that this provokes. "Wherever possible" means "In the kernel OR NOT
C++" (implying C).
There are places where (void *) pointers are not valid, such as for
function pointers, but in the special case of (void *)0, agreement
settles on it being OK.
Most of the fixes were NULL where an integer zero was needed; many
of the fixes were NULL where ascii <nul> ('\0') was needed, and a
few were just "other".
Tested on: i386 sparc64
but *only* for the kernel. We can do this because the kernel is not a
standard C application environment. This would have stopped the recent
mtx_* arg NULL/MTX_DEF mixups from going unnoticed for so long.
this definition. It fixes gnome for starters. I haven't tried *emacs yet.
Like IA64, amd64 uses registers for the first few arguments and then
the stack for the rest. This means the 64 bit promotion of the NULL (0)
value is lost and its just pushed on as an 'int' in a varargs call.
When the consumer walks the list and expects to pull off void * pointers
via va_arg, then all hell breaks loose.
Marcel: thanks a million for finding this!
an int constant to a long constant. This change improves consistency
in the following two ways:
1. The first 8 arguments are always passed in registers on ia64, which
by virtue of the generated code implicitly widens ints to longs and
allows the use of an 32-bit integral type for 64-bit arguments.
Subsequent arguments are passed onto the memory stack, which does
not exhibit the same behaviour and consequently do not allow this.
In practice this means that variadic functions taking pointers
and given NULL (without cast) work as long as the NULL is passed
in one of the first 8 arguments. A SIGSEGV is more likely the
result if such would be done for stack-based arguments. This is
due to the fact that the upper 4 bytes remain undefined.
2. All 64-bit platforms that FreeBSD supports, with the obvious
exception of ia64, allow 32-bit integral types (specifically NULL)
when 64-bit pointers are expected in variadic functions by way of
how the compiler generates code. As such, code that works correctly
(whether rightfully so or not) on any platform other than ia64, may
fail on ia64.
To more easily allow tweaking of the definition of NULL, this commit
removes the 12 definitions in the various headers and puts it in a
new header that can be included whenever NULL is to be made visible.
This commit fixes GNOME, emacs, xemacs and a whole bunch of ports
that I don't particularly care about at this time...
