Function lseek

components/dfs/dfs_v1/src/dfs_posix.c:287–334

* this function is a POSIX compliant version, which will Reposition the file offset for * an open file descriptor. * * The `lseek` function sets the file offset for the file descriptor `fd` * to a new value, determined by the `offset` and `whence` parameters. * It can be used to seek to specific positions in a file for reading or writing. * * @param fd the file descriptor. * @param offset

 * @return the resulting read/write position in the file, or -1 on failed.
 */
off_t lseek(int fd, off_t offset, int whence)
{
    int result;
    struct dfs_file *d;

    d = fd_get(fd);
    if (d == NULL)
    {
        rt_set_errno(-EBADF);

        return -1;
    }

    switch (whence)
    {
    case SEEK_SET:
        break;

    case SEEK_CUR:
        offset += d->pos;
        break;

    case SEEK_END:
        offset += d->vnode->size;
        break;

    default:
        rt_set_errno(-EINVAL);

        return -1;
    }

    if (offset < 0)
    {
        rt_set_errno(-EINVAL);

        return -1;
    }
    result = dfs_file_lseek(d, offset);
    if (result < 0)
    {
        rt_set_errno(result);

        return -1;
    }

    return offset;
}
RTM_EXPORT(lseek);

#ifndef _WIN32