The Tor Browser: gfx/harfbuzz/src/hb-shaper.cc@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 /*

     2  * Copyright © 2012  Google, Inc.

     3  *

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

     5  *

     6  * Permission is hereby granted, without written agreement and without

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

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

     9  * above copyright notice and the following two paragraphs appear in

    10  * all copies of this software.

    11  *

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

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

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

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

    16  * DAMAGE.

    17  *

    18  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,

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

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

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

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

    23  *

    24  * Google Author(s): Behdad Esfahbod

    25  */

    27 #include "hb-private.hh"

    28 #include "hb-shaper-private.hh"

    29 #include "hb-atomic-private.hh"

    32 static const hb_shaper_pair_t all_shapers[] = {

    33 #define HB_SHAPER_IMPLEMENT(name) {#name, _hb_##name##_shape},

    34 #include "hb-shaper-list.hh"

    35 #undef HB_SHAPER_IMPLEMENT

    36 };

    39 /* Thread-safe, lock-free, shapers */

    41 static const hb_shaper_pair_t *static_shapers;

    43 static inline

    44 void free_static_shapers (void)

    45 {

    46   if (unlikely (static_shapers != all_shapers))

    47     free ((void *) static_shapers);

    48 }

    50 const hb_shaper_pair_t *

    51 _hb_shapers_get (void)

    52 {

    53 retry:

    54   hb_shaper_pair_t *shapers = (hb_shaper_pair_t *) hb_atomic_ptr_get (&static_shapers);

    56   if (unlikely (!shapers))

    57   {

    58     char *env = getenv ("HB_SHAPER_LIST");

    59     if (!env || !*env) {

    60       (void) hb_atomic_ptr_cmpexch (&static_shapers, NULL, &all_shapers[0]);

    61       return (const hb_shaper_pair_t *) all_shapers;

    62     }

    64     /* Not found; allocate one. */

    65     shapers = (hb_shaper_pair_t *) malloc (sizeof (all_shapers));

    66     if (unlikely (!shapers)) {

    67       (void) hb_atomic_ptr_cmpexch (&static_shapers, NULL, &all_shapers[0]);

    68       return (const hb_shaper_pair_t *) all_shapers;

    69     }

    71     memcpy (shapers, all_shapers, sizeof (all_shapers));

    73      /* Reorder shaper list to prefer requested shapers. */

    74     unsigned int i = 0;

    75     char *end, *p = env;

    76     for (;;) {

    77       end = strchr (p, ',');

    78       if (!end)

    79 	end = p + strlen (p);

    81       for (unsigned int j = i; j < ARRAY_LENGTH (all_shapers); j++)

    82 	if (end - p == (int) strlen (shapers[j].name) &&

    83 	    0 == strncmp (shapers[j].name, p, end - p))

    84 	{

    85 	  /* Reorder this shaper to position i */

    86 	 struct hb_shaper_pair_t t = shapers[j];

    87 	 memmove (&shapers[i + 1], &shapers[i], sizeof (shapers[i]) * (j - i));

    88 	 shapers[i] = t;

    89 	 i++;

    90 	}

    92       if (!*end)

    93 	break;

    94       else

    95 	p = end + 1;

    96     }

    98     if (!hb_atomic_ptr_cmpexch (&static_shapers, NULL, shapers)) {

    99       free (shapers);

   100       goto retry;

   101     }

   103 #ifdef HAVE_ATEXIT

   104     atexit (free_static_shapers); /* First person registers atexit() callback. */

   105 #endif

   106   }

   108   return shapers;

   109 }

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