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From: RIZZI@USC-ISIB.ARPA
Newsgroups: mod.computers.vax
Subject: Dereferencing NULL pointer in C
Message-ID: <8602020523.AA28338@ucbvax.berkeley.edu>
Date: Fri, 31-Jan-86 03:48:49 EST
Article-I.D.: ucbvax.8602020523.AA28338
Posted: Fri Jan 31 03:48:49 1986
Date-Received: Sun, 2-Feb-86 11:52:54 EST
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	I am porting a UNIX application written in C to VAX/VMS.
Aside from file name translation, the biggest problem I have
is in dealing with code that blithely dereferences NULL pointers,
expecting a zero or null string. My understanding is that UNIX
allows this, however VMS insists on an access violation which
is disastrous. Not only does much of the application code ignore
NULL pointers, but the VAX/VMS C runtime library does as well!!
printf() and strcpy() among others are easily convinced to crash
and burn.

	I have been able to catch the SIGBUS signal, using both
signal() and sigvec() (VMS-specific), but have not been able to ignore
it or return from my handler without a stack trace and program exit.
I suspect that some mucking about with the sigcontext structure
that arrives with a sigvec()-style signal might produce better
results, but I am reluctant to attempt this.

	Is there someway available to recover from or ignore
the SIGBUS signal or am I fated to pore thousands of lines of
code in search of potential NULL pointer dereferences??

	Thanks,

		Bill 

ARPA: RIZZI@ISIB
UUCP: cca!ima!ism780b!billr
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