Improve option sanity checking

Any two conflicting options are reported only if they both occur in
the command line.  Otherwise, options defined in the command line
silently override those set in the TAR_OPTIONS environment variable.

* src/common.h (option_source): New enum.
(option_locus): New struct.
* src/names.c (name_elt): New member: line.
(name_add_file): Initialize line.
(read_name_from_file): Keep track of input line number for diagnostic
purposes.
(handle_option): Take a pointer to struct name_elt as 2nd parameter;
pass locus info to more_options().
* src/tar.c (tar_args): New member: loc.
(option_class): New enum.
(optloc_save,optloc_lookup)
(option_set_in_cl,optloc_eq): New functions.
(set_use_compress_program_option): Take into account option location.
(set_old_files_option): New function.
(parse_opt): Keep track of option locations.
(more_options): Improve error reporting.
(parse_default_options): New function.
(decode_options): Parse TAR_OPTION and command line separately.
Options from the latter silently override those from the former.

* lib/prepargs.c: Remove.
* lib/prepargs.h: Remove.
* lib/Makefile.am: Update.

lib/Makefile.am

@@ -41,7 +41,6 @@ noinst_HEADERS = \
 
 libtar_a_SOURCES = \
   paxerror.c paxexit-status.c paxlib.h paxnames.c \
-  prepargs.c prepargs.h \
   rtapelib.c \
   rmt.h \
   stdopen.c stdopen.h \

lib/prepargs.c

@@ -1,83 +0,0 @@
-/* Parse arguments from a string and prepend them to an argv.
-   Copyright 1999-2001, 2007, 2013-2014 Free Software Foundation, Inc.
-
-   This program is free software; you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 3, or (at your option)
-   any later version.
-
-   This program is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU General Public License for more details.
-
-   You should have received a copy of the GNU General Public License
-   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
-
-/* Written by Paul Eggert <eggert@twinsun.com>.  */
-
-#ifdef HAVE_CONFIG_H
-# include <config.h>
-#endif
-#include "prepargs.h"
-#include <sys/types.h>
-#include <xalloc.h>
-
-#if HAVE_STRING_H
-# include <string.h>
-#endif
-
-#include <ctype.h>
-
-/* Find the white-space-separated options specified by OPTIONS, and
-   using BUF to store copies of these options, set ARGV[0], ARGV[1],
-   etc. to the option copies.  Return the number N of options found.
-   Do not set ARGV[N].  If ARGV is null, do not store ARGV[0]
-   etc.  Backslash can be used to escape whitespace (and backslashes).  */
-static int
-prepend_args (char const *options, char *buf, char **argv)
-{
-  char const *o = options;
-  char *b = buf;
-  int n = 0;
-
-  for (;;)
-    {
-      while (isspace ((unsigned char) *o))
-	o++;
-      if (!*o)
-	return n;
-      if (argv)
-	argv[n] = b;
-      n++;
-
-      do
-	if ((*b++ = *o++) == '\\' && *o)
-	  b[-1] = *o++;
-      while (*o && ! isspace ((unsigned char) *o));
-
-      *b++ = '\0';
-    }
-}
-
-/* Prepend the whitespace-separated options in OPTIONS to the argument
-   vector of a main program with argument count *PARGC and argument
-   vector *PARGV.  */
-void
-prepend_default_options (char const *options, int *pargc, char ***pargv)
-{
-  if (options)
-    {
-      char *buf = xmalloc (strlen (options) + 1);
-      int prepended = prepend_args (options, buf, (char **) 0);
-      int argc = *pargc;
-      char * const *argv = *pargv;
-      char **pp = (char **) xmalloc ((prepended + argc + 1) * sizeof *pp);
-      *pargc = prepended + argc;
-      *pargv = pp;
-      *pp++ = *argv++;
-      pp += prepend_args (options, buf, pp);
-      while ((*pp++ = *argv++))
-	continue;
-    }
-}

lib/prepargs.h

@@ -1,3 +0,0 @@
-/* Parse arguments from a string and prepend them to an argv.  */
-
-void prepend_default_options (char const *, int *, char ***);