ls: allow -w0 to mean no limit on line length

* src/ls.c (print_with_separator): Renamed from print_with_commas,
and parameterized to accept the separator to print.
Also fix an edge case where '\n' not printed when
the POS variable overflows SIZE_MAX.
(print_current_files): Degenerate -x and -C to using the
cheaper print_with_separator() in the -w0 case.
* doc/coreutils.texi (ls invocation): Document the new feature.
* tests/ls/w-option.sh: A new test.
* tests/local.mk: Reference the new test.
* NEWS: Mention the improvement.
Fixes http://bugs.gnu.org/21325

NEWS

@@ -29,6 +29,8 @@ GNU coreutils NEWS                                    -*- outline -*-
   upon detection of a directory cycle.
   [issue introduced in coreutils-8.20]
 
+  ls -w0 is now interpreted as no limit on the length of the outputted line.
+
 
 * Noteworthy changes in release 8.24 (2015-07-03) [stable]
 

doc/coreutils.texi

@@ -7445,7 +7445,9 @@ TAB following a non-ASCII byte.  You can avoid that issue by using the
 Assume the screen is @var{cols} columns wide.  The default is taken
 from the terminal settings if possible; otherwise the environment
 variable @env{COLUMNS} is used if it is set; otherwise the default
-is 80.
+is 80.  With a @var{cols} value of @samp{0}, there is no limit on
+the length of the output line, and that single output line will
+be delimited with spaces, not tabs.
 
 @end table
 

src/ls.c

@@ -279,7 +279,7 @@ static size_t print_name_with_quoting (const struct fileinfo *f,
 static void prep_non_filename_text (void);
 static bool print_type_indicator (bool stat_ok, mode_t mode,
                                   enum filetype type);
-static void print_with_commas (void);
+static void print_with_separator (char sep);
 static void queue_directory (char const *name, char const *realname,
                              bool command_line_arg);
 static void sort_files (void);
@@ -1524,7 +1524,7 @@ main (int argc, char **argv)
 }
 
 /* Set the line length to the value given by SPEC.  Return true if
-   successful.  */
+   successful.  0 means no limit on line length.  */
 
 static bool
 set_line_length (char const *spec)
@@ -3647,15 +3647,21 @@ print_current_files (void)
       break;
 
     case many_per_line:
-      print_many_per_line ();
+      if (! line_length)
+        print_with_separator (' ');
+      else
+        print_many_per_line ();
       break;
 
     case horizontal:
-      print_horizontal ();
+      if (! line_length)
+        print_with_separator (' ');
+      else
+        print_horizontal ();
       break;
 
     case with_commas:
-      print_with_commas ();
+      print_with_separator (',');
       break;
 
     case long_format:
@@ -4242,7 +4248,8 @@ print_name_with_quoting (const struct fileinfo *f,
   if (used_color_this_time)
     {
       prep_non_filename_text ();
-      if (start_col / line_length != (start_col + width - 1) / line_length)
+      if (line_length
+          && (start_col / line_length != (start_col + width - 1) / line_length))
         put_indicator (&color_indicator[C_CLR_TO_EOL]);
     }
 
@@ -4583,8 +4590,10 @@ print_horizontal (void)
   putchar ('\n');
 }
 
+/* Output name + SEP + ' '.  */
+
 static void
-print_with_commas (void)
+print_with_separator (char sep)
 {
   size_t filesno;
   size_t pos = 0;
@@ -4592,13 +4601,15 @@ print_with_commas (void)
   for (filesno = 0; filesno < cwd_n_used; filesno++)
     {
       struct fileinfo const *f = sorted_file[filesno];
-      size_t len = length_of_file_name_and_frills (f);
+      size_t len = line_length ? length_of_file_name_and_frills (f) : 0;
 
       if (filesno != 0)
         {
           char separator;
 
-          if (pos + len + 2 < line_length)
+          if (! line_length
+              || ((pos + len + 2 < line_length)
+                  && (pos <= SIZE_MAX - len - 2)))
             {
               pos += 2;
               separator = ' ';
@@ -4609,7 +4620,7 @@ print_with_commas (void)
               separator = '\n';
             }
 
-          putchar (',');
+          putchar (sep);
           putchar (separator);
         }
 
@@ -4935,7 +4946,7 @@ Sort entries alphabetically if none of -cftuvSUX nor --sort is specified.\n\
   -v                         natural sort of (version) numbers within text\n\
 "), stdout);
       fputs (_("\
-  -w, --width=COLS           assume screen width instead of current value\n\
+  -w, --width=COLS           set output width to COLS.  0 means no limit\n\
   -x                         list entries by lines instead of by columns\n\
   -X                         sort alphabetically by entry extension\n\
   -Z, --context              print any security context of each file\n\

tests/local.mk

@@ -568,6 +568,7 @@ all_tests =					\
   tests/ls/infloop.sh				\
   tests/ls/inode.sh				\
   tests/ls/m-option.sh				\
+  tests/ls/w-option.sh				\
   tests/ls/multihardlink.sh			\
   tests/ls/no-arg.sh				\
   tests/ls/no-cap.sh				\

tests/ls/w-option.sh

@@ -0,0 +1,44 @@
+#!/bin/sh
+# exercise the -w option
+
+# Copyright (C) 2015 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/>.
+
+. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
+print_ver_ ls
+getlimits_
+
+touch a b || framework_failure_
+chmod a+x a || framework_failure_
+
+# Negative values disallowed
+returns_ 2 ls -w-1 || fail=1
+
+# Verify octal parsing (especially since 0 is allowed)
+returns_ 2 ls -w08 || fail=1
+
+# Overflowed values are capped at SIZE_MAX
+ls -w$SIZE_OFLOW || fail=1
+
+# After coreutils 8.24 -w0 means no limit
+# and delimiting with spaces
+ls -w0 -x -T1 a b > out || fail=1
+printf '%s\n' 'a  b' > exp || framework_failure_
+compare exp out || fail=1
+
+# Ensure that 0 line length doesn't cause division by zero
+TERM=xterm ls -w0 -x --color=always || fail=1
+
+Exit $fail