Node:libmailbox, Next:, Previous:Introduction, Up:Top



Framework

Wherever the mail is and whatever format it is stored in, it is operated upon using the same set of functions. To unified the C API, GNU Mailutils offers a heteroclite set of objects that work in aggregation to do operations on emails. Each object does a specific task and delegates non-related tasks to others. The object comes alive by specifying a URL parameter when created, it will indicate the storage format or protocol (POP3, IMAP4, MH, MAILDIR, etc ..).

                          folder_t                  url_t
  -/var/mail-    +- .. ->+-----------------+   +-->+------------+
 (  alain *-)-+  |       |   url_t       *-|---+   |   port     |
  ----------- |  |       |-----------------|       |   hostname |
 (  jakob *-)-+--+       |   auth_t      *-|---+   |   file     |
  ----------- |          |-----------------|   |   |   ...      |
 (  jeff  *-)-+          |   stream_t      |   |   +------------+
  ----------- |          |-----------------|   |
 (  shaleh*-)-+          |   .....         |   |    auth_t
  ----------             |-----------------|   +-->+------------+
                     +---|-* mailbox_t[]   |       |   ticket_t |
  mailbox_t          |   +-----------------+       +------------+
 +----------------+<-+
 |   locker_t  *--|-------------+
 |----------------|             |
 |   url_t        |             |          locker_t
 |----------------|             +-------->+---------+
 |   stream_t     |                       | lock    |
 |----------------|                       | unlock  |
 |  message_t[] *-|-------+               +---------+
 +----------------+       |                     envelope_t
                          |          +-------->+-----------+
  message_t               |          |         | date      |
 +----------------+<------+          |         | from      |
 |   envelope_t *-|------------------+         | to        |
 |----------------|              header_t      +-----------+
 |   header_t   *-|------------>+--------------+
 |----------------|             |   stream_t   |
 |   body_t     *-|----+        +--------------+
 +----------------+    |    body_t
                       +-->+--------------+
                           |   stream_t   |
                           +--------------+

As an example, here is a simplified version of from command. It lists the From and Subject headers of every mail in a mailbox.


/* sfrom, Simple From */
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

#include <mailutils/mailutils.h>

int
main (int argc, const char **argv)
{
  char *from;
  char *subject;
  mailbox_t mbox;
  int status;
  size_t msgno, total = 0;

  /* Register the type of mailbox. IMAP4, POP3 and local format  */
  {
    list_t registrar;
    registrar_get_list (&registrar);
    list_append (registrar, imap_record);
    list_append (registrar, path_record);
    list_append (registrar, pop_record);
  }

  status = mailbox_create_default (&mbox, argv[1]);

  if (status != 0)
    {
      fprintf (stderr, "mailbox_create: %s\n", mu_errstring (status));
      exit (EXIT_FAILURE);
    }

  status = mailbox_open (mbox, MU_STREAM_READ);
  if (status != 0)
    {
      fprintf (stderr, "mailbox_open: %s\n", mu_errstring (status));
      exit (EXIT_FAILURE);
    }

  mailbox_messages_count (mbox, &total);

  for (msgno = 1; msgno <= total; msgno++)
    {
      message_t msg;
      header_t hdr;

      if ((status = mailbox_get_message (mbox, msgno, &msg)) != 0
          || (status = message_get_header (msg, &hdr)) != 0)
        {
          fprintf (stderr, "Error message: %s\n",
                   mu_errstring (status));
          exit (EXIT_FAILURE);
        }

      if (header_aget_value (hdr, MU_HEADER_FROM, &from))
        from = strdup ("(NO FROM)");

      if (header_aget_value (hdr, MU_HEADER_SUBJECT, &subject))
        subject = strdup("(NO SUBJECT)");

      printf ("%s\t%s\n", from, subject);
      free (from);
      free (subject);
    }

  mailbox_close (mbox);
  mailbox_destroy (&mbox);
  return 0;
}

Here is a sample output produced by this program:

% MAIL=pop://[email protected] ./sfrom
Passwd: xxxx
Jim Meyering <[email protected]>      fetish(shellutils) beta
François Pinard <[email protected]> recode new alpha
...