ls: clean up after wrapped+colored file names with clear-to-EOL

This change addresses a relatively unusual case: ls --color, with
a highlighted name being printed initially in the last row of a
terminal emulator (possibly followed by other lines of output) such
that it is wrapped onto the following line, as the terminal emulator
scrolls the output.  That would cause the entire following line to
be highlighted, even if the name happened to use only one position.
The least-invasive patch would have made colorized output larger for
all uses.  The approach taken below is more invasive, but limits the
increase in overhead to only those lines that are expected to wrap.
* src/ls.c (enum indicator_no): Add C_CLR_TO_EOL.
(indicator_name): Add "cl".
(color_indicator): Add default escape codes for "cl".
(print_long_format): Propagate width to print_name_with_quoting.
(print_name_with_quoting): Print new C_CLR_TO_EOL string if needed.
Return the width of what we're printing.
(print_file_name_and_frills): Propagate width.
(print_type_indicator): Return bool (aka width).
(print_many_per_line): Pass column position to print_* function.
(print_current_files): Likewise.
(print_horizontal): Likewise.
(print_with_commas): Likewise.
* src/dircolors.c (slack_codes): Add "CLRTOEOL".
(ls_codes): Add "cl".
* tests/ls/color-clear-to-eol: New file.  Test for this fix.
* tests/Makefile.am (TESTS): Add ls/color-clear-to-eol.
* THANKS: Update.
Reported by Alexander V. Lukyanov.  See thread for details:
http://thread.gmane.org/gmane.linux.kernel/740021/focus=14824
Thanks to Jan Engelhardt for helping me reproduce the problem.

Demonstrate with this in an 80-column xterm:
  seq 200 # to start in the "bottom" row
  touch zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz.foo
  env LS_COLORS='*.foo=0;31;42' ls -og --color=always

Before the fix, you'd see something like this:
(where the file name is printed in red on a green background,
and each "=" denotes a space on a green background)
...
  -rw-r--r--  1       0 Feb  5 11:31 zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz\
  zzzzzzzzzzzzzz.foo===================================================

After the patch, the trailing green spaces are gone:

  -rw-r--r--  1       0 Feb  5 11:31 zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz\
  zzzzzzzzzzzzzz.foo

1 files changed, 41 insertions, 26 deletions

diff --git a/src/ls.c b/src/ls.c
index b03aebc1f..59d1fae01 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -231,18 +231,21 @@ static size_t calculate_columns (bool by_columns);
 static void print_current_files (void);
 static void print_dir (char const *name, char const *realname,
 		       bool command_line_arg);
-static void print_file_name_and_frills (const struct fileinfo *f);
+static size_t print_file_name_and_frills (const struct fileinfo *f,
+					  size_t start_col);
 static void print_horizontal (void);
 static int format_user_width (uid_t u);
 static int format_group_width (gid_t g);
 static void print_long_format (const struct fileinfo *f);
 static void print_many_per_line (void);
-static void print_name_with_quoting (const char *p, mode_t mode,
-				     int linkok, bool stat_ok,
-				     enum filetype type,
-				     struct obstack *stack, nlink_t nlink);
+static size_t print_name_with_quoting (const char *p, mode_t mode,
+				       int linkok, bool stat_ok,
+				       enum filetype type,
+				       struct obstack *stack,
+				       nlink_t nlink,
+				       size_t start_col);
 static void prep_non_filename_text (void);
-static void print_type_indicator (bool stat_ok, mode_t mode,
+static bool print_type_indicator (bool stat_ok, mode_t mode,
 				  enum filetype type);
 static void print_with_commas (void);
 static void queue_directory (char const *name, char const *realname,
@@ -521,14 +524,15 @@ enum indicator_no
     C_LEFT, C_RIGHT, C_END, C_RESET, C_NORM, C_FILE, C_DIR, C_LINK,
     C_FIFO, C_SOCK,
     C_BLK, C_CHR, C_MISSING, C_ORPHAN, C_EXEC, C_DOOR, C_SETUID, C_SETGID,
-    C_STICKY, C_OTHER_WRITABLE, C_STICKY_OTHER_WRITABLE, C_CAP, C_HARDLINK
+    C_STICKY, C_OTHER_WRITABLE, C_STICKY_OTHER_WRITABLE, C_CAP, C_HARDLINK,
+    C_CLR_TO_EOL
   };
 
 static const char *const indicator_name[]=
   {
     "lc", "rc", "ec", "rs", "no", "fi", "di", "ln", "pi", "so",
     "bd", "cd", "mi", "or", "ex", "do", "su", "sg", "st",
-    "ow", "tw", "ca", "hl", NULL
+    "ow", "tw", "ca", "hl", "cl", NULL
   };
 
 struct color_ext_type
@@ -563,6 +567,7 @@ static struct bin_str color_indicator[] =
     { LEN_STR_PAIR ("30;42") },		/* tw: ow w/ sticky: black on green */
     { LEN_STR_PAIR ("30;41") },		/* ca: black on red */
     { LEN_STR_PAIR ("44;37") },		/* hl: white on blue */
+    { LEN_STR_PAIR ("\033[K") },	/* cl: clear to end of line */
   };
 
 /* FIXME: comment  */
@@ -3284,7 +3289,7 @@ print_current_files (void)
     case one_per_line:
       for (i = 0; i < cwd_n_used; i++)
 	{
-	  print_file_name_and_frills (sorted_file[i]);
+	  print_file_name_and_frills (sorted_file[i], 0);
 	  putchar ('\n');
 	}
       break;
@@ -3636,9 +3641,9 @@ print_long_format (const struct fileinfo *f)
     }
 
   DIRED_FPUTS (buf, stdout, p - buf);
-  print_name_with_quoting (f->name, FILE_OR_LINK_MODE (f), f->linkok,
-			   f->stat_ok, f->filetype, &dired_obstack,
-			   f->stat.st_nlink);
+  size_t w = print_name_with_quoting (f->name, FILE_OR_LINK_MODE (f), f->linkok,
+				      f->stat_ok, f->filetype, &dired_obstack,
+				      f->stat.st_nlink, p - buf);
 
   if (f->filetype == symbolic_link)
     {
@@ -3647,7 +3652,7 @@ print_long_format (const struct fileinfo *f)
 	  DIRED_FPUTS_LITERAL (" -> ", stdout);
 	  print_name_with_quoting (f->linkname, f->linkmode, f->linkok - 1,
 				   f->stat_ok, f->filetype, NULL,
-				   f->stat.st_nlink);
+				   f->stat.st_nlink, (p - buf) + w + 4);
 	  if (indicator_style != none)
 	    print_type_indicator (true, f->linkmode, unknown);
 	}
@@ -3822,10 +3827,11 @@ quote_name (FILE *out, const char *name, struct quoting_options const *options,
   return len;
 }
 
-static void
+static size_t
 print_name_with_quoting (const char *p, mode_t mode, int linkok,
 			 bool stat_ok, enum filetype type,
-			 struct obstack *stack, nlink_t nlink)
+			 struct obstack *stack, nlink_t nlink,
+			 size_t start_col)
 {
   bool used_color_this_time
     = (print_with_color
@@ -3834,7 +3840,8 @@ print_name_with_quoting (const char *p, mode_t mode, int linkok,
   if (stack)
     PUSH_CURRENT_DIRED_POS (stack);
 
-  dired_pos += quote_name (stdout, p, filename_quoting_options, NULL);
+  size_t width = quote_name (stdout, p, filename_quoting_options, NULL);
+  dired_pos += width;
 
   if (stack)
     PUSH_CURRENT_DIRED_POS (stack);
@@ -3843,7 +3850,11 @@ print_name_with_quoting (const char *p, mode_t mode, int linkok,
     {
       process_signals ();
       prep_non_filename_text ();
+      if (start_col / line_length != (start_col + width - 1) / line_length)
+	put_indicator (&color_indicator[C_CLR_TO_EOL]);
     }
+
+  return width;
 }
 
 static void
@@ -3863,8 +3874,8 @@ prep_non_filename_text (void)
    Also print file size, inode number, and filetype indicator character,
    as requested by switches.  */
 
-static void
-print_file_name_and_frills (const struct fileinfo *f)
+static size_t
+print_file_name_and_frills (const struct fileinfo *f, size_t start_col)
 {
   char buf[MAX (LONGEST_HUMAN_READABLE + 1, INT_BUFSIZE_BOUND (uintmax_t))];
 
@@ -3880,11 +3891,14 @@ print_file_name_and_frills (const struct fileinfo *f)
   if (print_scontext)
     printf ("%*s ", format == with_commas ? 0 : scontext_width, f->scontext);
 
-  print_name_with_quoting (f->name, FILE_OR_LINK_MODE (f), f->linkok,
-			   f->stat_ok, f->filetype, NULL, f->stat.st_nlink);
+  size_t width = print_name_with_quoting (f->name, FILE_OR_LINK_MODE (f),
+					  f->linkok, f->stat_ok, f->filetype,
+					  NULL, f->stat.st_nlink, start_col);
 
   if (indicator_style != none)
-    print_type_indicator (f->stat_ok, f->stat.st_mode, f->filetype);
+    width += print_type_indicator (f->stat_ok, f->stat.st_mode, f->filetype);
+
+  return width;
 }
 
 /* Given these arguments describing a file, return the single-byte
@@ -3921,12 +3935,13 @@ get_type_indicator (bool stat_ok, mode_t mode, enum filetype type)
   return c;
 }
 
-static void
+static bool
 print_type_indicator (bool stat_ok, mode_t mode, enum filetype type)
 {
   char c = get_type_indicator (stat_ok, mode, type);
   if (c)
     DIRED_PUTCHAR (c);
+  return !!c;
 }
 
 #ifdef HAVE_CAP
@@ -4128,7 +4143,7 @@ print_many_per_line (void)
 	  struct fileinfo const *f = sorted_file[filesno];
 	  size_t name_length = length_of_file_name_and_frills (f);
 	  size_t max_name_length = line_fmt->col_arr[col++];
-	  print_file_name_and_frills (f);
+	  print_file_name_and_frills (f, pos);
 
 	  filesno += rows;
 	  if (filesno >= cwd_n_used)
@@ -4153,7 +4168,7 @@ print_horizontal (void)
   size_t max_name_length = line_fmt->col_arr[0];
 
   /* Print first entry.  */
-  print_file_name_and_frills (f);
+  print_file_name_and_frills (f, 0);
 
   /* Now the rest.  */
   for (filesno = 1; filesno < cwd_n_used; ++filesno)
@@ -4172,7 +4187,7 @@ print_horizontal (void)
 	}
 
       f = sorted_file[filesno];
-      print_file_name_and_frills (f);
+      print_file_name_and_frills (f, pos);
 
       name_length = length_of_file_name_and_frills (f);
       max_name_length = line_fmt->col_arr[col];
@@ -4210,7 +4225,7 @@ print_with_commas (void)
 	  putchar (separator);
 	}
 
-      print_file_name_and_frills (f);
+      print_file_name_and_frills (f, pos);
       pos += len;
     }
   putchar ('\n');