Avoid using malloc in scope guard logger.

Use a temporary object with its own buffer, which lives on the stack.

Reformat SCOPE_INFO_FMT to not be all on one line.
Other minor reformatting.

src/command.cpp

@@ -456,7 +456,8 @@ CommandCost DoCommand(const CommandContainer *container, DoCommandFlag flags)
  */
 CommandCost DoCommand(TileIndex tile, uint32 p1, uint32 p2, DoCommandFlag flags, uint32 cmd, const char *text)
 {
-	SCOPE_INFO_FMT([=], "DoCommand: tile: %dx%d, p1: 0x%X, p2: 0x%X, flags: 0x%X, company: %s, cmd: 0x%X (%s)", TileX(tile), TileY(tile), p1, p2, flags, DumpCompanyInfo(_current_company), cmd, GetCommandName(cmd));
+	SCOPE_INFO_FMT([=], "DoCommand: tile: %dx%d, p1: 0x%X, p2: 0x%X, flags: 0x%X, company: %s, cmd: 0x%X (%s)",
+			TileX(tile), TileY(tile), p1, p2, flags, scope_dumper().CompanyInfo(_current_company), cmd, GetCommandName(cmd));
 
 	CommandCost res;
 
@@ -551,7 +552,8 @@ bool DoCommandP(const CommandContainer *container, bool my_cmd)
  */
 bool DoCommandP(TileIndex tile, uint32 p1, uint32 p2, uint32 cmd, CommandCallback *callback, const char *text, bool my_cmd)
 {
-	SCOPE_INFO_FMT([=], "DoCommandP: tile: %dx%d, p1: 0x%X, p2: 0x%X, company: %s, cmd: 0x%X (%s), my_cmd: %d", TileX(tile), TileY(tile), p1, p2, DumpCompanyInfo(_current_company), cmd, GetCommandName(cmd), my_cmd);
+	SCOPE_INFO_FMT([=], "DoCommandP: tile: %dx%d, p1: 0x%X, p2: 0x%X, company: %s, cmd: 0x%X (%s), my_cmd: %d",
+			TileX(tile), TileY(tile), p1, p2, scope_dumper().CompanyInfo(_current_company), cmd, GetCommandName(cmd), my_cmd);
 
 	/* Cost estimation is generally only done when the
 	 * local user presses shift while doing somthing.

src/scope_info.cpp

@@ -39,34 +39,35 @@ int WriteScopeLog(char *buf, const char *last)
 }
 
 // helper functions
-char *DumpCompanyInfo(int company_id)
+const char *scope_dumper::CompanyInfo(int company_id)
 {
-	char buf[256];
-	char *b = buf + seprintf(buf, lastof(buf), "%d (", company_id);
+	char *b = this->buffer;
+	const char *last = lastof(this->buffer);
+	b += seprintf(b, last, "%d (", company_id);
 	SetDParam(0, company_id);
-	b = GetString(b, STR_COMPANY_NAME, lastof(buf));
-	b += seprintf(b, lastof(buf), ")");
-	return stredup(buf, lastof(buf));
+	b = GetString(b, STR_COMPANY_NAME, last);
+	b += seprintf(b, last, ")");
+	return buffer;
 }
 
-char *DumpVehicleInfo(const Vehicle *v)
+const char *scope_dumper::VehicleInfo(const Vehicle *v)
 {
-	char buf[256];
-	char *b = buf;
+	char *b = this->buffer;
+	const char *last = lastof(this->buffer);
 	if (v) {
-		b += seprintf(b, lastof(buf), "veh: %u: (", v->index);
+		b += seprintf(b, last, "veh: %u: (", v->index);
 		SetDParam(0, v->index);
-		b = GetString(b, STR_VEHICLE_NAME, lastof(buf));
+		b = GetString(b, STR_VEHICLE_NAME, last);
 		if (v->First() && v->First() != v) {
-			b += seprintf(b, lastof(buf), "), front: %u: (", v->First()->index);
+			b += seprintf(b, last, "), front: %u: (", v->First()->index);
 			SetDParam(0, v->First()->index);
-			b = GetString(b, STR_VEHICLE_NAME, lastof(buf));
+			b = GetString(b, STR_VEHICLE_NAME, last);
 		}
-		b += seprintf(b, lastof(buf), ")");
+		b += seprintf(b, last, ")");
 	} else {
-		b += seprintf(b, lastof(buf), "veh: NULL");
+		b += seprintf(b, last, "veh: NULL");
 	}
-	return stredup(buf, lastof(buf));
+	return this->buffer;
 }
 
 #endif

src/scope_info.h

@@ -43,15 +43,32 @@ int WriteScopeLog(char *buf, const char *last);
  * This lambda is then captured by reference in a std::function which is pushed onto the scope stack
  * The scope stack is popped at the end of the scope
  */
-#define SCOPE_INFO_FMT(capture, ...) auto SCOPE_INFO_PASTE(_sc_lm_, __LINE__) = capture (char *buf, const char *last) { return seprintf(buf, last, __VA_ARGS__); }; scope_info_func_obj SCOPE_INFO_PASTE(_sc_obj_, __LINE__) ([&](char *buf, const char *last) -> int { return SCOPE_INFO_PASTE(_sc_lm_, __LINE__) (buf, last); });
+#define SCOPE_INFO_FMT(capture, ...) \
+	auto SCOPE_INFO_PASTE(_sc_lm_, __LINE__) = capture (char *buf, const char *last) { \
+		return seprintf(buf, last, __VA_ARGS__); \
+	}; \
+	scope_info_func_obj SCOPE_INFO_PASTE(_sc_obj_, __LINE__) ([&](char *buf, const char *last) -> int { \
+		return SCOPE_INFO_PASTE(_sc_lm_, __LINE__) (buf, last); \
+	});
 
-// helper functions
-char *DumpCompanyInfo(int company_id);
-char *DumpVehicleInfo(const Vehicle *v);
+/**
+ * This is a set of helper functions to print useful info from within a SCOPE_INFO_FMT statement.
+ * The use of a struct is so that when used as an argument to SCOPE_INFO_FMT/seprintf/etc, the buffer lives
+ * on the stack with a lifetime which lasts until the end of the statement.
+ * This avoids needing to call malloc(), which is technically unsafe within the crash logger signal handler,
+ * writing directly into the seprintf buffer, or the use of a separate static buffer.
+ */
+struct scope_dumper {
+	const char *CompanyInfo(int company_id);
+	const char *VehicleInfo(const Vehicle *v);
+
+private:
+	char buffer[256];
+};
 
 #else /* USE_SCOPE_INFO */
 
-#define SCOPE_INFO_FMT(...)
+#define SCOPE_INFO_FMT(...) { }
 
 #endif /* USE_SCOPE_INFO */
 

src/vehicle.cpp

@@ -852,7 +852,7 @@ static void RunVehicleDayProc()
 
 	/* Run the day_proc for every DAY_TICKS vehicle starting at _date_fract. */
 	Vehicle *v = NULL;
-	SCOPE_INFO_FMT([&v], "RunVehicleDayProc: %s", DumpVehicleInfo(v));
+	SCOPE_INFO_FMT([&v], "RunVehicleDayProc: %s", scope_dumper().VehicleInfo(v));
 	for (size_t i = _date_fract; i < Vehicle::GetPoolSize(); i += DAY_TICKS) {
 		v = Vehicle::Get(i);
 		if (v == NULL) continue;
@@ -888,7 +888,7 @@ void CallVehicleTicks()
 	FOR_ALL_STATIONS(st) LoadUnloadStation(st);
 
 	Vehicle *v = NULL;
-	SCOPE_INFO_FMT([&v], "CallVehicleTicks: %s", DumpVehicleInfo(v));
+	SCOPE_INFO_FMT([&v], "CallVehicleTicks: %s", scope_dumper().VehicleInfo(v));
 	FOR_ALL_VEHICLES(v) {
 		/* Vehicle could be deleted in this tick */
 		if (!v->Tick()) {