Add logging!

Relies on kitling/flashcart_core#64

Makefile

@@ -42,6 +42,10 @@ CFLAGS	+=	$(INCLUDE) -DARM9 -D_GNU_SOURCE\
 			-DNTRBOOT_FLASHER_VERSION=\"$(NTRBOOT_FLASHER_VERSION)\"\
 			-DFLASHCART_CORE_VERSION=\"$(FLASHCART_CORE_VERSION)\"
 
+ifdef DEBUG
+CFLAGS += -D LOG_LEVEL=LOG_DEBUG
+endif
+
 CXXFLAGS	:= $(CFLAGS) -fno-rtti -fno-exceptions
 
 ASFLAGS	:=	-g $(ARCH)

source/main.cpp

@@ -113,9 +113,11 @@ void ntrboot_flasher()
                 goto reselect_cart; // keeps code complexity down ¯\_(ツ)_/¯
                 break;
             case MENU_EXIT:
+                close_logfile();
                 ELM_Unmount();
                 return;
             case MENU_REBOOT:
+                close_logfile();
                 ELM_Unmount();
                 i2cReboot();
                 return;

source/menu.cpp

@@ -41,6 +41,7 @@ bool menu_show_intro_warning()
 }
 
 void menu_unmount() {
+    close_logfile();
     ELM_Unmount();
     ClearScreen(TOP_SCREEN, STD_COLOR_BG);
     DrawStringF(TOP_SCREEN, 10, 10, STD_COLOR_FONT, STD_COLOR_BG, "It is now safe to remove your SD card.");

source/menu.h

@@ -17,3 +17,6 @@ bool menu_show_intro_warning();
 void menu_wait_cart_insert();
 int8_t menu_select_flashcart();
 uint8_t menu_flashcart_menu(const char* flashcart_name);
+
+// From platform.cpp
+void close_logfile(void);

source/platform.cpp

@@ -6,10 +6,60 @@
 #include "protocol_ntr.h"
 #include "ui.h"
 
+#include <cstdarg>
+
 void Flashcart::sendCommand(const uint8_t *cmdbuf, uint16_t response_len, uint8_t *resp, uint32_t flags) {
     NTR_SendCommand(cmdbuf, response_len, flags, resp);
 }
 
 void Flashcart::showProgress(uint32_t current, uint32_t total, const char* status_string) {
     ShowProgress(BOTTOM_SCREEN, current, total, status_string);
-}
+}
+
+static FILE *logfile = nullptr;
+
+static void open_logfile(void) {
+    static bool first_open = true;
+    // We want to overwrite if this is our first time opening the file this run.
+    logfile = fopen("fat1:/ntrboot/ntrboot.log", first_open ? "w" : "a");
+    first_open = false;
+}
+
+void close_logfile(void) {
+    fclose(logfile);
+    logfile = nullptr;
+}
+
+#ifndef LOG_LEVEL
+#define LOG_LEVEL LOG_INFO
+#endif
+
+int Flashcart::logMessage(log_priority priority, const char *fmt, ...) {
+    if (priority < LOG_LEVEL) return 0;
+    if (!logfile) {
+        open_logfile(); // automagicly open.
+        if (!logfile) return -1;
+    }
+    va_list args;
+    va_start(args, fmt);
+
+    static char const *const priority_strings[] = {
+        [LOG_DEBUG] = "DEBUG",
+        [LOG_INFO] = "INFO",
+        [LOG_NOTICE] = "NOTICE",
+        [LOG_WARN] = "WARN",
+        [LOG_ERR] = "ERROR"
+    };
+    const char *priority_str = (priority >= LOG_PRIORITY_MAX) ? "?!#$" : priority_strings[priority];
+
+    char *log_fmt;
+    if (asprintf(&log_fmt, "[%s]: %s\n", priority_str, fmt) < 0) {
+        return -1; // would pass the actual return value back, but I don't think we care.
+    }
+
+    int result = vfprintf(logfile, log_fmt, args);
+    va_end(args);
+
+    free(log_fmt);
+    return result;
+}