Crash log: Increase crash log length limit on Unix

Allocate buffer using mmap if possible

src/crashlog.cpp

@@ -696,7 +696,7 @@ bool CrashLog::WriteScreenshot(char *filename, const char *filename_last, const
  * information like paths to the console.
  * @return true when everything is made successfully.
  */
-bool CrashLog::MakeCrashLog()
+bool CrashLog::MakeCrashLog(char *buffer, const char *last)
 {
 	/* Don't keep looping logging crashes. */
 	static bool crashlogged = false;
@@ -708,7 +708,6 @@ bool CrashLog::MakeCrashLog()
 	}
 
 	char filename[MAX_PATH];
-	char buffer[65536 * 4];
 	bool ret = true;
 
 	char *name_buffer_date = this->name_buffer + seprintf(this->name_buffer, lastof(this->name_buffer), "crash-");
@@ -716,7 +715,7 @@ bool CrashLog::MakeCrashLog()
 	strftime(name_buffer_date, lastof(this->name_buffer) - name_buffer_date, "%Y%m%dT%H%M%SZ", gmtime(&cur_time));
 
 	printf("Crash encountered, generating crash log...\n");
-	this->FillCrashLog(buffer, lastof(buffer));
+	this->FillCrashLog(buffer, last);
 	printf("%s\n", buffer);
 	printf("Crash log generated.\n\n");
 
@@ -752,6 +751,12 @@ bool CrashLog::MakeCrashLog()
 	return ret;
 }
 
+bool CrashLog::MakeCrashLogWithStackBuffer()
+{
+	char buffer[65536 * 4];
+	return this->MakeCrashLog(buffer, lastof(buffer));
+}
+
 /**
  * Makes a desync crash log, writes it to a file and then subsequently tries
  * to make a crash savegame. It uses DEBUG to write

src/crashlog.h

@@ -152,7 +152,8 @@ public:
 	bool WriteSavegame(char *filename, const char *filename_last, const char *name = "crash") const;
 	bool WriteScreenshot(char *filename, const char *filename_last, const char *name = "crash") const;
 
-	bool MakeCrashLog();
+	bool MakeCrashLog(char *buffer, const char *last);
+	bool MakeCrashLogWithStackBuffer();
 	bool MakeDesyncCrashLog(const std::string *log_in, std::string *log_out, const DesyncExtraInfo &info) const;
 	bool MakeInconsistencyLog(const InconsistencyExtraInfo &info) const;
 	bool MakeVersionInfoLog() const;

src/os/unix/crashlog_unix.cpp

@@ -22,6 +22,7 @@
 #include <fcntl.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <sys/mman.h>
 
 #if defined(WITH_DBG_GDB)
 #include <sys/syscall.h>
@@ -585,7 +586,13 @@ static void CDECL HandleCrash(int signum)
 #else
 	CrashLogUnix log(signum);
 #endif
-	log.MakeCrashLog();
+	const size_t length = 65536 * 16;
+	char *buffer = (char *)mmap(nullptr, length, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (buffer != MAP_FAILED) {
+		log.MakeCrashLog(buffer, buffer + length - 1);
+	} else {
+		log.MakeCrashLogWithStackBuffer();
+	}
 
 	CrashLog::AfterCrashLogCleanup();
 	abort();