1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
|
/*
* qtmaildir - a Qt6 mail client for notmuch-indexed Maildirs
* Copyright (C) 2026 Danilo M. <danix@danix.xyz>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "maildirname.h"
#include <QCoreApplication>
#include <QDateTime>
#include <QHostInfo>
namespace MaildirName {
/// A fresh Maildir filename for a message being moved between folders,
/// preserving only its `:2,<flags>` suffix.
///
/// mbsync's manual is explicit about why this exists, under "the more
/// efficient default UID mapping scheme": "it is important that the MUA
/// renames files when moving them between Maildir folders", and "the general
/// expectation is that a completely new filename is generated as if the
/// message was new".
///
/// The `,U=<n>` infix mbsync writes is its per-folder IMAP UID. Carrying it
/// into another folder makes it a claim about a folder the file is no longer
/// in; moving a message out and back then reinserts a UID the server has
/// since reassigned, and mbsync refuses the folder with `Maildir error:
/// duplicate UID`. Measured on real mail, four collisions in one folder from
/// a single move-and-restore.
///
/// The FLAGS are kept, deliberately, and that is not a contradiction of
/// "as if the message was new". They record seen, flagged and replied, and
/// `maildir.synchronize_flags` is true, so notmuch reads them back as tags:
/// dropping them would mark every deleted message unread and lose Important
/// on the way to the trash. Only the unique part is regenerated.
QString fresh(const QString &oldName)
{
// The `:2,` suffix, when there is one. `info` is everything from the
// separator on, so an empty-flag `:2,` is preserved as faithfully as
// `:2,FS`.
QString info;
const int sep = oldName.indexOf(QStringLiteral(":2,"));
if (sep >= 0)
info = oldName.mid(sep);
// The conventional left-to-right unique part: time, a per-process counter,
// the pid, the host. The counter is what makes two messages moved in the
// same second distinct, which a timestamp alone does not guarantee.
static quint64 counter = 0;
const qint64 now = QDateTime::currentSecsSinceEpoch();
const QString host = QHostInfo::localHostName().isEmpty()
? QStringLiteral("localhost")
: QHostInfo::localHostName();
return QStringLiteral("%1.M%2P%3Q%4.%5%6")
.arg(now)
.arg(QDateTime::currentMSecsSinceEpoch() % 1000)
.arg(QCoreApplication::applicationPid())
.arg(++counter)
// A `/` or a `:` in a hostname would break the path or the flag
// separator. Neither is legal in a hostname, so this is belt and
// braces rather than a known case.
.arg(QString(host).replace(QLatin1Char('/'), QLatin1Char('_'))
.replace(QLatin1Char(':'), QLatin1Char('_')))
.arg(info);
}
} // namespace MaildirName
|
