m_malloc.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 1996, by Sun Microsystems, Inc.
* All rights reserved.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* MKS interface extension.
* Ensure that errno is set if malloc() fails.
*
* Copyright 1992 by Mortice Kern Systems Inc. All rights reserved.
*
*/
#ifdef M_RCSID
#ifndef lint
#endif /*lint*/
#endif /*M_RCSID*/
#include <mks.h>
#include <errno.h>
#include <stdlib.h>
#ifdef __STDC__
#define _VOID void
#else
#define _VOID char
#endif
/*f
* m_malloc:
* Portable replacement for malloc().
* If malloc() fails (e.g returns NULL)
* then return ENOMEM unless malloc() sets errno for us on this system
* and ensure malloc(0) returns a non-NULL pointer.
*
*/
{
/*l
* Prob 1:
* ANSI does not insist setting errno when malloc() fails.
* But UNIX existing practice (which MKS relies on) always returns
* an errno when malloc() fails.
* Thus, on systems that implement malloc() where an errno is not
* returned, we set ENOMEM.
*
* Note: we don't care about previous value of errno since
* POSIX.1 (Section 2.4) says you can only look at errno
* after a function returns a status indicating an error.
* (and the function explicitly states an errno value can be
* returned - Well, m_malloc() is so stated.)
*
* Prob 2:
* MKS code seems to rely on malloc(0) returning a valid pointer.
* This allows it to realloc() later when actual size is determined.
*
* According to ANSI (4.10.3 line 18-19) the result of malloc(0) is
* implementation-defined.
*/
errno = 0;
if (amount == 0) {
/*
* confirm we are really out of memory
*/
return (m_malloc(1));
}
if (errno==0) {
/*
* ensure errno is always set
*/
}
}
return (ptr);
}