From 454380382312014da27fcd5bd2a2adc6770693db Mon Sep 17 00:00:00 2001
From: Jonathan G Rennison <j.g.rennison@gmail.com>
Date: Mon, 6 Dec 2021 18:58:19 +0000
Subject: [PATCH] Crash log: Increase crash log length limit on Unix

Allocate buffer using mmap if possible
---
 src/crashlog.cpp              | 11 ++++++++---
 src/crashlog.h                |  3 ++-
 src/os/unix/crashlog_unix.cpp |  9 ++++++++-
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/src/crashlog.cpp b/src/crashlog.cpp
index 9b0cbc9b52..547ecd7523 100644
--- a/src/crashlog.cpp
+++ b/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
diff --git a/src/crashlog.h b/src/crashlog.h
index dfbd7a02bd..86116c0055 100644
--- a/src/crashlog.h
+++ b/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;
diff --git a/src/os/unix/crashlog_unix.cpp b/src/os/unix/crashlog_unix.cpp
index bfaee844d0..69290539eb 100644
--- a/src/os/unix/crashlog_unix.cpp
+++ b/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();