Re: pr: floating-point error

[Pádraig Brady]

On 10/24/2012 09:03 AM, Ondrej Oprala wrote:
> Hello,
> one of our customers made a bug report, stating that pr -nNUM FILE
> causes a floating point exception if NUM >= 32
> and I would really like to hear your opinion on how to solve this.
> The easiest solution would be to document the <32 limit for the -n option.
> The more difficult one would be to support numbers of arbitrary length.
> I was thinking about the second solution and  AFAIK the line number is not
> used in any arithmetic (apart from incrementation), so it could be represented 
> as
> an array of digits, with a function incrementing the array from the rightmost 
> element
> as needed. Then we would just print out the array one element at a time. It 
> would
> probably cause a performance penalty though.
> Thanks in advance for any advice or suggestions.

Ouch. Confirmed that this dumps core:

  echo . | pr -T -n.32

We can fix that up with something like the following.
I'll add a test and commit.

cheers,
Pádraig.

diff --git a/src/pr.c b/src/pr.c
index e97c434..3fada19 100644
--- a/src/pr.c
+++ b/src/pr.c
@@ -630,10 +630,6 @@ static uintmax_t page_number;
    2    moo     4       hoo     6       zoo */
 static int line_number;

-/* With line_number overflow, we use power_10 to cut off the higher-order
-   digits of the line_number */
-static int power_10;
-
 /* (-n) True means lines should be preceded by numbers. */
 static bool numbered_lines = false;

@@ -1289,12 +1285,6 @@ init_parameters (int number_of_files)
          printing files in parallel. */
       if (parallel_files)
         chars_used_by_number = number_width;
-
-      /* We use power_10 to cut off the higher-order digits of the
-         line_number in function add_line_number */
-      tmp_i = chars_per_number;
-      for (power_10 = 1; tmp_i > 0; --tmp_i)
-        power_10 = 10 * power_10;
     }

   chars_per_column = (chars_per_line - chars_used_by_number
@@ -1306,7 +1296,8 @@ init_parameters (int number_of_files)
   if (numbered_lines)
     {
       free (number_buff);
-      number_buff = xmalloc (2 * chars_per_number);
+      number_buff = xmalloc (MAX (chars_per_number,
+                                  INT_BUFSIZE_BOUND (line_number)) + 1);
     }

   /* Pick the maximum between the tab width and the width of an
@@ -2029,19 +2020,13 @@ add_line_number (COLUMN *p)
 {
   int i;
   char *s;
-  int left_cut;
+  int num_width;

   /* Cutting off the higher-order digits is more informative than
-     lower-order cut off*/
-  if (line_number < power_10)
-    sprintf (number_buff, "%*d", chars_per_number, line_number);
-  else
-    {
-      left_cut = line_number % power_10;
-      sprintf (number_buff, "%0*d", chars_per_number, left_cut);
-    }
+     lower-order cut off. */
+  num_width = sprintf (number_buff, "%*d", chars_per_number, line_number);
   line_number++;
-  s = number_buff;
+  s = number_buff + (num_width - chars_per_number);
   for (i = chars_per_number; i > 0; i--)
     (p->char_func) (*s++);