libexplain  1.4.D001
libexplain/getpriority_or_die.c
Go to the documentation of this file.
00001 /*
00002  * libexplain - Explain errno values returned by libc functions
00003  * Copyright (C) 2013 Peter Miller
00004  *
00005  * This program is free software; you can redistribute it and/or modify it
00006  * under the terms of the GNU Lesser General Public License as published by
00007  * the Free Software Foundation; either version 3 of the License, or (at
00008  * your option) any later version.
00009  *
00010  * This program is distributed in the hope that it will be useful, but
00011  * WITHOUT ANY WARRANTY; without even the implied warranty of
00012  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
00013  * General Public License for more details.
00014  *
00015  * You should have received a copy of the GNU Lesser General Public License
00016  * along with this program. If not, see <http://www.gnu.org/licenses/>.
00017  */
00018 
00019 #include <libexplain/ac/errno.h>
00020 #include <libexplain/ac/sys/resource.h>
00021 
00022 #include <libexplain/getpriority.h>
00023 #include <libexplain/output.h>
00024 
00025 
00026 int
00027 explain_getpriority_or_die(int which, int who)
00028 {
00029     int             hold_errno;
00030     int             result;
00031 
00032     hold_errno = errno;
00033     errno = 0;
00034     /*
00035      * Since getpriority() can legitimately return the value -1, it is
00036      * necessary to clear the external variable errno prior to the call, then
00037      * check it afterward to determine if -1 is an error or a legitimate value.
00038      */
00039     result = explain_getpriority_on_error(which, who);
00040     if (errno != 0)
00041         hold_errno = errno;
00042     if (result == -1 && hold_errno != 0)
00043     {
00044         explain_output_exit_failure();
00045     }
00046     errno = hold_errno;
00047     return result;
00048 }
00049 
00050 
00051 int
00052 explain_getpriority_on_error(int which, int who)
00053 {
00054     int             hold_errno;
00055     int             result;
00056 
00057     hold_errno = errno;
00058     errno = 0;
00059 #ifdef HAVE_GETPRIORITY
00060     result = getpriority(which, who);
00061 #else
00062     errno = ENOSYS;
00063     result = -1;
00064 #endif
00065     if (result == -1 && errno != 0)
00066     {
00067         hold_errno = errno;
00068         explain_output_error
00069         (
00070             "%s",
00071             explain_errno_getpriority(hold_errno, which, who)
00072         );
00073         errno = hold_errno;
00074         result = -1;
00075     }
00076     return result;
00077 }
00078 
00079 
00080 /* vim: set ts=8 sw=4 et : */