1 /*
2 __ __ _
3 ___\ \/ /_ __ __ _| |_
4 / _ \\ /| '_ \ / _` | __|
5 | __// \| |_) | (_| | |_
6 \___/_/\_\ .__/ \__,_|\__|
7 |_| XML parser
8
9 Copyright (c) 2019 David Loffredo <loffredo@steptools.com>
10 Copyright (c) 2019-2026 Sebastian Pipping <sebastian@pipping.org>
11 Copyright (c) 2019 Ben Wagner <bungeman@chromium.org>
12 Copyright (c) 2019 Vadim Zeitlin <vadim@zeitlins.org>
13 Copyright (c) 2026 Matthew Fernandez <matthew.fernandez@gmail.com>
14 Licensed under the MIT license:
15
16 Permission is hereby granted, free of charge, to any person obtaining
17 a copy of this software and associated documentation files (the
18 "Software"), to deal in the Software without restriction, including
19 without limitation the rights to use, copy, modify, merge, publish,
20 distribute, sublicense, and/or sell copies of the Software, and to permit
21 persons to whom the Software is furnished to do so, subject to the
22 following conditions:
23
24 The above copyright notice and this permission notice shall be included
25 in all copies or substantial portions of the Software.
26
27 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
28 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
29 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
30 NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
31 DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
32 OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
33 USE OR OTHER DEALINGS IN THE SOFTWARE.
34 */
35
36 #include "random_rand_s.h"
37
38 /* force stdlib to define rand_s() */
39 #if ! defined(_CRT_RAND_S)
40 # define _CRT_RAND_S
41 #endif
42
43 // Workaround MinGW GCC trouble with recognizing `rand_s`, likely related
44 // to return type `error_t`; the symptom was:
45 // > error: implicit declaration of function ‘rand_s’
46 #if defined(__MINGW32__)
47 # include <errno.h>
48 #endif
49
50 #include <stdlib.h> // for rand_s
51 #include <string.h> // for memcpy
52
53 // Help clang-tidy out with prototype of function `rand_s`
54 #if defined(XML_CLANG_TIDY)
55 int rand_s(unsigned int *);
56 #endif
57
58 /* Provide declaration of rand_s() for MinGW-32 (not 64, which has it),
59 as it didn't declare it in its header prior to version 5.3.0 of its
60 runtime package (mingwrt, containing stdlib.h). The upstream fix
61 was introduced at https://osdn.net/projects/mingw/ticket/39658 . */
62 #if defined(__MINGW32__) && defined(__MINGW32_VERSION) \
63 && __MINGW32_VERSION < 5003000L && ! defined(__MINGW64_VERSION_MAJOR)
64 __declspec(dllimport) int rand_s(unsigned int *);
65 #endif
66
67 /* Obtain entropy on Windows using the rand_s() function which
68 * generates cryptographically secure random numbers. Internally it
69 * uses RtlGenRandom API which is present in Windows XP and later.
70 */
71 bool
writeRandomBytes_rand_s(void * target,size_t count)72 writeRandomBytes_rand_s(void *target, size_t count) {
73 size_t bytesWrittenTotal = 0;
74
75 while (bytesWrittenTotal < count) {
76 unsigned int random32 = 0;
77
78 if (rand_s(&random32))
79 return false; /* failure */
80
81 size_t toUse = count - bytesWrittenTotal;
82 if (toUse > sizeof(random32))
83 toUse = sizeof(random32);
84 memcpy((char *)target + bytesWrittenTotal, &random32, toUse);
85 bytesWrittenTotal += toUse;
86 }
87 return true; /* success */
88 }
89