Some utilities.

+/* GNU mailutils - a suite of utilities for electronic mail
+   Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+#include "guimb.h"
+
+void
+util_error (char *fmt, ...)
+{
+  va_list ap;
+
+  va_start (ap, fmt);
+  fprintf (stderr, "guimb: ");
+  vfprintf (stderr, fmt, ap);
+  fprintf (stderr, "\n");
+  va_end (ap);
+}
+
+int
+util_tempfile (char **namep)
+{
+  char *filename;
+  char *tmpdir;
+  int fd;
+
+  /* We have to be extra careful about opening temporary files, since we
+     may be running with extra privilege i.e setgid().  */
+  tmpdir = (getenv ("TMPDIR")) ? getenv ("TMPDIR") : "/tmp";
+
+  filename = malloc (strlen (tmpdir) + /*'/' */ 1 + /* "muXXXXXX" */ 8 + 1);
+  if (!filename)
+    return -1;
+  sprintf (filename, "%s/muXXXXXX", tmpdir);
+
+#ifdef HAVE_MKSTEMP
+  {
+    int save_mask = umask (077);
+    fd = mkstemp (filename);
+    umask (save_mask);
+  }
+#else
+  if (mktemp (filename))
+    fd = open (filename, O_CREAT | O_EXCL | O_RDWR, 0600);
+  else
+    fd = -1;
+#endif
+
+  if (fd == -1)
+    {
+      util_error ("Can not open temporary file: %s", strerror (errno));
+      free (filename);
+      return -1;
+    }
+
+  if (namep)
+    *namep = filename;
+  else
+    {
+      unlink (filename);
+      free (filename);
+    }
+
+  return fd;
+}
+
+char *
+util_get_sender (int msgno)
+{
+  header_t header = NULL;
+  address_t addr = NULL;
+  message_t msg = NULL;
+  char buffer[512];
+
+  mailbox_get_message (mbox, msgno, &msg);
+  message_get_header (msg, &header);
+  if (header_get_value (header, MU_HEADER_FROM, buffer, sizeof (buffer), NULL)
+      || address_create (&addr, buffer))
+    {
+      envelope_t env = NULL;
+      message_get_envelope (msg, &env);
+      if (envelope_sender (env, buffer, sizeof (buffer), NULL)
+	  || address_create (&addr, buffer))
+	{
+	  util_error ("can't determine sender name (msg %d)", msgno);
+	  return NULL;
+	}
+    }
+
+  if (address_get_email (addr, 1, buffer, sizeof (buffer), NULL))
+    {
+      util_error ("can't determine sender name (msg %d)", msgno);
+      address_destroy (&addr);
+      return NULL;
+    }
+
+  address_destroy (&addr);
+  return strdup (buffer);
+}