littlefs/tests/test_seek.toml

# simple file seek
[cases.test_seek_read]
defines = [
    {COUNT=132, SKIP=4},
    {COUNT=132, SKIP=128},
    {COUNT=200, SKIP=10},
    {COUNT=200, SKIP=100},
    {COUNT=4,   SKIP=1},
    {COUNT=4,   SKIP=2},
]
code = '''
    lfs_t lfs;
    lfs_format(&lfs, cfg) => 0;
    lfs_mount(&lfs, cfg) => 0;
    lfs_file_t file;
    lfs_file_open(&lfs, &file, "kitty",
            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
    size_t size = strlen("kittycatcat");
    uint8_t buffer[1024];
    memcpy(buffer, "kittycatcat", size);
    for (int j = 0; j < COUNT; j++) {
        lfs_file_write(&lfs, &file, buffer, size);
    }
    lfs_file_close(&lfs, &file) => 0;
    lfs_unmount(&lfs) => 0;

    lfs_mount(&lfs, cfg) => 0;
    lfs_file_open(&lfs, &file, "kitty", LFS_O_RDONLY) => 0;

    lfs_soff_t pos = -1;
    size = strlen("kittycatcat");
    for (int i = 0; i < SKIP; i++) {
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer, "kittycatcat", size) => 0;
        pos = lfs_file_tell(&lfs, &file);
    }
    assert(pos >= 0);

    lfs_file_seek(&lfs, &file, pos, LFS_SEEK_SET) => pos;
    lfs_file_read(&lfs, &file, buffer, size) => size;
    memcmp(buffer, "kittycatcat", size) => 0;

    lfs_file_rewind(&lfs, &file) => 0;
    lfs_file_read(&lfs, &file, buffer, size) => size;
    memcmp(buffer, "kittycatcat", size) => 0;

    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_CUR) => size;
    lfs_file_read(&lfs, &file, buffer, size) => size;
    memcmp(buffer, "kittycatcat", size) => 0;

    lfs_file_seek(&lfs, &file, size, LFS_SEEK_CUR) => 3*size;
    lfs_file_read(&lfs, &file, buffer, size) => size;
    memcmp(buffer, "kittycatcat", size) => 0;

    lfs_file_seek(&lfs, &file, pos, LFS_SEEK_SET) => pos;
    lfs_file_read(&lfs, &file, buffer, size) => size;
    memcmp(buffer, "kittycatcat", size) => 0;

    lfs_file_seek(&lfs, &file, -size, LFS_SEEK_CUR) => pos;
    lfs_file_read(&lfs, &file, buffer, size) => size;
    memcmp(buffer, "kittycatcat", size) => 0;

    lfs_file_seek(&lfs, &file, -size, LFS_SEEK_END) >= 0 => 1;
    lfs_file_read(&lfs, &file, buffer, size) => size;
    memcmp(buffer, "kittycatcat", size) => 0;

    size = lfs_file_size(&lfs, &file);
    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_CUR) => size;

    lfs_file_close(&lfs, &file) => 0;
    lfs_unmount(&lfs) => 0;
'''

# simple file seek and write
[cases.test_seek_write]
defines = [
    {COUNT=132, SKIP=4},
    {COUNT=132, SKIP=128},
    {COUNT=200, SKIP=10},
    {COUNT=200, SKIP=100},
    {COUNT=4,   SKIP=1},
    {COUNT=4,   SKIP=2},
]
code = '''
    lfs_t lfs;
    lfs_format(&lfs, cfg) => 0;
    lfs_mount(&lfs, cfg) => 0;
    lfs_file_t file;
    lfs_file_open(&lfs, &file, "kitty",
            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
    size_t size = strlen("kittycatcat");
    uint8_t buffer[1024];
    memcpy(buffer, "kittycatcat", size);
    for (int j = 0; j < COUNT; j++) {
        lfs_file_write(&lfs, &file, buffer, size);
    }
    lfs_file_close(&lfs, &file) => 0;
    lfs_unmount(&lfs) => 0;

    lfs_mount(&lfs, cfg) => 0;
    lfs_file_open(&lfs, &file, "kitty", LFS_O_RDWR) => 0;

    lfs_soff_t pos = -1;
    size = strlen("kittycatcat");
    for (int i = 0; i < SKIP; i++) {
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer, "kittycatcat", size) => 0;
        pos = lfs_file_tell(&lfs, &file);
    }
    assert(pos >= 0);

    memcpy(buffer, "doggodogdog", size);
    lfs_file_seek(&lfs, &file, pos, LFS_SEEK_SET) => pos;
    lfs_file_write(&lfs, &file, buffer, size) => size;

    lfs_file_seek(&lfs, &file, pos, LFS_SEEK_SET) => pos;
    lfs_file_read(&lfs, &file, buffer, size) => size;
    memcmp(buffer, "doggodogdog", size) => 0;

    lfs_file_rewind(&lfs, &file) => 0;
    lfs_file_read(&lfs, &file, buffer, size) => size;
    memcmp(buffer, "kittycatcat", size) => 0;

    lfs_file_seek(&lfs, &file, pos, LFS_SEEK_SET) => pos;
    lfs_file_read(&lfs, &file, buffer, size) => size;
    memcmp(buffer, "doggodogdog", size) => 0;

    lfs_file_seek(&lfs, &file, -size, LFS_SEEK_END) >= 0 => 1;
    lfs_file_read(&lfs, &file, buffer, size) => size;
    memcmp(buffer, "kittycatcat", size) => 0;

    size = lfs_file_size(&lfs, &file);
    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_CUR) => size;

    lfs_file_close(&lfs, &file) => 0;
    lfs_unmount(&lfs) => 0;
'''

# boundary seek and reads
[cases.test_seek_boundary_read]
defines.COUNT = 132
code = '''
    lfs_t lfs;
    lfs_format(&lfs, cfg) => 0;
    lfs_mount(&lfs, cfg) => 0;
    lfs_file_t file;
    lfs_file_open(&lfs, &file, "kitty",
            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
    size_t size = strlen("kittycatcat");
    uint8_t buffer[1024];
    memcpy(buffer, "kittycatcat", size);
    for (int j = 0; j < COUNT; j++) {
        lfs_file_write(&lfs, &file, buffer, size);
    }
    lfs_file_close(&lfs, &file) => 0;
    lfs_unmount(&lfs) => 0;

    lfs_mount(&lfs, cfg) => 0;
    lfs_file_open(&lfs, &file, "kitty", LFS_O_RDONLY) => 0;

    size = strlen("kittycatcat");
    const lfs_soff_t offsets[] = {
        512,
        1024-4,
        512+1,
        1024-4+1,
        512-1,
        1024-4-1,

        512-strlen("kittycatcat"),
        1024-4-strlen("kittycatcat"),
        512-strlen("kittycatcat")+1,
        1024-4-strlen("kittycatcat")+1,
        512-strlen("kittycatcat")-1,
        1024-4-strlen("kittycatcat")-1,

        strlen("kittycatcat")*(COUNT-2)-1,
    };

    for (unsigned i = 0; i < sizeof(offsets) / sizeof(offsets[0]); i++) {
        lfs_soff_t off = offsets[i];
        // read @ offset
        lfs_file_seek(&lfs, &file, off, LFS_SEEK_SET) => off;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer,
                &"kittycatcatkittycatcat"[off % strlen("kittycatcat")],
                size) => 0;
        // read after
        lfs_file_seek(&lfs, &file, off+strlen("kittycatcat")+1, LFS_SEEK_SET)
                => off+strlen("kittycatcat")+1;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer,
                &"kittycatcatkittycatcat"[(off+1) % strlen("kittycatcat")],
                size) => 0;
        // read before
        lfs_file_seek(&lfs, &file, off-strlen("kittycatcat")-1, LFS_SEEK_SET)
                => off-strlen("kittycatcat")-1;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer,
                &"kittycatcatkittycatcat"[(off-1) % strlen("kittycatcat")],
                size) => 0;

        // read @ 0
        lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer, "kittycatcat", size) => 0;

        // read @ offset
        lfs_file_seek(&lfs, &file, off, LFS_SEEK_SET) => off;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer,
                &"kittycatcatkittycatcat"[off % strlen("kittycatcat")],
                size) => 0;
        // read after
        lfs_file_seek(&lfs, &file, off+strlen("kittycatcat")+1, LFS_SEEK_SET)
                => off+strlen("kittycatcat")+1;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer,
                &"kittycatcatkittycatcat"[(off+1) % strlen("kittycatcat")],
                size) => 0;
        // read before
        lfs_file_seek(&lfs, &file, off-strlen("kittycatcat")-1, LFS_SEEK_SET)
                => off-strlen("kittycatcat")-1;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer,
                &"kittycatcatkittycatcat"[(off-1) % strlen("kittycatcat")],
                size) => 0;

        // sync
        lfs_file_sync(&lfs, &file) => 0;

        // read @ 0
        lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer, "kittycatcat", size) => 0;

        // read @ offset
        lfs_file_seek(&lfs, &file, off, LFS_SEEK_SET) => off;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer,
                &"kittycatcatkittycatcat"[off % strlen("kittycatcat")],
                size) => 0;
        // read after
        lfs_file_seek(&lfs, &file, off+strlen("kittycatcat")+1, LFS_SEEK_SET)
                => off+strlen("kittycatcat")+1;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer,
                &"kittycatcatkittycatcat"[(off+1) % strlen("kittycatcat")],
                size) => 0;
        // read before
        lfs_file_seek(&lfs, &file, off-strlen("kittycatcat")-1, LFS_SEEK_SET)
                => off-strlen("kittycatcat")-1;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer,
                &"kittycatcatkittycatcat"[(off-1) % strlen("kittycatcat")],
                size) => 0;
    }

    lfs_file_close(&lfs, &file) => 0;
    lfs_unmount(&lfs) => 0;
'''

# boundary seek and writes
[cases.test_seek_boundary_write]
defines.COUNT = 132
code = '''
    lfs_t lfs;
    lfs_format(&lfs, cfg) => 0;
    lfs_mount(&lfs, cfg) => 0;
    lfs_file_t file;
    lfs_file_open(&lfs, &file, "kitty",
            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
    size_t size = strlen("kittycatcat");
    uint8_t buffer[1024];
    memcpy(buffer, "kittycatcat", size);
    for (int j = 0; j < COUNT; j++) {
        lfs_file_write(&lfs, &file, buffer, size);
    }
    lfs_file_close(&lfs, &file) => 0;
    lfs_unmount(&lfs) => 0;

    lfs_mount(&lfs, cfg) => 0;
    lfs_file_open(&lfs, &file, "kitty", LFS_O_RDWR) => 0;

    size = strlen("hedgehoghog");
    const lfs_soff_t offsets[] = {
        512,
        1024-4,
        512+1,
        1024-4+1,
        512-1,
        1024-4-1,

        512-strlen("kittycatcat"),
        1024-4-strlen("kittycatcat"),
        512-strlen("kittycatcat")+1,
        1024-4-strlen("kittycatcat")+1,
        512-strlen("kittycatcat")-1,
        1024-4-strlen("kittycatcat")-1,

        strlen("kittycatcat")*(COUNT-2)-1,
    };

    for (unsigned i = 0; i < sizeof(offsets) / sizeof(offsets[0]); i++) {
        lfs_soff_t off = offsets[i];
        // write @ offset
        memcpy(buffer, "hedgehoghog", size);
        lfs_file_seek(&lfs, &file, off, LFS_SEEK_SET) => off;
        lfs_file_write(&lfs, &file, buffer, size) => size;

        // read @ offset
        lfs_file_seek(&lfs, &file, off, LFS_SEEK_SET) => off;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer, "hedgehoghog", size) => 0;

        // read @ 0
        lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer, "kittycatcat", size) => 0;

        // read @ offset
        lfs_file_seek(&lfs, &file, off, LFS_SEEK_SET) => off;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer, "hedgehoghog", size) => 0;

        lfs_file_sync(&lfs, &file) => 0;

        // read @ 0
        lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer, "kittycatcat", size) => 0;

        // read @ offset
        lfs_file_seek(&lfs, &file, off, LFS_SEEK_SET) => off;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        memcmp(buffer, "hedgehoghog", size) => 0;
    }

    lfs_file_close(&lfs, &file) => 0;
    lfs_unmount(&lfs) => 0;
'''

# out of bounds seek
[cases.test_seek_out_of_bounds]
defines = [
    {COUNT=132, SKIP=4},
    {COUNT=132, SKIP=128},
    {COUNT=200, SKIP=10},
    {COUNT=200, SKIP=100},
    {COUNT=4,   SKIP=2},
    {COUNT=4,   SKIP=3},
]
code = '''
    lfs_t lfs;
    lfs_format(&lfs, cfg) => 0;
    lfs_mount(&lfs, cfg) => 0;
    lfs_file_t file;
    lfs_file_open(&lfs, &file, "kitty",
            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
    size_t size = strlen("kittycatcat");
    uint8_t buffer[1024];
    memcpy(buffer, "kittycatcat", size);
    for (int j = 0; j < COUNT; j++) {
        lfs_file_write(&lfs, &file, buffer, size);
    }
    lfs_file_close(&lfs, &file) => 0;
    lfs_unmount(&lfs) => 0;
    lfs_mount(&lfs, cfg) => 0;
    lfs_file_open(&lfs, &file, "kitty", LFS_O_RDWR) => 0;

    size = strlen("kittycatcat");
    lfs_file_size(&lfs, &file) => COUNT*size;
    lfs_file_seek(&lfs, &file, (COUNT+SKIP)*size,
            LFS_SEEK_SET) => (COUNT+SKIP)*size;
    lfs_file_read(&lfs, &file, buffer, size) => 0;

    memcpy(buffer, "porcupineee", size);
    lfs_file_write(&lfs, &file, buffer, size) => size;

    lfs_file_seek(&lfs, &file, (COUNT+SKIP)*size,
            LFS_SEEK_SET) => (COUNT+SKIP)*size;
    lfs_file_read(&lfs, &file, buffer, size) => size;
    memcmp(buffer, "porcupineee", size) => 0;

    lfs_file_seek(&lfs, &file, COUNT*size,
            LFS_SEEK_SET) => COUNT*size;
    lfs_file_read(&lfs, &file, buffer, size) => size;
    memcmp(buffer, "\0\0\0\0\0\0\0\0\0\0\0", size) => 0;

    lfs_file_seek(&lfs, &file, -((COUNT+SKIP)*size),
            LFS_SEEK_CUR) => LFS_ERR_INVAL;
    lfs_file_tell(&lfs, &file) => (COUNT+1)*size;

    lfs_file_seek(&lfs, &file, -((COUNT+2*SKIP)*size),
            LFS_SEEK_END) => LFS_ERR_INVAL;
    lfs_file_tell(&lfs, &file) => (COUNT+1)*size;

    lfs_file_close(&lfs, &file) => 0;
    lfs_unmount(&lfs) => 0;
'''

# inline write and seek
[cases.test_seek_inline_write]
defines.SIZE = [2, 4, 128, 132]
code = '''
    lfs_t lfs;
    lfs_format(&lfs, cfg) => 0;
    lfs_mount(&lfs, cfg) => 0;
    lfs_file_t file;
    lfs_file_open(&lfs, &file, "tinykitty",
            LFS_O_RDWR | LFS_O_CREAT) => 0;
    int j = 0;
    int k = 0;

    uint8_t buffer[1024];
    memcpy(buffer, "abcdefghijklmnopqrstuvwxyz", 26);
    for (unsigned i = 0; i < SIZE; i++) {
        lfs_file_write(&lfs, &file, &buffer[j++ % 26], 1) => 1;
        lfs_file_tell(&lfs, &file) => i+1;
        lfs_file_size(&lfs, &file) => i+1;
    }

    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
    lfs_file_tell(&lfs, &file) => 0;
    lfs_file_size(&lfs, &file) => SIZE;
    for (unsigned i = 0; i < SIZE; i++) {
        uint8_t c;
        lfs_file_read(&lfs, &file, &c, 1) => 1;
        c => buffer[k++ % 26];
    }

    lfs_file_sync(&lfs, &file) => 0;
    lfs_file_tell(&lfs, &file) => SIZE;
    lfs_file_size(&lfs, &file) => SIZE;

    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
    for (unsigned i = 0; i < SIZE; i++) {
        lfs_file_write(&lfs, &file, &buffer[j++ % 26], 1) => 1;
        lfs_file_tell(&lfs, &file) => i+1;
        lfs_file_size(&lfs, &file) => SIZE;
        lfs_file_sync(&lfs, &file) => 0;
        lfs_file_tell(&lfs, &file) => i+1;
        lfs_file_size(&lfs, &file) => SIZE;
        if (i < SIZE-2) {
            uint8_t c[3];
            lfs_file_seek(&lfs, &file, -1, LFS_SEEK_CUR) => i;
            lfs_file_read(&lfs, &file, &c, 3) => 3;
            lfs_file_tell(&lfs, &file) => i+3;
            lfs_file_size(&lfs, &file) => SIZE;
            lfs_file_seek(&lfs, &file, i+1, LFS_SEEK_SET) => i+1;
            lfs_file_tell(&lfs, &file) => i+1;
            lfs_file_size(&lfs, &file) => SIZE;
        }
    }

    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
    lfs_file_tell(&lfs, &file) => 0;
    lfs_file_size(&lfs, &file) => SIZE;
    for (unsigned i = 0; i < SIZE; i++) {
        uint8_t c;
        lfs_file_read(&lfs, &file, &c, 1) => 1;
        c => buffer[k++ % 26];
    }

    lfs_file_sync(&lfs, &file) => 0;
    lfs_file_tell(&lfs, &file) => SIZE;
    lfs_file_size(&lfs, &file) => SIZE;

    lfs_file_close(&lfs, &file) => 0;
    lfs_unmount(&lfs) => 0;
'''

# file seek and write with power-loss
[cases.test_seek_reentrant_write]
# must be power-of-2 for quadratic probing to be exhaustive
defines.COUNT = [4, 64, 128]
reentrant = true
defines.POWERLOSS_BEHAVIOR = [
    'LFS_EMUBD_POWERLOSS_NOOP',
    'LFS_EMUBD_POWERLOSS_OOO',
]
code = '''
    lfs_t lfs;
    int err = lfs_mount(&lfs, cfg);
    if (err) {
        lfs_format(&lfs, cfg) => 0;
        lfs_mount(&lfs, cfg) => 0;
    }
    lfs_file_t file;
    uint8_t buffer[1024];
    err = lfs_file_open(&lfs, &file, "kitty", LFS_O_RDONLY);
    assert(!err || err == LFS_ERR_NOENT);
    if (!err) {
        if (lfs_file_size(&lfs, &file) != 0) {
            lfs_file_size(&lfs, &file) => 11*COUNT;
            for (int j = 0; j < COUNT; j++) {
                memset(buffer, 0, 11+1);
                lfs_file_read(&lfs, &file, buffer, 11) => 11;
                assert(memcmp(buffer, "kittycatcat", 11) == 0 ||
                       memcmp(buffer, "doggodogdog", 11) == 0);
            }
        }
        lfs_file_close(&lfs, &file) => 0;
    }

    lfs_file_open(&lfs, &file, "kitty", LFS_O_WRONLY | LFS_O_CREAT) => 0;
    if (lfs_file_size(&lfs, &file) == 0) {
        for (int j = 0; j < COUNT; j++) {
            strcpy((char*)buffer, "kittycatcat");
            size_t size = strlen((char*)buffer);
            lfs_file_write(&lfs, &file, buffer, size) => size;
        }
    }
    lfs_file_close(&lfs, &file) => 0;

    strcpy((char*)buffer, "doggodogdog");
    size_t size = strlen((char*)buffer);

    lfs_file_open(&lfs, &file, "kitty", LFS_O_RDWR) => 0;
    lfs_file_size(&lfs, &file) => COUNT*size;
    // seek and write using quadratic probing to touch all
    // 11-byte words in the file
    lfs_off_t off = 0;
    for (int j = 0; j < COUNT; j++) {
        off = (5*off + 1) % COUNT;
        lfs_file_seek(&lfs, &file, off*size, LFS_SEEK_SET) => off*size;
        lfs_file_read(&lfs, &file, buffer, size) => size;
        assert(memcmp(buffer, "kittycatcat", size) == 0 ||
               memcmp(buffer, "doggodogdog", size) == 0);
        if (memcmp(buffer, "doggodogdog", size) != 0) {
            lfs_file_seek(&lfs, &file, off*size, LFS_SEEK_SET) => off*size;
            strcpy((char*)buffer, "doggodogdog");
            lfs_file_write(&lfs, &file, buffer, size) => size;
            lfs_file_seek(&lfs, &file, off*size, LFS_SEEK_SET) => off*size;
            lfs_file_read(&lfs, &file, buffer, size) => size;
            assert(memcmp(buffer, "doggodogdog", size) == 0);
            lfs_file_sync(&lfs, &file) => 0;
            lfs_file_seek(&lfs, &file, off*size, LFS_SEEK_SET) => off*size;
            lfs_file_read(&lfs, &file, buffer, size) => size;
            assert(memcmp(buffer, "doggodogdog", size) == 0);
        }
    }
    lfs_file_close(&lfs, &file) => 0;

    lfs_file_open(&lfs, &file, "kitty", LFS_O_RDWR) => 0;
    lfs_file_size(&lfs, &file) => COUNT*size;
    for (int j = 0; j < COUNT; j++) {
        lfs_file_read(&lfs, &file, buffer, size) => size;
        assert(memcmp(buffer, "doggodogdog", size) == 0);
    }
    lfs_file_close(&lfs, &file) => 0;
    lfs_unmount(&lfs) => 0;
'''


# test possible overflow/underflow conditions
#
# note these need -fsanitize=undefined to consistently detect
# overflow/underflow conditions

[cases.test_seek_filemax]
code = '''
    lfs_t lfs;
    lfs_format(&lfs, cfg) => 0;
    lfs_mount(&lfs, cfg) => 0;
    lfs_file_t file;
    lfs_file_open(&lfs, &file, "kitty",
            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
    uint8_t buffer[1024];
    strcpy((char*)buffer, "kittycatcat");
    size_t size = strlen((char*)buffer);
    lfs_file_write(&lfs, &file, buffer, size) => size;

    // seek with LFS_SEEK_SET
    lfs_file_seek(&lfs, &file, LFS_FILE_MAX, LFS_SEEK_SET) => LFS_FILE_MAX;

    // seek with LFS_SEEK_CUR
    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_CUR) => LFS_FILE_MAX;

    // the file hasn't changed size, so seek end takes us back to the offset=0
    lfs_file_seek(&lfs, &file, +10, LFS_SEEK_END) => size+10;

    lfs_file_close(&lfs, &file) => 0;
    lfs_unmount(&lfs) => 0;
'''

[cases.test_seek_underflow]
code = '''
    lfs_t lfs;
    lfs_format(&lfs, cfg) => 0;
    lfs_mount(&lfs, cfg) => 0;
    lfs_file_t file;
    lfs_file_open(&lfs, &file, "kitty",
            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
    uint8_t buffer[1024];
    strcpy((char*)buffer, "kittycatcat");
    size_t size = strlen((char*)buffer);
    lfs_file_write(&lfs, &file, buffer, size) => size;

    // underflow with LFS_SEEK_CUR, should error
    lfs_file_seek(&lfs, &file, -(size+10), LFS_SEEK_CUR) => LFS_ERR_INVAL;
    lfs_file_seek(&lfs, &file, -LFS_FILE_MAX, LFS_SEEK_CUR) => LFS_ERR_INVAL;
    lfs_file_seek(&lfs, &file, -(size+LFS_FILE_MAX), LFS_SEEK_CUR)
            => LFS_ERR_INVAL;

    // underflow with LFS_SEEK_END, should error
    lfs_file_seek(&lfs, &file, -(size+10), LFS_SEEK_END) => LFS_ERR_INVAL;
    lfs_file_seek(&lfs, &file, -LFS_FILE_MAX, LFS_SEEK_END) => LFS_ERR_INVAL;
    lfs_file_seek(&lfs, &file, -(size+LFS_FILE_MAX), LFS_SEEK_END)
            => LFS_ERR_INVAL;

    // file pointer should not have changed
    lfs_file_tell(&lfs, &file) => size;

    lfs_file_close(&lfs, &file) => 0;
    lfs_unmount(&lfs) => 0;
'''

[cases.test_seek_overflow]
code = '''
    lfs_t lfs;
    lfs_format(&lfs, cfg) => 0;
    lfs_mount(&lfs, cfg) => 0;
    lfs_file_t file;
    lfs_file_open(&lfs, &file, "kitty",
            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
    uint8_t buffer[1024];
    strcpy((char*)buffer, "kittycatcat");
    size_t size = strlen((char*)buffer);
    lfs_file_write(&lfs, &file, buffer, size) => size;

    // seek to LFS_FILE_MAX
    lfs_file_seek(&lfs, &file, LFS_FILE_MAX, LFS_SEEK_SET) => LFS_FILE_MAX;

    // overflow with LFS_SEEK_CUR, should error
    lfs_file_seek(&lfs, &file, +10, LFS_SEEK_CUR) => LFS_ERR_INVAL;
    lfs_file_seek(&lfs, &file, +LFS_FILE_MAX, LFS_SEEK_CUR) => LFS_ERR_INVAL;

    // LFS_SEEK_SET/END don't care about the current file position, but we can
    // still overflow with a large offset

    // overflow with LFS_SEEK_SET, should error
    lfs_file_seek(&lfs, &file,
            +((uint32_t)LFS_FILE_MAX+10),
            LFS_SEEK_SET) => LFS_ERR_INVAL;
    lfs_file_seek(&lfs, &file,
            +((uint32_t)LFS_FILE_MAX+(uint32_t)LFS_FILE_MAX),
            LFS_SEEK_SET) => LFS_ERR_INVAL;

    // overflow with LFS_SEEK_END, should error
    lfs_file_seek(&lfs, &file, +(LFS_FILE_MAX-size+10), LFS_SEEK_END)
            => LFS_ERR_INVAL;
    lfs_file_seek(&lfs, &file, +(LFS_FILE_MAX-size+LFS_FILE_MAX), LFS_SEEK_END)
            => LFS_ERR_INVAL;

    // file pointer should not have changed
    lfs_file_tell(&lfs, &file) => LFS_FILE_MAX;

    lfs_file_close(&lfs, &file) => 0;
    lfs_unmount(&lfs) => 0;
'''