ggentropy

A string formatting library for C++
Log | Files | Refs | README

ggentropy.cpp (1885B)


      1 /*
      2  * ggentropy v1.0
      3  *
      4  * Copyright (c) 2021 Michael Savage <mike@mikejsavage.co.uk>
      5  *
      6  * Permission to use, copy, modify, and distribute this software for any
      7  * purpose with or without fee is hereby granted, provided that the above
      8  * copyright notice and this permission notice appear in all copies.
      9  *
     10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
     11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
     12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
     13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
     15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
     16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     17  */
     18 
     19 #if defined( _WIN32 )
     20 #  define PLATFORM_WINDOWS 1
     21 
     22 #elif defined( __linux__ )
     23 #  define PLATFORM_LINUX 1
     24 
     25 #elif defined( __APPLE__ )
     26 #  define PLATFORM_HAS_ARC4RANDOM 1
     27 
     28 #elif defined( __FreeBSD__ ) || defined( __OpenBSD__ ) || defined( __NetBSD__ )
     29 #  define PLATFORM_HAS_ARC4RANDOM 1
     30 
     31 #else
     32 #  error new platform
     33 #endif
     34 
     35 #include <stddef.h>
     36 #include <assert.h>
     37 
     38 #if PLATFORM_WINDOWS
     39 
     40 #pragma comment( lib, "bcrypt.lib" )
     41 
     42 #define WIN32_LEAN_AND_MEAN
     43 #include <windows.h>
     44 #include <bcrypt.h>
     45 
     46 bool ggentropy( void * buf, size_t n ) {
     47 	assert( n <= 256 );
     48 	return !FAILED( BCryptGenRandom( NULL, ( PUCHAR ) buf, n, BCRYPT_USE_SYSTEM_PREFERRED_RNG ) );
     49 }
     50 
     51 #elif PLATFORM_LINUX
     52 
     53 #include <unistd.h>
     54 #include <sys/syscall.h>
     55 
     56 bool ggentropy( void * buf, size_t n ) {
     57 	assert( n <= 256 );
     58 	int ok = syscall( SYS_getrandom, buf, n, 0 );
     59 	return ok >= 0 && size_t( ok ) == n;
     60 }
     61 
     62 #elif PLATFORM_HAS_ARC4RANDOM
     63 
     64 #include <stdlib.h>
     65 
     66 bool ggentropy( void * buf, size_t n ) {
     67 	assert( n <= 256 );
     68 	arc4random_buf( buf, n );
     69 	return true;
     70 }
     71 
     72 #else
     73 #error new platform
     74 #endif