/*
 *	aegis - project change supervisor
 *	Copyright (C) 1991-1994, 1999, 2002, 2003 Peter Miller;
 *	All rights reserved.
 *
 *	This program is free software; you can redistribute it and/or modify
 *	it under the terms of the GNU General Public License as published by
 *	the Free Software Foundation; either version 2 of the License, or
 *	(at your option) any later version.
 *
 *	This program is distributed in the hope that it will be useful,
 *	but WITHOUT ANY WARRANTY; without even the implied warranty of
 *	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *	GNU General Public License for more details.
 *
 *	You should have received a copy of the GNU General Public License
 *	along with this program; if not, write to the Free Software
 *	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 * MANIFEST: functions to manipulate dynamic memory
 */

#include <ac/stddef.h>
#include <ac/string.h>
#include <ac/stdlib.h>
#include <ac/errno.h>

#include <mem.h>
#include <error.h>


#ifdef _AIX

/*
 * Yet another AIX stupidity:
 * malloc does not guarantee that the space is available in swap.
 */

#include <ac/signal.h>
#include <setjmp.h>

static jmp_buf  aix_bungy;


/*
 * Catch SIGDANGER and longjmp to aix_touch.
 */

static void
aix_danger(int n)
{
    longjmp(aix_bungy, 1);
}

/*
 * Touch the pages that cover [p, p+nbytes-1].
 */

static int
aix_touch(void *vp, size_t nbytes)
{
    char            *p;
    char            *endp;
    int             pgsize;
    volatile char   c;
    void            (*oldsig)(int);

    oldsig = signal(SIGDANGER, aix_danger);
    if (setjmp(aix_bungy))
    {
	signal(SIGDANGER, oldsig);
	return -1;
    }

    /*
     * A load is enough to cause the
     * allocation of the paging space
     */
    p = vp;
    pgsize = getpagesize();
    endp = p + nbytes;
    while (p < endp)
    {
	c = *(volatile char *)p;
	p += pgsize;
    }

    /*
     * restore the signal handler
     */
    signal(SIGDANGER, oldsig);
    return 0;
}

#endif


/*
 *  NAME
 *	mem_alloc - allocate memory
 *
 *  SYNOPSIS
 *	char *mem_alloc(size_t n);
 *
 *  DESCRIPTION
 *	mem_alloc uses malloc to allocate the required sized chunk of memory.
 *	If any error is returned from malloc() an fatal diagnostic is issued.
 *
 *  CAVEAT
 *	It is the responsibility of the caller to ensure that the space is
 *	freed when finished with, by a call to free().
 */

void *
mem_alloc(size_t n)
{
    void            *cp;

    if (n < 1)
	n = 1;
    errno = 0;
    cp = malloc(n);
    if (!cp)
    {
	if (!errno)
	    errno = ENOMEM;
	nfatal("malloc");
    }
#ifdef _AIX
    /*
     * watch out for AIX stupidity
     */
    if (aix_touch(cp, n))
    {
	errno = ENOMEM;
	nfatal("malloc");
    }
#endif
    return cp;
}


/*
 *  NAME
 *	mem_alloc_clear - allocate and clear memory
 *
 *  SYNOPSIS
 *	char *mem_alloc_clear(size_t n);
 *
 *  DESCRIPTION
 *	mem_alloc_clear uses malloc to allocate the required sized chunk
 *	of memory.  If any error is returned from malloc() an fatal
 *	diagnostic is issued.  The memory is zeroed befor it is returned.
 *
 *  CAVEAT
 *	It is the responsibility of the caller to ensure that the space is
 *	freed when finished with, by a call to free().
 */

void *
mem_alloc_clear(size_t n)
{
    void            *cp;

    cp = mem_alloc(n);
    memset(cp, 0, n);
    return cp;
}


void *
mem_change_size(void *cp, size_t n)
{
    if (n < 1)
	n = 1;
    errno = 0;
    if (!cp)
	cp = malloc(n);
    else
	cp = realloc(cp, n);
    if (!cp)
    {
	if (!errno)
	    errno = ENOMEM;
	nfatal("realloc");
    }
    return cp;
}


void
mem_free(void *cp)
{
    free(cp);
}


char *
mem_copy_string(const char *s)
{
    char            *cp;

    if (s)
    {
	cp = (char *)mem_alloc(strlen(s) + 1);
	strcpy(cp, s);
    }
    else
    {
	cp = (char *)mem_alloc(1);
	*cp = 0;
    }
    return cp;
}
