🚀 go-pugleaf

In article <1993Jan7.145117.8220@jarvis.csri.toronto.edu> flaps@dgp.toronto.edu (Alan J Rosenthal) writes:
>steve@taumet.com (Steve Clamage) writes:
>>An implementation is allowed to add padding to the end of a struct.
>>Suppose that the implementation adds space to the end of each struct
>>type where it encodes information used for run-time error checking.
>
>Can't do that... what happens when you malloc one of them?
>
>	struct whatever *p = (struct whatever *)malloc(sizeof(struct whatever));
>
>Immediately after the malloc, if p is not null you can start using the struct,
>but it won't have that run-time-error-checking information, so it will fault.

I don't know whether or not implementations are allowed to
do what Steve is suggesting here, but I don't think this
is a reason why it couldn't. Couldn't the compiler, as part
of the code it emits to convert the (void *) returned by
malloc also emit instructions to set up the information that
Steve is postulating here? Or is there language in the the
standard that forbids a conversion from one pointer type to
another to affect the block of memory to which this pointer 
points?


-- 
Dave Eisen                               Sequoia Peripherals: (415) 967-5644
dkeisen@leland.Stanford.EDU              Home:                (415) 321-5154
       There's something in my library to offend everybody. 
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