/*
 *	vii - buffer and display output
 *	Copyright (C) 1991-1995, 1999, 2005 Peter Miller
 *
 *	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/errno.h>
#include <ac/signal.h>
#include <ac/stddef.h>
#include <ac/stdlib.h>
#include <ac/string.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 <setjmp.h>

static jmp_buf	aix_bungy;


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

static void aix_danger _((int));

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

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

static int aix_touch _((void *, size_t));

static int
aix_touch(vp, nbytes)
	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(n)
	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(n)
	size_t		n;
{
	void		*cp;

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


void *
mem_change_size(cp, n)
	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(cp)
	void		*cp;
{
	free(cp);
}


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

	cp = mem_alloc(strlen(s) + 1);
	strcpy(cp, s);
	return cp;
}