/*

 * Copyright © 2009  Red Hat, Inc.

 *

 *  This is part of HarfBuzz, a text shaping library.

 *

 * Permission is hereby granted, without written agreement and without

 * license or royalty fees, to use, copy, modify, and distribute this

 * software and its documentation for any purpose, provided that the

 * above copyright notice and the following two paragraphs appear in

 * all copies of this software.

 *

 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR

 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES

 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN

 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH

 * DAMAGE.

 *

 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,

 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS

 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO

 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

 *

 * Red Hat Author(s): Behdad Esfahbod

 */

/* http://www.oracle.com/technetwork/articles/servers-storage-dev/standardheaderfiles-453865.html */

#ifndef _POSIX_C_SOURCE

#define _POSIX_C_SOURCE 199309L

#endif

#include "hb-private.hh"

#include "hb-object-private.hh"

#ifdef HAVE_SYS_MMAN_H

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif /* HAVE_UNISTD_H */

#include <sys/mman.h>

#endif /* HAVE_SYS_MMAN_H */

#include <stdio.h>

#include <errno.h>

#ifndef HB_DEBUG_BLOB

#define HB_DEBUG_BLOB (HB_DEBUG+0)

#endif

struct hb_blob_t {

  hb_object_header_t header;

  ASSERT_POD ();

  bool immutable;

  const char *data;

  unsigned int length;

  hb_memory_mode_t mode;

  void *user_data;

  hb_destroy_func_t destroy;

};

static bool _try_writable (hb_blob_t *blob);

static void

_hb_blob_destroy_user_data (hb_blob_t *blob)

{

  if (blob->destroy) {

    blob->destroy (blob->user_data);

    blob->user_data = NULL;

    blob->destroy = NULL;

  }

}

/**

 * hb_blob_create: (skip)

 * @data: Pointer to blob data.

 * @length: Length of @data in bytes.

 * @mode: Memory mode for @data.

 * @user_data: Data parameter to pass to @destroy.

 * @destroy: Callback to call when @data is not needed anymore.

 *

 * Creates a new "blob" object wrapping @data.  The @mode parameter is used

 * to negotiate ownership and lifecycle of @data.

 *

 * Return value: New blob, or the empty blob if something failed or if @length is

 * zero.  Destroy with hb_blob_destroy().

 *

 * Since: 0.9.2

 **/

hb_blob_t *

hb_blob_create (const char        *data,

		unsigned int       length,

		hb_memory_mode_t   mode,

		void              *user_data,

		hb_destroy_func_t  destroy)

{

  hb_blob_t *blob;

  if (!length ||

      length >= 1u << 31 ||

      !(blob = hb_object_create<hb_blob_t> ())) {

    if (destroy)

      destroy (user_data);

    return hb_blob_get_empty ();

  }

  blob->data = data;

  blob->length = length;

  blob->mode = mode;

  blob->user_data = user_data;

  blob->destroy = destroy;

  if (blob->mode == HB_MEMORY_MODE_DUPLICATE) {

    blob->mode = HB_MEMORY_MODE_READONLY;

    if (!_try_writable (blob)) {

      hb_blob_destroy (blob);

      return hb_blob_get_empty ();

    }

  }

  return blob;

}

/**

 * hb_blob_create_sub_blob:

 * @parent: Parent blob.

 * @offset: Start offset of sub-blob within @parent, in bytes.

 * @length: Length of sub-blob.

 *

 * Returns a blob that represents a range of bytes in @parent.  The new

 * blob is always created with %HB_MEMORY_MODE_READONLY, meaning that it

 * will never modify data in the parent blob.  The parent data is not

 * expected to be modified, and will result in undefined behavior if it

 * is.

 *

 * Makes @parent immutable.

 *

 * Return value: New blob, or the empty blob if something failed or if

 * @length is zero or @offset is beyond the end of @parent's data.  Destroy

 * with hb_blob_destroy().

 *

 * Since: 0.9.2

 **/

hb_blob_t *

hb_blob_create_sub_blob (hb_blob_t    *parent,

			 unsigned int  offset,

			 unsigned int  length)

{

  hb_blob_t *blob;

  if (!length || offset >= parent->length)

    return hb_blob_get_empty ();

  hb_blob_make_immutable (parent);

  blob = hb_blob_create (parent->data + offset,

			 MIN (length, parent->length - offset),

			 HB_MEMORY_MODE_READONLY,

			 hb_blob_reference (parent),

			 (hb_destroy_func_t) hb_blob_destroy);

  return blob;

}

/**

 * hb_blob_get_empty:

 *

 * Returns the singleton empty blob.

 *

 * See TODO:link object types for more information.

 *

 * Return value: (transfer full): the empty blob.

 *

 * Since: 0.9.2

 **/

hb_blob_t *

hb_blob_get_empty (void)

{

  static const hb_blob_t _hb_blob_nil = {

    HB_OBJECT_HEADER_STATIC,

    true, /* immutable */

    NULL, /* data */

    0, /* length */

    HB_MEMORY_MODE_READONLY, /* mode */

    NULL, /* user_data */

    NULL  /* destroy */

  };

  return const_cast<hb_blob_t *> (&_hb_blob_nil);

}

/**

 * hb_blob_reference: (skip)

 * @blob: a blob.

 *

 * Increases the reference count on @blob.

 *

 * See TODO:link object types for more information.

 *

 * Return value: @blob.

 *

 * Since: 0.9.2

 **/

hb_blob_t *

hb_blob_reference (hb_blob_t *blob)

{

  return hb_object_reference (blob);

}

/**

 * hb_blob_destroy: (skip)

 * @blob: a blob.

 *

 * Descreases the reference count on @blob, and if it reaches zero, destroys

 * @blob, freeing all memory, possibly calling the destroy-callback the blob

 * was created for if it has not been called already.

 *

 * See TODO:link object types for more information.

 *

 * Since: 0.9.2

 **/

void

hb_blob_destroy (hb_blob_t *blob)

{

  if (!hb_object_destroy (blob)) return;

  _hb_blob_destroy_user_data (blob);

  free (blob);

}

/**

 * hb_blob_set_user_data: (skip)

 * @blob: a blob.

 * @key: key for data to set.

 * @data: data to set.

 * @destroy: callback to call when @data is not needed anymore.

 * @replace: whether to replace an existing data with the same key.

 *

 * Return value: 

 *

 * Since: 0.9.2

 **/

hb_bool_t

hb_blob_set_user_data (hb_blob_t          *blob,

		       hb_user_data_key_t *key,

		       void *              data,

		       hb_destroy_func_t   destroy,

		       hb_bool_t           replace)

{

  return hb_object_set_user_data (blob, key, data, destroy, replace);

}

/**

 * hb_blob_get_user_data: (skip)

 * @blob: a blob.

 * @key: key for data to get.

 *

 * 

 *

 * Return value: (transfer none): 

 *

 * Since: 0.9.2

 **/

void *

hb_blob_get_user_data (hb_blob_t          *blob,

		       hb_user_data_key_t *key)

{

  return hb_object_get_user_data (blob, key);

}

/**

 * hb_blob_make_immutable:

 * @blob: a blob.

 *

 * 

 *

 * Since: 0.9.2

 **/

void

hb_blob_make_immutable (hb_blob_t *blob)

{

  if (hb_object_is_inert (blob))

    return;

  blob->immutable = true;

}

/**

 * hb_blob_is_immutable:

 * @blob: a blob.

 *

 * 

 *

 * Return value: TODO

 *

 * Since: 0.9.2

 **/

hb_bool_t

hb_blob_is_immutable (hb_blob_t *blob)

{

  return blob->immutable;

}

/**

 * hb_blob_get_length:

 * @blob: a blob.

 *

 * 

 *

 * Return value: the length of blob data in bytes.

 *

 * Since: 0.9.2

 **/

unsigned int

hb_blob_get_length (hb_blob_t *blob)

{

  return blob->length;

}

/**

 * hb_blob_get_data:

 * @blob: a blob.

 * @length: (out):

 *

 * 

 *

 * Returns: (transfer none) (array length=length): 

 *

 * Since: 0.9.2

 **/

const char *

hb_blob_get_data (hb_blob_t *blob, unsigned int *length)

{

  if (length)

    *length = blob->length;

  return blob->data;

}

/**

 * hb_blob_get_data_writable:

 * @blob: a blob.

 * @length: (out): output length of the writable data.

 *

 * Tries to make blob data writable (possibly copying it) and

 * return pointer to data.

 *

 * Fails if blob has been made immutable, or if memory allocation

 * fails.

 *

 * Returns: (transfer none) (array length=length): Writable blob data,

 * or %NULL if failed.

 *

 * Since: 0.9.2

 **/

char *

hb_blob_get_data_writable (hb_blob_t *blob, unsigned int *length)

{

  if (!_try_writable (blob)) {

    if (length)

      *length = 0;

    return NULL;

  }

  if (length)

    *length = blob->length;

  return const_cast<char *> (blob->data);

}

static hb_bool_t

_try_make_writable_inplace_unix (hb_blob_t *blob)

{

#if defined(HAVE_SYS_MMAN_H) && defined(HAVE_MPROTECT)

  uintptr_t pagesize = -1, mask, length;

  const char *addr;

#if defined(HAVE_SYSCONF) && defined(_SC_PAGE_SIZE)

  pagesize = (uintptr_t) sysconf (_SC_PAGE_SIZE);

#elif defined(HAVE_SYSCONF) && defined(_SC_PAGESIZE)

  pagesize = (uintptr_t) sysconf (_SC_PAGESIZE);

#elif defined(HAVE_GETPAGESIZE)

  pagesize = (uintptr_t) getpagesize ();

#endif

  if ((uintptr_t) -1L == pagesize) {

    DEBUG_MSG_FUNC (BLOB, blob, "failed to get pagesize: %s", strerror (errno));

    return false;

  }

  DEBUG_MSG_FUNC (BLOB, blob, "pagesize is %lu", (unsigned long) pagesize);

  mask = ~(pagesize-1);

  addr = (const char *) (((uintptr_t) blob->data) & mask);

  length = (const char *) (((uintptr_t) blob->data + blob->length + pagesize-1) & mask)  - addr;

  DEBUG_MSG_FUNC (BLOB, blob,

		  "calling mprotect on [%p..%p] (%lu bytes)",

		  addr, addr+length, (unsigned long) length);

  if (-1 == mprotect ((void *) addr, length, PROT_READ | PROT_WRITE)) {

    DEBUG_MSG_FUNC (BLOB, blob, "mprotect failed: %s", strerror (errno));

    return false;

  }

  blob->mode = HB_MEMORY_MODE_WRITABLE;

  DEBUG_MSG_FUNC (BLOB, blob,

		  "successfully made [%p..%p] (%lu bytes) writable\n",

		  addr, addr+length, (unsigned long) length);

  return true;

#else

  return false;

#endif

}

static bool

_try_writable_inplace (hb_blob_t *blob)

{

  DEBUG_MSG_FUNC (BLOB, blob, "making writable inplace\n");

  if (_try_make_writable_inplace_unix (blob))

    return true;

  DEBUG_MSG_FUNC (BLOB, blob, "making writable -> FAILED\n");

  /* Failed to make writable inplace, mark that */

  blob->mode = HB_MEMORY_MODE_READONLY;

  return false;

}

static bool

_try_writable (hb_blob_t *blob)

{

  if (blob->immutable)

    return false;

  if (blob->mode == HB_MEMORY_MODE_WRITABLE)

    return true;

  if (blob->mode == HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITABLE && _try_writable_inplace (blob))

    return true;

  if (blob->mode == HB_MEMORY_MODE_WRITABLE)

    return true;

  DEBUG_MSG_FUNC (BLOB, blob, "current data is -> %p\n", blob->data);

  char *new_data;

  new_data = (char *) malloc (blob->length);

  if (unlikely (!new_data))

    return false;

  DEBUG_MSG_FUNC (BLOB, blob, "dupped successfully -> %p\n", blob->data);

  memcpy (new_data, blob->data, blob->length);

  _hb_blob_destroy_user_data (blob);

  blob->mode = HB_MEMORY_MODE_WRITABLE;

  blob->data = new_data;

  blob->user_data = new_data;

  blob->destroy = free;

  return true;

}