Implemented exception handler.

The exception handler is capable of logging CPU registers and a stack trace using the current log implementation.

Furthermore, if borealis has been initialized, it'll also display the PC register value using a CrashFrame. Otherwise, console output is used to display the same message.

Other changes include:

* utils: made utilsPrintConsoleError non-static.
* utils: implemented a workaround to restore console output after initializing nxlink.

include/core/nxdt_utils.h

@@ -151,6 +151,9 @@ void utilsCreateDirectoryTree(const char *path, bool create_last_element);
 /// Furthermore, if the full length for the generated path is >= FS_MAX_PATH, NULL will be returned.
 char *utilsGeneratePath(const char *prefix, const char *filename, const char *extension);
 
+/// Prints an error message using the standard console output and waits for the user to press a button.
+void utilsPrintConsoleError(const char *msg);
+
 /// Returns the current application updated state.
 bool utilsGetApplicationUpdatedState(void);
 

romfs/i18n/en-US/about_tab.json

@@ -24,7 +24,7 @@
         "line_07": "\uE016  The folks from NSWDB.COM and No-Intro.org, for being kind enough to put up public APIs to perform online checksum lookups.",
         "line_08": "\uE016  The folks at the nxdumptool Discord server.",
         "line_09": "\uE016  The Comfy Boyes, for always being awesome and supportive. You know who you are.",
-        "line_10": "\uE016  My girlfriend, for always being by my side and motivating me to keep working on all my projects. I love you. \uE87D",
+        "line_10": "\uE016  Andreína, for always being by my side and motivating me to keep working on all my projects.",
         "line_11": "\uE016  And, at last but not least, you! Thank you for using my work!"
     },
     

romfs/i18n/en-US/generic.json

@@ -9,5 +9,8 @@
     "__time_format_comment__": "Use 12 for a 12-hour clock, or 24 for a 24-hour clock",
     
     "date": "{1:02d}/{2:02d}/{0} {3:02d}:{4:02d}:{5:02d} {6}",
-    "__date_comment__": "{0} = Year, {1} = Month, {2} = Day, {3} = Hour, {4} = Minute, {5} = Second, {6} = AM/PM (if time_format is set to 12)"
+    "__date_comment__": "{0} = Year, {1} = Month, {2} = Day, {3} = Hour, {4} = Minute, {5} = Second, {6} = AM/PM (if time_format is set to 12)",
+    
+    "libnx_abort": "Fatal error triggered in libnx!\nError code: 0x{:08X}.",
+    "exception_triggered": "Fatal exception triggered!\nReason: {} (0x{:X})."
 }

source/core/nxdt_utils.c

@@ -65,7 +65,7 @@ static AppletHookCookie g_systemOverclockCookie = {0};
 
 static bool g_longRunningProcess = false;
 
-static int g_nxLinkSocketFd = -1;
+static int g_stdoutFd = -1, g_stderrFd = -1, g_nxLinkSocketFd = -1;
 
 static const char *g_sizeSuffixes[] = { "B", "KiB", "MiB", "GiB" };
 static const u32 g_sizeSuffixesCount = MAX_ELEMENTS(g_sizeSuffixes);
@@ -106,7 +106,8 @@ static void utilsOverclockSystemAppletHook(AppletHookType hook, void *param);
 
 static void utilsChangeHomeButtonBlockStatus(bool block);
 
-static void utilsPrintConsoleError(void);
+NX_INLINE void utilsCloseFileDescriptor(int *fd);
+static void utilsRestoreConsoleOutput(void);
 
 static size_t utilsGetUtf8CodepointCount(const char *str, size_t str_size, size_t cp_limit, size_t *last_cp_pos);
 
@@ -120,6 +121,9 @@ bool utilsInitializeResources(const int program_argc, const char **program_argv)
         ret = g_resourcesInit;
         if (ret) break;
         
+        /* Lock applet exit. */
+        appletLockExit();
+        
         /* Retrieve pointer to the application launch path. */
         _utilsGetLaunchPath(program_argc, program_argv);
         
@@ -132,7 +136,7 @@ bool utilsInitializeResources(const int program_argc, const char **program_argv)
         
         /* Create logfile. */
         logWriteStringToLogFile("________________________________________________________________\r\n");
-        LOG_MSG(APP_TITLE " v%u.%u.%u starting (" GIT_REV "). Built on " __DATE__ " - " __TIME__ ".", VERSION_MAJOR, VERSION_MINOR, VERSION_MICRO);
+        LOG_MSG(APP_TITLE " v" APP_VERSION " starting (" GIT_REV "). Built on " __DATE__ " - " __TIME__ ".");
         
         /* Log Horizon OS version. */
         u32 hos_version = hosversionGet();
@@ -237,14 +241,33 @@ bool utilsInitializeResources(const int program_argc, const char **program_argv)
             if (R_SUCCEEDED(rc) && flag) appletInitializeGamePlayRecording();
         }
         
-        /* Redirect stdout and stderr over network to nxlink. */
+        /* Duplicate the stdout and stderr file handles, then redirect stdout and stderr over network to nxlink. */
+        g_stdoutFd = dup(STDOUT_FILENO);
+        g_stderrFd = dup(STDERR_FILENO);
         g_nxLinkSocketFd = nxlinkConnectToHost(true, true);
         
         /* Update flags. */
         ret = g_resourcesInit = true;
     }
     
-    if (!ret) utilsPrintConsoleError();
+    if (!ret)
+    {
+        size_t msg_size = 0;
+        char log_msg[0x100] = {0}, *msg = NULL;
+        
+        /* Get last log message. */
+        logGetLastMessage(log_msg, sizeof(log_msg));
+        
+        /* Generate error message. */
+        utilsAppendFormattedStringToBuffer(&msg, &msg_size, "An error occurred while initializing resources.");
+        if (*log_msg) utilsAppendFormattedStringToBuffer(&msg, &msg_size, "\n\n%s", log_msg);
+        
+        /* Print error message. */
+        utilsPrintConsoleError(msg);
+        
+        /* Free error message. */
+        if (msg) free(msg);
+    }
     
     return ret;
 }
@@ -253,12 +276,8 @@ void utilsCloseResources(void)
 {
     SCOPED_LOCK(&g_resourcesMutex)
     {
-        /* Close nxlink socket. */
+        /* Restore console output. */
-        if (g_nxLinkSocketFd >= 0)
+        utilsRestoreConsoleOutput();
-        {
-            close(g_nxLinkSocketFd);
-            g_nxLinkSocketFd = -1;
-        }
         
         /* Unset long running process state. */
         utilsSetLongRunningProcessState(false);
@@ -316,6 +335,9 @@ void utilsCloseResources(void)
         /* Close logfile. */
         logCloseLogFile();
         
+        /* Unlock applet exit. */
+        appletUnlockExit();
+        
         g_resourcesInit = false;
     }
 }
@@ -836,6 +858,48 @@ end:
     return path;
 }
 
+void utilsPrintConsoleError(const char *msg)
+{
+    PadState pad = {0};
+    
+    /* Don't consider stick movement as button inputs. */
+    u64 flag = ~(HidNpadButton_StickLLeft | HidNpadButton_StickLRight | HidNpadButton_StickLUp | HidNpadButton_StickLDown | HidNpadButton_StickRLeft | HidNpadButton_StickRRight | \
+                 HidNpadButton_StickRUp | HidNpadButton_StickRDown);
+    
+    /* Configure input. */
+    /* Up to 8 different, full controller inputs. */
+    /* Individual Joy-Cons not supported. */
+    padConfigureInput(8, HidNpadStyleSet_NpadFullCtrl);
+    padInitializeWithMask(&pad, 0x1000000FFUL);
+    
+    /* Restore console output. */
+    utilsRestoreConsoleOutput();
+    
+    /* Initialize console output. */
+    consoleInit(NULL);
+    
+    /* Print message. */
+    if (msg && *msg)
+    {
+        printf("%s", msg);
+    } else {
+        printf("An error occurred.");
+    }
+    
+    printf("\n\nFor more information, please check the logfile. Press any button to exit.");
+    consoleUpdate(NULL);
+    
+    /* Wait until the user presses a button. */
+    while(appletMainLoop())
+    {
+        padUpdate(&pad);
+        if (padGetButtonsDown(&pad) & flag) break;
+    }
+    
+    /* Deinitialize console output. */
+    consoleExit(NULL);
+}
+
 bool utilsGetApplicationUpdatedState(void)
 {
     bool ret = false;
@@ -1078,39 +1142,31 @@ static void utilsChangeHomeButtonBlockStatus(bool block)
     }
 }
 
-static void utilsPrintConsoleError(void)
+NX_INLINE void utilsCloseFileDescriptor(int *fd)
 {
-    PadState pad = {0};
+    if (!fd || *fd < 0) return;
-    char msg[0x100] = {0};
+    close(*fd);
-    
+    *fd = -1;
-    /* Don't consider stick movement as button inputs. */
-    u64 flag = ~(HidNpadButton_StickLLeft | HidNpadButton_StickLRight | HidNpadButton_StickLUp | HidNpadButton_StickLDown | HidNpadButton_StickRLeft | HidNpadButton_StickRRight | \
-                 HidNpadButton_StickRUp | HidNpadButton_StickRDown);
-    
-    /* Configure input. */
-    /* Up to 8 different, full controller inputs. */
-    /* Individual Joy-Cons not supported. */
-    padConfigureInput(8, HidNpadStyleSet_NpadFullCtrl);
-    padInitializeWithMask(&pad, 0x1000000FFUL);
-    
-    /* Get last log message. */
-    logGetLastMessage(msg, sizeof(msg));
-    
-    consoleInit(NULL);
-    
-    printf("An error occurred while initializing resources.\n\n");
-    if (*msg) printf("%s\n\n", msg);
-    printf("For more information, please check the logfile. Press any button to exit.");
-    
-    consoleUpdate(NULL);
-    
-    while(appletMainLoop())
-    {
-        padUpdate(&pad);
-        if (padGetButtonsDown(&pad) & flag) break;
 }
 
-    consoleExit(NULL);
+static void utilsRestoreConsoleOutput(void)
+{
+    SCOPED_LOCK(&g_resourcesMutex)
+    {
+        if (g_nxLinkSocketFd >= 0) utilsCloseFileDescriptor(&g_nxLinkSocketFd);
+        
+        if (g_stdoutFd >= 0)
+        {
+            dup2(g_stdoutFd, STDOUT_FILENO);
+            utilsCloseFileDescriptor(&g_stdoutFd);
+        }
+        
+        if (g_stderrFd >= 0)
+        {
+            dup2(g_stderrFd, STDERR_FILENO);
+            utilsCloseFileDescriptor(&g_stderrFd);
+        }
+    }
 }
 
 static size_t utilsGetUtf8CodepointCount(const char *str, size_t str_size, size_t cp_limit, size_t *last_cp_pos)

source/core/title.c

@@ -846,7 +846,7 @@ void titleFreeUserApplicationData(TitleUserApplicationData *user_app_data)
 bool titleAreOrphanTitlesAvailable(void)
 {
     bool ret = false;
-    SCOPED_LOCK(&g_titleMutex) ret = (g_titleInterfaceInit && g_orphanTitleInfo && *g_orphanTitleInfo && g_orphanTitleInfoCount > 0);
+    SCOPED_TRY_LOCK(&g_titleMutex) ret = (g_titleInterfaceInit && g_orphanTitleInfo && *g_orphanTitleInfo && g_orphanTitleInfoCount > 0);
     return ret;
 }
 

source/exception_handler.cpp

@@ -0,0 +1,223 @@
+/*
+ * exception_handler.cpp
+ *
+ * Copyright (c) 2020-2021, DarkMatterCore <pabloacurielz@gmail.com>.
+ * Copyright (c) 2019-2020, WerWolv.
+ *
+ * This file is part of nxdumptool (https://github.com/DarkMatterCore/nxdumptool).
+ * Loosely based on debug_helpers.cpp from EdiZon-Rewrite.
+ * 
+ * nxdumptool is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * nxdumptool is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <nxdt_utils.h>
+#include <borealis.hpp>
+
+#define FP_MASK             0xFFFFFFFFFF000000UL
+#define STACK_TRACE_SIZE    0x20
+#define IS_HB_ADDR(x)       (info.addr && info.size && (x) >= info.addr && (x) < (info.addr + info.size))
+
+namespace i18n = brls::i18n;    /* For getStr(). */
+using namespace i18n::literals; /* For _i18n. */
+
+extern bool g_borealisInitialized;
+
+extern "C" {
+    /* Overrides for libnx weak symbols. */
+    u32 __nx_applet_exit_mode = 0;
+    alignas(16) u8 __nx_exception_stack[0x8000];
+    u64 __nx_exception_stack_size = sizeof(__nx_exception_stack);
+}
+
+namespace nxdt::utils {
+    static void GetHomebrewMemoryInfo(MemoryInfo *out)
+    {
+        if (!out)
+        {
+            LOG_MSG("Invalid parameters!");
+            return;
+        }
+        
+        u32 p = 0;
+        Result rc = 0;
+        
+        /* Find the memory region in which this function is stored. */
+        /* The start of it will be the base address the homebrew was mapped to. */
+        rc = svcQueryMemory(out, &p, static_cast<u64>(reinterpret_cast<uintptr_t>(&GetHomebrewMemoryInfo)));
+        if (R_FAILED(rc)) LOG_MSG("svcQueryMemory failed! (0x%08X).", rc);
+    }
+    
+    static bool UnwindStack(u64 *out_stack_trace, u32 *out_stack_trace_size, size_t max_stack_trace_size, u64 cur_fp)
+    {
+        if (!out_stack_trace || !out_stack_trace_size || !max_stack_trace_size || !cur_fp)
+        {
+            LOG_MSG("Invalid parameters!");
+            return false;
+        }
+        
+        struct StackFrame {
+            u64 fp; ///< Frame Pointer (pointer to previous stack frame).
+            u64 lr; ///< Link Register (return address).
+        };
+        
+        *out_stack_trace_size = 0;
+        u64 fp_base = (cur_fp & FP_MASK);
+        
+        for(size_t i = 0; i < max_stack_trace_size; i++)
+        {
+            /* Last check fixes a crash while dealing with certain stack frame addresses. */
+            if (!cur_fp || (cur_fp % sizeof(u64)) || (cur_fp & FP_MASK) != fp_base) break;
+            
+            auto cur_trace = reinterpret_cast<StackFrame*>(cur_fp);
+            out_stack_trace[(*out_stack_trace_size)++] = cur_trace->lr;
+            cur_fp = cur_trace->fp;
+        }
+        
+        return (*out_stack_trace_size > 0);
+    }
+    
+    static void NORETURN AbortProgramExecution(std::string str)
+    {
+        if (g_borealisInitialized)
+        {
+            /* Display crash frame and exit Borealis. */
+            brls::Application::crash(str);
+            while(brls::Application::mainLoop());
+        } else {
+            /* Print error message using console output. */
+            utilsPrintConsoleError(str.c_str());
+        }
+        
+        /* Clean up resources. */
+        utilsCloseResources();
+        
+        /* Exit application. */
+        __nx_applet_exit_mode = 1;
+        exit(EXIT_FAILURE);
+        
+        __builtin_unreachable();
+    }
+}
+
+extern "C" {
+    /* libnx abort function override. */
+    void diagAbortWithResult(Result res)
+    {
+        /* Log error. */
+        LOG_MSG("*** libnx aborted with error code: 0x%08X ***", res);
+        
+        /* Abort program execution. */
+        std::string crash_str = (g_borealisInitialized ? i18n::getStr("generic/libnx_abort"_i18n, res) : fmt::format("Fatal error triggered in libnx!\nError code: 0x{:08X}.", res));
+        nxdt::utils::AbortProgramExecution(crash_str);
+    }
+    
+    /* libnx exception handler override. */
+    void __libnx_exception_handler(ThreadExceptionDump *ctx)
+    {
+        MemoryInfo info = {0};
+        u32 stack_trace_size = 0;
+        u64 stack_trace[STACK_TRACE_SIZE] = {0};
+        
+        char *exception_str = NULL;
+        size_t exception_str_size = 0;
+        
+        std::string error_desc_str, crash_str;
+        
+        /* Get homebrew memory info. */
+        nxdt::utils::GetHomebrewMemoryInfo(&info);
+        
+        /* Log exception type. */
+        LOG_MSG("*** Exception Triggered ***");
+        
+        switch(ctx->error_desc)
+        {
+            case ThreadExceptionDesc_InstructionAbort:
+                error_desc_str = "Instruction Abort";
+                break;
+            case ThreadExceptionDesc_MisalignedPC:
+                error_desc_str = "Misaligned Program Counter";
+                break;
+            case ThreadExceptionDesc_MisalignedSP:
+                error_desc_str = "Misaligned Stack Pointer";
+                break;
+            case ThreadExceptionDesc_SError:
+                error_desc_str = "SError";
+                break;
+            case ThreadExceptionDesc_BadSVC:
+                error_desc_str = "Bad SVC";
+                break;
+            case ThreadExceptionDesc_Trap:
+                error_desc_str = "SIGTRAP";
+                break;
+            case ThreadExceptionDesc_Other:
+                error_desc_str = "Segmentation Fault";
+                break;
+            default:
+                error_desc_str = "Unknown";
+                break;
+        }
+        
+        utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, "Type: %s (0x%X)\r\n", error_desc_str.c_str(), ctx->error_desc);
+        
+        /* Log CPU registers. */
+        utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, "Registers:");
+        
+        for(size_t i = 0; i < MAX_ELEMENTS(ctx->cpu_gprs); i++)
+        {
+            u64 reg = ctx->cpu_gprs[i].x;
+            utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, "\r\n    X%02lu:  0x%lX", i, reg);
+            if (IS_HB_ADDR(reg)) utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, " (BASE + 0x%lX)", reg - info.addr);
+        }
+        
+        utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, "\r\n    FP:   0x%lX", ctx->fp.x);
+        if (IS_HB_ADDR(ctx->fp.x)) utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, " (BASE + 0x%lX)", ctx->fp.x - info.addr);
+        
+        utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, "\r\n    LR:   0x%lX", ctx->lr.x);
+        if (IS_HB_ADDR(ctx->lr.x)) utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, " (BASE + 0x%lX)", ctx->lr.x - info.addr);
+        
+        utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, "\r\n    SP:   0x%lX", ctx->sp.x);
+        if (IS_HB_ADDR(ctx->sp.x)) utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, " (BASE + 0x%lX)", ctx->sp.x - info.addr);
+        
+        utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, "\r\n    PC:   0x%lX", ctx->pc.x);
+        if (IS_HB_ADDR(ctx->pc.x)) utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, " (BASE + 0x%lX)", ctx->pc.x - info.addr);
+        utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, "\r\n");
+        
+        /* Unwind stack. */
+        if (nxdt::utils::UnwindStack(stack_trace, &stack_trace_size, STACK_TRACE_SIZE, ctx->fp.x))
+        {
+            /* Log stack trace. */
+            utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, "Stack Trace:");
+            
+            for(u32 i = 0; i < stack_trace_size; i++)
+            {
+                u64 addr = stack_trace[i];
+                utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, "\r\n    [%02u]: 0x%lX", stack_trace_size - i - 1, addr);
+                if (IS_HB_ADDR(addr)) utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, " (BASE + 0x%lX)", addr - info.addr);
+            }
+            
+            utilsAppendFormattedStringToBuffer(&exception_str, &exception_str_size, "\r\n");
+        }
+        
+        /* Write log string. */
+        logWriteStringToLogFile(exception_str);
+        
+        /* Free exception info string. */
+        if (exception_str) free(exception_str);
+        
+        /* Abort program execution. */
+        crash_str = (g_borealisInitialized ? i18n::getStr("generic/exception_triggered"_i18n, error_desc_str, ctx->error_desc) : fmt::format("Fatal exception triggered!\nReason: {} (0x{:X}).", error_desc_str, ctx->error_desc));
+        crash_str += (fmt::format("\nPC: 0x{:X}", ctx->pc.x) + (IS_HB_ADDR(ctx->pc.x) ? fmt::format(" (BASE + 0x{:X}).", ctx->pc.x - info.addr) : "."));
+        nxdt::utils::AbortProgramExecution(crash_str);
+    }
+}

source/main.cpp

@@ -25,6 +25,8 @@
 
 using namespace brls::i18n::literals;   /* For _i18n. */
 
+bool g_borealisInitialized = false;
+
 int main(int argc, char *argv[])
 {
     /* Set scope guard to clean up resources at exit. */
@@ -45,6 +47,7 @@ int main(int argc, char *argv[])
     
     /* Initialize Borealis. */
     if (!brls::Application::init(APP_TITLE)) return EXIT_FAILURE;
+    g_borealisInitialized = true;
     
     /* Check if we're running under applet mode. */
     if (utilsAppletModeCheck())