From 006f8b49d9ebe1ca334b934d0a127c0029300871 Mon Sep 17 00:00:00 2001
From: Tom Smeding <tom@tomsmeding.com>
Date: Sat, 16 Oct 2021 11:28:38 +0200
Subject: 'writemaybe' command to allow broken pipe errors

---
 main.cpp    |  2 +-
 process.cpp |  5 +++--
 process.h   |  2 +-
 referee.cpp | 21 ++++++++++++++++-----
 referee.h   |  5 +++++
 5 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/main.cpp b/main.cpp
index 24edd5b..306c5cc 100644
--- a/main.cpp
+++ b/main.cpp
@@ -287,7 +287,7 @@ static void playMatch(Player &p1, Player &p2, int index, const Params &params) {
 			}
 
 		} else if (auto writeEvent = get_if<Referee::WriteEvent>(&event)) {
-			if (!procs[writeEvent->player].writeLine(writeEvent->line)) {
+			if (!procs[writeEvent->player].writeLine(writeEvent->line, writeEvent->allowBrokenPipe)) {
 				cout << "ERROR writing move to player " << writeEvent->player + 1
 					 << " (game " << gameCodeName(p1, p2, index) << ")" << endl;
 				throw StopCompetitionError();
diff --git a/process.cpp b/process.cpp
index 6f1ec92..6adc417 100644
--- a/process.cpp
+++ b/process.cpp
@@ -131,7 +131,7 @@ void Process::unStop() {
 	if (pid != -1) kill(pid, SIGCONT);
 }
 
-bool Process::writeLine(const string_view line) {
+bool Process::writeLine(const string_view line, bool allowBrokenPipe) {
 	if (pid == -1) return false;
 
 	string str;
@@ -144,7 +144,8 @@ bool Process::writeLine(const string_view line) {
 		ssize_t nw = write(infd, str.data() + cursor, str.size() - cursor);
 		if (nw < 0) {
 			if (errno == EINTR) continue;
-			// perror("write");
+			if (allowBrokenPipe && errno == EPIPE) continue;
+			perror("write");
 			return false;
 		}
 		cursor += nw;
diff --git a/process.h b/process.h
index 3505e8e..0588a40 100644
--- a/process.h
+++ b/process.h
@@ -38,7 +38,7 @@ public:
 
 	pid_t getPid() const;
 
-	bool writeLine(const string_view line);
+	bool writeLine(const string_view line, bool allowBrokenPipe);
 	optional<string> readLine();
 	optional<string> readLineTimeout(size_t millis);
 };
diff --git a/referee.cpp b/referee.cpp
index 2701e78..d215c3d 100644
--- a/referee.cpp
+++ b/referee.cpp
@@ -30,9 +30,9 @@ Referee::Referee(const string_view execname, const vector<string> &players)
 		exit(1);
 	}
 
-	proc.writeLine(to_string(players.size()));
+	proc.writeLine(to_string(players.size()), false);
 	for (const string &p : players) {
-		proc.writeLine(p);
+		proc.writeLine(p, false);
 	}
 }
 
@@ -86,7 +86,7 @@ Referee::Event Referee::nextEvent() {
 					cout << reftag << "write <" << line << ">" << endl;
 				}
 
-				if (!proc.writeLine(line)) {
+				if (!proc.writeLine(line, false)) {
 					cout << reftag << "Referee exited unexpectedly after 'read' command!" << endl;
 					exit(1);
 				}
@@ -102,7 +102,18 @@ Referee::Event Referee::nextEvent() {
 			exit(1);
 		}
 
-		return WriteEvent{player, command.substr(afterIndex)};
+		return WriteEvent{player, false, command.substr(afterIndex)};
+	} else if (command.substr(0, 11) == "writemaybe ") {
+		int player;
+		size_t afterIndex;
+		tie(player, afterIndex) = getPlayer(command, "writemaybe", 11);
+
+		if (afterIndex == string::npos) {
+			cout << reftag << "Protocol violation in 'writemaybe' command: no line!" << endl;
+			exit(1);
+		}
+
+		return WriteEvent{player, true, command.substr(afterIndex)};
 	} else if (command.substr(0, 8) == "gamelog ") {
 		int player;
 		size_t afterIndex;
@@ -150,7 +161,7 @@ Referee::Event Referee::nextEvent() {
 		}
 
 		proc.terminate();
-		return ErrorEvent{player, command.substr(6)};
+		return ErrorEvent{player, command.substr(afterIndex)};
 	} else {
 		cout << reftag << "Protocol violation: unknown command '" << command << "'!" << endl;
 		exit(1);
diff --git a/referee.h b/referee.h
index 1b9d507..11b10ae 100644
--- a/referee.h
+++ b/referee.h
@@ -35,6 +35,7 @@ public:
 	};
 	struct WriteEvent {
 		int player;
+		bool allowBrokenPipe;
 		string line;
 	};
 	struct GamelogEvent {
@@ -77,6 +78,10 @@ Then, the referee has the following commands available:
   is written directly to the referee afterwards. The first player is 0, the
   second player is 1, etc.
 - 'write <player> <line>': write a line to the player with index <player>.
+- 'writemaybe <player> <line>': write a line to the player with index <player>,
+  without considering a broken pipe error to be fatal. This is useful for Quit
+  messages because codecup players tend to exit before getting a formal Quit
+  sometimes.
 - 'gamelog <player> <line>': write a line in the game log indicating that the
   player with index <player> made the move given by <line>.
 - 'end <score> <score> ...': signify that the game has ended. The final scores
-- 
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