[glibc] hurd: clamp the setpriority prio argument to the range [-NZERO, NZERO-1]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=58ae7f8f0c1d7e69adbe07ef374ac65706dda0ba

commit 58ae7f8f0c1d7e69adbe07ef374ac65706dda0ba
Author: Diego Nieto Cid <[email protected]>
Date:   Mon May 25 22:56:42 2026 +0200

    hurd: clamp the setpriority prio argument to the range [-NZERO, NZERO-1]
    
    The Open Group Base Specifications Issue 8
    getpriority ( https://pubs.opengroup.org/onlinepubs/9799919799/ )
    
    << The nice value is in the range [0,2*{NZERO} -1], while the
       return value for getpriority() and the third parameter for
       setpriority() are in the range [-{NZERO},{NZERO} -1]. >>
    
    So given that NZERO is defined to 20, we shall use it to clamp to the range
    specified by POSIX.
    
    That range is then mapped to something similar to [0, 2*{NZERO}-1], as
    specified by POSIX, through the usage of the macro NICE_TO_MACH_PRIORITY
    and MACH_PRIORITY_TO_NICE. (i.e. [5, 45] )

Diff:
---
 sysdeps/mach/hurd/setpriority.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sysdeps/mach/hurd/setpriority.c b/sysdeps/mach/hurd/setpriority.c
index 23d678bf40..8107098991 100644
--- a/sysdeps/mach/hurd/setpriority.c
+++ b/sysdeps/mach/hurd/setpriority.c
@@ -28,7 +28,7 @@ __setpriority (enum __priority_which which, id_t who, int prio)
   error_t pidloser, priloser;
   unsigned int npids, ntasks, nwin, nperm, nacces;
 
-  prio = MAX (0, MIN (2 * NZERO - 1, prio));
+  prio = MAX ((-NZERO), MIN ((NZERO - 1), prio));
 
   error_t setonepriority (pid_t pid, struct procinfo *pi)
     {