Enable more flexible usage of blobs in parcels.
Add functions to allow a client to take over the ashmem region
that was transferred so that it can claim it for its own and
reuse it.
Add support for mutable ashmem regions too.
Bug: 21428802
Change-Id: I16eca338cdb99b07d81fc43573d53ce86dbc60c8
diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index 58bbb26..bae4eb5 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -72,9 +72,6 @@
// Note: must be kept in sync with android/os/Parcel.java's EX_HAS_REPLY_HEADER
#define EX_HAS_REPLY_HEADER -128
-// Maximum size of a blob to transfer in-place.
-static const size_t IN_PLACE_BLOB_LIMIT = 40 * 1024;
-
// XXX This can be made public if we want to provide
// support for typed data.
struct small_flat_data
@@ -89,6 +86,15 @@
static size_t gParcelGlobalAllocSize = 0;
static size_t gParcelGlobalAllocCount = 0;
+// Maximum size of a blob to transfer in-place.
+static const size_t BLOB_INPLACE_LIMIT = 16 * 1024;
+
+enum {
+ BLOB_INPLACE = 0,
+ BLOB_ASHMEM_IMMUTABLE = 1,
+ BLOB_ASHMEM_MUTABLE = 2,
+};
+
void acquire_object(const sp<ProcessState>& proc,
const flat_binder_object& obj, const void* who)
{
@@ -516,6 +522,11 @@
return err;
}
+bool Parcel::allowFds() const
+{
+ return mAllowFds;
+}
+
bool Parcel::pushAllowFds(bool allowFds)
{
const bool origValue = mAllowFds;
@@ -886,25 +897,24 @@
return err;
}
-status_t Parcel::writeBlob(size_t len, WritableBlob* outBlob)
+status_t Parcel::writeBlob(size_t len, bool mutableCopy, WritableBlob* outBlob)
{
- status_t status;
-
if (len > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
- if (!mAllowFds || len <= IN_PLACE_BLOB_LIMIT) {
+ status_t status;
+ if (!mAllowFds || len <= BLOB_INPLACE_LIMIT) {
ALOGV("writeBlob: write in place");
- status = writeInt32(0);
+ status = writeInt32(BLOB_INPLACE);
if (status) return status;
void* ptr = writeInplace(len);
if (!ptr) return NO_MEMORY;
- outBlob->init(false /*mapped*/, ptr, len);
+ outBlob->init(-1, ptr, len, false);
return NO_ERROR;
}
@@ -922,15 +932,17 @@
if (ptr == MAP_FAILED) {
status = -errno;
} else {
- result = ashmem_set_prot_region(fd, PROT_READ);
+ if (!mutableCopy) {
+ result = ashmem_set_prot_region(fd, PROT_READ);
+ }
if (result < 0) {
status = result;
} else {
- status = writeInt32(1);
+ status = writeInt32(mutableCopy ? BLOB_ASHMEM_MUTABLE : BLOB_ASHMEM_IMMUTABLE);
if (!status) {
status = writeFileDescriptor(fd, true /*takeOwnership*/);
if (!status) {
- outBlob->init(true /*mapped*/, ptr, len);
+ outBlob->init(fd, ptr, len, mutableCopy);
return NO_ERROR;
}
}
@@ -942,6 +954,15 @@
return status;
}
+status_t Parcel::writeDupImmutableBlobFileDescriptor(int fd)
+{
+ // Must match up with what's done in writeBlob.
+ if (!mAllowFds) return FDS_NOT_ALLOWED;
+ status_t status = writeInt32(BLOB_ASHMEM_IMMUTABLE);
+ if (status) return status;
+ return writeDupFileDescriptor(fd);
+}
+
status_t Parcel::write(const FlattenableHelperInterface& val)
{
status_t err;
@@ -1354,27 +1375,29 @@
status_t Parcel::readBlob(size_t len, ReadableBlob* outBlob) const
{
- int32_t useAshmem;
- status_t status = readInt32(&useAshmem);
+ int32_t blobType;
+ status_t status = readInt32(&blobType);
if (status) return status;
- if (!useAshmem) {
+ if (blobType == BLOB_INPLACE) {
ALOGV("readBlob: read in place");
const void* ptr = readInplace(len);
if (!ptr) return BAD_VALUE;
- outBlob->init(false /*mapped*/, const_cast<void*>(ptr), len);
+ outBlob->init(-1, const_cast<void*>(ptr), len, false);
return NO_ERROR;
}
ALOGV("readBlob: read from ashmem");
+ bool isMutable = (blobType == BLOB_ASHMEM_MUTABLE);
int fd = readFileDescriptor();
if (fd == int(BAD_TYPE)) return BAD_VALUE;
- void* ptr = ::mmap(NULL, len, PROT_READ, MAP_SHARED, fd, 0);
+ void* ptr = ::mmap(NULL, len, isMutable ? PROT_READ | PROT_WRITE : PROT_READ,
+ MAP_SHARED, fd, 0);
if (ptr == MAP_FAILED) return NO_MEMORY;
- outBlob->init(true /*mapped*/, ptr, len);
+ outBlob->init(fd, ptr, len, isMutable);
return NO_ERROR;
}
@@ -1890,7 +1913,7 @@
// --- Parcel::Blob ---
Parcel::Blob::Blob() :
- mMapped(false), mData(NULL), mSize(0) {
+ mFd(-1), mData(NULL), mSize(0), mMutable(false) {
}
Parcel::Blob::~Blob() {
@@ -1898,22 +1921,24 @@
}
void Parcel::Blob::release() {
- if (mMapped && mData) {
+ if (mFd != -1 && mData) {
::munmap(mData, mSize);
}
clear();
}
-void Parcel::Blob::init(bool mapped, void* data, size_t size) {
- mMapped = mapped;
+void Parcel::Blob::init(int fd, void* data, size_t size, bool isMutable) {
+ mFd = fd;
mData = data;
mSize = size;
+ mMutable = isMutable;
}
void Parcel::Blob::clear() {
- mMapped = false;
+ mFd = -1;
mData = NULL;
mSize = 0;
+ mMutable = false;
}
}; // namespace android