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unixgc.c

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is the Netscape Portable Runtime (NSPR).
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998-2000
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#include "prlock.h"
#include "prlog.h"
#include "prmem.h"
#include "gcint.h"

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>

#define _PR_GC_VMBASE 0x40000000

#if defined(SOLARIS)
#define _MD_MMAP_FLAGS MAP_SHARED
#elif defined(RELIANTUNIX)
#define _MD_MMAP_FLAGS MAP_PRIVATE|MAP_FIXED
#else
#define _MD_MMAP_FLAGS MAP_PRIVATE
#endif

static PRInt32 zero_fd = -1;
static PRLock *zero_fd_lock = NULL;

void _MD_InitGC(void)
{
#ifdef DEBUG
    /*
     * Disable using mmap(2) if NSPR_NO_MMAP is set
     */
    if (getenv("NSPR_NO_MMAP")) {
        zero_fd = -2;
        return;
    }
#endif
    zero_fd = open("/dev/zero",O_RDWR , 0);
    zero_fd_lock = PR_NewLock();
}

/* This static variable is used by _MD_GrowGCHeap and _MD_ExtendGCHeap */
static void *lastaddr = (void*) _PR_GC_VMBASE;

void *_MD_GrowGCHeap(PRUint32 *sizep)
{
      void *addr;
      PRUint32 size;

      size = *sizep;

      PR_Lock(zero_fd_lock);
      if (zero_fd < 0) {
            goto mmap_loses;
      }

      /* Extend the mapping */
      addr = mmap(lastaddr, size, PROT_READ|PROT_WRITE|PROT_EXEC,
          _MD_MMAP_FLAGS,
          zero_fd, 0);
      if (addr == (void*)-1) {
            zero_fd = -1;
            goto mmap_loses;
      }
      lastaddr = ((char*)addr + size);
#ifdef DEBUG
      PR_LOG(_pr_msgc_lm, PR_LOG_WARNING,
          ("GC: heap extends from %08x to %08x\n",
          _PR_GC_VMBASE,
          _PR_GC_VMBASE + (char*)lastaddr - (char*)_PR_GC_VMBASE));
#endif
      PR_Unlock(zero_fd_lock);
      return addr;

mmap_loses:
      PR_Unlock(zero_fd_lock);
      return PR_MALLOC(size);
}

/* XXX - This is disabled.  MAP_FIXED just does not work. */
#if 0
PRBool _MD_ExtendGCHeap(char *base, PRInt32 oldSize, PRInt32 newSize) {
      PRBool rv = PR_FALSE;
      void* addr;
      PRInt32 allocSize = newSize - oldSize;

      PR_Lock(zero_fd_lock);
      addr = mmap(base + oldSize, allocSize, PROT_READ|PROT_WRITE|PROT_EXEC,
          _MD_MMAP_FLAGS | MAP_FIXED, zero_fd, 0);
      if (addr == (void*)-1) {
            goto loser;
      }
      if (addr != (void*) (base + oldSize)) {
            munmap(base + oldSize, allocSize);
            goto loser;
      }
      lastaddr = ((char*)base + newSize);
      PR_LOG(_pr_msgc_lm, PR_LOG_ALWAYS,
          ("GC: heap now extends from %p to %p",
          base, base + newSize));
      rv = PR_TRUE;

loser:
      PR_Unlock(zero_fd_lock);
      return rv;
}
#else
PRBool _MD_ExtendGCHeap(char *base, PRInt32 oldSize, PRInt32 newSize) {
      return PR_FALSE;
}
#endif

void _MD_FreeGCSegment(void *base, PRInt32 len)
{
      if (zero_fd < 0) {
            PR_DELETE(base);
      } else {
            (void) munmap(base, len);
      }
}

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