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/*
% Copyright (C) 2009-2015 GraphicsMagick Group
%
% This program is covered by multiple licenses, which are described in
% Copyright.txt. You should have received a copy of Copyright.txt with this
% package; otherwise see http://www.graphicsmagick.org/www/Copyright.html.
%
% Random number generator.
%
% Currently based on George Marsaglia's multiply-with-carry generator.
% This is a k=2 generator with a period >2^60.
%
*/
#include "magick/studio.h"
#include "magick/random-private.h"
#include "magick/random.h"
#include "magick/semaphore.h"
#include "magick/tsd.h"
#include "magick/utility.h"
#if defined(HAVE_PTHREAD)
# define USE_POSIX_THREADS 1
#elif defined(MSWINDOWS)
# define USE_WIN32_THREADS 1
#endif
#if defined(USE_POSIX_THREADS)
# include <pthread.h>
#endif
#if defined(USE_WIN32_THREADS)
# include <windows.h>
#endif
#if defined(MSWINDOWS) && HAVE_CRYPTGENRANDOM && HAVE_WINCRYPT_H
# include <wincrypt.h>
#endif
static MagickBool initialized = MagickFalse;
static SemaphoreInfo *semaphore = (SemaphoreInfo *) 0;
static MagickTsdKey_t kernel_key = (MagickTsdKey_t) 0;
/*
Acquire the default random number kernel. Memory is owned by
library and should not be freed.
*/
MagickExport MagickRandomKernel* AcquireMagickRandomKernel()
{
MagickRandomKernel
*kernel;
if (!initialized)
InitializeMagickRandomGenerator();
kernel=(MagickRandomKernel *) MagickTsdGetSpecific(kernel_key);
if (kernel == (MagickRandomKernel *) NULL)
{
kernel=MagickAllocateAlignedMemory(MagickRandomKernel *,
MAGICK_CACHE_LINE_SIZE,
sizeof(MagickRandomKernel));
if (kernel == (MagickRandomKernel *) NULL)
MagickFatalError3(ResourceLimitFatalError,MemoryAllocationFailed,
UnableToAllocateRandomKernel);
InitializeMagickRandomKernel(kernel);
MagickTsdSetSpecific(kernel_key,(const void *) kernel);
}
return kernel;
}
/*
Initialize the random number generator system.
*/
void InitializeMagickRandomGenerator()
{
assert(semaphore == (SemaphoreInfo *) NULL);
semaphore=AllocateSemaphoreInfo();
if (!initialized)
{
MagickTsdKeyCreate2(&kernel_key,MagickFreeAligned);
initialized=MagickTrue;
}
}
/*
Destroy the random number generator system.
*/
void DestroyMagickRandomGenerator()
{
if (initialized)
{
MagickRandomKernel
*kernel;
/* FIXME: This only frees memory associated with one thread */
kernel=(MagickRandomKernel *) MagickTsdGetSpecific(kernel_key);
MagickFreeAlignedMemory(kernel);
(void) MagickTsdSetSpecific(kernel_key,kernel);
MagickTsdKeyDelete(kernel_key);
}
kernel_key=(MagickTsdKey_t) 0;
initialized=MagickFalse;
DestroySemaphoreInfo(&semaphore);
}
/*
Initialize the random kernel with suitable entropy
*/
MagickExport void
InitializeMagickRandomKernel(MagickRandomKernel *kernel)
{
MagickBool
done = MagickFalse;
kernel->z = 0U;
kernel->w = 0U;
#if defined(POSIX) && HAVE_DEV_URANDOM
/*
Read from /dev/urandom
MinGW's MSYS emulates /dev/random in its shell so a configure
test for it produces an invalid result.
*/
{
int
file;
if ((file=open("/dev/urandom",O_RDONLY | O_BINARY)) != -1)
{
if (read(file,(void *) kernel,sizeof(*kernel)) == sizeof(*kernel))
done=MagickTrue;
(void) close(file);
}
if (!done)
MagickFatalError(ResourceLimitFatalError,UnableToObtainRandomEntropy,
NULL);
}
#elif defined(MSWINDOWS) && HAVE_CRYPTGENRANDOM
/*
Use Windows advapi32.lib CryptGenRandom
Is claimed to be supported under Windows XP
*/
{
HCRYPTPROV
hProvider = 0;
if (CryptAcquireContextW(&hProvider, 0, 0, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT | CRYPT_SILENT))
{
/* Returns zero (FALSE) on failure */
if (CryptGenRandom(hProvider, (DWORD) sizeof(*kernel), (BYTE *) kernel))
done=MagickTrue;
(void) CryptReleaseContext(hProvider, 0);
}
if (!done)
MagickFatalError(ResourceLimitFatalError,UnableToObtainRandomEntropy,
NULL);
}
#else
/*
Fallback implementation
*/
/*
Initial time of day.
*/
kernel->z ^= (magick_uint32_t) time(0);
/*
Let's hash with the address of kernel as well.
*/
kernel->z ^= (magick_uint32_t) ((magick_uintptr_t) kernel & 4294967295UL);
/*
Process ID
*/
kernel->w ^= (magick_uint32_t) getpid();
/*
Thread ID
*/
#if defined(USE_POSIX_THREADS)
{
union
{
pthread_t thread_id;
magick_uint32_t intval;
} pthread_union;
pthread_union.intval=0U;
pthread_union.thread_id=pthread_self();
kernel->w ^= pthread_union.intval;
}
#elif defined(USE_WIN32_THREADS)
kernel->w ^= ((magick_uint32_t) GetCurrentThreadId());
#endif
/*
It is quite likely that multiple threads will invoke this function
during the same second so we also tap into the default random
number generator to help produce a more random seed.
*/
kernel->w ^= (magick_uint32_t) rand();
#endif
}
/*
Generate a random integer value
*/
MagickExport magick_uint32_t MagickRandomInteger(void)
{
MagickRandomKernel
*kernel;
kernel=AcquireMagickRandomKernel();
return MagickRandomIntegerInlined(kernel);
}
/*
Generate a random double value
*/
MagickExport double MagickRandomReal(void)
{
MagickRandomKernel
*kernel;
kernel=AcquireMagickRandomKernel();
return MagickRandomRealInlined(kernel);
}
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