diff options
Diffstat (limited to 'lib/random_getrandom.c')
| -rw-r--r-- | lib/random_getrandom.c | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/lib/random_getrandom.c b/lib/random_getrandom.c new file mode 100644 index 000000000000..e5724a211cc6 --- /dev/null +++ b/lib/random_getrandom.c @@ -0,0 +1,90 @@ +/* + __ __ _ + ___\ \/ /_ __ __ _| |_ + / _ \\ /| '_ \ / _` | __| + | __// \| |_) | (_| | |_ + \___/_/\_\ .__/ \__,_|\__| + |_| XML parser + + Copyright (c) 2017-2026 Sebastian Pipping <sebastian@pipping.org> + Copyright (c) 2017 Chanho Park <chanho61.park@samsung.com> + Copyright (c) 2022 Sean McBride <sean@rogue-research.com> + Copyright (c) 2026 Matthew Fernandez <matthew.fernandez@gmail.com> + Licensed under the MIT license: + + Permission is hereby granted, free of charge, to any person obtaining + a copy of this software and associated documentation files (the + "Software"), to deal in the Software without restriction, including + without limitation the rights to use, copy, modify, merge, publish, + distribute, sublicense, and/or sell copies of the Software, and to permit + persons to whom the Software is furnished to do so, subject to the + following conditions: + + The above copyright notice and this permission notice shall be included + in all copies or substantial portions of the Software. + + THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN + NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, + DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR + OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE + USE OR OTHER DEALINGS IN THE SOFTWARE. +*/ + +#include "random_getrandom.h" + +#include "expat_config.h" // for HAVE_GETRANDOM, HAVE_SYSCALL_GETRANDOM + +#if defined(HAVE_GETRANDOM) +# include <sys/random.h> /* getrandom */ +#endif + +#if defined(HAVE_SYSCALL_GETRANDOM) +# if ! defined(_GNU_SOURCE) +# define _GNU_SOURCE 1 /* syscall prototype */ +# endif +# include <unistd.h> /* syscall */ +# include <sys/syscall.h> /* SYS_getrandom */ +#endif // defined(HAVE_SYSCALL_GETRANDOM) + +#if ! defined(GRND_NONBLOCK) +# define GRND_NONBLOCK 0x0001 +#endif /* defined(GRND_NONBLOCK) */ + +#include <assert.h> +#include <errno.h> +#include <limits.h> // for INT_MAX + +/* Obtain entropy on Linux 3.17+ */ +bool +writeRandomBytes_getrandom_nonblock(void *target, size_t count) { + int success = false; /* full count bytes written? */ + size_t bytesWrittenTotal = 0; + const unsigned int getrandomFlags = GRND_NONBLOCK; + + do { + void *const currentTarget = (void *)((char *)target + bytesWrittenTotal); + const size_t bytesToWrite = count - bytesWrittenTotal; + + assert(bytesToWrite <= INT_MAX); + + errno = 0; + + const int bytesWrittenMore = +#if defined(HAVE_GETRANDOM) + (int)getrandom(currentTarget, bytesToWrite, getrandomFlags); +#else + (int)syscall(SYS_getrandom, currentTarget, bytesToWrite, + getrandomFlags); +#endif + + if (bytesWrittenMore > 0) { + bytesWrittenTotal += bytesWrittenMore; + if (bytesWrittenTotal >= count) + success = true; + } + } while (! success && (errno == EINTR)); + + return success; +} |