• Jonathan Wilkes's avatar
    get rid of undefined behavior in union member mismatch for $@ · 9d30a7cd
    Jonathan Wilkes authored
    The code for $@ depends on reading a_w.w_symbol values, but the other
    A_DOLLAR branch (i.e., for $1 - $n) depend on reading a_w.w_index.
    
    So for the conditional at the top of binbuf_eval, this means that any
    normal A_DOLLAR that has its a_w.w_index set is actually trying to read
    a_w.w_symbol. On a 64-bit arch with certain compilers, this will result
    in a read of uninitalized data in the padding of the part of w_symbol
    that exceeds the sizeof(int).
    
    The workaround here is to define a sentinel value DOLLARALL to a negative
    int unlikely to ever be used in real A_DOLLAR values. We then use DOLLARALL
    to mean the "@" in "$@" so we can create a special branch for it in the
    parser.
    
    One consequence-- we probably need to add a special case error when
    this value is out of range. So rather than confusing the user with the
    mysterious negative value of DOLLARALL we print "$@" for them. (Currently,
    the only place I can see this happening is when "$@" is used as the
    target for a Pd message.)
    9d30a7cd
m_binbuf.c 60.1 KB