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From: allbery@ncoast.UUCP (Brandon Allbery)
Newsgroups: net.unix
Subject: if (pointer) command
Message-ID: <1427@ncoast.UUCP>
Date: Fri, 5-Sep-86 18:18:10 EDT
Article-I.D.: ncoast.1427
Posted: Fri Sep  5 18:18:10 1986
Date-Received: Sat, 6-Sep-86 20:33:49 EDT
References: <3325@brl-smoke.ARPA> <241@bsdpkh.UUCP> <1170@ttrdc.UUCP>
Reply-To: allbery@ncoast.UUCP (Brandon Allbery)
Followup-To: net.unix
Organization: Cleveland Public Access UNIX (ncoast), Cleveland, OH
Lines: 37
Summary: potential problems

Quoted from <1170@ttrdc.UUCP> ["Re: strdup"], by levy@ttrdc.UUCP (Daniel R. Levy)...
+---------------
| In article <241@bsdpkh.UUCP>, heff@bsdpkh.UUCP (Paul K Heffner) writes:
| 
| >> /* hjb 08/25/86 */
| >> char * strdup(s)
| >> char *s;
| >> {
| >> 	char *p;
| >> 	extern char *malloc();
| >> 	if(p=malloc(strlen(s)+1)) strcpy(p,s);
| >> 	return p;
| >> }
| 
| >The above code doesn't return a null if malloc fails
| 
| It DOESN'T???  Gee, then maybe you have a busted malloc().  If malloc()
| fails, it should return the null pointer.  That is what is being tested in
| the clause 'if(p=malloc(strlen(s)+1))'.  As so many people have expounded
| in net.lang.c:  a null pointer is semantically the same as zero in the C
| language (except for sizeof(), should pointers exist of sizes other than
| sizeof(int)).
+---------------

But if a pointer is 4 bits and an int is 2 bits (some 68000 implementations),
you'll get spurious failures if the pointer returned by malloc is a multiple
of 0x10000!

++Brandon
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