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/*
* Copyright © 2012 Google, 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.
*
* Google Author(s): Behdad Esfahbod
*/
#include "hb-private.hh"
#include "hb-shaper-private.hh"
#include "hb-atomic-private.hh"
static const hb_shaper_pair_t all_shapers[] = {
#define HB_SHAPER_IMPLEMENT(name) {#name, _hb_##name##_shape},
#include "hb-shaper-list.hh"
#undef HB_SHAPER_IMPLEMENT
};
/* Thread-safe, lock-free, shapers */
static const hb_shaper_pair_t *static_shapers;
#ifdef HB_USE_ATEXIT
static
void free_static_shapers (void)
{
if (unlikely (static_shapers != all_shapers))
free ((void *) static_shapers);
}
#endif
const hb_shaper_pair_t *
_hb_shapers_get (void)
{
retry:
hb_shaper_pair_t *shapers = (hb_shaper_pair_t *) hb_atomic_ptr_get (&static_shapers);
if (unlikely (!shapers))
{
char *env = getenv ("HB_SHAPER_LIST");
if (!env || !*env) {
(void) hb_atomic_ptr_cmpexch (&static_shapers, NULL, &all_shapers[0]);
return (const hb_shaper_pair_t *) all_shapers;
}
/* Not found; allocate one. */
shapers = (hb_shaper_pair_t *) calloc (1, sizeof (all_shapers));
if (unlikely (!shapers)) {
(void) hb_atomic_ptr_cmpexch (&static_shapers, NULL, &all_shapers[0]);
return (const hb_shaper_pair_t *) all_shapers;
}
memcpy (shapers, all_shapers, sizeof (all_shapers));
/* Reorder shaper list to prefer requested shapers. */
unsigned int i = 0;
char *end, *p = env;
for (;;) {
end = strchr (p, ',');
if (!end)
end = p + strlen (p);
for (unsigned int j = i; j < ARRAY_LENGTH (all_shapers); j++)
if (end - p == (int) strlen (shapers[j].name) &&
0 == strncmp (shapers[j].name, p, end - p))
{
/* Reorder this shaper to position i */
struct hb_shaper_pair_t t = shapers[j];
memmove (&shapers[i + 1], &shapers[i], sizeof (shapers[i]) * (j - i));
shapers[i] = t;
i++;
}
if (!*end)
break;
else
p = end + 1;
}
if (!hb_atomic_ptr_cmpexch (&static_shapers, NULL, shapers)) {
free (shapers);
goto retry;
}
#ifdef HB_USE_ATEXIT
atexit (free_static_shapers); /* First person registers atexit() callback. */
#endif
}
return shapers;
}
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