POSIX most likely will require a new -C option for 'sort'

[Paul Eggert]

<http://www.opengroup.org/austin/mailarchives/ag/msg10185.html>
suggests that the next edition of POSIX will require 'sort' to support
a new -C option.  There's no guarantee of this new requirement, but at
this point I think we should probably just put in -C.  Here is a
proposed patch.

2007-01-21  Paul Eggert  <address@hidden>

        * NEWS: New option sort -C, proposed by XCU ERN 127, which looks
        like it will be approved.  Also add --check=quiet, --check=silent
        as long aliases, and --check=diagnose-first as an alias for -c.
        * doc/coreutils.texi (sort invocation): Document this.
        Also, mention that sort -c can take at most one file.
        * src/sort.c: Implement this.
        Include argmatch.h.
        (usage): Document the change.
        (CHECK_OPTION): New constant.
        (long_options): --check now takes an optional argument, and is now
        treated differently from 'c'.
        (check_args, check_types): New constant arrays.
        (check): New arg CHECKONLY, which suppresses diagnostic if -C.
        (main): Parse the new options.
        * tests/sort/Test.pm (02d, 02d, incompat5, incompat6):
        New tests for -C.

diff --git a/NEWS b/NEWS
index a30b17e..99f6b93 100644
--- a/NEWS
+++ b/NEWS
@@ -29,6 +29,13 @@ GNU coreutils NEWS                                    -*- 
outline -*-

   "rm --interactive=never F" no longer prompts for an unwritable F

+** New features
+
+  sort accepts the new option -C, which acts like -c except no diagnostic
+  is printed.  Its --check option now accepts an optional argument, and
+  --check=quiet and --check=silent are now aliases for -C, while
+  --check=diagnose-first is an alias for -c or plain --check.
+

 * Noteworthy changes in release 6.7 (2006-12-08) [stable]

diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 89e97d8..c534223 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -3342,12 +3342,26 @@ mode:

 @item -c
 @itemx --check
address@hidden --check=diagnose-first
 @opindex -c
 @opindex --check
 @cindex checking for sortedness
-Check whether the given files are already sorted: if they are not all
-sorted, print an error message and exit with a status of 1.
+Check whether the given file is already sorted: if it is not all
+sorted, print a diagnostic containing the first out-of-order line and
+exit with a status of 1.
 Otherwise, exit successfully.
+At most one input file can be given.
+
address@hidden -C
address@hidden --check=quiet
address@hidden --check=silent
address@hidden -c
address@hidden --check
address@hidden checking for sortedness
+Exit successfully if the given file is already sorted, and
+exit with status 1 otherwise.
+At most one input file can be given.
+This is like @option{-c}, except it does not print a diagnostic.

 @item -m
 @itemx --merge
@@ -3401,7 +3415,7 @@ Exit status:

 @display
 0 if no error occurred
-1 if invoked with @option{-c} and the input is not properly sorted
+1 if invoked with @option{-c} or @option{-C} and the input is not sorted
 2 if an error occurred
 @end display

@@ -3703,7 +3717,7 @@ disks and controllers.
 @cindex uniquifying output

 Normally, output only the first of a sequence of lines that compare
-equal.  For the @option{--check} (@option{-c}) option,
+equal.  For the @option{--check} (@option{-c} or @option{-C}) option,
 check that no pair of consecutive lines compares equal.

 This option also disables the default last-resort comparison.
diff --git a/src/sort.c b/src/sort.c
index 8a22796..e54db00 100644
--- a/src/sort.c
+++ b/src/sort.c
@@ -27,6 +27,7 @@
 #include <sys/types.h>
 #include <signal.h>
 #include "system.h"
+#include "argmatch.h"
 #include "error.h"
 #include "hard-locale.h"
 #include "inttostr.h"
@@ -315,7 +316,8 @@ Ordering options:\n\
       fputs (_("\
 Other options:\n\
 \n\
-  -c, --check               check whether input is sorted; do not sort\n\
+  -c, --check, --check=diagnose-first  check for sorted input; do not sort\n\
+  -C, --check=quiet, --check=silent  like -c, but do not report first bad 
line\n\
   -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\
   -o, --output=FILE         write result to FILE instead of standard output\n\
@@ -364,15 +366,16 @@ native byte values.\n\
    non-character as a pseudo short option, starting with CHAR_MAX + 1.  */
 enum
 {
-  RANDOM_SOURCE_OPTION = CHAR_MAX + 1
+  CHECK_OPTION = CHAR_MAX + 1,
+  RANDOM_SOURCE_OPTION
 };

-static char const short_options[] = "-bcdfgik:mMno:rRsS:t:T:uy:z";
+static char const short_options[] = "-bcCdfgik:mMno:rRsS:t:T:uy:z";

 static struct option const long_options[] =
 {
   {"ignore-leading-blanks", no_argument, NULL, 'b'},
-  {"check", no_argument, NULL, 'c'},
+  {"check", optional_argument, NULL, CHECK_OPTION},
   {"dictionary-order", no_argument, NULL, 'd'},
   {"ignore-case", no_argument, NULL, 'f'},
   {"general-numeric-sort", no_argument, NULL, 'g'},
@@ -396,6 +399,16 @@ static struct option const long_options[] =
   {NULL, 0, NULL, 0},
 };

+static char const *const check_args[] =
+{
+  "quiet", "silent", "diagnose-first", NULL
+};
+static char const check_types[] =
+{
+  'C', 'C', 'c'
+};
+ARGMATCH_VERIFY (check_args, check_types);
+
 /* The set of signals that are caught.  */
 static sigset_t caught_signals;

@@ -1512,13 +1525,13 @@ compare (const struct line *a, const struct line *b)
   return reverse ? -diff : diff;
 }

-/* Check that the lines read from FILE_NAME come in order.  Print a
-   diagnostic (FILE_NAME, line number, contents of line) to stderr and return
-   false if they are not in order.  Otherwise, print no diagnostic
-   and return true.  */
+/* Check that the lines read from FILE_NAME come in order.  Return
+   true if they are in order.  If CHECKONLY == 'c', also print a
+   diagnostic (FILE_NAME, line number, contents of line) to stderr if
+   they are not in order.  */

 static bool
-check (char const *file_name)
+check (char const *file_name, char checkonly)
 {
   FILE *fp = xfopen (file_name, "r");
   struct buffer buf;           /* Input buffer. */
@@ -1544,15 +1557,19 @@ check (char const *file_name)
        {
        found_disorder:
          {
-           struct line const *disorder_line = line - 1;
-           uintmax_t disorder_line_number =
-             buffer_linelim (&buf) - disorder_line + line_number;
-           char hr_buf[INT_BUFSIZE_BOUND (uintmax_t)];
-           fprintf (stderr, _("%s: %s:%s: disorder: "),
-                    program_name, file_name,
-                    umaxtostr (disorder_line_number, hr_buf));
-           write_bytes (disorder_line->text, disorder_line->length, stderr,
-                        _("standard error"));
+           if (checkonly == 'c')
+             {
+               struct line const *disorder_line = line - 1;
+               uintmax_t disorder_line_number =
+                 buffer_linelim (&buf) - disorder_line + line_number;
+               char hr_buf[INT_BUFSIZE_BOUND (uintmax_t)];
+               fprintf (stderr, _("%s: %s:%s: disorder: "),
+                        program_name, file_name,
+                        umaxtostr (disorder_line_number, hr_buf));
+               write_bytes (disorder_line->text, disorder_line->length,
+                            stderr, _("standard error"));
+             }
+
            ordered = false;
            break;
          }
@@ -2305,7 +2322,7 @@ main (int argc, char **argv)
   struct keyfield gkey;
   char const *s;
   int c = 0;
-  bool checkonly = false;
+  char checkonly = 0;
   bool mergeonly = false;
   char *random_source = NULL;
   bool need_random = false;
@@ -2497,8 +2514,16 @@ main (int argc, char **argv)
          }
          break;

+       case CHECK_OPTION:
+         c = (optarg
+              ? XARGMATCH ("--check", optarg, check_args, check_types)
+              : 'c');
+         /* Fall through.  */
        case 'c':
-         checkonly = true;
+       case 'C':
+         if (checkonly && checkonly != c)
+           incompatible_options ("cC");
+         checkonly = c;
          break;

        case 'k':
@@ -2705,15 +2730,19 @@ main (int argc, char **argv)
   if (checkonly)
     {
       if (nfiles > 1)
-       error (SORT_FAILURE, 0, _("extra operand %s not allowed with -c"),
-              quote (files[1]));
+       error (SORT_FAILURE, 0, _("extra operand %s not allowed with -%c"),
+              quote (files[1]), checkonly);

       if (outfile)
-       incompatible_options ("co");
+       {
+         static char opts[] = {0, 'o', 0};
+         opts[0] = checkonly;
+         incompatible_options (opts);
+       }

-      /* POSIX requires that sort return 1 IFF invoked with -c and the
+      /* POSIX requires that sort return 1 IFF invoked with -c or -C and the
         input is not properly sorted.  */
-      exit (check (files[0]) ? EXIT_SUCCESS : SORT_OUT_OF_ORDER);
+      exit (check (files[0], checkonly) ? EXIT_SUCCESS : SORT_OUT_OF_ORDER);
     }

   if (mergeonly)
diff --git a/tests/sort/Test.pm b/tests/sort/Test.pm
index 6bed61b..dc41d92 100755
--- a/tests/sort/Test.pm
+++ b/tests/sort/Test.pm
@@ -51,6 +51,8 @@ my @tv = (
 ["02a", '-c', "A\nB\nC\n", '', 0],
 ["02b", '-c', "A\nC\nB\n", '', 1],
 ["02c", '-c -k1,1', "a\na b\n", '', 0],
+["02d", '-C', "A\nB\nC\n", '', 0],
+["02e", '-C', "A\nC\nB\n", '', 1],
 # This should fail because there are duplicate keys
 ["02m", '-cu', "A\nA\n", '', 1],
 ["02n", '-cu', "A\nB\n", '', 0],
@@ -272,6 +274,8 @@ my @tv = (
 ["incompat2", '-fR', '', '', 2],
 ["incompat3", '-dfgiMnR', '', '', 2],
 ["incompat4", '-c -o /dev/null', '', '', 2],
+["incompat5", '-C -o /dev/null', '', '', 2],
+["incompat6", '-cC', '', '', 2],

 # -t '\0' is accepted, as of coreutils-5.0.91
 ['nul-tab', "-k2,2 -t '\\0'", "a\0z\01\nb\0y\02\n", "b\0y\02\na\0z\01\n", 0],