"seq .1 .1" would mistakenly generate no output on some systems

* NEWS: Say this.
* src/seq.c (print_numbers): Handle another floating point corner case.
This avoids failure of seq's eq-wid-7 test on FreeBSD 6.1.

3 files changed, 16 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 0e6c87a34..d563ae900 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2007-11-17  Jim Meyering  <meyering@redhat.com>
+
+	"seq .1 .1" would mistakenly generate no output on some systems
+	* NEWS: Say this.
+	* src/seq.c (print_numbers): Handle another floating point corner case.
+	This avoids failure of seq's eq-wid-7 test on FreeBSD 6.1.
+
 2007-11-16  Paul Eggert  <eggert@cs.ucla.edu>
 
 	Port tests/rmdir/ignore away from GNU/Linux.
diff --git a/NEWS b/NEWS
index a8434c54c..11efa7582 100644
--- a/NEWS
+++ b/NEWS
@@ -142,6 +142,8 @@ GNU coreutils NEWS                                    -*- outline -*-
   seq would mistakenly reject some valid format strings containing %%,
   and would mistakenly accept some invalid ones. e.g., %g%% and %%g, resp.
 
+  "seq .1 .1" would mistakenly generate no output on some systems
+
   Obsolete sort usage with an invalid ordering-option character, e.g.,
   "env _POSIX2_VERSION=199209 sort +1x" no longer makes sort free an
   invalid pointer [introduced in coreutils-6.5]
diff --git a/src/seq.c b/src/seq.c
index d7d2521b1..77d558697 100644
--- a/src/seq.c
+++ b/src/seq.c
@@ -280,7 +280,13 @@ print_numbers (char const *fmt, struct layout layout,
 	      free (x_str);
 	    }
 
-	  break;
+	  /* With floating point arithmetic, we may well reach this point
+	     with i == 0 and first == last.  E.g., ./seq .1 .1 on FreeBSD 6.1.
+	     Hence the first conjunct: don't break out of this loop when
+	     i == 0.  *unless* first and last themselves are out of order,
+	     in which case we must print nothing, e.g. for ./seq -1  */
+	  if (i || last < first)
+	    break;
 	}
 
       if (i)