sort: add new option --files0-from=F

* src/sort.c: Support new option.
* tests/misc/sort-files0-from: Test new option.
* tests/misc/Makefile.am: Indicate new test.
* docs/coreutils.texi: Explain new option.
* NEWS: Advertise new option.

Signed-off-by: Bo Borgerson <gigabo@gmail.com>

NEWS

@@ -18,6 +18,11 @@ GNU coreutils NEWS                                    -*- outline -*-
   md5sum now accepts the new option, --quiet, to suppress the printing of
   'OK' messages.  sha1sum, sha224sum, sha384sum, and sha512sum accept it, too.
 
+  sort accepts a new option, --files0-from=F, that specifies a file
+  containing a null-separated list of files to sort.  This list is used
+  instead of filenames passed on the command-line to avoid problems with
+  maximum command-line (argv) length.
+
 ** Bug fixes
 
   chcon --verbose now prints a newline after each message

doc/coreutils.texi

@@ -3172,7 +3172,7 @@ Print only the newline counts.
 @opindex --max-line-length
 Print only the maximum line lengths.
 
-@macro filesZeroFromOption{cmd,withTotalOption}
+@macro filesZeroFromOption{cmd,withTotalOption,subListOutput}
 @itemx --files0-from=@var{FILE}
 @opindex --files0-from=@var{FILE}
 @c This is commented out to avoid a texi2dvi failure.
@@ -3184,13 +3184,13 @@ This is useful \withTotalOption\
 when the list of file names is so long that it may exceed a command line
 length limitation.
 In such cases, running @command{\cmd\} via @command{xargs} is undesirable
-because it splits the list into pieces and makes @command{\cmd\} print a
-total for each sublist rather than for the entire list.
+because it splits the list into pieces and makes @command{\cmd\} print
+\subListOutput\ for each sublist rather than for the entire list.
 One way to produce a list of null-byte-terminated file names is with @sc{gnu}
 @command{find}, using its @option{-print0} predicate.
 Do not specify any @var{FILE} on the command line when using this option.
 @end macro
-@filesZeroFromOption{wc,}
+@filesZeroFromOption{wc,,a total}
 
 For example, to find the length of the longest line in any @file{.c} or
 @file{.h} file in the current hierarchy, do this:
@@ -3779,6 +3779,8 @@ Terminate with an error if @var{prog} exits with nonzero status.
 White space and the backslash character should not appear in
 @var{prog}; they are reserved for future use.
 
+@filesZeroFromOption{sort,,sorted output}
+
 @item -k @var{pos1}[,@var{pos2}]
 @itemx --key=@var{pos1}[,@var{pos2}]
 @opindex -k

src/sort.c

@@ -36,7 +36,9 @@
 #include "physmem.h"
 #include "posixver.h"
 #include "quote.h"
+#include "quotearg.h"
 #include "randread.h"
+#include "readtokens0.h"
 #include "stdio--.h"
 #include "stdlib--.h"
 #include "strnumcmp.h"
@@ -303,8 +305,9 @@ usage (int status)
     {
       printf (_("\
 Usage: %s [OPTION]... [FILE]...\n\
+  or:  %s [OPTION]... --files0-from=F\n\
 "),
-	      program_name);
+	      program_name, program_name);
       fputs (_("\
 Write sorted concatenation of all FILE(s) to standard output.\n\
 \n\
@@ -341,6 +344,10 @@ Other options:\n\
   -C, --check=quiet, --check=silent  like -c, but do not report first bad line\n\
       --compress-program=PROG  compress temporaries with PROG;\n\
                               decompress them with PROG -d\n\
+      --files0-from=F       read input from the files specified by\n\
+                            NUL-terminated names in file F\n\
+"), stdout);
+      fputs (_("\
   -k, --key=POS1[,POS2]     start a key at POS1, end it at POS2 (origin 1)\n\
   -m, --merge               merge already sorted files; do not sort\n\
 "), stdout);
@@ -393,6 +400,7 @@ enum
 {
   CHECK_OPTION = CHAR_MAX + 1,
   COMPRESS_PROGRAM_OPTION,
+  FILES0_FROM_OPTION,
   RANDOM_SOURCE_OPTION,
   SORT_OPTION
 };
@@ -406,6 +414,7 @@ static struct option const long_options[] =
   {"compress-program", required_argument, NULL, COMPRESS_PROGRAM_OPTION},
   {"dictionary-order", no_argument, NULL, 'd'},
   {"ignore-case", no_argument, NULL, 'f'},
+  {"files0-from", required_argument, NULL, FILES0_FROM_OPTION},
   {"general-numeric-sort", no_argument, NULL, 'g'},
   {"ignore-nonprinting", no_argument, NULL, 'i'},
   {"key", required_argument, NULL, 'k'},
@@ -2751,6 +2760,8 @@ main (int argc, char **argv)
   bool posixly_correct = (getenv ("POSIXLY_CORRECT") != NULL);
   bool obsolete_usage = (posix2_version () < 200112);
   char **files;
+  char *files_from = NULL;
+  struct Tokens tok;
   char const *outfile = NULL;
 
   initialize_main (&argc, &argv);
@@ -2954,6 +2965,10 @@ main (int argc, char **argv)
 	  compress_program = optarg;
 	  break;
 
+	case FILES0_FROM_OPTION:
+	  files_from = optarg;
+	  break;
+
 	case 'k':
 	  key = key_init (&key_buf);
 
@@ -3098,6 +3113,65 @@ main (int argc, char **argv)
 	}
     }
 
+  if (files_from)
+    {
+      FILE *stream;
+
+      /* When using --files0-from=F, you may not specify any files
+	 on the command-line.  */
+      if (nfiles)
+	{
+	  error (0, 0, _("extra operand %s"), quote (files[0]));
+	  fprintf (stderr, "%s\n",
+		   _("file operands cannot be combined with --files0-from"));
+	  usage (SORT_FAILURE);
+	}
+
+      if (STREQ (files_from, "-"))
+	stream = stdin;
+      else
+	{
+	  stream = fopen (files_from, "r");
+	  if (stream == NULL)
+	    error (SORT_FAILURE, errno, _("cannot open %s for reading"),
+		   quote (files_from));
+	}
+
+      readtokens0_init (&tok);
+
+      if (! readtokens0 (stream, &tok) || fclose (stream) != 0)
+	error (SORT_FAILURE, 0, _("cannot read file names from %s"),
+	       quote (files_from));
+
+      if (tok.n_tok)
+	{
+	  size_t i;
+	  free (files);
+	  files = tok.tok;
+	  nfiles = tok.n_tok;
+	  for (i = 0; i < nfiles; i++)
+	  {
+	      if (STREQ (files[i], "-"))
+		error (SORT_FAILURE, 0, _("when reading file names from stdin, "
+					  "no file name of %s allowed"),
+		       quote (files[i]));
+	      else if (files[i][0] == '\0')
+		{
+		  /* Using the standard `filename:line-number:' prefix here is
+		     not totally appropriate, since NUL is the separator, not NL,
+		     but it might be better than nothing.  */
+		  unsigned long int file_number = i + 1;
+		  error (SORT_FAILURE, 0,
+			 _("%s:%lu: invalid zero-length file name"),
+			 quotearg_colon (files_from), file_number);
+		}
+	  }
+	}
+      else
+	error (SORT_FAILURE, 0, _("no input from %s"),
+	       quote (files_from));
+    }
+
   /* Inheritance of global options to individual keys. */
   for (key = keylist; key; key = key->next)
     {

tests/Makefile.am

@@ -193,6 +193,7 @@ TESTS =						\
   misc/shuf					\
   misc/sort					\
   misc/sort-compress				\
+  misc/sort-files0-from				\
   misc/sort-merge				\
   misc/sort-rand				\
   misc/split-a					\

tests/misc/sort-files0-from

@@ -0,0 +1,96 @@
+#!/usr/bin/perl
+# Exercise sort's --files0-from option.
+# FIXME: keep this file in sync with tests/du/files0-from.
+
+# Copyright (C) 2006-2008 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 of the License, 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/>.
+
+use strict;
+
+(my $program_name = $0) =~ s|.*/||;
+
+my $prog = 'sort';
+
+# Turn off localization of executable's output.
+@ENV{qw(LANGUAGE LANG LC_ALL)} = ('C') x 3;
+
+my @Tests =
+  (
+   # invalid extra command line argument
+   ['f-extra-arg', '--files0-from=- no-such', {IN=>"a"}, {EXIT=>2},
+    {ERR => "$prog: extra operand `no-such'\n"
+	. "file operands cannot be combined with --files0-from\n"
+	. "Try `$prog --help' for more information.\n"}
+    ],
+
+   # missing input file
+   ['missing', '--files0-from=missing', {EXIT=>2},
+    {ERR => "$prog: cannot open `missing' for reading: "
+     . "No such file or directory\n"}],
+
+   # input file name of '-'
+   ['minus-in-stdin', '--files0-from=-', '<', {IN=>{f=>'-'}}, {EXIT=>2},
+    {ERR => "$prog: when reading file names from stdin, no file name of"
+     . " `-' allowed\n"}],
+
+   # empty input, regular file
+   ['empty', '--files0-from=@AUX@', {AUX=>''}, {EXIT=>2},
+    {ERR_SUBST => 's/no input from.+$//'}, {ERR => "$prog: \n"}],
+
+   # empty input, from non-regular file
+   ['empty-nonreg', '--files0-from=/dev/null', {EXIT=>2},
+    {ERR => "$prog: no input from `/dev/null'\n"}],
+
+   # one NUL
+   ['nul-1', '--files0-from=-', '<', {IN=>"\0"}, {EXIT=>2},
+    {ERR => "$prog: -:1: invalid zero-length file name\n"}],
+
+   # two NULs
+   # Note that the behavior here differs from `wc' in that the
+   # first zero-length file name is treated as fatal, so there
+   # is only one line of diagnostic output.
+   ['nul-2', '--files0-from=-', '<', {IN=>"\0\0"}, {EXIT=>2},
+    {ERR => "$prog: -:1: invalid zero-length file name\n"}],
+
+   # one file name, no NUL
+   ['1', '--files0-from=-', '<',
+    {IN=>{f=>"g"}}, {AUX=>{g=>'a'}}, {OUT=>"a\n"} ],
+
+   # one file name, with NUL
+   ['1a', '--files0-from=-', '<',
+    {IN=>{f=>"g\0"}}, {AUX=>{g=>'a'}}, {OUT=>"a\n"} ],
+
+   # two file names, no final NUL
+   ['2', '--files0-from=-', '<',
+    {IN=>{f=>"g\0g"}}, {AUX=>{g=>'a'}}, {OUT=>"a\na\n"} ],
+
+   # two file names, with final NUL
+   ['2a', '--files0-from=-', '<',
+    {IN=>{f=>"g\0g\0"}}, {AUX=>{g=>'a'}}, {OUT=>"a\na\n"} ],
+
+   # Ensure that $prog performs no processing when there is a zero-length filename
+   # Note that the behavior here differs from `wc' in that the
+   # first zero-length file name is treated as fatal, so there
+   # should be no output on STDOUT.
+   ['zero-len', '--files0-from=-', '<',
+    {IN=>{f=>"\0g\0"}}, {AUX=>{g=>''}},
+    {ERR => "$prog: -:1: invalid zero-length file name\n"}, {EXIT=>2} ],
+  );
+
+my $save_temps = $ENV{DEBUG};
+my $verbose = $ENV{VERBOSE};
+
+my $fail = run_tests ($program_name, $prog, \@Tests, $save_temps, $verbose);
+exit $fail;