1 /* 2 __ __ _ 3 ___\ \/ /_ __ __ _| |_ 4 / _ \\ /| '_ \ / _` | __| 5 | __// \| |_) | (_| | |_ 6 \___/_/\_\ .__/ \__,_|\__| 7 |_| XML parser 8 9 Copyright (c) 2017-2026 Sebastian Pipping <sebastian@pipping.org> 10 Copyright (c) 2026 Matthew Fernandez <matthew.fernandez@gmail.com> 11 Licensed under the MIT license: 12 13 Permission is hereby granted, free of charge, to any person obtaining 14 a copy of this software and associated documentation files (the 15 "Software"), to deal in the Software without restriction, including 16 without limitation the rights to use, copy, modify, merge, publish, 17 distribute, sublicense, and/or sell copies of the Software, and to permit 18 persons to whom the Software is furnished to do so, subject to the 19 following conditions: 20 21 The above copyright notice and this permission notice shall be included 22 in all copies or substantial portions of the Software. 23 24 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 25 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 26 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN 27 NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 28 DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR 29 OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE 30 USE OR OTHER DEALINGS IN THE SOFTWARE. 31 */ 32 33 #include "random_dev_urandom.h" 34 35 #if ! defined(_POSIX_C_SOURCE) \ 36 || (defined(_POSIX_C_SOURCE) && (_POSIX_C_SOURCE < 200809L)) 37 # define _POSIX_C_SOURCE 200809L // for O_CLOEXEC 38 #endif 39 40 #include <errno.h> 41 #include <fcntl.h> // open 42 #include <unistd.h> // close 43 44 /* Extract entropy from /dev/urandom */ 45 bool 46 writeRandomBytes_dev_urandom(void *target, size_t count) { 47 int success = false; /* full count bytes written? */ 48 size_t bytesWrittenTotal = 0; 49 50 const int fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC); 51 if (fd < 0) { 52 return 0; 53 } 54 55 do { 56 void *const currentTarget = (void *)((char *)target + bytesWrittenTotal); 57 const size_t bytesToWrite = count - bytesWrittenTotal; 58 59 errno = 0; 60 61 const ssize_t bytesWrittenMore = read(fd, currentTarget, bytesToWrite); 62 63 if (bytesWrittenMore > 0) { 64 bytesWrittenTotal += bytesWrittenMore; 65 if (bytesWrittenTotal >= count) 66 success = true; 67 } 68 } while (! success && (errno == EINTR)); 69 70 close(fd); 71 return success; 72 } 73