(copy_rest): Don't copy past end of prefix. Output

trailing spaces if the prefix had any.  Before, the command
perl -e 'print "| S";' |fmt -p' |  '|tr '\0' @ output `|@S'.
Reported by François Pinard.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/fmt.c b/src/fmt.c
index 534bdb13d..6c7b569ce 100644
--- a/src/fmt.c
+++ b/src/fmt.c
@@ -575,8 +575,9 @@ copy_rest (FILE *f, register int c)
   if (in_column > next_prefix_indent && c != '\n' && c != EOF)
     {
       put_space (next_prefix_indent);
-      for (s = prefix; out_column != in_column; out_column++)
+      for (s = prefix; out_column != in_column && *s; out_column++)
 	putchar (*s++);
+      put_space (in_column - out_column);
     }
   while (c != '\n' && c != EOF)
     {