NAME
    Lock -- Lock a directory or file

SYNOPSIS
    lock  = Lock( name, accessMode )
    D0            D1        D2

    BPTR Lock(STRPTR, LONG)

FUNCTION
    A filing system lock on the file or directory 'name' is returned if
    possible.

    If the accessMode is ACCESS_READ, the lock is a shared read lock;
    if the accessMode is ACCESS_WRITE then it is an exclusive write
    lock.  Do not use random values for mode.

    If Lock() fails (that is, if it cannot obtain a filing system lock
    on the file or directory) it returns a zero.

    Tricky assumptions about the internal format of a lock are unwise,
    as are any attempts to use the fl_Link or fl_Access fields.

INPUTS
    name       - pointer to a null-terminated string
    accessMode - integer

RESULTS
    lock - BCPL pointer to a lock

SEE ALSO
    UnLock(), DupLock(), ChangeMode(), NameFromLock(), DupLockFromFH()