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From: andreas@hpcvlx.cv.hp.com (Jim Andreas)
Newsgroups: comp.sys.hp
Subject: Re: Re: X11R4 under HP-UX 7.0
Message-ID: <101950110@hpcvlx.cv.hp.com>
Date: 18 Mar 90 00:31:14 GMT
References: <1990Mar2.185840.24495@arnor.uucp>
Organization: Hewlett-Packard Co., Corvallis, OR, USA
Lines: 39

Regarding the:

    cannot perform realloc

problem in clients in MIT X11R4:

Yes the True Answer is to define MALLOC_0_RETURNS_NULL
when you compile your libs.  Here is the relevant code
fragment from Xlibos.h in MIT X11R4 (./mit/lib/X/Xlibos.h):

/*
 * Note that some machines do not return a valid pointer for malloc(0), in
 * which case we provide an alternate under the control of the
 * define MALLOC_0_RETURNS_NULL.  This is necessary because some
 * Xlib code expects malloc(0) to return a valid pointer to storage.
 */
#ifdef MALLOC_0_RETURNS_NULL

# define Xmalloc(size) malloc(((size) > 0 ? (size) : 1))
# define Xrealloc(ptr, size) realloc((ptr), ((size) > 0 ? (size) : 1))
# define Xcalloc(nelem, elsize) calloc(((nelem) > 0 ? (nelem) : 1), (elsize))

#else

# define Xmalloc(size) malloc((size))
# define Xrealloc(ptr, size) realloc((ptr), (size))
# define Xcalloc(nelem, elsize) calloc((nelem), (elsize))

#endif
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