1#include <unistd.h> 2#include <errno.h> 3#include <sys/resource.h> 4#include <limits.h> 5#include "syscall.h" 6 7int nice(int inc) 8{ 9 int prio = inc; 10 // Only query old priority if it can affect the result. 11 // This also avoids issues with integer overflow. 12 if (inc > -2*NZERO && inc < 2*NZERO) 13 prio += getpriority(PRIO_PROCESS, 0); 14 if (prio > NZERO-1) prio = NZERO-1; 15 if (prio < -NZERO) prio = -NZERO; 16 if (setpriority(PRIO_PROCESS, 0, prio)) { 17 if (errno == EACCES) 18 errno = EPERM; 19 return -1; 20 } else { 21 return prio; 22 } 23} 24