1 /* Copyright (C) 1992-2022 Free Software Foundation, Inc. 2 This file is part of the GNU C Library. 3 4 The GNU C Library is free software; you can redistribute it and/or 5 modify it under the terms of the GNU Lesser General Public 6 License as published by the Free Software Foundation; either 7 version 2.1 of the License, or (at your option) any later version. 8 9 The GNU C Library is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 Lesser General Public License for more details. 13 14 You should have received a copy of the GNU Lesser General Public 15 License along with the GNU C Library; if not, see 16 <https://www.gnu.org/licenses/>. */ 17 18 #include <errno.h> 19 #include <unistd.h> 20 #include <sys/resource.h> 21 22 /* Increment the scheduling priority of the calling process by INCR. 23 The superuser may use a negative INCR to decrement the priority. */ 24 int nice(int incr)25nice (int incr) 26 { 27 int save; 28 int prio; 29 int result; 30 31 /* -1 is a valid priority, so we use errno to check for an error. */ 32 save = errno; 33 __set_errno (0); 34 prio = __getpriority (PRIO_PROCESS, 0); 35 if (prio == -1) 36 { 37 if (errno != 0) 38 return -1; 39 } 40 41 result = __setpriority (PRIO_PROCESS, 0, prio + incr); 42 if (result == -1) 43 { 44 if (errno == EACCES) 45 __set_errno (EPERM); 46 return -1; 47 } 48 49 __set_errno (save); 50 return __getpriority (PRIO_PROCESS, 0); 51 } 52