X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Funistd%2Fnice.c;h=1c2295ffc6591e7642cf17c352dfce7e168dad73;hb=3aba2150d0efc80df30d7fc6c22d6041e14d445e;hp=f38db678d892c7c570e2f4226090922bda1d55c5;hpb=2cdfb7ca26f46f151afbc23d5d94fc68597137f5;p=musl

diff --git a/src/unistd/nice.c b/src/unistd/nice.c
index f38db678..1c2295ff 100644
--- a/src/unistd/nice.c
+++ b/src/unistd/nice.c
@@ -1,12 +1,23 @@
 #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;
+	}
 }