new file.

+/* GNU mailutils - a suite of utilities for electronic mail
+   Copyright (C) 2004 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Library Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <string.h>
+#include <strings.h>
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <mailutils/sys/pop3.h>
+
+static int  pop3_itr_dup     (void **ptr, void *owner);
+static int  pop3_itr_destroy (iterator_t itr, void *owner);
+static int  pop3_itr_first   (void *owner);
+static int  pop3_itr_next    (void *woner);
+static int  pop3_itr_getitem (void *owner, void **pret);
+static int  pop3_itr_curitem_p (void *owner, void *data);
+static int  pop3_itr_finished_p (void *owner);
+
+struct pop3_iterator
+{
+  mu_pop3_t pop3;
+  int done;
+  char *item;
+};
+
+int
+mu_pop3_iterator_create (mu_pop3_t pop3, iterator_t *piterator)
+{
+  struct pop3_iterator *pop3_iterator;
+  iterator_t iterator;
+  int status;
+
+  pop3_iterator = malloc (sizeof *pop3_iterator);
+  if (pop3_iterator == NULL)
+    return ENOMEM;
+
+  pop3_iterator->item = NULL;
+  pop3_iterator->done = 0;
+  pop3_iterator->pop3= pop3;
+
+  status = iterator_create (&iterator, pop3_iterator);
+  if (status != 0)
+    {
+      free (pop3_iterator);
+      return status;
+    }
+  iterator_set_first (iterator, pop3_itr_first);
+  iterator_set_next (iterator, pop3_itr_next);
+  iterator_set_getitem (iterator, pop3_itr_getitem);
+  iterator_set_finished_p (iterator, pop3_itr_finished_p);
+  iterator_set_curitem_p (iterator, pop3_itr_curitem_p);
+  iterator_set_destroy (iterator, pop3_itr_destroy);
+  iterator_set_dup (iterator, pop3_itr_dup);
+
+  *piterator = iterator;
+  return 0;
+}
+
+static int
+pop3_itr_dup (void **ptr, void *owner)
+{
+  struct pop3_iterator *pop3_iterator = (struct pop3_iterator *)owner;
+  struct pop3_iterator *clone = malloc (sizeof *pop3_iterator);
+  if (clone == NULL)
+    return ENOMEM;
+  /* let the assignement operator copy the elements.  */
+  *clone = *pop3_iterator;
+  *ptr = clone;
+  return 0;
+}
+
+static int
+pop3_itr_destroy (iterator_t iterator, void *owner)
+{
+  struct pop3_iterator *pop3_iterator = (struct pop3_iterator *)owner;
+  /* Delicate situation if they did not finish to drain the result
+     We take te approach to do it for the user.  FIXME: Not sure
+     if this is the rigth thing to do. The other way is to close the stream  */
+  if (!pop3_iterator->done)
+    {
+      char buf[128];
+      size_t n = 0;
+      while (mu_pop3_readline (pop3_iterator->pop3, buf, sizeof buf, &n) > 0 && n > 0)
+	n = 0;
+    }
+  if (pop3_iterator->item)
+    free (pop3_iterator->item);
+  pop3_iterator->pop3->state = MU_POP3_NO_STATE;
+  free (pop3_iterator);
+  return 0;
+}
+
+static int
+pop3_itr_first  (void *data)
+{
+  return pop3_itr_next (data);
+}
+
+static int
+pop3_itr_next (void *owner)
+{
+  struct pop3_iterator *pop3_iterator = (struct pop3_iterator *)owner;
+  size_t n = 0;
+  int status = 0;
+
+  if (!pop3_iterator->done)
+    {
+      /* The first readline will not consume the buffer, we just need to
+	 know how much to read.  */
+      status = mu_pop3_readline (pop3_iterator->pop3, NULL, 0, &n);
+      if (status == 0)
+	{
+	  if (n)
+	    {
+	      char *buf;
+	      buf = calloc (n + 1, 1);
+	      if (buf)
+		{
+		  /* Consume.  */
+		  mu_pop3_readline (pop3_iterator->pop3, buf, n + 1, NULL);
+		  if (buf[n - 1] == '\n')
+		    buf[n - 1] = '\0';
+		  if (pop3_iterator->item)
+		    free (pop3_iterator->item);
+		  pop3_iterator->item = buf;
+		}
+	      else
+		status = ENOMEM;
+	    }
+	  else
+	    {
+	      pop3_iterator->done = 1;
+	      pop3_iterator->pop3->state = MU_POP3_NO_STATE;
+	    }
+	}
+    }
+  return status;
+}
+
+static int
+pop3_itr_getitem (void *owner, void **item)
+{
+  struct pop3_iterator *pop3_iterator = (struct pop3_iterator *)owner;
+  if (item)
+    {
+      *((char **)item) = pop3_iterator->item;
+      pop3_iterator->item = NULL;
+    }
+  return 0;
+}
+
+static int
+pop3_itr_finished_p (void *owner)
+{
+  struct pop3_iterator *pop3_iterator = (struct pop3_iterator *)owner;
+  return pop3_iterator->done;
+}
+
+static int
+pop3_itr_curitem_p (void *owner, void *item)
+{
+  struct pop3_iterator *pop3_iterator = (struct pop3_iterator *)owner;
+  return *((char **)item) == pop3_iterator->item;
+}
+