paging.h

/*
 * DUMA - Red-Zone memory allocator.
 * Copyright (C) 2002-2009 Hayati Ayguen <h_ayguen@web.de>, Procitec GmbH
 * Copyright (C) 2006 Michael Eddington <meddington@gmail.com>
 * Copyright (C) 1987-1999 Bruce Perens <bruce@perens.com>
 * License: GNU GPL (GNU General Public License, see COPYING-GPL)
 *
 * 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  02111-1307  USA
 *
 *
 * FILE CONTENTS:
 * internal implementation file
 * contains system/platform dependent paging functions
 */

#ifndef DUMA_PAGING_H
#define DUMA_PAGING_H

/*
 * Lots of systems are missing the definition of PROT_NONE.
 */
#ifndef PROT_NONE
#define PROT_NONE 0
#endif

/*
 * 386 BSD has MAP_ANON instead of MAP_ANONYMOUS.
 */
#if (!defined(MAP_ANONYMOUS) && defined(MAP_ANON))
#define MAP_ANONYMOUS MAP_ANON
#endif

/* declarations */
#include "print.h"

/*
 * For some reason, I can't find mprotect() in any of the headers on
 * IRIX or SunOS 4.1.2
 */
/* extern C_LINKAGE int mprotect(void * addr, size_t len, int prot); */

#if !defined(WIN32)
static void *startAddr = (void *)0;
#endif

/* Function: stringErrorReport
 *
 * Get formatted error string and return.  For WIN32
 * FormatMessage is used, strerror all else.
 */
static const char *stringErrorReport(void) {
#if defined(WIN32)
  DWORD LastError;
  LPVOID lpMsgBuf;

  LastError = GetLastError();
  FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
                    FORMAT_MESSAGE_IGNORE_INSERTS,
                NULL, LastError,
                MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT) /* Default language */
                ,
                (LPTSTR)&lpMsgBuf, 0, NULL);
  return (char *)lpMsgBuf; /* "Unknown error.\n"; */
#else
#ifndef DUMA_NO_STRERROR
  static int failing;

  if (!failing) {
    const char *str;

    failing++;
    str = strerror(errno);
    failing--;

    if (str != NULL)
      return str;
  }
#endif

  return DUMA_strerror(errno);
#endif
}

/* Function: mprotectFailed
 *
 * Report that VirtualProtect or mprotect failed and abort
 * program execution.
 */
static void mprotectFailed(void) {
#if defined(WIN32)
  DUMA_Abort("VirtualProtect() failed: %s", stringErrorReport());
#else
  DUMA_Abort("mprotect() failed: %s.\nCheck README section 'MEMORY USAGE AND "
             "EXECUTION SPEED'\n  your (Linux) system may limit the number of "
             "different page mappings per process",
             stringErrorReport());
#endif
}

/* Function: Page_Create
 *
 * Create memory.  Allocates actual memory. Uses
 * VirtualAlloc on windows and mmap on unix.
 *
 * See Also:
 *  <Page_Delete>
 */
static void *Page_Create(size_t size, int exitonfail, int printerror) {
  void *allocation;

#if defined(WIN32)

  allocation =
      VirtualAlloc(NULL /* address of region to reserve or commit */
                   ,
                   (DWORD)size /* size of region */
                   ,
                   (DWORD)MEM_COMMIT /* type of allocation */
                   ,
                   (DWORD)PAGE_READWRITE /* type of access protection */
      );

  if ((void *)0 == allocation) {
    if (exitonfail)
      DUMA_Abort("VirtualAlloc(%d) failed: %s", (DUMA_SIZE)size,
                 stringErrorReport());
    else if (printerror)
      DUMA_Print("\nDUMA warning: VirtualAlloc(%d) failed: %s", (DUMA_SIZE)size,
                 stringErrorReport());
  }

#elif defined(MAP_ANONYMOUS)

  /*
   * In this version, "startAddr" is a _hint_, not a demand.
   * When the memory I map here is contiguous with other
   * mappings, the allocator can coalesce the memory from two
   * or more mappings into one large contiguous chunk, and thus
   * might be able to find a fit that would not otherwise have
   * been possible. I could _force_ it to be contiguous by using
   * the MMAP_FIXED flag, but I don't want to stomp on memory mappings
   * generated by other software, etc.
   */
  allocation = mmap(startAddr, (int)size, PROT_READ | PROT_WRITE,
                    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

#ifndef __hpux
  /*
   * Set the "address hint" for the next mmap() so that it will abut
   * the mapping we just created.
   *
   * HP/UX 9.01 has a kernel bug that makes mmap() fail sometimes
   * when given a non-zero address hint, so we'll leave the hint set
   * to zero on that system. HP recently told me this is now fixed.
   * Someone please tell me when it is probable to assume that most
   * of those systems that were running 9.01 have been upgraded.
   */
  startAddr = allocation + size;
#endif

  if (allocation == (void *)-1) {
    allocation = (void *)0;
    if (exitonfail)
      DUMA_Abort("mmap(%d) failed: %s", (DUMA_SIZE)size, stringErrorReport());
    else if (printerror)
      DUMA_Print("\nDUMA warning: mmap(%d) failed: %s", (DUMA_SIZE)size,
                 stringErrorReport());
  }

#else
  static int devZeroFd = -1;

  if (devZeroFd == -1) {
    devZeroFd = open("/dev/zero", O_RDWR);
    if (devZeroFd < 0)
      DUMA_Abort("open() on /dev/zero failed: %s", stringErrorReport());
  }

  /*
   * In this version, "startAddr" is a _hint_, not a demand.
   * When the memory I map here is contiguous with other
   * mappings, the allocator can coalesce the memory from two
   * or more mappings into one large contiguous chunk, and thus
   * might be able to find a fit that would not otherwise have
   * been possible. I could _force_ it to be contiguous by using
   * the MMAP_FIXED flag, but I don't want to stomp on memory mappings
   * generated by other software, etc.
   */
  allocation = mmap(startAddr, (int)size, PROT_READ | PROT_WRITE, MAP_PRIVATE,
                    devZeroFd, 0);

  startAddr = allocation + size;

  if (allocation == (void *)-1) {
    allocation = (void *)0;
    if (exitonfail)
      DUMA_Abort("mmap(%d) failed: %s", (DUMA_SIZE)size, stringErrorReport());
    else if (printerror)
      DUMA_Print("\nDUMA warning: mmap(%d) failed: %s", (DUMA_SIZE)size,
                 stringErrorReport());
  }

#endif

  // TESTING
  //  memset((void*)allocation, 0, startAddr);

  return (void *)allocation;
}

/* Function: Page_AllowAccess
 *
 * Allow memory access to allocated memory.
 *
 * See Also:
 *  <Page_DenyAccess>
 */
void Page_AllowAccess(void *address, size_t size) {
#if defined(WIN32)
  SIZE_T OldProtect, retQuery;
  MEMORY_BASIC_INFORMATION MemInfo;
  size_t tail_size;
  BOOL ret;

  while (size > 0) {
    retQuery = VirtualQuery(address, &MemInfo, sizeof(MemInfo));
    if (retQuery < sizeof(MemInfo))
      DUMA_Abort("VirtualQuery() failed\n");
    tail_size = (size > MemInfo.RegionSize) ? MemInfo.RegionSize : size;
    ret = VirtualProtect(
        (LPVOID)address /* address of region of committed pages */
        ,
        (DWORD)tail_size /* size of the region */
        ,
        (DWORD)PAGE_READWRITE /* desired access protection */
        ,
        (PDWORD)&OldProtect /* address of variable to get old protection */
    );
    if (0 == ret)
      mprotectFailed();

    address = ((char *)address) + tail_size;
    size -= tail_size;
  }

#else
  if (mprotect(address, size, PROT_READ | PROT_WRITE) < 0)
    mprotectFailed();
#endif
}

/* Function: Page_DenyAccess
 *
 * Deny access to allocated memory region.
 *
 * See Also:
 *  <Page_AllowAccess>
 */
static void Page_DenyAccess(void *address, size_t size) {
#if defined(WIN32)
  SIZE_T OldProtect, retQuery;
  MEMORY_BASIC_INFORMATION MemInfo;
  size_t tail_size;
  BOOL ret;

  while (size > 0) {
    retQuery = VirtualQuery(address, &MemInfo, sizeof(MemInfo));
    if (retQuery < sizeof(MemInfo))
      DUMA_Abort("VirtualQuery() failed\n");
    tail_size = (size > MemInfo.RegionSize) ? MemInfo.RegionSize : size;
    ret = VirtualProtect(
        (LPVOID)address /* address of region of committed pages */
        ,
        (DWORD)tail_size /* size of the region */
        ,
        (DWORD)PAGE_NOACCESS /* desired access protection */
        ,
        (PDWORD)&OldProtect /* address of variable to get old protection */
    );
    if (0 == ret)
      mprotectFailed();

    address = ((char *)address) + tail_size;
    size -= tail_size;
  }

#else
  if (mprotect(address, size, PROT_NONE) < 0)
    mprotectFailed();
#endif
}

/* Function: Page_Delete
 *
 * Free's DUMA allocated memory.  This is the real deal, make sure
 * the page is no longer in our slot list first!
 *
 * See Also:
 *  <Page_Create>
 */
static void Page_Delete(void *address, size_t size) {
#if defined(WIN32)

  void *alloc_address = address;
  SIZE_T retQuery;
  MEMORY_BASIC_INFORMATION MemInfo;
  BOOL ret;

  /* release physical memory commited to virtual address space */
  while (size > 0) {
    retQuery = VirtualQuery(address, &MemInfo, sizeof(MemInfo));

    if (retQuery < sizeof(MemInfo))
      DUMA_Abort("VirtualQuery() failed\n");

    if (MemInfo.State == MEM_COMMIT) {
      ret =
          VirtualFree((LPVOID)MemInfo.BaseAddress /* base of committed pages */
                      ,
                      (DWORD)MemInfo.RegionSize /* size of the region */
                      ,
                      (DWORD)MEM_DECOMMIT /* type of free operation */
          );

      if (0 == ret)
        DUMA_Abort("VirtualFree(,,MEM_DECOMMIT) failed: %s",
                   stringErrorReport());
    }

    address = ((char *)address) + MemInfo.RegionSize;
    size -= MemInfo.RegionSize;
  }

  /* release virtual address space */
  ret = VirtualFree((LPVOID)alloc_address, (DWORD)0, (DWORD)MEM_RELEASE);

  if (0 == ret)
    DUMA_Abort("VirtualFree(,,MEM_RELEASE) failed: %s", stringErrorReport());

#else

  if (munmap(address, size) < 0)
    Page_DenyAccess(address, size);

#endif
}

/* Function: Page_Size
 *
 * Retrieve page size.
 */
static size_t Page_Size(void) {
#if defined(WIN32)
  SYSTEM_INFO SystemInfo;
  GetSystemInfo(&SystemInfo);
  return (size_t)SystemInfo.dwPageSize;
#elif defined(_SC_PAGESIZE)
  return (size_t)sysconf(_SC_PAGESIZE);
#elif defined(_SC_PAGE_SIZE)
  return (size_t)sysconf(_SC_PAGE_SIZE);
#else
  return getpagesize();
#endif
}

#endif /* DUMA_PAGING_H */