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Implement the system RNG on Windows.

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On Windows we implement the system RNG by calling the CRT's rand_s() function.

library/random.system_rng.m:
    Implement the system RNG on Windows using rand_s().

runtime/mercury_std.h:
    On Windows define the macro _CRT_RAND_S before the initial
    inclusion of stdlib.h -- we must do this otherwise the declaration
    of rand_s() will not be visible.
This commit is contained in:
Julien Fischer
2021-02-13 15:06:23 +11:00
parent 6cd07540fe
commit 2ff14bd80b
2 changed files with 66 additions and 2 deletions
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59
library/random.system_rng.m
View File

@@ -119,6 +119,9 @@
#include <errno.h>
#include <stdint.h>
// On Windows we need to ensure that _CRT_RAND_S is defined before stdlib.h
// is included but this must be done in runtime/mercury_std.h.
#include <stdlib.h>
// The following macros define if the system random number exists on this
@@ -136,7 +139,7 @@
// PRNG, such as ChaCha20; it should _not_ be enabled on systems where
// arc4random() still uses RC4.
//
// ML_SYSRAND_IMPL_RAND_S (NYI)
// ML_SYSRAND_IMPL_RAND_S
// the system RNG is implemented by calling the rand_s() function
// (Windows only).
//
@@ -169,6 +172,8 @@
#else
#define ML_SYSRAND_IMPL_URANDOM
#endif
#elif defined(MR_WIN32)
#define ML_SYSRAND_IMPL_RAND_S
#else
#define ML_SYSRAND_IMPL_NONE
#endif
@@ -675,6 +680,58 @@ ML_random_generate_bytes(ML_SystemRandomHandle handle,
return MR_TRUE;
}
#elif defined(ML_SYSRAND_IMPL_RAND_S)
ML_SystemRandomHandle
ML_random_open(MR_Bool *succeeded, MR_String *err_msg)
{
*succeeded = MR_TRUE;
*err_msg = MR_make_string_const(\"\");
return 0;
}
MR_Bool
ML_random_close(ML_SystemRandomHandle handle, MR_String *err_msg)
{
*err_msg = MR_make_string_const(\"\");
return MR_TRUE;
}
MR_Bool
ML_random_generate_bytes(ML_SystemRandomHandle handle,
unsigned char *buffer, size_t len, MR_String *err_msg)
{
int err;
unsigned int n;
size_t num_to_read = len;
while (num_to_read > 0) {
if (num_to_read < 4) {
err = rand_s(&n);
if (err != 0) {
goto rand_s_failure_handler;
}
MR_memcpy(buffer, (unsigned char *) &n, num_to_read);
break;
} else {
err = rand_s((unsigned int *) buffer);
if (err != 0) {
goto rand_s_failure_handler;
}
num_to_read -= 4;
buffer += 4;
}
}
*err_msg = MR_make_string_const(\"\");
return MR_TRUE;
rand_s_failure_handler:
*err_msg = MR_make_string_const(\"rand_s failed\");
return MR_FALSE;
}
#else // ML_SYSRAND_IMPL_NONE
ML_SystemRandomHandle

9
runtime/mercury_std.h
View File

@@ -1,7 +1,7 @@
// vim: ts=4 sw=4 expandtab ft=c
// Copyright (C) 1993-1995, 1997-2005, 2011-2012 The University of Melbourne.
// Copyright (C) 2014, 2016-2018 The Mercury team.
// Copyright (C) 2014, 2016-2019, 2021 The Mercury team.
// This file is distributed under the terms specified in COPYING.LIB.
// std.h - "standard" [sic] definitions for C:
@@ -22,7 +22,14 @@
#error "Mercury requires a system that provides stdint.h"
#endif
// On Windows we need to define _CRT_RAND_S *before* stdlib.h is included,
// otherwise the declaration for rand_s() will not be visible.
//
#if defined(MR_WIN32) && !defined(_CRT_RAND_S)
#define _CRT_RAND_S
#endif
#include <stdlib.h> // for size_t
#include <assert.h> // for assert()
#include <errno.h> // for EINTR
#include <ctype.h> // for isalnum(), etc.