Merge "MemoryHeapBase: Map as read-only when needed" (6ccc9f38) · Commits · e / os / platform_frameworks_native

libs/binder/MemoryHeapBase.cpp

+9 −5

Original line number	Diff line number	Diff line
		@@ -49,7 +49,7 @@ MemoryHeapBase::MemoryHeapBase(size_t size, uint32_t flags, char const * name)
		int fd = ashmem_create_region(name == nullptr ? "MemoryHeapBase" : name, size);
		ALOGE_IF(fd<0, "error creating ashmem region: %s", strerror(errno));
		if (fd >= 0) {
		if (mapfd(fd, size) == NO_ERROR) {
		if (mapfd(fd, true, size) == NO_ERROR) {
		if (flags & READ_ONLY) {
		ashmem_set_prot_region(fd, PROT_READ);
		}
		@@ -70,7 +70,7 @@ MemoryHeapBase::MemoryHeapBase(const char* device, size_t size, uint32_t flags)
		if (fd >= 0) {
		const size_t pagesize = getpagesize();
		size = ((size + pagesize-1) & ~(pagesize-1));
		if (mapfd(fd, size) == NO_ERROR) {
		if (mapfd(fd, false, size) == NO_ERROR) {
		mDevice = device;
		}
		}
		@@ -82,7 +82,7 @@ MemoryHeapBase::MemoryHeapBase(int fd, size_t size, uint32_t flags, off_t offset
		{
		const size_t pagesize = getpagesize();
		size = ((size + pagesize-1) & ~(pagesize-1));
		mapfd(fcntl(fd, F_DUPFD_CLOEXEC, 0), size, offset);
		mapfd(fcntl(fd, F_DUPFD_CLOEXEC, 0), false, size, offset);
		}

		status_t MemoryHeapBase::init(int fd, void base, size_t size, int flags, const char device)
		@@ -98,7 +98,7 @@ status_t MemoryHeapBase::init(int fd, void *base, size_t size, int flags, const
		return NO_ERROR;
		}

		status_t MemoryHeapBase::mapfd(int fd, size_t size, off_t offset)
		status_t MemoryHeapBase::mapfd(int fd, bool writeableByCaller, size_t size, off_t offset)
		{
		if (size == 0) {
		// try to figure out the size automatically
		@@ -116,8 +116,12 @@ status_t MemoryHeapBase::mapfd(int fd, size_t size, off_t offset)
		}

		if ((mFlags & DONT_MAP_LOCALLY) == 0) {
		int prot = PROT_READ;
		if (writeableByCaller \|\| (mFlags & READ_ONLY) == 0) {
		prot \|= PROT_WRITE;
		}
		void* base = (uint8_t*)mmap(nullptr, size,
		PROT_READ\|PROT_WRITE, MAP_SHARED, fd, offset);
		prot, MAP_SHARED, fd, offset);
		if (base == MAP_FAILED) {
		ALOGE("mmap(fd=%d, size=%zu) failed (%s)",
		fd, size, strerror(errno));

libs/binder/include/binder/MemoryHeapBase.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -51,6 +51,8 @@ public:

		/*
		* maps memory from ashmem, with the given name for debugging
		* if the READ_ONLY flag is set, the memory will be writeable by the calling process,
		* but not by others. this is NOT the case with the other ctors.
		*/
		explicit MemoryHeapBase(size_t size, uint32_t flags = 0, char const* name = nullptr);

		@@ -78,7 +80,7 @@ protected:
		int flags = 0, const char* device = nullptr);

		private:
		status_t mapfd(int fd, size_t size, off_t offset = 0);
		status_t mapfd(int fd, bool writeableByCaller, size_t size, off_t offset = 0);

		int mFD;
		size_t mSize;