(_IO_new_file_overflow): Handle switching to write mode from read of backup buffer.

diff --git a/libio/fileops.c b/libio/fileops.c
index be683cd..1a63319 100644 (file)
--- a/libio/fileops.c
+++ b/libio/fileops.c
@@ -841,12 +841,23 @@ _IO_new_file_overflow (f, ch)
         makes room for subsequent output.
         Otherwise, set the read pointers to _IO_read_end (leaving that
         alone, so it can continue to correspond to the external position). */
-      if (f->_IO_read_ptr == f->_IO_buf_end)
-       f->_IO_read_end = f->_IO_read_ptr = f->_IO_buf_base;
-      f->_IO_write_ptr = f->_IO_read_ptr;
-      f->_IO_write_base = f->_IO_write_ptr;
-      f->_IO_write_end = f->_IO_buf_end;
-      f->_IO_read_base = f->_IO_read_ptr = f->_IO_read_end;
+      if (__builtin_expect (_IO_in_backup (f), 0))
+       {
+         size_t nbackup = f->_IO_read_end - f->_IO_read_ptr;
+         _IO_free_backup_area (f);
+         f->_IO_read_base -= MIN (nbackup,
+                                  f->_IO_read_base - f->_IO_buf_base);
+         f->_IO_read_ptr = f->_IO_read_base;
+       }
+      else
+       {
+         if (f->_IO_read_ptr == f->_IO_buf_end)
+           f->_IO_read_end = f->_IO_read_ptr = f->_IO_buf_base;
+         f->_IO_write_ptr = f->_IO_read_ptr;
+         f->_IO_write_base = f->_IO_write_ptr;
+         f->_IO_write_end = f->_IO_buf_end;
+         f->_IO_read_base = f->_IO_read_ptr = f->_IO_read_end;
+       }
 
       f->_flags |= _IO_CURRENTLY_PUTTING;
       if (f->_mode <= 0 && f->_flags & (_IO_LINE_BUF+_IO_UNBUFFERED))