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glibc  2.9
getpriority.c
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00001 /* getpriority for Linux.
00002    Copyright (C) 1996,98,2000,02,03 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <errno.h>
00021 #include <sys/resource.h>
00022 
00023 #include <sysdep.h>
00024 #include <sys/syscall.h>
00025 
00026 /* The return value of getpriority syscall is biased by this value
00027    to avoid returning negative values.  */
00028 #define PZERO 20
00029 
00030 /* Return the highest priority of any process specified by WHICH and WHO
00031    (see above); if WHO is zero, the current process, process group, or user
00032    (as specified by WHO) is used.  A lower priority number means higher
00033    priority.  Priorities range from PRIO_MIN to PRIO_MAX.  */
00034 
00035 int
00036 getpriority (enum __priority_which which, id_t who)
00037 {
00038   int res;
00039 
00040   res = INLINE_SYSCALL (getpriority, 2, (int) which, who);
00041   if (res >= 0)
00042     res = PZERO - res;
00043   return res;
00044 }
00045 libc_hidden_def (getpriority)