2 files changed, 9 insertions, 3 deletions
diff --git a/ChangeLog b/ChangeLog
index eba6188d96..bff389903a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Mon Nov 29 01:18:18 2004  Tanaka Akira  <akr@m17n.org>
+
+	* io.c (rb_io_check_writable): restrict io_seek by
+	  READ_DATA_PENDING because io_seek(fptr, 0, SEEK_CUR) is
+	  meaningful only if read buffer is not empty.
+	  call io_seek regardless of NEED_IO_SEEK_BETWEEN_RW.
+
 Sun Nov 28 15:57:58 2004  Kouhei Sutou  <kou@cozmixng.org>
 
 	* lib/rss/rss.rb (RSS::Element#tag): not use block_given? for
diff --git a/io.c b/io.c
index 9c4ef1b987..8bc6d9b74d 100644
--- a/io.c
+++ b/io.c
@@ -261,11 +261,10 @@ rb_io_check_writable(fptr)
     if (!(fptr->mode & FMODE_WRITABLE)) {
 	rb_raise(rb_eIOError, "not opened for writing");
     }
-#if NEED_IO_SEEK_BETWEEN_RW
-    if ((fptr->mode & FMODE_RBUF) && !feof(fptr->f) && !fptr->f2) {
+    if ((fptr->mode & FMODE_RBUF) && !feof(fptr->f) && !fptr->f2 &&
+        READ_DATA_PENDING(fptr->f)) {
 	io_seek(fptr, 0, SEEK_CUR);
     }
-#endif
     if (!fptr->f2) {
 	fptr->mode &= ~FMODE_RBUF;
     }