Merge "ashmem: Test for ASHMEM_GET_SIZE for ashmem-memfd compatibility" into main (bf9d9f75) · Commits · e / os / android_system_core

libcutils/ashmem-dev.cpp

+14 −4

Original line number	Diff line number	Diff line
		@@ -120,8 +120,11 @@ static bool __has_memfd_support() {
		// permissions of the buffer (i.e. they cannot be changed by fchmod()).
		//
		// MFD_NOEXEC_SEAL implies MFD_ALLOW_SEALING.
		const char *test_buf_name = "test_android_memfd";
		size_t buf_size = getpagesize();

		android::base::unique_fd fd(
		syscall(__NR_memfd_create, "test_android_memfd", MFD_CLOEXEC \| MFD_NOEXEC_SEAL));
		syscall(__NR_memfd_create, test_buf_name, MFD_CLOEXEC \| MFD_NOEXEC_SEAL));
		if (fd == -1) {
		ALOGE("memfd_create failed: %m, no memfd support");
		return false;
		@@ -132,13 +135,20 @@ static bool __has_memfd_support() {
		return false;
		}

		if (ftruncate(fd, buf_size) == -1) {
		ALOGE("ftruncate(%s, %zd) failed to set memfd buffer size: %m, no memfd support",
		test_buf_name, buf_size);
		return false;
		}

		/*
		* Ensure that the kernel supports ashmem ioctl commands on memfds. If not,
		* fall back to using ashmem.
		*/
		if (TEMP_FAILURE_RETRY(ioctl(fd, ASHMEM_SET_SIZE, getpagesize())) < 0) {
		ALOGE("ioctl(ASHMEM_SET_SIZE, %d) failed: %m, no ashmem-memfd compat support",
		getpagesize());
		int ashmem_size = TEMP_FAILURE_RETRY(ioctl(fd, ASHMEM_GET_SIZE, 0));
		if (ashmem_size != static_cast<int>(buf_size)) {
		ALOGE("ioctl(ASHMEM_GET_SIZE): %d != buf_size: %zd , no ashmem-memfd compat support",
		ashmem_size, buf_size);
		return false;
		}