harfbuzz/src/hb-blob.c

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/*
* Copyright (C) 2009 Red Hat, Inc.
*
* This is part of HarfBuzz, an OpenType Layout engine 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
*/
#include "hb-private.h"
#include "hb-blob.h"
#ifdef HAVE_SYS_MMAN_H
#ifdef HAVE_UNISTD_H
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#include <unistd.h>
#endif /* HAVE_UNISTD_H */
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#include <sys/mman.h>
#endif /* HAVE_SYS_MMAN_H */
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struct _hb_blob_t {
hb_reference_count_t ref_count;
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unsigned int length;
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hb_mutex_t lock;
/* the rest are protected by lock */
unsigned int lock_count;
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hb_memory_mode_t mode;
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const char *data;
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hb_destroy_func_t destroy;
void *user_data;
};
static hb_blob_t _hb_blob_nil = {
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HB_REFERENCE_COUNT_INVALID, /* ref_count */
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0, /* length */
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HB_MUTEX_INIT, /* lock */
0, /* lock_count */
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HB_MEMORY_MODE_READONLY_NEVER_DUPLICATE, /* mode */
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NULL, /* data */
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NULL, /* destroy */
NULL /* user_data */
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};
static void
_hb_blob_destroy_user_data (hb_blob_t *blob)
{
if (blob->destroy) {
blob->destroy (blob->user_data);
blob->destroy = NULL;
blob->user_data = NULL;
}
}
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static void
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_hb_blob_unlock_and_destroy (hb_blob_t *blob)
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{
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hb_blob_unlock (blob);
hb_blob_destroy (blob);
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}
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hb_blob_t *
hb_blob_create (const char *data,
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unsigned int length,
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hb_memory_mode_t mode,
hb_destroy_func_t destroy,
void *user_data)
{
hb_blob_t *blob;
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if (!length || !HB_OBJECT_DO_CREATE (hb_blob_t, blob)) {
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if (destroy)
destroy (user_data);
return &_hb_blob_nil;
}
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hb_mutex_init (blob->lock);
blob->lock_count = 0;
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blob->data = data;
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blob->length = length;
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blob->mode = mode;
blob->destroy = destroy;
blob->user_data = user_data;
if (blob->mode == HB_MEMORY_MODE_DUPLICATE) {
blob->mode = HB_MEMORY_MODE_READONLY;
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if (!hb_blob_try_writeable (blob)) {
hb_blob_destroy (blob);
return &_hb_blob_nil;
}
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}
return blob;
}
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hb_blob_t *
hb_blob_create_sub_blob (hb_blob_t *parent,
unsigned int offset,
unsigned int length)
{
hb_blob_t *blob;
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const char *pdata;
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if (!length || offset >= parent->length || !HB_OBJECT_DO_CREATE (hb_blob_t, blob))
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return &_hb_blob_nil;
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pdata = hb_blob_lock (parent);
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blob->data = pdata + offset;
blob->length = MIN (length, parent->length - offset);
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hb_mutex_lock (parent->lock);
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blob->mode = parent->mode;
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hb_mutex_unlock (parent->lock);
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blob->destroy = (hb_destroy_func_t) _hb_blob_unlock_and_destroy;
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blob->user_data = hb_blob_reference (parent);
return blob;
}
hb_blob_t *
hb_blob_create_empty (void)
{
return &_hb_blob_nil;
}
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hb_blob_t *
hb_blob_reference (hb_blob_t *blob)
{
HB_OBJECT_DO_REFERENCE (blob);
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}
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unsigned int
hb_blob_get_reference_count (hb_blob_t *blob)
{
HB_OBJECT_DO_GET_REFERENCE_COUNT (blob);
}
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void
hb_blob_destroy (hb_blob_t *blob)
{
HB_OBJECT_DO_DESTROY (blob);
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_hb_blob_destroy_user_data (blob);
free (blob);
}
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unsigned int
hb_blob_get_length (hb_blob_t *blob)
{
return blob->length;
}
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const char *
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hb_blob_lock (hb_blob_t *blob)
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{
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if (HB_OBJECT_IS_INERT (blob))
return NULL;
hb_mutex_lock (blob->lock);
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blob->lock_count++;
#if HB_DEBUG
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fprintf (stderr, "%p %s (%d) -> %p\n", blob, __FUNCTION__,
blob->lock_count, blob->data);
#endif
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hb_mutex_unlock (blob->lock);
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return blob->data;
}
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void
hb_blob_unlock (hb_blob_t *blob)
{
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if (HB_OBJECT_IS_INERT (blob))
return;
hb_mutex_lock (blob->lock);
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assert (blob->lock_count > 0);
blob->lock_count--;
#if HB_DEBUG
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fprintf (stderr, "%p %s (%d) -> %p\n", blob, __FUNCTION__,
hb_atomic_int_get (blob->lock_count), blob->data);
#endif
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hb_mutex_unlock (blob->lock);
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}
hb_bool_t
hb_blob_is_writeable (hb_blob_t *blob)
{
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hb_memory_mode_t mode;
if (HB_OBJECT_IS_INERT (blob))
return FALSE;
hb_mutex_lock (blob->lock);
mode = blob->mode;
hb_mutex_unlock (blob->lock);
return mode == HB_MEMORY_MODE_WRITEABLE;
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}
hb_bool_t
hb_blob_try_writeable_inplace (hb_blob_t *blob)
{
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hb_memory_mode_t mode;
if (HB_OBJECT_IS_INERT (blob))
return FALSE;
hb_mutex_lock (blob->lock);
#ifdef HAVE_SYS_MMAN_H
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if (blob->mode == HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITEABLE) {
unsigned int pagesize, mask, length;
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const char *addr;
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#if HB_DEBUG
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fprintf (stderr, "%p %s: making writeable\n", blob, __FUNCTION__);
#endif
pagesize = (unsigned int) sysconf(_SC_PAGE_SIZE);
if ((unsigned int) -1 == pagesize) {
#if HB_DEBUG
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fprintf (stderr, "%p %s: %s\n", blob, __FUNCTION__, strerror (errno));
#endif
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goto done;
}
#if HB_DEBUG
fprintf (stderr, "%p %s: pagesize is %u\n", blob, __FUNCTION__, pagesize);
#endif
mask = ~(pagesize-1);
addr = (const char *) (((size_t) blob->data) & mask);
length = (const char *) (((size_t) blob->data + blob->length + pagesize-1) & mask) - addr;
#if HB_DEBUG
fprintf (stderr, "%p %s: calling mprotect on [%p..%p] (%d bytes)\n",
blob, __FUNCTION__,
addr, addr+length, length);
#endif
if (-1 == mprotect ((void *) addr, length, PROT_READ | PROT_WRITE)) {
#if HB_DEBUG
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fprintf (stderr, "%p %s: %s\n", blob, __FUNCTION__, strerror (errno));
#endif
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goto done;
}
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blob->mode = HB_MEMORY_MODE_WRITEABLE;
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#if HB_DEBUG
fprintf (stderr, "%p %s: successfully made [%p..%p] (%d bytes) writeable\n",
blob, __FUNCTION__,
addr, addr+length, length);
#endif
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}
#else /* !HAVE_SYS_MMAN_H */
#warning "No way to make readonly memory writeable. This is suboptimal."
#endif
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done:
mode = blob->mode;
hb_mutex_unlock (blob->lock);
return mode == HB_MEMORY_MODE_WRITEABLE;
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}
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hb_bool_t
hb_blob_try_writeable (hb_blob_t *blob)
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{
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hb_memory_mode_t mode;
if (HB_OBJECT_IS_INERT (blob))
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return FALSE;
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hb_mutex_lock (blob->lock);
if (blob->mode == HB_MEMORY_MODE_READONLY_NEVER_DUPLICATE)
goto done;
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if (blob->mode == HB_MEMORY_MODE_READONLY)
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{
char *new_data;
#if HB_DEBUG
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fprintf (stderr, "%p %s (%d) -> %p\n", blob, __FUNCTION__,
blob->lock_count, blob->data);
#endif
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if (blob->lock_count)
goto done;
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new_data = malloc (blob->length);
if (new_data) {
#if HB_DEBUG
fprintf (stderr, "%p %s: dupped successfully -> %p\n", blob, __FUNCTION__, blob->data);
#endif
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memcpy (new_data, blob->data, blob->length);
blob->data = new_data;
blob->mode = HB_MEMORY_MODE_WRITEABLE;
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_hb_blob_destroy_user_data (blob);
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}
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}
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done:
mode = blob->mode;
hb_mutex_unlock (blob->lock);
if (blob->mode == HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITEABLE)
return hb_blob_try_writeable_inplace (blob);
return mode == HB_MEMORY_MODE_WRITEABLE;
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}