diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/CMakeLists.txt | 1 | ||||
| -rw-r--r-- | src/messagesender.cpp | 197 | ||||
| -rw-r--r-- | src/messagesender.h | 164 |
3 files changed, 362 insertions, 0 deletions
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt index a4d7c55..eac2fab 100644 --- a/src/CMakeLists.txt +++ b/src/CMakeLists.txt @@ -14,6 +14,7 @@ add_library(qtmaildir_lib STATIC notmuchworker.cpp maildirname.cpp draftstore.cpp + messagesender.cpp tagchip.cpp tagcolors.cpp savequerydialog.cpp diff --git a/src/messagesender.cpp b/src/messagesender.cpp new file mode 100644 index 0000000..f336028 --- /dev/null +++ b/src/messagesender.cpp @@ -0,0 +1,197 @@ +/* + * 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 "messagesender.h" + +MessageSender::MessageSender(QObject *parent) + : QObject(parent) +{ + // Separate channels, unlike MailSync's MergedChannels: there is no log + // pane to fill here, and stderr alone is what a failure has to report. + // Merging them would put the command's ordinary chatter into the error + // message shown for a rejected send. + m_process.setProcessChannelMode(QProcess::SeparateChannels); + + connect(&m_process, &QProcess::finished, + this, &MessageSender::handleFinished); + connect(&m_process, &QProcess::errorOccurred, + this, &MessageSender::handleError); +} + +MessageSender::~MessageSender() +{ + if (m_process.state() == QProcess::NotRunning) + return; + + // A send is a live SMTP conversation and abandoning one has a genuinely + // unknown outcome, so give the command a bounded chance to finish rather + // than killing it outright. Measured: without this, a one-second command + // destroyed 100ms in is killed and its work does not complete, announced + // only by a Qt warning on stderr. With it, the same command completes and + // the destructor costs the ~1s the command actually needed. + // + // The write channel is closed first because the command may still be + // reading: a command blocked on stdin would otherwise never reach EOF and + // would burn the whole timeout for no reason. + m_process.closeWriteChannel(); + if (m_process.waitForFinished(kShutdownWaitMs)) + return; + + // Still running. A destructor cannot block a quitting application forever, + // so the process is killed deliberately here rather than by ~QProcess. + // + // NOTHING IS EMITTED. The outcome after a kill is unknown: the message may + // have been fully delivered, partially delivered, or not sent at all, and + // this class reports two outcomes only. Emitting finished(false, ...) would + // report "not sent" for a message that may well have been, which is the + // mailsync.sh mistake pointing the other way. Emitting finished(true, ...) + // would be worse. A caller that must know has to keep this object alive + // until finished() arrives. + // + // Claiming the report BEFORE the kill is what makes that true, and it is + // not optional: kill() makes QProcess deliver finished(CrashExit), which + // reaches handleFinished and would emit exactly the untruthful "not sent" + // this comment forbids. Measured, by a test that failed against the + // version without these two lines. This is also the one place m_reported + // does live work, rather than the defence-in-depth it is on the signal + // paths. + m_reported = true; + m_process.kill(); + m_process.waitForFinished(kShutdownWaitMs); +} + +bool MessageSender::isRunning() const +{ + return m_process.state() != QProcess::NotRunning; +} + +bool MessageSender::send(const QString &command, const QByteArray &bytes) +{ + if (command.trimmed().isEmpty() || isRunning()) + return false; + + // splitCommand gives an argument list; running through a shell would make + // every recipient address, display name and config value a potential + // injection point. QProcess hands the list to execve, so a `;` or a + // `$(...)` in the configured command is a literal argument with nothing to + // interpret it. Note that splitCommand strips DOUBLE quotes only. + // + // Nothing from the message reaches the argument list at all: the command + // reads its recipients from the message's own headers, which is what `-t` + // means in the documented example. + const QStringList parts = QProcess::splitCommand(command); + if (parts.isEmpty()) + return false; + + m_command = command; + m_reported = false; + + m_process.setProgram(parts.first()); + m_process.setArguments(parts.mid(1)); + + // Deliberately no waitForStarted(): this runs on the GUI thread and the + // interface must stay responsive while a send is in flight. A failed + // launch arrives via errorOccurred(FailedToStart) instead, which QProcess + // emits INSTEAD OF finished() rather than before it (measured). + m_process.start(); + + // Written after start() and before the process has necessarily launched, + // which is safe: QProcess buffers and drains as the reader consumes. + // Measured with a 320KB payload against a `cat` stub, which arrived + // byte-identical, so a message with an attachment does not deadlock on the + // 64KB pipe buffer. + m_process.write(bytes); + + // The message goes on stdin and the channel is closed, so a command + // reading to EOF terminates. Without closeWriteChannel() a command like + // `cat` waits forever and the popup never leaves its Sending stage. + m_process.closeWriteChannel(); + + return true; +} + +void MessageSender::handleFinished(int exitCode, QProcess::ExitStatus status) +{ + // errorOccurred may already have reported this failure. Reporting twice + // would close the popup and then act on a second result. + // + // This guard IS load-bearing, on exactly one path: the destructor sets + // m_reported before kill(), because kill() makes QProcess deliver + // finished(CrashExit) and without the flag this handler would emit a + // "not sent" for a message whose fate is genuinely unknown. A test fails + // against its removal. + // + // On the two signal paths it is defence in depth and currently cannot + // fire: handleError is filtered to FailedToStart, and FailedToStart is + // never followed by finished() (measured). An instrumented run of the + // whole suite recorded zero hits there, including on the crash and + // write-error paths that DO emit both signals. It stays because the day + // someone widens handleError to report another error, the double report is + // silent and costs a duplicate sent copy. + if (m_reported) + return; + m_reported = true; + + // The exit status is the only authority. Nothing is inferred from what the + // command printed: mailsync.sh records what a wrong answer here costs, and + // a send reported as succeeding files a sent copy for a message that never + // left the machine. + const bool sent = status == QProcess::NormalExit && exitCode == 0; + if (sent) { + emit finished(true, QString()); + return; + } + + // Exit 75 is deliberately NOT special. See the header. + QString error = QString::fromUtf8(m_process.readAllStandardError()).trimmed(); + if (error.isEmpty()) { + // A failure with a blank explanation gives the user nothing to act on, + // so the status stands in for the reason the command did not give. + error = status == QProcess::CrashExit + ? tr("The send command crashed.") + : tr("The send command exited with status %1 and said nothing.") + .arg(exitCode); + } + emit finished(false, error); +} + +void MessageSender::handleError(QProcess::ProcessError error) +{ + // QProcess emits errorOccurred(FailedToStart) INSTEAD OF finished(), so + // without this the caller waits forever. Measured on Qt 6.11 for both a + // missing binary and a non-executable file: one errorOccurred, no + // finished(). + // + // Every other error IS followed by finished() and is left to it, which is + // not merely tidiness. A command that exits without draining a large stdin + // emits errorOccurred(WriteError) and then finished() with the command's + // real exit code and its real stderr; reporting the write error here would + // replace the server's own rejection message with a plumbing detail, and + // reporting it as well as finished() would deliver two results for one + // message. + if (error != QProcess::FailedToStart) + return; + if (m_reported) + return; + m_reported = true; + + emit finished(false, + tr("The send command '%1' could not be started. Check that " + "the path is correct and the file is executable.") + .arg(m_command)); +} diff --git a/src/messagesender.h b/src/messagesender.h new file mode 100644 index 0000000..86dde68 --- /dev/null +++ b/src/messagesender.h @@ -0,0 +1,164 @@ +/* + * 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. + */ + +#pragma once + +#include <QObject> +#include <QProcess> +#include <QString> + +/// Runs an account's send_command with the message on stdin. +/// +/// EXACTLY TWO OUTCOMES: sent, or not sent with a reason. Exit code 75 has no +/// special meaning here, unlike in the sync path. Item 125 is open precisely +/// because mailsync.sh treats 75 as neither success nor failure and hangs on +/// it; that exists because the script contends for a lock and there is no lock +/// here. Recorded so the two paths are not later "harmonised". +/// +/// **The exit status is the only authority on whether a message was sent.** +/// This is the same rule assets/mailsync.sh exists to honour, and the same +/// class of bug is available here: a sender that reported success on anything +/// other than exit 0 would file a sent copy and close the composer for a +/// message that never left the machine. Nothing is derived from the command's +/// output, which belongs to whatever the user installed behind send_command. +/// +/// **No shell, ever.** The command is a config value and is split into an +/// argument list with QProcess::splitCommand, then handed to QProcess, which +/// calls execve directly. A `;`, `&&`, `$(...)` or a backtick in the +/// configured string therefore arrives as a literal argument with nothing to +/// interpret it. Note that splitCommand understands DOUBLE quotes only: +/// `-a 'my acct'` splits into three arguments, so a path or an argument +/// containing a space must be written with double quotes. Measured, not +/// assumed. +/// +/// **No message content ever reaches the argument list.** The bytes go on +/// stdin and only on stdin; the command reads its recipients from the +/// message's own headers, which is what `-t` means in the documented example. +/// A recipient address or a display name therefore cannot become an argument +/// however it is spelled. +/// +/// This is the outbox seam. An outbox is built by calling this from a drain +/// loop; nothing in the composer would need to change. +/// +/// Nothing here blocks the GUI thread DURING a send. send() hands the process +/// to the event loop and returns; there is no waitForStarted() and no +/// waitForFinished() on that path, so a command that hangs leaves the +/// interface responsive and the caller waiting on finished(). Timing a hung +/// command out is deliberately NOT this class's job: a timeout here would kill +/// a slow but working send. The one place this class does block is its +/// destructor, and that is the subject of the next paragraph. +/// +/// **Destruction mid-send waits, briefly, and then kills.** A send is a live +/// SMTP conversation, so the outcome of abandoning one is genuinely unknown: +/// the message may be fully delivered, partially delivered, or not sent at +/// all. Measured with a one-second command destroyed 100ms in: plain +/// destruction returns in 100ms, kills the child, and the work does NOT +/// complete, announced by nothing but a `QProcess: Destroyed while process is +/// still running` warning on stderr. That is the mailsync.sh failure in a new +/// place, an unknown real outcome reported as a definite one, and it is +/// reachable by closing the composer with the window manager's X button while +/// a send is in flight. +/// +/// So the destructor waits up to kShutdownWaitMs for the command to finish on +/// its own, which is the outcome that makes the report truthful: the same +/// measurement with a bounded wait completes the child and costs only the +/// ~1s the command actually needed. A command still running after that is +/// killed, because a destructor cannot block a quitting application forever. +/// +/// **No finished() is emitted from the destructor, in either branch, and that +/// is deliberate rather than an omission.** After a kill the outcome is +/// unknown, and this class reports two outcomes only; inventing a third by +/// guessing would be the exact lie the rest of this header is built to avoid. +/// After a successful late finish the emit would reach handlers on a +/// half-destroyed caller. A caller that must know the result has to keep the +/// sender alive until finished() arrives, which is what refusing to close a +/// composer mid-send would express. +/// +/// **There is no cancel(), and the caller does not have one either.** An +/// earlier revision of this comment deferred cancellation to "the caller's +/// popup", which overstated what exists: SendDialog offers an undo BEFORE the +/// send is committed and none after, by an explicit design decision that a +/// post-commit cancel is worse than either clean outcome. If a real cancel is +/// ever wanted it belongs HERE, killing the process and emitting one +/// finished(false, ...) through m_reported, which is the shape that flag +/// already has. It is not built now, and this header does not promise it. +class MessageSender : public QObject +{ + Q_OBJECT + +public: + explicit MessageSender(QObject *parent = nullptr); + + /// Waits briefly for an in-flight send, then kills it. See the class + /// comment: this is the one blocking call in the class, and it emits + /// nothing. + ~MessageSender() override; + + /// How long the destructor gives an in-flight command to finish on its + /// own before killing it. Long enough for a local MTA handing off to a + /// queue, short enough not to hang a quitting application. + static constexpr int kShutdownWaitMs = 5000; + + /// Starts \p command with \p bytes on stdin. + /// + /// Returns false without emitting anything when the command is empty or + /// only whitespace, when it splits to nothing, or when a send is already + /// running. A true return means the process was handed to the event loop, + /// NOT that it launched: a missing or non-executable binary surfaces + /// asynchronously through finished(false, ...), exactly as MailSync + /// documents. + bool send(const QString &command, const QByteArray &bytes); + + bool isRunning() const; + +signals: + /// \p error is empty on success and carries the command's stderr, or a + /// description of why it could not start, on failure. + /// + /// EMITTED exactly once per accepted send, and the distinction between + /// emitted and RECEIVED is the whole of this paragraph. QProcess can report + /// both an error and a finish for one run (measured: a command that exits + /// without draining a large stdin emits errorOccurred(WriteError) and then + /// finished()), and m_reported collapses that to one emit. + /// + /// **m_reported guards the emit, not the receivers, and a caller can still + /// see one result twice.** A MessageSender is normally a long-lived member + /// reused for every send, so a caller that connects INSIDE its send path + /// adds a permanent connection each time: send, fail, correct the + /// recipient, send again, and the second result runs BOTH lambdas. The + /// first still holds the first message's bytes, so it files a sent copy of + /// the wrong message and acts on a dialog it already destroyed. That is + /// precisely the harm this signal's contract exists to prevent, arriving + /// by the one route no guard inside this class can cover. + /// + /// A caller connecting per-send must therefore pass + /// `Qt::SingleShotConnection` (Qt 6.0+; this project is on 6.11), which + /// disconnects the moment the lambda runs. Connecting ONCE in the caller's + /// constructor and keeping the per-send state in members is the other + /// correct shape. What is not correct, and what reads as permitted if this + /// paragraph is skipped, is a bare connect() next to a send() call. + void finished(bool sent, const QString &error); + +private: + void handleFinished(int exitCode, QProcess::ExitStatus status); + void handleError(QProcess::ProcessError error); + + QProcess m_process; + QString m_command; + bool m_reported = false; +}; |