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mem.cc

/*
 *    tardy - a tar post-processor
 *    Copyright (C) 1991-1995, 1998-1999, 2001 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 <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 = ENOMEM;
      cp = malloc(n);
      if (!cp)
            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 = ENOMEM;
      if (!cp)
            cp = malloc(n);
      else
            cp = realloc(cp, n);
      if (!cp)
            nfatal("realloc");
      return cp;
}


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


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

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

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