The Tor Browser / file revision

 /*

  * 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 */

 #define _POSIX_C_SOURCE 199309L

 #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: (Xconstructor)

  * @data: (array length=length) (closure user_data) (destroy destroy) (scope notified) (transfer none): 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: 1.0

  **/

 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 || !(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: 1.0

  **/

 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: 1.0

  **/

 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: 1.0

  **/

 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: 1.0

  **/

 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: 1.0

  **/

 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: 1.0

  **/

 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: 1.0

  **/

 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: 1.0

  **/

 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: 1.0

  **/

 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: 1.0

  **/

 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: 1.0

  **/

 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;

 }