# Many tests already test the internal machinery under powerloss, these
# tests are more interested in running the filesystem under
# difficult/weird powerloss environments
#
# Try to keep these below O(n^2), which can be tricky
after = [
    'test_mtree',
    'test_dirs',
    'test_files',
    'test_stickynotes',
    'test_traversal',
    'test_gc',
    'test_mount',
    'test_ck',
    'test_compat',
]


# Create many dirs under powerloss
#
# We always make progress so this should be O(n) progs, (but maybe
# O(n^2) reads)
#
[cases.test_powerloss_spam_dir_many]
defines.POWERLOSS_BEHAVIOR = [
    'LFS_EMUBD_POWERLOSS_ATOMIC',
    'LFS_EMUBD_POWERLOSS_SOMEBITS',
    'LFS_EMUBD_POWERLOSS_MOSTBITS',
    'LFS_EMUBD_POWERLOSS_OOO',
]
defines.MKCONSISTENT = [false, true]
defines.N = [1, 2, 4, 8, 16, 32, 64, 128, 256, 512]
reentrant = true
code = '''
    // format once per test
    lfs_t lfs;
    int err = lfsr_mount(&lfs, LFS_M_RDWR, CFG);
    if (err) {
        lfsr_format(&lfs, LFS_F_RDWR, CFG) => 0;
        lfsr_mount(&lfs, LFS_M_RDWR, CFG) => 0;
    }
    if (MKCONSISTENT) {
        lfsr_fs_mkconsistent(&lfs) => 0;
    }

    // make this many directories
    for (lfs_size_t i = 0; i < N; i++) {
        char name[256];
        sprintf(name, "dir%03x", i);
        err = lfsr_mkdir(&lfs, name);
        assert(!err || (TEST_PLS && err == LFS_ERR_EXIST));
    }

    for (int remount = 0; remount < 2; remount++) {
        // remount?
        if (remount) {
            lfsr_unmount(&lfs) => 0;
            lfsr_mount(&lfs, LFS_M_RDWR, CFG) => 0;
        }

        // grm should be zero here
        assert(lfs.grm_p[0] == 0);

        // check that our mkdir worked
        for (lfs_size_t i = 0; i < N; i++) {
            char name[256];
            sprintf(name, "dir%03x", i);
            struct lfs_info info;
            lfsr_stat(&lfs, name, &info) => 0;
            assert(strcmp(info.name, name) == 0);
            assert(info.type == LFS_TYPE_DIR);
            assert(info.size == 0);
        }

        lfsr_dir_t dir;
        lfsr_dir_open(&lfs, &dir, "/") => 0;
        struct lfs_info info;
        lfsr_dir_read(&lfs, &dir, &info) => 0;
        assert(strcmp(info.name, ".") == 0);
        assert(info.type == LFS_TYPE_DIR);
        assert(info.size == 0);
        lfsr_dir_read(&lfs, &dir, &info) => 0;
        assert(strcmp(info.name, "..") == 0);
        assert(info.type == LFS_TYPE_DIR);
        assert(info.size == 0);
        for (lfs_size_t i = 0; i < N; i++) {
            char name[256];
            sprintf(name, "dir%03x", i);
            lfsr_dir_read(&lfs, &dir, &info) => 0;
            assert(strcmp(info.name, name) == 0);
            assert(info.type == LFS_TYPE_DIR);
            assert(info.size == 0);
        }
        lfsr_dir_read(&lfs, &dir, &info) => LFS_ERR_NOENT;
        lfsr_dir_close(&lfs, &dir) => 0;

        for (lfs_size_t i = 0; i < N; i++) {
            char name[256];
            sprintf(name, "dir%03x", i);
            lfsr_dir_open(&lfs, &dir, name) => 0;
            lfsr_dir_read(&lfs, &dir, &info) => 0;
            assert(strcmp(info.name, ".") == 0);
            assert(info.type == LFS_TYPE_DIR);
            assert(info.size == 0);
            lfsr_dir_read(&lfs, &dir, &info) => 0;
            assert(strcmp(info.name, "..") == 0);
            assert(info.type == LFS_TYPE_DIR);
            assert(info.size == 0);
            lfsr_dir_read(&lfs, &dir, &info) => LFS_ERR_NOENT;
            lfsr_dir_close(&lfs, &dir) => 0;
        }
    }

    lfsr_unmount(&lfs) => 0;
'''

# Create many files under powerloss
#
# We always make progress so this should be O(n) progs, (but maybe
# O(n^2) reads)
#
[cases.test_powerloss_spam_file_many]
defines.POWERLOSS_BEHAVIOR = [
    'LFS_EMUBD_POWERLOSS_ATOMIC',
    'LFS_EMUBD_POWERLOSS_SOMEBITS',
    'LFS_EMUBD_POWERLOSS_MOSTBITS',
    'LFS_EMUBD_POWERLOSS_OOO',
]
defines.MKCONSISTENT = [false, true]
# inlining has a tendency to hide sync issues, so try without
defines.INLINE_SIZE = ['BLOCK_SIZE/4', '0']
defines.N = [1, 2, 4, 8, 16, 32, 64]
defines.SIZE = [
    '0',
    'FILE_CACHE_SIZE/2',
    '2*FILE_CACHE_SIZE',
    'BLOCK_SIZE/2',
    'BLOCK_SIZE',
    '2*BLOCK_SIZE',
    '4*BLOCK_SIZE',
]
if = '(SIZE*N)/BLOCK_SIZE <= 32'
reentrant = true
code = '''
    // format once per test
    lfs_t lfs;
    int err = lfsr_mount(&lfs, LFS_M_RDWR, CFG);
    if (err) {
        lfsr_format(&lfs, LFS_F_RDWR, CFG) => 0;
        lfsr_mount(&lfs, LFS_M_RDWR, CFG) => 0;
    }
    if (MKCONSISTENT) {
        lfsr_fs_mkconsistent(&lfs) => 0;
    }

    // create this many files
    uint32_t prng = 42;
    for (lfs_size_t i = 0; i < N; i++) {
        char name[256];
        sprintf(name, "amethyst%03x", i);

        uint8_t wbuf[SIZE];
        for (lfs_size_t j = 0; j < SIZE; j++) {
            wbuf[j] = 'a' + (TEST_PRNG(&prng) % 26);
        }

        lfsr_file_t file;
        err = lfsr_file_open(&lfs, &file, name,
                LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL);
        assert(!err || (TEST_PLS && err == LFS_ERR_EXIST));
        if (!err) {
            lfsr_file_write(&lfs, &file, wbuf, SIZE) => SIZE;
            lfsr_file_close(&lfs, &file) => 0;
        }
    }

    for (int remount = 0; remount < 2; remount++) {
        // remount?
        if (remount) {
            lfsr_unmount(&lfs) => 0;
            lfsr_mount(&lfs, LFS_M_RDWR, CFG) => 0;
        }

        // check that our writes worked
        prng = 42;
        for (lfs_size_t i = 0; i < N; i++) {
            // check with stat
            char name[256];
            sprintf(name, "amethyst%03x", i);
            struct lfs_info info;
            lfsr_stat(&lfs, name, &info) => 0;
            assert(strcmp(info.name, name) == 0);
            assert(info.type == LFS_TYPE_REG);
            assert(info.size == SIZE);

            // try reading the file, note we reset prng above
            uint8_t wbuf[SIZE];
            for (lfs_size_t j = 0; j < SIZE; j++) {
                wbuf[j] = 'a' + (TEST_PRNG(&prng) % 26);
            }

            lfsr_file_t file;
            uint8_t rbuf[SIZE];
            lfsr_file_open(&lfs, &file, name, LFS_O_RDONLY) => 0;
            lfsr_file_read(&lfs, &file, rbuf, SIZE) => SIZE;
            assert(memcmp(rbuf, wbuf, SIZE) == 0);
            lfsr_file_close(&lfs, &file) => 0;
        }
    }

    lfsr_unmount(&lfs) => 0;
'''

# A general purpose powerloss fuzz test
#
# Under powerloss, we can't really keep track of a sim reliably/
# efficiently, instead just do random operations, store a counter in a
# special file so we know how much progress has been made, and hope for
# the best. Most likely an internal assert will trigger if anything goes
# wrong.
#
[cases.test_powerloss_spam_f_pl_fuzz]
defines.POWERLOSS_BEHAVIOR = [
    'LFS_EMUBD_POWERLOSS_ATOMIC',
    'LFS_EMUBD_POWERLOSS_SOMEBITS',
    'LFS_EMUBD_POWERLOSS_MOSTBITS',
    'LFS_EMUBD_POWERLOSS_OOO',
]
defines.MKCONSISTENT = [false, true]
# inlining has a tendency to hide sync issues, so try without
defines.INLINE_SIZE = ['BLOCK_SIZE/4', '0']
defines.N = [1, 2, 4, 8, 16, 32, 64]
defines.OPS = 256
defines.SIZE = [
    '0',
    'FILE_CACHE_SIZE/2',
    '2*FILE_CACHE_SIZE',
    'BLOCK_SIZE/2',
    'BLOCK_SIZE',
    '2*BLOCK_SIZE',
    '4*BLOCK_SIZE',
]
defines.SEED = 'range(10)'
fuzz = 'SEED'
if = '(SIZE*N)/BLOCK_SIZE <= 16'
reentrant = true
code = '''
    // format once per test
    lfs_t lfs;
    int err = lfsr_mount(&lfs, LFS_M_RDWR, CFG);
    if (err) {
        lfsr_format(&lfs, LFS_F_RDWR, CFG) => 0;
        lfsr_mount(&lfs, LFS_M_RDWR, CFG) => 0;
    }
    if (MKCONSISTENT) {
        lfsr_fs_mkconsistent(&lfs) => 0;
    }

    // keep some test state on disk to survive powerloss
    typedef struct fuzz_state {
        lfs_size_t i;
        uint32_t prng;
    } fuzz_state_t;
    fuzz_state_t state = {.i = 0, .prng = SEED};

    lfsr_file_t state_file;
    lfsr_file_open(&lfs, &state_file, "state", LFS_O_RDWR | LFS_O_CREAT) => 0;
    lfs_ssize_t d = lfsr_file_read(&lfs, &state_file, &state, sizeof(state));
    assert(d == 0 || d == sizeof(state));

    // keep test files in a separate directory
    err = lfsr_mkdir(&lfs, "test");
    assert(!err || err == LFS_ERR_EXIST);

    uint32_t prng = state.prng;
    for (lfs_size_t i = state.i; i < OPS; i++) {
        // choose which operation to do
        uint8_t op = TEST_PRNG(&prng) % 3;

        // how many files do we have?
        lfs_size_t count = 0;
        lfsr_dir_t dir;
        lfsr_dir_open(&lfs, &dir, "test") => 0;
        struct lfs_info info;
        lfsr_dir_read(&lfs, &dir, &info) => 0;
        assert(strcmp(info.name, ".") == 0);
        assert(info.type == LFS_TYPE_DIR);
        assert(info.size == 0);
        lfsr_dir_read(&lfs, &dir, &info) => 0;
        assert(strcmp(info.name, "..") == 0);
        assert(info.type == LFS_TYPE_DIR);
        assert(info.size == 0);
        while (true) {
            int err = lfsr_dir_read(&lfs, &dir, &info);
            assert(!err || err == LFS_ERR_NOENT);
            if (err == LFS_ERR_NOENT) {
                break;
            }
            assert(strlen(info.name) == strlen("amethyst..."));
            assert(memcmp(info.name, "amethyst", strlen("amethyst")) == 0);
            assert(info.type == LFS_TYPE_REG);
            assert(info.size == SIZE);
            count++;
        }
        lfsr_dir_close(&lfs, &dir) => 0;

        // creating a new file?
        if (op == 0 || count == 0) {
            // choose a pseudo-random number
            lfs_size_t x = TEST_PRNG(&prng) % N;
            uint32_t wprng = TEST_PRNG(&prng);

            // create a file here
            char name[256];
            sprintf(name, "test/amethyst%03x", x);
            uint8_t wbuf[SIZE];
            uint8_t ck = 0;
            for (lfs_size_t j = 0; j < SIZE-1; j++) {
                wbuf[j] = 'a' + (TEST_PRNG(&wprng) % 26);
                ck = (ck + (wbuf[j] - 'a')) % 26;
            }
            // make the sum equal to 'a' mod 26
            if (SIZE > 0) {
                wbuf[SIZE-1] = 'a' + ((26 - ck) % 26);
            }

            lfsr_file_t file;
            lfsr_file_open(&lfs, &file, name,
                    LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
            lfsr_file_write(&lfs, &file, wbuf, SIZE) => SIZE;
            lfsr_file_close(&lfs, &file) => 0;

        // deleting a file?
        } else if (op == 1) {
            // choose a random file to delete
            lfs_size_t j = TEST_PRNG(&prng) % count;
            // find the file
            lfsr_dir_open(&lfs, &dir, "test") => 0;
            lfsr_dir_read(&lfs, &dir, &info) => 0;
            lfsr_dir_read(&lfs, &dir, &info) => 0;
            for (lfs_size_t k = 0; k <= j; k++) {
                lfsr_dir_read(&lfs, &dir, &info) => 0;
            }
            lfsr_dir_close(&lfs, &dir) => 0;

            // delete this file
            char name[256];
            assert(strlen(info.name) == strlen("amethyst..."));
            sprintf(name, "test/%s", info.name);
            lfsr_remove(&lfs, name) => 0;

        // renaming a file?
        } else {
            // choose a random file to rename, and a random number to
            // rename to
            lfs_size_t j = TEST_PRNG(&prng) % count;
            lfs_size_t y = TEST_PRNG(&prng) % N;
            // find the file
            lfsr_dir_open(&lfs, &dir, "test") => 0;
            lfsr_dir_read(&lfs, &dir, &info) => 0;
            lfsr_dir_read(&lfs, &dir, &info) => 0;
            for (lfs_size_t k = 0; k <= j; k++) {
                lfsr_dir_read(&lfs, &dir, &info) => 0;
            }
            lfsr_dir_close(&lfs, &dir) => 0;

            // rename this file
            char old_name[256];
            assert(strlen(info.name) == strlen("amethyst..."));
            sprintf(old_name, "test/%s", info.name);
            char new_name[256];
            sprintf(new_name, "test/amethyst%03x", y);
            lfsr_rename(&lfs, old_name, new_name) => 0;
        }

        // update our state file
        state.i = i;
        state.prng = prng;
        lfsr_file_rewind(&lfs, &state_file) => 0;
        lfsr_file_write(&lfs, &state_file, &state, sizeof(state))
                => sizeof(state);
        lfsr_file_sync(&lfs, &state_file) => 0;
    }

    // go ahead and close our state file in case we remount
    lfsr_file_close(&lfs, &state_file) => 0;

    for (int remount = 0; remount < 2; remount++) {
        // remount?
        if (remount) {
            lfsr_unmount(&lfs) => 0;
            lfsr_mount(&lfs, LFS_M_RDWR, CFG) => 0;
        }

        // check that things look more-or-less ok
        lfsr_dir_t dir;
        lfsr_dir_open(&lfs, &dir, "test") => 0;
        struct lfs_info info;
        lfsr_dir_read(&lfs, &dir, &info) => 0;
        assert(strcmp(info.name, ".") == 0);
        assert(info.type == LFS_TYPE_DIR);
        assert(info.size == 0);
        lfsr_dir_read(&lfs, &dir, &info) => 0;
        assert(strcmp(info.name, "..") == 0);
        assert(info.type == LFS_TYPE_DIR);
        assert(info.size == 0);
        while (true) {
            int err = lfsr_dir_read(&lfs, &dir, &info);
            assert(!err || err == LFS_ERR_NOENT);
            if (err == LFS_ERR_NOENT) {
                break;
            }
            assert(strlen(info.name) == strlen("amethyst..."));
            assert(memcmp(info.name, "amethyst", strlen("amethyst")) == 0);
            assert(info.type == LFS_TYPE_REG);
            assert(info.size == SIZE);

            // at least try to read the files
            char name[256];
            sprintf(name, "test/%s", info.name);
            lfsr_file_t file;
            lfsr_file_open(&lfs, &file, name, LFS_O_RDONLY) => 0;

            uint8_t rbuf[SIZE];
            lfsr_file_read(&lfs, &file, rbuf, SIZE) => SIZE;
            // all data should be lowercase ascii
            for (lfs_size_t j = 0; j < SIZE; j++) {
                assert(rbuf[j] >= 'a' && rbuf[j] <= 'z');
            }
            // sum should be equal to 'a' mod 26
            uint8_t ck = 0;
            for (lfs_size_t j = 0; j < SIZE; j++) {
                ck = (ck + (rbuf[j] - 'a')) % 26;
            }
            assert(ck == 0);
            lfsr_file_close(&lfs, &file) => 0;
        }
        lfsr_dir_close(&lfs, &dir) => 0;
    }

    lfsr_unmount(&lfs) => 0;
'''

# A general purpose powerloss fuzz test, with directories!
#
# Under powerloss, we can't really keep track of a sim reliably/
# efficiently, instead just do random operations, store a counter in a
# special file so we know how much progress has been made, and hope for
# the best. Most likely an internal assert will trigger if anything goes
# wrong.
#
[cases.test_powerloss_spam_fd_pl_fuzz]
defines.POWERLOSS_BEHAVIOR = [
    'LFS_EMUBD_POWERLOSS_ATOMIC',
    'LFS_EMUBD_POWERLOSS_SOMEBITS',
    'LFS_EMUBD_POWERLOSS_MOSTBITS',
    'LFS_EMUBD_POWERLOSS_OOO',
]
defines.MKCONSISTENT = [false, true]
# inlining has a tendency to hide sync issues, so try without
defines.INLINE_SIZE = ['BLOCK_SIZE/4', '0']
# note dirs x files grows O(n^2)
defines.N = [1, 2, 4, 8]
defines.M = 'N'
defines.OPS = 256
defines.SIZE = [
    '0',
    'FILE_CACHE_SIZE/2',
    '2*FILE_CACHE_SIZE',
    'BLOCK_SIZE/2',
    'BLOCK_SIZE',
    '2*BLOCK_SIZE',
    '4*BLOCK_SIZE',
]
defines.SEED = 'range(10)'
fuzz = 'SEED'
if = '(SIZE*N)/BLOCK_SIZE <= 16'
reentrant = true
code = '''
    // format once per test
    lfs_t lfs;
    int err = lfsr_mount(&lfs, LFS_M_RDWR, CFG);
    if (err) {
        lfsr_format(&lfs, LFS_F_RDWR, CFG) => 0;
        lfsr_mount(&lfs, LFS_M_RDWR, CFG) => 0;
    }
    if (MKCONSISTENT) {
        lfsr_fs_mkconsistent(&lfs) => 0;
    }

    // keep some test state on disk to survive powerloss
    typedef struct fuzz_state {
        lfs_size_t i;
        uint32_t prng;
    } fuzz_state_t;
    fuzz_state_t state = {.i = 0, .prng = SEED};

    lfsr_file_t state_file;
    lfsr_file_open(&lfs, &state_file, "state", LFS_O_RDWR | LFS_O_CREAT) => 0;
    lfs_ssize_t d = lfsr_file_read(&lfs, &state_file, &state, sizeof(state));
    assert(d == 0 || d == sizeof(state));

    // keep test files in a separate directory
    err = lfsr_mkdir(&lfs, "test");
    assert(!err || err == LFS_ERR_EXIST);

    uint32_t prng = state.prng;
    for (lfs_size_t i = state.i; i < OPS; i++) {
        // choose which operation to do
        uint8_t op = TEST_PRNG(&prng) % 6;

        // how many dirs do we have?
        lfs_size_t dir_count = 0;
        lfsr_dir_t dir;
        lfsr_dir_open(&lfs, &dir, "test") => 0;
        struct lfs_info info;
        lfsr_dir_read(&lfs, &dir, &info) => 0;
        assert(strcmp(info.name, ".") == 0);
        assert(info.type == LFS_TYPE_DIR);
        assert(info.size == 0);
        lfsr_dir_read(&lfs, &dir, &info) => 0;
        assert(strcmp(info.name, "..") == 0);
        assert(info.type == LFS_TYPE_DIR);
        assert(info.size == 0);
        while (true) {
            int err = lfsr_dir_read(&lfs, &dir, &info);
            assert(!err || err == LFS_ERR_NOENT);
            if (err == LFS_ERR_NOENT) {
                break;
            }
            assert(strlen(info.name) == strlen("quartz..."));
            assert(memcmp(info.name, "quartz", strlen("quartz")) == 0);
            assert(info.type == LFS_TYPE_DIR);
            assert(info.size == 0);
            dir_count++;
        }
        lfsr_dir_close(&lfs, &dir) => 0;

        // dir op?
        if (op < 3 || dir_count == 0) {
            // creating a new dir?
            if (op == 0 || dir_count == 0) {
                // choose a pseudo-random number
                lfs_size_t x = TEST_PRNG(&prng) % N;

                // create a dir here
                char name[256];
                sprintf(name, "test/quartz%03x", x);
                int err = lfsr_mkdir(&lfs, name);
                assert(!err || err == LFS_ERR_EXIST);

            // deleting a dir?
            } else if (op == 1) {
                // choose a random dir to delete
                lfs_size_t j = TEST_PRNG(&prng) % dir_count;
                // find the dir
                lfsr_dir_open(&lfs, &dir, "test") => 0;
                lfsr_dir_read(&lfs, &dir, &info) => 0;
                lfsr_dir_read(&lfs, &dir, &info) => 0;
                for (lfs_size_t k = 0; k <= j; k++) {
                    lfsr_dir_read(&lfs, &dir, &info) => 0;
                }
                lfsr_dir_close(&lfs, &dir) => 0;

                // try to delete this dir, ignore non-empty dirs!
                char name[256];
                assert(strlen(info.name) == strlen("quartz..."));
                sprintf(name, "test/%s", info.name);
                int err = lfsr_remove(&lfs, name);
                assert(!err || err == LFS_ERR_NOTEMPTY);

            // renaming a dir?
            } else {
                // choose a random dir to rename, and a random number to
                // rename to
                lfs_size_t j = TEST_PRNG(&prng) % dir_count;
                lfs_size_t y = TEST_PRNG(&prng) % N;
                // find the dir
                lfsr_dir_open(&lfs, &dir, "test") => 0;
                lfsr_dir_read(&lfs, &dir, &info) => 0;
                lfsr_dir_read(&lfs, &dir, &info) => 0;
                for (lfs_size_t k = 0; k <= j; k++) {
                    lfsr_dir_read(&lfs, &dir, &info) => 0;
                }
                lfsr_dir_close(&lfs, &dir) => 0;

                // rename this dir, ignore conflicts!
                char old_name[256];
                assert(strlen(info.name) == strlen("quartz..."));
                sprintf(old_name, "test/%s", info.name);
                char new_name[256];
                sprintf(new_name, "test/quartz%03x", y);
                int err = lfsr_rename(&lfs, old_name, new_name);
                assert(!err || err == LFS_ERR_NOTEMPTY);
            }

        // file op?
        } else {
            // choose a pseudo-random dir
            lfs_size_t dir_i = TEST_PRNG(&prng) % dir_count;
            // find the dir
            lfsr_dir_open(&lfs, &dir, "test") => 0;
            lfsr_dir_read(&lfs, &dir, &info) => 0;
            lfsr_dir_read(&lfs, &dir, &info) => 0;
            for (lfs_size_t k = 0; k <= dir_i; k++) {
                lfsr_dir_read(&lfs, &dir, &info) => 0;
            }
            lfsr_dir_close(&lfs, &dir) => 0;
            char dir_path[256];
            sprintf(dir_path, "test/%s", info.name);

            // how many files do we have?
            lfs_size_t count = 0;
            lfsr_dir_open(&lfs, &dir, dir_path) => 0;
            lfsr_dir_read(&lfs, &dir, &info) => 0;
            assert(strcmp(info.name, ".") == 0);
            assert(info.type == LFS_TYPE_DIR);
            assert(info.size == 0);
            lfsr_dir_read(&lfs, &dir, &info) => 0;
            assert(strcmp(info.name, "..") == 0);
            assert(info.type == LFS_TYPE_DIR);
            assert(info.size == 0);
            while (true) {
                int err = lfsr_dir_read(&lfs, &dir, &info);
                assert(!err || err == LFS_ERR_NOENT);
                if (err == LFS_ERR_NOENT) {
                    break;
                }
                assert(strlen(info.name) == strlen("amethyst..."));
                assert(memcmp(
                        info.name,
                        "amethyst", strlen("amethyst")) == 0);
                assert(info.type == LFS_TYPE_REG);
                assert(info.size == SIZE);
                count++;
            }
            lfsr_dir_close(&lfs, &dir) => 0;

            // creating a new file?
            if (op == 3 || count == 0) {
                // choose a pseudo-random number
                lfs_size_t x = TEST_PRNG(&prng) % M;
                uint32_t wprng = TEST_PRNG(&prng);

                // create a file here
                char name[256];
                sprintf(name, "%s/amethyst%03x", dir_path, x);
                uint8_t wbuf[SIZE];
                uint8_t ck = 0;
                for (lfs_size_t j = 0; j < SIZE-1; j++) {
                    wbuf[j] = 'a' + (TEST_PRNG(&wprng) % 26);
                    ck = (ck + (wbuf[j] - 'a')) % 26;
                }
                // make the sum equal to 'a' mod 26
                if (SIZE > 0) {
                    wbuf[SIZE-1] = 'a' + ((26 - ck) % 26);
                }

                lfsr_file_t file;
                lfsr_file_open(&lfs, &file, name,
                        LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
                lfsr_file_write(&lfs, &file, wbuf, SIZE) => SIZE;
                lfsr_file_close(&lfs, &file) => 0;

            // deleting a file?
            } else if (op == 4) {
                // choose a random file to delete
                lfs_size_t j = TEST_PRNG(&prng) % count;
                // find the file
                lfsr_dir_open(&lfs, &dir, dir_path) => 0;
                lfsr_dir_read(&lfs, &dir, &info) => 0;
                lfsr_dir_read(&lfs, &dir, &info) => 0;
                for (lfs_size_t k = 0; k <= j; k++) {
                    lfsr_dir_read(&lfs, &dir, &info) => 0;
                }
                lfsr_dir_close(&lfs, &dir) => 0;

                // delete this file
                char name[256];
                assert(strlen(info.name) == strlen("amethyst..."));
                sprintf(name, "%s/%s", dir_path, info.name);
                lfsr_remove(&lfs, name) => 0;

            // renaming a file?
            } else {
                // choose a random file to rename
                lfs_size_t j = TEST_PRNG(&prng) % count;
                // find the file
                lfsr_dir_open(&lfs, &dir, dir_path) => 0;
                lfsr_dir_read(&lfs, &dir, &info) => 0;
                lfsr_dir_read(&lfs, &dir, &info) => 0;
                for (lfs_size_t k = 0; k <= j; k++) {
                    lfsr_dir_read(&lfs, &dir, &info) => 0;
                }
                lfsr_dir_close(&lfs, &dir) => 0;

                // choose a random dir to rename to
                lfs_size_t dir_j = TEST_PRNG(&prng) % dir_count;
                // find the dir
                struct lfs_info info_;
                lfsr_dir_open(&lfs, &dir, "test") => 0;
                lfsr_dir_read(&lfs, &dir, &info_) => 0;
                lfsr_dir_read(&lfs, &dir, &info_) => 0;
                for (lfs_size_t k = 0; k <= dir_j; k++) {
                    lfsr_dir_read(&lfs, &dir, &info_) => 0;
                }
                lfsr_dir_close(&lfs, &dir) => 0;

                // choose a random file to rename to
                lfs_size_t y = TEST_PRNG(&prng) % M;

                // rename this file
                char old_name[256];
                assert(strlen(info.name) == strlen("amethyst..."));
                sprintf(old_name, "%s/%s", dir_path, info.name);
                char new_name[256];
                sprintf(new_name, "test/%s/amethyst%03x", info_.name, y);
                lfsr_rename(&lfs, old_name, new_name) => 0;
            }
        }

        // update our state file
        state.i = i;
        state.prng = prng;
        lfsr_file_rewind(&lfs, &state_file) => 0;
        lfsr_file_write(&lfs, &state_file, &state, sizeof(state))
                => sizeof(state);
        lfsr_file_sync(&lfs, &state_file) => 0;
    }

    // go ahead and close our state file in case we remount
    lfsr_file_close(&lfs, &state_file) => 0;

    for (int remount = 0; remount < 2; remount++) {
        // remount?
        if (remount) {
            lfsr_unmount(&lfs) => 0;
            lfsr_mount(&lfs, LFS_M_RDWR, CFG) => 0;
        }

        // check that things look more-or-less ok
        lfsr_dir_t dir;
        lfsr_dir_open(&lfs, &dir, "test") => 0;
        struct lfs_info info;
        lfsr_dir_read(&lfs, &dir, &info) => 0;
        assert(strcmp(info.name, ".") == 0);
        assert(info.type == LFS_TYPE_DIR);
        assert(info.size == 0);
        lfsr_dir_read(&lfs, &dir, &info) => 0;
        assert(strcmp(info.name, "..") == 0);
        assert(info.type == LFS_TYPE_DIR);
        assert(info.size == 0);
        while (true) {
            int err = lfsr_dir_read(&lfs, &dir, &info);
            assert(!err || err == LFS_ERR_NOENT);
            if (err == LFS_ERR_NOENT) {
                break;
            }
            assert(strlen(info.name) == strlen("quartz..."));
            assert(memcmp(info.name, "quartz", strlen("quartz")) == 0);
            assert(info.type == LFS_TYPE_DIR);
            assert(info.size == 0);

            // check that our dirs look more-or-less ok
            char name[256];
            sprintf(name, "test/%s", info.name);
            lfsr_dir_t dir_;
            lfsr_dir_open(&lfs, &dir_, name) => 0;
            struct lfs_info info_;
            lfsr_dir_read(&lfs, &dir_, &info_) => 0;
            assert(strcmp(info_.name, ".") == 0);
            assert(info_.type == LFS_TYPE_DIR);
            assert(info_.size == 0);
            lfsr_dir_read(&lfs, &dir_, &info_) => 0;
            assert(strcmp(info_.name, "..") == 0);
            assert(info_.type == LFS_TYPE_DIR);
            assert(info_.size == 0);

            while (true) {
                err = lfsr_dir_read(&lfs, &dir_, &info_);
                assert(!err || err == LFS_ERR_NOENT);
                if (err == LFS_ERR_NOENT) {
                    break;
                }
                assert(strlen(info_.name) == strlen("amethyst..."));
                assert(memcmp(
                        info_.name,
                        "amethyst", strlen("amethyst")) == 0);
                assert(info_.type == LFS_TYPE_REG);
                assert(info_.size == SIZE);

                // at least try to read the files
                sprintf(name, "test/%s/%s", info.name, info_.name);
                lfsr_file_t file;
                lfsr_file_open(&lfs, &file, name, LFS_O_RDONLY) => 0;

                uint8_t rbuf[SIZE];
                lfsr_file_read(&lfs, &file, rbuf, SIZE) => SIZE;
                // all data should be lowercase ascii
                for (lfs_size_t j = 0; j < SIZE; j++) {
                    assert(rbuf[j] >= 'a' && rbuf[j] <= 'z');
                }
                // sum should be equal to 'a' mod 26
                uint8_t ck = 0;
                for (lfs_size_t j = 0; j < SIZE; j++) {
                    ck = (ck + (rbuf[j] - 'a')) % 26;
                }
                assert(ck == 0);
                lfsr_file_close(&lfs, &file) => 0;
            }
            lfsr_dir_close(&lfs, &dir_) => 0;
        }
        lfsr_dir_close(&lfs, &dir) => 0;
    }

    lfsr_unmount(&lfs) => 0;
'''