parcel data, reply;
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data.writeInterfaceToken(String16("android.app.IActivityManager"));
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data.writeString16(uri);
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status_t ret = am->transact(OPEN_CONTENT_URI_TRANSACTION, data, &reply);
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if (ret == NO_ERROR) {
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int32_t exceptionCode = reply.readExceptionCode();
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if (!exceptionCode) {
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// Success is indicated here by a nonzero int followed by the fd;
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// failure by a zero int with no data following.
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if (reply.readInt32() != 0) {
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fd = dup(reply.readFileDescriptor());
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}
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} else {
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// An exception was thrown back; fall through to return failure
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LOGD("openContentUri(%s) caught exception %d\n",
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String8(uri).string(), exceptionCode);
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}
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}
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}
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return fd;
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}
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} /* namespace android */
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