more "nice" fixes in the area of terminology

[Paul Eggert]

I see that I didn't fix all the misuses of the term "nice value"
so I installed this further patch.  I added a NEWS item.

2005-09-09  Paul Eggert  <address@hidden>

        * NEWS: Document "niceness" vs "nice value".
        * configure.ac (utils_cv_func_setpriority): Simplify the tests.
        Define HAVE_NICE rather than NICE_PRIORITY (since a niceness is
        not a priority); all uses changed.
        * src/nice.c (main): Hoist errno=0 outside the ifdef.
        * doc/coreutils.texi (nice invocation): Document "niceness" versus
        "nice value" versus "scheduling priority".

--- NEWS        29 Aug 2005 21:14:06 -0000      1.305
+++ NEWS        9 Sep 2005 19:57:59 -0000
@@ -103,6 +103,11 @@ GNU coreutils NEWS                      
     --indicator-style=slash.  Use --file-type or
     --indicator-style=file-type to get -p's old behavior.
 
+  nice changes:
+
+    Documentation and diagnostics now refer to "nicenesses" (commonly
+    in the range -20...19 rather than "nice values" (commonly 0...39).
+
   nohup changes:
 
     nohup now ignores the umask when creating nohup.out.
@@ -270,15 +275,15 @@ GNU coreutils NEWS                      
 
   Fixes for "nice":
 
-    If it fails to lower the nice value due to lack of permissions,
+    If it fails to lower the niceness due to lack of permissions,
     it goes ahead and runs the command anyway, as POSIX requires.
 
-    It no longer incorrectly reports an error if the current nice
-    value happens to be -1.
+    It no longer incorrectly reports an error if the current niceness
+    happens to be -1.
 
-    It no longer assumes that nice values range from -20 through 19.
+    It no longer assumes that nicenesses range from -20 through 19.
 
-    It now consistently adjusts out-of-range nice values to the
+    It now consistently adjusts out-of-range nicenesses to the
     closest values in range; formerly it sometimes reported an error.
 
   pathchk no longer accepts trailing options, e.g., "pathchk -p foo -b"
--- configure.ac        23 Aug 2005 16:38:45 -0000      1.61
+++ configure.ac        9 Sep 2005 19:57:59 -0000
@@ -114,29 +114,24 @@ if test $ac_cv_func_syslog = no; then
   done
 fi
 
-AC_MSG_CHECKING(for 3-argument setpriority function)
-AC_CACHE_VAL(utils_cv_func_setpriority,
-[AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <sys/time.h>
-  #include <sys/resource.h>]], [[setpriority(0, 0, 0);]])],
-  [utils_cv_func_setpriority=yes],
-  [utils_cv_func_setpriority=no])])
-AC_MSG_RESULT($utils_cv_func_setpriority)
-if test $utils_cv_func_setpriority = yes; then
-  OPTIONAL_BIN_PROGS="$OPTIONAL_BIN_PROGS nice\$(EXEEXT)"
-  MAN="$MAN nice.1"
-else
-  AC_MSG_CHECKING(for nice function)
-  AC_CACHE_VAL(utils_cv_func_nice,
-    [AC_LINK_IFELSE([AC_LANG_PROGRAM([[]], [[nice();]])],
-                   [utils_cv_func_nice=yes],
-                   [utils_cv_func_nice=no])])
-  AC_MSG_RESULT($utils_cv_func_nice)
-  if test $utils_cv_func_nice = yes; then
-    AC_DEFINE(NICE_PRIORITY, 1, [FIXME])
-    OPTIONAL_BIN_PROGS="$OPTIONAL_BIN_PROGS nice\$(EXEEXT)"
-    MAN="$MAN nice.1"
-  fi
+AC_CACHE_CHECK([for 3-argument setpriority function],
+  [utils_cv_func_setpriority],
+  [AC_LINK_IFELSE(
+    [AC_LANG_PROGRAM(
+       [[#include <sys/time.h>
+        #include <sys/resource.h>
+       ]],
+       [[setpriority (0, 0, 0);]])],
+    [utils_cv_func_setpriority=yes],
+    [utils_cv_func_setpriority=no])])
+if test $utils_cv_func_setpriority = no; then
+  AC_CHECK_FUNCS([nice])
 fi
+case $utils_cv_func_setpriority,$ac_cv_func_nice in
+*yes*)
+  OPTIONAL_BIN_PROGS="$OPTIONAL_BIN_PROGS nice\$(EXEEXT)"
+  MAN="$MAN nice.1";;
+esac
 
 AC_DEFUN([coreutils_DUMMY_1],
 [
--- doc/coreutils.texi.~1.277.~ 2005-09-07 22:34:10.000000000 -0700
+++ doc/coreutils.texi  2005-09-09 13:49:19.000000000 -0700
@@ -12517,6 +12517,16 @@ enforce more restrictive limits.  An att
 outside the supported range is treated as an attempt to use the
 minimum or maximum supported value.
 
+A niceness should not be confused with a scheduling priority, which
+lets applications determine the order in which threads are scheduled
+to run.  Unlike a priority, a niceness is merely advice to the
+scheduler, which the scheduler is free to ignore.  Also, as a point of
+terminology, @acronym{POSIX} defines the behavior of @command{nice} in
+terms of a @dfn{nice value}, which is the nonnegative difference
+between a niceness and the minimum niceness.  Though @command{nice}
+conforms to @command{POSIX}, its documentation and diagnostics use the
+term ``niceness'' for compatibility with historical practice.
+
 @var{command} must not be a special built-in utility (@pxref{Special
 built-in utilities}).
 
--- src/nice.c  8 Sep 2005 06:52:09 -0000       1.84
+++ src/nice.c  9 Sep 2005 19:58:04 -0000
@@ -1,4 +1,4 @@
-/* nice -- run a program with modified nice value
+/* nice -- run a program with modified niceness
    Copyright (C) 1990-2005 Free Software Foundation, Inc.
 
    This program is free software; you can redistribute it and/or modify
@@ -27,7 +27,7 @@
 
 #include "system.h"
 
-#ifndef NICE_PRIORITY
+#if ! HAVE_NICE
 /* Include this after "system.h" so we're sure to have definitions
    (from time.h or sys/time.h) required for e.g. the ru_utime member.  */
 # include <sys/resource.h>
@@ -43,7 +43,7 @@
 
 #define AUTHORS "David MacKenzie"
 
-#ifdef NICE_PRIORITY
+#if HAVE_NICE
 # define GET_NICENESS() nice (0)
 #else
 # define GET_NICENESS() getpriority (PRIO_PROCESS, 0)
@@ -167,7 +167,7 @@ main (int argc, char **argv)
          error (0, 0, _("a command must be given with an adjustment"));
          usage (EXIT_FAIL);
        }
-      /* No command given; print the nice value.  */
+      /* No command given; print the niceness.  */
       errno = 0;
       current_niceness = GET_NICENESS ();
       if (current_niceness == -1 && errno != 0)
@@ -176,15 +176,14 @@ main (int argc, char **argv)
       exit (EXIT_SUCCESS);
     }
 
-#ifndef NICE_PRIORITY
   errno = 0;
+#if HAVE_NICE
+  ok = (nice (adjustment) != -1 || errno == 0);
+#else
   current_niceness = GET_NICENESS ();
   if (current_niceness == -1 && errno != 0)
     error (EXIT_FAIL, errno, _("cannot get niceness"));
   ok = (setpriority (PRIO_PROCESS, 0, current_niceness + adjustment) == 0);
-#else
-  errno = 0;
-  ok = (nice (adjustment) != -1 || errno == 0);
 #endif
   if (!ok)
     error (errno == EPERM ? 0 : EXIT_FAIL, errno, _("cannot set niceness"));