[TALK] Proving fundamental Unix guarantees

Peter Jeremy peter.jeremy at alcatel.com.au
Mon Jun 30 11:44:16 EST 2003

This may be a bit too work-related for this list, but anyway:

In response to a query, one of our Unix vendors has stated
"OS-name-deleted-to-protect-the-guilty does not guarantee that all
memory given to a program is necessarily initialised" and "there are
regions known as BSS which hold data (i.e. program variables) which
ARE NOT INITIALISED.  What this means is that these variables will
hold whatever was in that memory location before it was allocated to
them. ...  This is designed behaviour".

This is, of course, nonsense - Unix does guarantee that all memory
handed to userland by the kernel _is_ initialised - either from a disk
image (for text, data) or to zero (for bss).  My problem is that this
is such a fundamental assumption that it's hard to find this statement
written down.  Having searched the relevant vendor's on-line
documentation, I can only find two indirect references to bss being
initialised to zero.

Can anyone point me to online POSIX or SVID documents where this is
stated as a requirement?


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