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      1 /* Copyright libuv contributors. All rights reserved.
      2  *
      3  * Permission is hereby granted, free of charge, to any person obtaining a copy
      4  * of this software and associated documentation files (the "Software"), to
      5  * deal in the Software without restriction, including without limitation the
      6  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
      7  * sell copies of the Software, and to permit persons to whom the Software is
      8  * furnished to do so, subject to the following conditions:
      9  *
     10  * The above copyright notice and this permission notice shall be included in
     11  * all copies or substantial portions of the Software.
     12  *
     13  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     14  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     15  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     16  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     17  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
     18  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
     19  * IN THE SOFTWARE.
     20  */
     21 
     22 #include "uv.h"
     23 #include "internal.h"
     24 
     25 #include <stddef.h>
     26 #include <dlfcn.h>
     27 
     28 typedef int (*uv__getentropy_cb)(void *, size_t);
     29 
     30 static uv__getentropy_cb uv__getentropy;
     31 static uv_once_t once = UV_ONCE_INIT;
     32 
     33 
     34 static void uv__random_getentropy_init(void) {
     35   uv__getentropy = (uv__getentropy_cb) dlsym(RTLD_DEFAULT, "getentropy");
     36 }
     37 
     38 
     39 int uv__random_getentropy(void* buf, size_t buflen) {
     40   size_t pos;
     41   size_t stride;
     42 
     43   uv_once(&once, uv__random_getentropy_init);
     44 
     45   if (uv__getentropy == NULL)
     46     return UV_ENOSYS;
     47 
     48   /* getentropy() returns an error for requests > 256 bytes. */
     49   for (pos = 0, stride = 256; pos + stride < buflen; pos += stride)
     50     if (uv__getentropy((char *) buf + pos, stride))
     51       return UV__ERR(errno);
     52 
     53   if (uv__getentropy((char *) buf + pos, buflen - pos))
     54     return UV__ERR(errno);
     55 
     56   return 0;
     57 }
     58