bug+patch: du output 'corrupt' (messy) by relying on fixed-sized tabs

[Linda Walsh]

This is related to bug#19849 which was about adding an "expand
tabs option" or an option to set a tabsize.

Without that enhancement, the current output is just messed
up on terminals/consoles that don't use hard-coded-constant
widths for tabs (like most of the Xterm & linux consoles).

Adding the switches is more work than I want to chew
off right now, but the bad output was really getting annoying,
so I threw together a patch against the current git source.

If someone wants to look it over and try it out and
add it to the current coreutils (it's a patch against 'src/du.c'),
that would fix the garbled output until such time as the
RFE can be addressed.

This takes du output (example from my tmp dir):

Ishtar:tools/coreutils/work/src> /usr/bin/du 
/tmp/t*                          
4 /tmp/t
1160  /tmp/t1
680 /tmp/t2
4 /tmp/tab2.patch
20  /tmp/tabs
4 /tmp/tmpf
4 /tmp/topcmds
24  /tmp/topcmds-hlps
24  /tmp/topcmds2
8 /tmp/topcmds2.txt
4 /tmp/tq1
32  /tmp/tt
32  /tmp/tt

and expands tabs w/spaces (using 8 spaces/tab as default).  That
way terminals and consoles that use other spacing will see:

Ishtar:tools/coreutils/work/src> ./du /tmp/t*       
4       /tmp/t
1160    /tmp/t1
680     /tmp/t2
4       /tmp/tab2.patch
20      /tmp/tabs
4       /tmp/tmpf
4       /tmp/topcmds
24      /tmp/topcmds-hlps
24      /tmp/topcmds2
8       /tmp/topcmds2.txt
4       /tmp/tq1
32      /tmp/tt


At least with this patch, the output will look the same regardless
of tab support. 


--- src/du.c    2015-04-01 17:31:02.000000000 -0700
+++ src/du.c    2015-04-26 16:16:43.829602843 -0700
@@ -1,3 +1,4 @@
+
 /* du -- summarize disk usage
    Copyright (C) 1988-2015 Free Software Foundation, Inc.
 
@@ -370,52 +371,86 @@
 
 /* FIXME: this code is nearly identical to code in date.c  */
 /* Display the date and time in WHEN according to the format specified
-   in FORMAT.  */
+   in FORMAT.
+   Note modificatino to return # of chars (exclusive of NUL)  */
 
-static void
+static int
 show_date (const char *format, struct timespec when)
 {
   struct tm *tm = localtime (&when.tv_sec);
+  int slen = 0;
   if (! tm)
     {
       char buf[INT_BUFSIZE_BOUND (intmax_t)];
       char *when_str = timetostr (when.tv_sec, buf);
       error (0, 0, _("time %s is out of range"), when_str);
+      slen=strlen(when_str);
       fputs (when_str, stdout);
-      return;
+      return slen;
     }
 
-  fprintftime (stdout, format, tm, 0, when.tv_nsec);
+  slen += fprintftime (stdout, format, tm, 0, when.tv_nsec);
+  return slen;
 }
 
 /* Print N_BYTES.  Convert it to a readable value before printing.  */
 
-static void
+static int
 print_only_size (uintmax_t n_bytes)
 {
   char buf[LONGEST_HUMAN_READABLE + 1];
-  fputs ((n_bytes == UINTMAX_MAX
+       char * outp;
+  fputs (outp = ((n_bytes == UINTMAX_MAX
           ? _("Infinity")
           : human_readable (n_bytes, buf, human_output_opts,
-                            1, output_block_size)),
+                            1, output_block_size))),
          stdout);
+       return strlen(outp);
+}
+
+
+/* using buf of len 'n', return a nul-term. string w/# spaces to ins for tab.
+ * If tabsize is 0, a 0-len string will be returned.
+ */
+
+static char *
+tabnspaces(char * buf, int n, int cur_output_len, int tabsize)
+{
+  char * obuf = buf;
+  int spaces =  tabsize ? tabsize - (cur_output_len % tabsize) : 0;
+
+  if (!n) return NULL;
+
+  /* pre-dec 'n' to reserve space for nul */
+  while(--n > 0  &&  spaces-- > 0) *obuf++ = ' ';
+  *obuf = '\0';
+  return buf;
 }
 
 /* Print size (and optionally time) indicated by *PDUI, followed by STRING.  */
 
+int term_tabsize = 8; /* default for now */
+
 static void
 print_size (const struct duinfo *pdui, const char *string)
 {
-  print_only_size (opt_inodes
-                   ? pdui->inodes
-                   : pdui->size);
+       int print_len = print_only_size (opt_inodes
+                                   ? pdui->inodes
+                                   : pdui->size);
+  char Xtab[1024];  /* Xpanded tab */
+  char * myspaces;
 
   if (opt_time)
     {
-      putchar ('\t');
-      show_date (time_format, pdui->tmax);
+               myspaces = tabnspaces(Xtab, sizeof(Xtab), print_len, 
term_tabsize);
+                       print_len+=strlen(myspaces);
+      fputs (myspaces, stdout);
+      print_len+= show_date (time_format, pdui->tmax);
     }
-  printf ("\t%s%c", string, opt_nul_terminate_output ? '\0' : '\n');
+ 
+  myspaces = tabnspaces(Xtab, sizeof(Xtab), print_len, term_tabsize);
+  fputs(myspaces, stdout);
+  printf ("%s%c", string, opt_nul_terminate_output ? '\0' : '\n');
   fflush (stdout);
 }