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authorManuel Novoa III <mjn3@codepoet.org>2005-02-14 04:40:39 +0000
committerManuel Novoa III <mjn3@codepoet.org>2005-02-14 04:40:39 +0000
commit67256bd81271093c911a516aa00a5b33a63d6cbd (patch)
tree66977d3a91596e402c00b3e475b43470064e90cf /libc/sysdeps/linux
parent8b7d5c86ca6e6679ae8ad7bc16e97b3b204f217d (diff)
Fix some issues with nice(). SUSv3 specifies that it return the new
priority if successful, while the linux syscall returns 0. Also, in the non-syscall version, we must be sure to set errno to EPERM on failure since setpriority() can set errno to several possible values. Note: The version of glibc on my debian system is broken wrt EPERM too.
Diffstat (limited to 'libc/sysdeps/linux')
-rw-r--r--libc/sysdeps/linux/common/nice.c68
1 files changed, 52 insertions, 16 deletions
diff --git a/libc/sysdeps/linux/common/nice.c b/libc/sysdeps/linux/common/nice.c
index 27b0a7590..b21f63e08 100644
--- a/libc/sysdeps/linux/common/nice.c
+++ b/libc/sysdeps/linux/common/nice.c
@@ -3,35 +3,71 @@
* nice() for uClibc
*
* Copyright (C) 2000-2004 by Erik Andersen <andersen@codepoet.org>
+ * Copyright (C) 2005 by Manuel Novoa III <mjn3@codepoet.org>
*
* GNU Library General Public License (LGPL) version 2 or later.
*/
#include "syscalls.h"
#include <unistd.h>
+#include <sys/resource.h>
+
#ifdef __NR_nice
-_syscall1(int, nice, int, inc);
+
+#define __NR___syscall_nice __NR_nice
+static inline _syscall1(int, __syscall_nice, int, incr);
+
#else
-#include <sys/resource.h>
-int nice(int incr)
+
+#include <limits.h>
+
+static inline int int_add_no_wrap(int a, int b)
{
- int save, prio, result;
+ int s = a + b;
- save = errno;
+ if (b < 0) {
+ if (s > a) s = INT_MIN;
+ } else {
+ if (s < a) s = INT_MAX;
+ }
+
+ return s;
+}
+
+static inline int __syscall_nice(int incr)
+{
+ int old_priority;
+#if 1
+ /* This should never fail. */
+ old_priority = getpriority(PRIO_PROCESS, 0);
+#else
+ /* But if you want to be paranoid... */
+ int old_errno;
+
+ old_errno = errno;
__set_errno(0);
- prio = getpriority(PRIO_PROCESS, 0);
- if (prio == -1) {
- if (errno != 0) {
- return -1;
- } else {
- __set_errno(save);
- }
+ old_priority = getpriority(PRIO_PROCESS, 0);
+ if ((old_priority == -1) && errno) {
+ return -1;
}
- result = setpriority(PRIO_PROCESS, 0, prio + incr);
- if (result != -1) {
- return prio + incr;
- } else {
+ __set_errno(old_errno);
+#endif
+
+ if (setpriority(PRIO_PROCESS, 0, int_add_no_wrap(old_priority, incr))) {
+ __set_errno(EPERM); /* SUSv3 mandates EPERM for nice failure. */
return -1;
}
+
+ return 0;
}
+
#endif
+
+int nice(int incr)
+{
+ if (__syscall_nice(incr)) {
+ return -1;
+ }
+
+ return getpriority(PRIO_PROCESS, 0);
+}