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Commit 01f60e4b authored by Isaac J. Manjarres's avatar Isaac J. Manjarres
Browse files

ashmem: Test for ASHMEM_GET_SIZE for ashmem-memfd compatibility 



ASHMEM_SET_SIZE will return  an error in the ashmem-memfd compatibility
logic, but ASHMEM_GET_SIZE will work as expected, so exercise that ioctl
command when testing for ashmem-memfd compatibility.

Bug: 111903542
Change-Id: I3a042063082fdf6d8d836ad9b37becc318e8d89d
Signed-off-by: default avatarIsaac J. Manjarres <isaacmanjarres@google.com>
parent 099460c5

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;

    }