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/* java_nio_MappedByteBufferImpl.c - Native methods for MappedByteBufferImpl

   Copyright (C) 2004, 2005, 2006  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath 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, or (at your option)

any later version.

GNU Classpath 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 GNU Classpath; see the file COPYING.  If not, write to the

Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301 USA.

Linking this library statically or dynamically with other modules is

making a combined work based on this library.  Thus, the terms and

conditions of the GNU General Public License cover the whole

combination.

As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent

modules, and to copy and distribute the resulting executable under

terms of your choice, provided that you also meet, for each linked

independent module, the terms and conditions of the license of that

module.  An independent module is a module which is not derived from

or based on this library.  If you modify this library, you may extend

this exception to your version of the library, but you are not

obligated to do so.  If you do not wish to do so, delete this

exception statement from your version. */

#include <config.h>

#include <errno.h>

#include <jni.h>

#include <jcl.h>

#include "java_nio_MappedByteBufferImpl.h"

#include <string.h>

#include <stdlib.h>

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif /* HAVE_UNISTD_H */

#ifdef HAVE_SYS_MMAN_H

#include <sys/mman.h>

#endif /* HAVE_SYS_MMAN_H */

#define IO_EXCEPTION "java/io/IOException"

/* FIXME these are defined in gnu_java_nio_channels_FileChannelImpl

   too; should be someplace common. */

#define ALIGN_DOWN(p,s) ((jpointer)(p) - ((jpointer)(p) % (s)))

#define ALIGN_UP(p,s) ((jpointer)(p) + ((s) - ((jpointer)(p) % (s))))

/**

 * Returns the memory page size of this platform.

 *

 * \return The page size.

 */

static long

get_pagesize (void)

{

  /* FIXME can we just try HAVE_SYSCONF? */

#if defined(HAVE_GETPAGESIZE)

  return getpagesize ();

#elif defined (HAVE_SYSCONF)

  return sysconf (_SC_PAGESIZE);

#endif /* HAVE_GETPAGESIZE / HAVE_SYSCONF */

}

/**

 * Retrieve the 'address' and 'cap' (the mapped size) fields of this

 * buffer.

 *

 * This function will align the address down to the nearest page

 * boundary, and the size up to the nearest page boundary. Thus, it is

 * safe to use these values in 'mman' functions.

 *

 * \param env The JNI environment pointer.

 * \param this The MappedByteBufferImpl instance.

 * \param address A pointer to where the actual pointer should be

 * stored.

 * \param size A pointer to where the mapped region's size should be

 * stored

 */

static void

get_raw_values (JNIEnv *env, jobject this, void **address, size_t *size)

{

  const long pagesize = get_pagesize ();

  jfieldID MappedByteBufferImpl_address;

  jfieldID MappedByteBufferImpl_size;

  jobject MappedByteBufferImpl_address_value = NULL;

  *address = NULL;

  /* 'address' is declared in java.nio.Buffer */

  MappedByteBufferImpl_address

    = (*env)->GetFieldID (env, (*env)->GetObjectClass (env, this),

                          "address", "Lgnu/classpath/Pointer;");

  /* 'cap' -- likewise, the capacity */

  MappedByteBufferImpl_size

    = (*env)->GetFieldID (env, (*env)->GetObjectClass (env, this),

                          "cap", "I");

  if (MappedByteBufferImpl_address != NULL)

    {

      MappedByteBufferImpl_address_value =

        (*env)->GetObjectField (env, this, MappedByteBufferImpl_address);

    }

  if ((*env)->ExceptionOccurred (env))

    return;

  if (MappedByteBufferImpl_address_value == NULL)

    {

      JCL_ThrowException (env, "java/lang/NullPointerException",

                          "mapped address is NULL");

      return;

    }

  *address = (void *)

    ALIGN_DOWN (JCL_GetRawData (env, MappedByteBufferImpl_address_value), pagesize);

  *size = (size_t)

    ALIGN_UP ((*env)->GetIntField (env, this, MappedByteBufferImpl_size),

              pagesize);

}

JNIEXPORT void JNICALL

Java_java_nio_MappedByteBufferImpl_unmapImpl (JNIEnv *env, jobject this)

{

#ifdef HAVE_MUNMAP

  void *address;

  size_t size;

  get_raw_values (env, this, &address, &size);

  if (address == NULL)

    return;

  if (munmap (address, size) != 0)

    {

      JCL_ThrowException (env, IO_EXCEPTION, strerror (errno));

      return;

    }

#else

  JCL_ThrowException (env, IO_EXCEPTION,

                      "unmapping files not implemented");

#endif /* HAVE_MUNMAP */

}

JNIEXPORT jboolean JNICALL

Java_java_nio_MappedByteBufferImpl_isLoadedImpl (JNIEnv * env, jobject this)

{

#ifdef HAVE_MINCORE

  void *address;

  size_t size;

  char *vec;

  size_t count, i;

  const long pagesize = get_pagesize ();

  /*

   * FIXME on Darwin this does not work if the mapped region is

   * exactly one page long; i.e., 'mincore' tells us it isn't loaded.

   */

  get_raw_values (env, this, &address, &size);

  if (address == NULL)

    return JNI_FALSE;

  count = (size_t) ((size + pagesize - 1) / pagesize);

  vec = (char *) malloc (count * sizeof (unsigned char));

  /*

   * Darwin (and BSD?) define argument 3 of 'mincore' to be 'char *',

   * while GNU libc defines it to be 'unsigned char *'. Casting the

   * argument to 'void *' fixes this, but not with C++. So you might

   * be SOL if you compile this with g++ (!) on GNU with -Werror.

   */

#ifdef __cplusplus

  if (mincore (address, size, vec) != 0)

#else

  if (mincore (address, size, (void *) vec) != 0)

#endif /* __cplusplus */

    {

      free (vec);

      JCL_ThrowException (env, IO_EXCEPTION, strerror (errno));

      return JNI_FALSE;

    }

  for (i = 0; i < count; i++)

    {

      if ((vec[i] & 1) == 0)

        return JNI_FALSE;

    }

  return JNI_TRUE;

#else

  return JNI_FALSE;

#endif

}

JNIEXPORT void JNICALL

Java_java_nio_MappedByteBufferImpl_loadImpl (JNIEnv *env, jobject this)

{

#ifdef HAVE_MADVISE

  void *address;

  size_t size;

  get_raw_values (env, this, &address, &size);

  if (address == NULL)

    return;

  madvise (address, size, MADV_WILLNEED);

#else

  JCL_ThrowException (env, IO_EXCEPTION,

                      "forcing mapped files into core not implemented");

#endif /* HAVE_MADVISE */

}

JNIEXPORT void JNICALL

Java_java_nio_MappedByteBufferImpl_forceImpl (JNIEnv *env, jobject this)

{

#ifdef HAVE_MSYNC

  void *address;

  size_t size;

  get_raw_values (env, this, &address, &size);

  if (address == NULL)

    return;

  /* FIXME: is using MS_SYNC ok? Should we use MS_INVALIDATE? */

  if (msync (address, size, MS_SYNC) != 0)

    {

      JCL_ThrowException (env, IO_EXCEPTION, strerror (errno));

    }

#else

  JCL_ThrowException (env, IO_EXCEPTION,

                      "forcing mapped files to disk not implemented");

#endif /* HAVE_MSYNC */

}