xref: /aosp_15_r20/external/musl/src/unistd/nice.c (revision c9945492fdd68bbe62686c5b452b4dc1be3f8453)
1*c9945492SAndroid Build Coastguard Worker #include <unistd.h>
2*c9945492SAndroid Build Coastguard Worker #include <errno.h>
3*c9945492SAndroid Build Coastguard Worker #include <sys/resource.h>
4*c9945492SAndroid Build Coastguard Worker #include <limits.h>
5*c9945492SAndroid Build Coastguard Worker #include "syscall.h"
6*c9945492SAndroid Build Coastguard Worker 
nice(int inc)7*c9945492SAndroid Build Coastguard Worker int nice(int inc)
8*c9945492SAndroid Build Coastguard Worker {
9*c9945492SAndroid Build Coastguard Worker 	int prio = inc;
10*c9945492SAndroid Build Coastguard Worker 	// Only query old priority if it can affect the result.
11*c9945492SAndroid Build Coastguard Worker 	// This also avoids issues with integer overflow.
12*c9945492SAndroid Build Coastguard Worker 	if (inc > -2*NZERO && inc < 2*NZERO)
13*c9945492SAndroid Build Coastguard Worker 		prio += getpriority(PRIO_PROCESS, 0);
14*c9945492SAndroid Build Coastguard Worker 	if (prio > NZERO-1) prio = NZERO-1;
15*c9945492SAndroid Build Coastguard Worker 	if (prio < -NZERO) prio = -NZERO;
16*c9945492SAndroid Build Coastguard Worker 	if (setpriority(PRIO_PROCESS, 0, prio)) {
17*c9945492SAndroid Build Coastguard Worker 		if (errno == EACCES)
18*c9945492SAndroid Build Coastguard Worker 			errno = EPERM;
19*c9945492SAndroid Build Coastguard Worker 		return -1;
20*c9945492SAndroid Build Coastguard Worker 	} else {
21*c9945492SAndroid Build Coastguard Worker 		return prio;
22*c9945492SAndroid Build Coastguard Worker 	}
23*c9945492SAndroid Build Coastguard Worker }
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