#include <unistd.h>
+#include <errno.h>
#include <sys/resource.h>
+#include <limits.h>
#include "syscall.h"
int nice(int inc)
{
-#ifdef __NR_nice
- return syscall1(__NR_nice, inc);
-#else
- return setpriority(PRIO_PROCESS, 0, getpriority(PRIO_PROCESS, 0)+inc);
-#endif
+ int prio = inc;
+ // Only query old priority if it can affect the result.
+ // This also avoids issues with integer overflow.
+ if (inc > -2*NZERO && inc < 2*NZERO)
+ prio += getpriority(PRIO_PROCESS, 0);
+ if (prio > NZERO-1) prio = NZERO-1;
+ if (prio < -NZERO) prio = -NZERO;
+ if (setpriority(PRIO_PROCESS, 0, prio)) {
+ if (errno == EACCES)
+ errno = EPERM;
+ return -1;
+ } else {
+ return prio;
+ }
}