notmuch-filenames.md

Here is a notmuch-using program that adds two messages to the index, rewrites their maildir filenames with the right flags, showing the filename list from the message object and from a query at each step:

#include <stdio.h>
#include <stdlib.h>
#include <notmuch.h>

void check_error(const char *func, notmuch_status_t st) {
  if (st != NOTMUCH_STATUS_SUCCESS && st != NOTMUCH_STATUS_DUPLICATE_MESSAGE_ID) {
    printf("%s: %s\n", func, notmuch_status_to_string(st));
    abort();
  }
}

void _dump_message_filenames(notmuch_message_t *msg) {
  notmuch_filenames_t *filenames = notmuch_message_get_filenames(msg);
  while(notmuch_filenames_valid(filenames)) {
    printf("    %s\n", notmuch_filenames_get(filenames));
    notmuch_filenames_move_to_next(filenames);
  }
  notmuch_filenames_destroy(filenames);
}

void dump_message_filenames(notmuch_message_t *msg) {
  printf("filename from message:\n");
  _dump_message_filenames(msg);
}

void dump_query_filenames(notmuch_database_t *db) {
  notmuch_status_t st;
  notmuch_messages_t *msgs;

  printf("filename from query:\n");

  notmuch_query_t *query = notmuch_query_create(db, "id:aaa@bbb");

  st = notmuch_query_search_messages(query, &msgs);
  check_error("notmuch_query_search_messages", st);

  while (notmuch_messages_valid(msgs)) {
    _dump_message_filenames(notmuch_messages_get(msgs));
    notmuch_messages_move_to_next(msgs);
  }

  notmuch_query_destroy(query);
}

int main (int argc, char **argv) {
  notmuch_status_t st;
  notmuch_database_t *db = NULL;
  notmuch_message_t *m1 = NULL, *m2 = NULL;
  char *err = NULL;

  st = notmuch_database_open_with_config(NULL, NOTMUCH_DATABASE_MODE_READ_WRITE, NULL, NULL, &db, &err);
  if (st != NOTMUCH_STATUS_SUCCESS) {
    printf("notmuch_database_open_with_config: %s\n", err);
    return 1;
  }

  printf("\nadding message #1\n");
  st = notmuch_database_index_file(db, "test/cur/one", NULL, &m1);
  check_error("notmuch_database_index_file", st);
  dump_message_filenames(m1);
  dump_query_filenames(db);

  printf("\nadding message #2\n");
  st = notmuch_database_index_file(db, "test/cur/two", NULL, &m2);
  check_error("notmuch_database_index_file", st);
  dump_message_filenames(m2);
  dump_query_filenames(db);

  printf("\nrewriting message #1\n");
  st = notmuch_message_tags_to_maildir_flags(m1);
  check_error("notmuch_message_tags_to_maildir_flags", st);
  dump_message_filenames(m1);
  dump_query_filenames(db);

  printf("\nrewriting message #2\n");
  st = notmuch_message_tags_to_maildir_flags(m2);
  check_error("notmuch_message_tags_to_maildir_flags", st);
  dump_message_filenames(m2);
  dump_query_filenames(db);

  printf("\ndestroying messages\n");
  notmuch_message_destroy(m1);
  notmuch_message_destroy(m2);
  dump_query_filenames(db);

  st = notmuch_database_close(db);
  check_error("notmuch_database_close", st);

  return 0;
}

Compile the program:

$ gcc -ggdb -Wall -o notmuch-filename-check notmuch-filename-check.c -lnotmuch

Set up an empty notmuch index and drop two identical mail files into it (adjust paths to taste).

$ rm -rf ~/mail/.notmuch/xapian ~/mail/test/cur/* && notmuch new && cat <<EOF > ~/mail/test/cur/one && cp ~/mail/test/cur/one ~/mail/test/cur/two
From: nobody@example.com
To: nobody@example.com
Subject: test message
Message-Id: <aaa@bbb>

oh no
EOF
Found 0 total files (that's not much mail).
Processed 0 total files in almost no time.
No new mail.

Run the program:

$ ./notmuch-filename-check
adding message #1
filename from message:
    /home/robn/mail/test/cur/one
filename from query:
    /home/robn/mail/test/cur/one

adding message #2
filename from message:
    /home/robn/mail/test/cur/one
    /home/robn/mail/test/cur/two
filename from query:
    /home/robn/mail/test/cur/one
    /home/robn/mail/test/cur/two

rewriting message #1
filename from message:
    /home/robn/mail/test/cur/one:2,S
filename from query:
    /home/robn/mail/test/cur/one:2,S

rewriting message #2
filename from message:
    /home/robn/mail/test/cur/one
    /home/robn/mail/test/cur/two:2,S
filename from query:
    /home/robn/mail/test/cur/one
    /home/robn/mail/test/cur/two:2,S

destroying messages
filename from query:
    /home/robn/mail/test/cur/one
    /home/robn/mail/test/cur/two:2,S

Observation #1: the filename list is cached inside the message object

Observation #2: when rewriting the filename, the cached filename list is pushed back into the index

The second observation is more noticeable if the "rewriting message #2" block is commented out and the program recompiled:

$ ./notmuch-filename-check
adding message #1
filename from message:
    /home/robn/mail/test/cur/one
filename from query:
    /home/robn/mail/test/cur/one

adding message #2
filename from message:
    /home/robn/mail/test/cur/one
    /home/robn/mail/test/cur/two
filename from query:
    /home/robn/mail/test/cur/one
    /home/robn/mail/test/cur/two

rewriting message #1
filename from message:
    /home/robn/mail/test/cur/one:2,S
filename from query:
    /home/robn/mail/test/cur/one:2,S

destroying messages
filename from query:
    /home/robn/mail/test/cur/one:2,S

Notice that after the first rewrite, the second message is now entirely gone from the index.