Output a log, savegame and screenshot on desync events

src/crashlog.cpp

@@ -372,6 +372,36 @@ char *CrashLog::FillCrashLog(char *buffer, const char *last) const
 	return buffer;
 }
 
+/**
+ * Fill the crash log buffer with all data of a desync event.
+ * @param buffer The begin where to write at.
+ * @param last   The last position in the buffer to write to.
+ * @return the position of the \c '\0' character after the buffer.
+ */
+char *CrashLog::FillDesyncCrashLog(char *buffer, const char *last) const
+{
+	time_t cur_time = time(nullptr);
+	buffer += seprintf(buffer, last, "*** OpenTTD Multiplayer %s Desync Report ***\n\n", _network_server ? "Server" : "Client");
+
+	buffer += seprintf(buffer, last, "Desync at: %s", asctime(gmtime(&cur_time)));
+
+	YearMonthDay ymd;
+	ConvertDateToYMD(_date, &ymd);
+	buffer += seprintf(buffer, last, "In game date: %i-%02i-%02i (%i)\n\n", ymd.year, ymd.month + 1, ymd.day, _date_fract);
+
+	buffer = this->LogOpenTTDVersion(buffer, last);
+	buffer = this->LogOSVersion(buffer, last);
+	buffer = this->LogCompiler(buffer, last);
+	buffer = this->LogConfiguration(buffer, last);
+	buffer = this->LogLibraries(buffer, last);
+	buffer = this->LogGamelog(buffer, last);
+	buffer = this->LogRecentNews(buffer, last);
+	buffer = this->LogRecentCommands(buffer, last);
+
+	buffer += seprintf(buffer, last, "*** End of OpenTTD Multiplayer %s Desync Report ***\n", _network_server ? "Server" : "Client");
+	return buffer;
+}
+
 /**
  * Write the crash log to a file.
  * @note On success the filename will be filled with the full path of the
@@ -381,9 +411,9 @@ char *CrashLog::FillCrashLog(char *buffer, const char *last) const
  * @param filename_last The last position in the filename buffer.
  * @return true when the crash log was successfully written.
  */
-bool CrashLog::WriteCrashLog(const char *buffer, char *filename, const char *filename_last) const
+bool CrashLog::WriteCrashLog(const char *buffer, char *filename, const char *filename_last, const char *name) const
 {
-	seprintf(filename, filename_last, "%scrash.log", _personal_dir);
+	seprintf(filename, filename_last, "%s%s.log", _personal_dir, name);
 
 	FILE *file = FioFOpenFile(filename, "w", NO_DIRECTORY);
 	if (file == nullptr) return false;
@@ -409,7 +439,7 @@ bool CrashLog::WriteCrashLog(const char *buffer, char *filename, const char *fil
  * @param filename_last The last position in the filename buffer.
  * @return true when the crash save was successfully made.
  */
-bool CrashLog::WriteSavegame(char *filename, const char *filename_last) const
+bool CrashLog::WriteSavegame(char *filename, const char *filename_last, const char *name) const
 {
 	/* If the map array doesn't exist, saving will fail too. If the map got
 	 * initialised, there is a big chance the rest is initialised too. */
@@ -418,7 +448,7 @@ bool CrashLog::WriteSavegame(char *filename, const char *filename_last) const
 	try {
 		GamelogEmergency();
 
-		seprintf(filename, filename_last, "%scrash.sav", _personal_dir);
+		seprintf(filename, filename_last, "%s%s.sav", _personal_dir, name);
 
 		/* Don't do a threaded saveload. */
 		return SaveOrLoad(filename, SLO_SAVE, DFT_GAME_FILE, NO_DIRECTORY, false) == SL_OK;
@@ -435,12 +465,12 @@ bool CrashLog::WriteSavegame(char *filename, const char *filename_last) const
  * @param filename_last The last position in the filename buffer.
  * @return true when the crash screenshot was successfully made.
  */
-bool CrashLog::WriteScreenshot(char *filename, const char *filename_last) const
+bool CrashLog::WriteScreenshot(char *filename, const char *filename_last, const char *name) const
 {
 	/* Don't draw when we have invalid screen size */
 	if (_screen.width < 1 || _screen.height < 1 || _screen.dst_ptr == nullptr) return false;
 
-	bool res = MakeScreenshot(SC_CRASHLOG, "crash");
+	bool res = MakeScreenshot(SC_CRASHLOG, name);
 	if (res) strecpy(filename, _full_screenshot_name, filename_last);
 	return res;
 }
@@ -506,6 +536,57 @@ bool CrashLog::MakeCrashLog() const
 	return ret;
 }
 
+/**
+ * Makes a desync crash log, writes it to a file and then subsequently tries
+ * to make a crash savegame. It uses DEBUG to write
+ * information like paths to the console.
+ * @return true when everything is made successfully.
+ */
+bool CrashLog::MakeDesyncCrashLog() const
+{
+	char filename[MAX_PATH];
+	char buffer[65536 * 2];
+	bool ret = true;
+
+	const char *mode = _network_server ? "server" : "client";
+
+	char name_buffer[64];
+	char *name_buffer_date = name_buffer + seprintf(name_buffer, lastof(name_buffer), "desync-%s-", mode);
+	time_t cur_time = time(nullptr);
+	strftime(name_buffer_date, lastof(name_buffer) - name_buffer_date, "%Y%m%dT%H%M%SZ", gmtime(&cur_time));
+
+	printf("Desync encountered (%s), generating desync log...\n", mode);
+	this->FillDesyncCrashLog(buffer, lastof(buffer));
+
+	bool bret = this->WriteCrashLog(buffer, filename, lastof(filename), name_buffer);
+	if (bret) {
+		printf("Desync log written to %s. Please add this file to any bug reports.\n\n", filename);
+	} else {
+		printf("Writing desync log failed.\n\n");
+		ret = false;
+	}
+
+	bret = this->WriteSavegame(filename, lastof(filename), name_buffer);
+	if (bret) {
+		printf("Desync savegame written to %s. Please add this file and the last (auto)save to any bug reports.\n\n", filename);
+	} else {
+		ret = false;
+		printf("Writing desync savegame failed. Please attach the last (auto)save to any bug reports.\n\n");
+	}
+
+	if (!(_screen.width < 1 || _screen.height < 1 || _screen.dst_ptr == nullptr)) {
+		bret = this->WriteScreenshot(filename, lastof(filename), name_buffer);
+		if (bret) {
+			printf("Desync screenshot written to %s. Please add this file to any bug reports.\n\n", filename);
+		} else {
+			ret = false;
+			printf("Writing desync screenshot failed.\n\n");
+		}
+	}
+
+	return ret;
+}
+
 /**
  * Sets a message for the error message handler.
  * @param message The error message of the error.

src/crashlog.h

@@ -91,7 +91,8 @@ public:
 	virtual ~CrashLog() {}
 
 	char *FillCrashLog(char *buffer, const char *last) const;
-	bool WriteCrashLog(const char *buffer, char *filename, const char *filename_last) const;
+	char *FillDesyncCrashLog(char *buffer, const char *last) const;
+	bool WriteCrashLog(const char *buffer, char *filename, const char *filename_last, const char *name = "crash") const;
 
 	/**
 	 * Write the (crash) dump to a file.
@@ -103,10 +104,11 @@ public:
 	 *         was successful (not all OSes support dumping files).
 	 */
 	virtual int WriteCrashDump(char *filename, const char *filename_last) const;
-	bool WriteSavegame(char *filename, const char *filename_last) const;
+	bool WriteSavegame(char *filename, const char *filename_last, const char *name = "crash") const;
-	bool WriteScreenshot(char *filename, const char *filename_last) const;
+	bool WriteScreenshot(char *filename, const char *filename_last, const char *name = "crash") const;
 
 	bool MakeCrashLog() const;
+	bool MakeDesyncCrashLog() const;
 
 	/**
 	 * Initialiser for crash logs; do the appropriate things so crashes are
@@ -115,6 +117,8 @@ public:
 	 */
 	static void InitialiseCrashLog();
 
+	static void DesyncCrashLog();
+
 	static void SetErrorMessage(const char *message);
 	static void AfterCrashLogCleanup();
 };

src/network/network_client.cpp

@@ -28,6 +28,7 @@
 #include "network_client.h"
 #include "../core/backup_type.hpp"
 #include "../thread.h"
+#include "../crashlog.h"
 
 #include "table/strings.h"
 
@@ -277,6 +278,8 @@ void ClientNetworkGameSocketHandler::ClientError(NetworkRecvStatus res)
 				DEBUG(net, 0, "Sync error detected!");
 				my_client->ClientError(NETWORK_RECV_STATUS_DESYNC);
 
+				CrashLog::DesyncCrashLog();
+
 				extern void CheckCaches(bool force_check);
 				CheckCaches(true);
 				return false;

src/network/network_server.cpp

@@ -28,6 +28,7 @@
 #include "../core/pool_func.hpp"
 #include "../core/random_func.hpp"
 #include "../rev.h"
+#include "../crashlog.h"
 #include <mutex>
 #include <condition_variable>
 
@@ -1159,6 +1160,8 @@ NetworkRecvStatus ServerNetworkGameSocketHandler::Receive_CLIENT_ERROR(Packet *p
 	NetworkAdminClientError(this->client_id, errorno);
 
 	if (errorno == NETWORK_ERROR_DESYNC) {
+		CrashLog::DesyncCrashLog();
+
 		// have the server and all clients run some sanity checks
 		NetworkSendCommand(0, 0, 0, CMD_DESYNC_CHECK, NULL, NULL, _local_company);
 	}

src/os/macosx/crashlog_osx.cpp

@@ -152,6 +152,8 @@ class CrashLogOSX : public CrashLog {
 	}
 
 public:
+	struct DesyncTag {};
+
 	/**
 	 * A crash log is always generated by signal.
 	 * @param signum the signal that was caused by the crash.
@@ -163,6 +165,13 @@ public:
 		filename_screenshot[0] = '\0';
 	}
 
+	CrashLogOSX(DesyncTag tag) : signum(0), si(nullptr), context(nullptr), signal_instruction_ptr_valid(false)
+	{
+		filename_log[0] = '\0';
+		filename_save[0] = '\0';
+		filename_screenshot[0] = '\0';
+	}
+
 	/** Generate the crash log. */
 	bool MakeCrashLog()
 	{
@@ -257,3 +266,9 @@ void CDECL HandleCrash(int signum)
 		signal(*i, HandleCrash);
 	}
 }
+
+/* static */ void CrashLog::DesyncCrashLog()
+{
+	CrashLogOSX log(CrashLogOSX::DesyncTag{});
+	log.MakeDesyncCrashLog();
+}

src/os/unix/crashlog_unix.cpp

@@ -181,3 +181,9 @@ static void CDECL HandleCrash(int signum)
 		signal(*i, HandleCrash);
 	}
 }
+
+/* static */ void CrashLog::DesyncCrashLog()
+{
+	CrashLogUnix log(0);
+	log.MakeDesyncCrashLog();
+}

src/os/windows/crashlog_win.cpp

@@ -633,6 +633,12 @@ static void CDECL CustomAbort(int signal)
 	SetUnhandledExceptionFilter(ExceptionHandler);
 }
 
+/* static */ void CrashLog::DesyncCrashLog()
+{
+	CrashLogWindows log(nullptr);
+	log.MakeDesyncCrashLog();
+}
+
 /* The crash log GUI */
 
 static bool _expanded;