set.mitm: Parse settings from SD card (closes #268)

stratosphere/set_mitm/Makefile

@@ -31,7 +31,7 @@ DATA		:=	data
 INCLUDES	:=	include ../../common/include
 EXEFS_SRC	:=	exefs_src
 
-DEFINES	:=	-DDISABLE_IPC -DATMOSPHERE_GIT_BRANCH=\"$(AMSBRANCH)\" -DATMOSPHERE_GIT_REV=\"$(AMSREV)\"
+DEFINES	:=	-DDISABLE_IPC -DATMOSPHERE_GIT_BRANCH=\"$(AMSBRANCH)\" -DATMOSPHERE_GIT_REV=\"$(AMSREV)\" -DINI_MAX_LINE=768
 
 #---------------------------------------------------------------------------------
 # options for code generation

stratosphere/set_mitm/source/ini.c

@@ -0,0 +1,269 @@
+/* inih -- simple .INI file parser
+
+inih is released under the New BSD license (see LICENSE.txt). Go to the project
+home page for more info:
+
+https://github.com/benhoyt/inih
+
+*/
+
+#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_WARNINGS)
+#define _CRT_SECURE_NO_WARNINGS
+#endif
+
+#include <stdio.h>
+#include <ctype.h>
+#include <string.h>
+
+#include "ini.h"
+
+#if !INI_USE_STACK
+#include <stdlib.h>
+#endif
+
+#define MAX_SECTION 72
+#define MAX_NAME 72
+
+/* Used by ini_parse_string() to keep track of string parsing state. */
+typedef struct {
+    const char* ptr;
+    size_t num_left;
+} ini_parse_string_ctx;
+
+/* Strip whitespace chars off end of given string, in place. Return s. */
+static char* rstrip(char* s)
+{
+    char* p = s + strlen(s);
+    while (p > s && isspace((unsigned char)(*--p)))
+        *p = '\0';
+    return s;
+}
+
+/* Return pointer to first non-whitespace char in given string. */
+static char* lskip(const char* s)
+{
+    while (*s && isspace((unsigned char)(*s)))
+        s++;
+    return (char*)s;
+}
+
+/* Return pointer to first char (of chars) or inline comment in given string,
+   or pointer to null at end of string if neither found. Inline comment must
+   be prefixed by a whitespace character to register as a comment. */
+static char* find_chars_or_comment(const char* s, const char* chars)
+{
+#if INI_ALLOW_INLINE_COMMENTS
+    int was_space = 0;
+    while (*s && (!chars || !strchr(chars, *s)) &&
+           !(was_space && strchr(INI_INLINE_COMMENT_PREFIXES, *s))) {
+        was_space = isspace((unsigned char)(*s));
+        s++;
+    }
+#else
+    while (*s && (!chars || !strchr(chars, *s))) {
+        s++;
+    }
+#endif
+    return (char*)s;
+}
+
+/* Version of strncpy that ensures dest (size bytes) is null-terminated. */
+static char* strncpy0(char* dest, const char* src, size_t size)
+{
+    strncpy(dest, src, size - 1);
+    dest[size - 1] = '\0';
+    return dest;
+}
+
+/* See documentation in header file. */
+int ini_parse_stream(ini_reader reader, void* stream, ini_handler handler,
+                     void* user)
+{
+    /* Uses a fair bit of stack (use heap instead if you need to) */
+#if INI_USE_STACK
+    char line[INI_MAX_LINE];
+    int max_line = INI_MAX_LINE;
+#else
+    char* line;
+    int max_line = INI_INITIAL_ALLOC;
+#endif
+#if INI_ALLOW_REALLOC
+    char* new_line;
+    int offset;
+#endif
+    char section[MAX_SECTION] = "";
+    char prev_name[MAX_NAME] = "";
+
+    char* start;
+    char* end;
+    char* name;
+    char* value;
+    int lineno = 0;
+    int error = 0;
+
+#if !INI_USE_STACK
+    line = (char*)malloc(INI_INITIAL_ALLOC);
+    if (!line) {
+        return -2;
+    }
+#endif
+
+#if INI_HANDLER_LINENO
+#define HANDLER(u, s, n, v) handler(u, s, n, v, lineno)
+#else
+#define HANDLER(u, s, n, v) handler(u, s, n, v)
+#endif
+
+    /* Scan through stream line by line */
+    while (reader(line, max_line, stream) != NULL) {
+#if INI_ALLOW_REALLOC
+        offset = strlen(line);
+        while (offset == max_line - 1 && line[offset - 1] != '\n') {
+            max_line *= 2;
+            if (max_line > INI_MAX_LINE)
+                max_line = INI_MAX_LINE;
+            new_line = realloc(line, max_line);
+            if (!new_line) {
+                free(line);
+                return -2;
+            }
+            line = new_line;
+            if (reader(line + offset, max_line - offset, stream) == NULL)
+                break;
+            if (max_line >= INI_MAX_LINE)
+                break;
+            offset += strlen(line + offset);
+        }
+#endif
+
+        lineno++;
+
+        start = line;
+#if INI_ALLOW_BOM
+        if (lineno == 1 && (unsigned char)start[0] == 0xEF &&
+                           (unsigned char)start[1] == 0xBB &&
+                           (unsigned char)start[2] == 0xBF) {
+            start += 3;
+        }
+#endif
+        start = lskip(rstrip(start));
+
+        if (strchr(INI_START_COMMENT_PREFIXES, *start)) {
+            /* Start-of-line comment */
+        }
+#if INI_ALLOW_MULTILINE
+        else if (*prev_name && *start && start > line) {
+            /* Non-blank line with leading whitespace, treat as continuation
+               of previous name's value (as per Python configparser). */
+            if (!HANDLER(user, section, prev_name, start) && !error)
+                error = lineno;
+        }
+#endif
+        else if (*start == '[') {
+            /* A "[section]" line */
+            end = find_chars_or_comment(start + 1, "]");
+            if (*end == ']') {
+                *end = '\0';
+                strncpy0(section, start + 1, sizeof(section));
+                *prev_name = '\0';
+            }
+            else if (!error) {
+                /* No ']' found on section line */
+                error = lineno;
+            }
+        }
+        else if (*start) {
+            /* Not a comment, must be a name[=:]value pair */
+            end = find_chars_or_comment(start, "=:");
+            if (*end == '=' || *end == ':') {
+                *end = '\0';
+                name = rstrip(start);
+                value = end + 1;
+#if INI_ALLOW_INLINE_COMMENTS
+                end = find_chars_or_comment(value, NULL);
+                if (*end)
+                    *end = '\0';
+#endif
+                value = lskip(value);
+                rstrip(value);
+
+                /* Valid name[=:]value pair found, call handler */
+                strncpy0(prev_name, name, sizeof(prev_name));
+                if (!HANDLER(user, section, name, value) && !error)
+                    error = lineno;
+            }
+            else if (!error) {
+                /* No '=' or ':' found on name[=:]value line */
+                error = lineno;
+            }
+        }
+
+#if INI_STOP_ON_FIRST_ERROR
+        if (error)
+            break;
+#endif
+    }
+
+#if !INI_USE_STACK
+    free(line);
+#endif
+
+    return error;
+}
+
+/* See documentation in header file. */
+int ini_parse_file(FILE* file, ini_handler handler, void* user)
+{
+    return ini_parse_stream((ini_reader)fgets, file, handler, user);
+}
+
+/* See documentation in header file. */
+int ini_parse(const char* filename, ini_handler handler, void* user)
+{
+    FILE* file;
+    int error;
+
+    file = fopen(filename, "r");
+    if (!file)
+        return -1;
+    error = ini_parse_file(file, handler, user);
+    fclose(file);
+    return error;
+}
+
+/* An ini_reader function to read the next line from a string buffer. This
+   is the fgets() equivalent used by ini_parse_string(). */
+static char* ini_reader_string(char* str, int num, void* stream) {
+    ini_parse_string_ctx* ctx = (ini_parse_string_ctx*)stream;
+    const char* ctx_ptr = ctx->ptr;
+    size_t ctx_num_left = ctx->num_left;
+    char* strp = str;
+    char c;
+
+    if (ctx_num_left == 0 || num < 2)
+        return NULL;
+
+    while (num > 1 && ctx_num_left != 0) {
+        c = *ctx_ptr++;
+        ctx_num_left--;
+        *strp++ = c;
+        if (c == '\n')
+            break;
+        num--;
+    }
+
+    *strp = '\0';
+    ctx->ptr = ctx_ptr;
+    ctx->num_left = ctx_num_left;
+    return str;
+}
+
+/* See documentation in header file. */
+int ini_parse_string(const char* string, ini_handler handler, void* user) {
+    ini_parse_string_ctx ctx;
+
+    ctx.ptr = string;
+    ctx.num_left = strlen(string);
+    return ini_parse_stream((ini_reader)ini_reader_string, &ctx, handler,
+                            user);
+}

stratosphere/set_mitm/source/ini.h

@@ -0,0 +1,130 @@
+/* inih -- simple .INI file parser
+
+inih is released under the New BSD license (see LICENSE.txt). Go to the project
+home page for more info:
+
+https://github.com/benhoyt/inih
+
+*/
+
+#ifndef __INI_H__
+#define __INI_H__
+
+/* Make this header file easier to include in C++ code */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdio.h>
+
+/* Nonzero if ini_handler callback should accept lineno parameter. */
+#ifndef INI_HANDLER_LINENO
+#define INI_HANDLER_LINENO 0
+#endif
+
+/* Typedef for prototype of handler function. */
+#if INI_HANDLER_LINENO
+typedef int (*ini_handler)(void* user, const char* section,
+                           const char* name, const char* value,
+                           int lineno);
+#else
+typedef int (*ini_handler)(void* user, const char* section,
+                           const char* name, const char* value);
+#endif
+
+/* Typedef for prototype of fgets-style reader function. */
+typedef char* (*ini_reader)(char* str, int num, void* stream);
+
+/* Parse given INI-style file. May have [section]s, name=value pairs
+   (whitespace stripped), and comments starting with ';' (semicolon). Section
+   is "" if name=value pair parsed before any section heading. name:value
+   pairs are also supported as a concession to Python's configparser.
+
+   For each name=value pair parsed, call handler function with given user
+   pointer as well as section, name, and value (data only valid for duration
+   of handler call). Handler should return nonzero on success, zero on error.
+
+   Returns 0 on success, line number of first error on parse error (doesn't
+   stop on first error), -1 on file open error, or -2 on memory allocation
+   error (only when INI_USE_STACK is zero).
+*/
+int ini_parse(const char* filename, ini_handler handler, void* user);
+
+/* Same as ini_parse(), but takes a FILE* instead of filename. This doesn't
+   close the file when it's finished -- the caller must do that. */
+int ini_parse_file(FILE* file, ini_handler handler, void* user);
+
+/* Same as ini_parse(), but takes an ini_reader function pointer instead of
+   filename. Used for implementing custom or string-based I/O (see also
+   ini_parse_string). */
+int ini_parse_stream(ini_reader reader, void* stream, ini_handler handler,
+                     void* user);
+
+/* Same as ini_parse(), but takes a zero-terminated string with the INI data
+instead of a file. Useful for parsing INI data from a network socket or
+already in memory. */
+int ini_parse_string(const char* string, ini_handler handler, void* user);
+
+/* Nonzero to allow multi-line value parsing, in the style of Python's
+   configparser. If allowed, ini_parse() will call the handler with the same
+   name for each subsequent line parsed. */
+#ifndef INI_ALLOW_MULTILINE
+#define INI_ALLOW_MULTILINE 1
+#endif
+
+/* Nonzero to allow a UTF-8 BOM sequence (0xEF 0xBB 0xBF) at the start of
+   the file. See http://code.google.com/p/inih/issues/detail?id=21 */
+#ifndef INI_ALLOW_BOM
+#define INI_ALLOW_BOM 1
+#endif
+
+/* Chars that begin a start-of-line comment. Per Python configparser, allow
+   both ; and # comments at the start of a line by default. */
+#ifndef INI_START_COMMENT_PREFIXES
+#define INI_START_COMMENT_PREFIXES ";#"
+#endif
+
+/* Nonzero to allow inline comments (with valid inline comment characters
+   specified by INI_INLINE_COMMENT_PREFIXES). Set to 0 to turn off and match
+   Python 3.2+ configparser behaviour. */
+#ifndef INI_ALLOW_INLINE_COMMENTS
+#define INI_ALLOW_INLINE_COMMENTS 1
+#endif
+#ifndef INI_INLINE_COMMENT_PREFIXES
+#define INI_INLINE_COMMENT_PREFIXES ";"
+#endif
+
+/* Nonzero to use stack for line buffer, zero to use heap (malloc/free). */
+#ifndef INI_USE_STACK
+#define INI_USE_STACK 1
+#endif
+
+/* Maximum line length for any line in INI file (stack or heap). Note that
+   this must be 3 more than the longest line (due to '\r', '\n', and '\0'). */
+#ifndef INI_MAX_LINE
+#define INI_MAX_LINE 200
+#endif
+
+/* Nonzero to allow heap line buffer to grow via realloc(), zero for a
+   fixed-size buffer of INI_MAX_LINE bytes. Only applies if INI_USE_STACK is
+   zero. */
+#ifndef INI_ALLOW_REALLOC
+#define INI_ALLOW_REALLOC 0
+#endif
+
+/* Initial size in bytes for heap line buffer. Only applies if INI_USE_STACK
+   is zero. */
+#ifndef INI_INITIAL_ALLOC
+#define INI_INITIAL_ALLOC 200
+#endif
+
+/* Stop parsing on first error (default is to keep parsing). */
+#ifndef INI_STOP_ON_FIRST_ERROR
+#define INI_STOP_ON_FIRST_ERROR 0
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __INI_H__ */

stratosphere/set_mitm/source/setmitm_main.cpp

@@ -24,13 +24,14 @@
 #include <stratosphere.hpp>
 
 #include "setsys_mitm_service.hpp"
+#include "setsys_settings_items.hpp"
 
 extern "C" {
     extern u32 __start__;
 
     u32 __nx_applet_type = AppletType_None;
 
-    #define INNER_HEAP_SIZE 0x20000
+    #define INNER_HEAP_SIZE 0x40000
     size_t nx_inner_heap_size = INNER_HEAP_SIZE;
     char   nx_inner_heap[INNER_HEAP_SIZE];
     
@@ -81,6 +82,9 @@ int main(int argc, char **argv)
 {
     consoleDebugInit(debugDevice_SVC);
     
+    /* Load settings from SD card. */
+    SettingsItemManager::RefreshConfiguration();
+        
     /* TODO: What's a good timeout value to use here? */
     auto server_manager = new SetMitmManager(1);
         

stratosphere/set_mitm/source/setsys_mitm_service.cpp

@@ -19,6 +19,7 @@
 #include <switch.h>
 #include "setsys_mitm_service.hpp"
 #include "setsys_firmware_version.hpp"
+#include "setsys_settings_items.hpp"
 
 void SetSysMitmService::PostProcess(IMitmServiceObject *obj, IpcResponseContext *ctx) {
     /* No commands need postprocessing. */    
@@ -44,6 +45,16 @@ Result SetSysMitmService::GetSettingsItemValueSize(Out<u64> out_size, InPointer<
     char name[SET_MAX_NAME_SIZE] = {0};
     char key[SET_MAX_NAME_SIZE] = {0};
     
+    Result rc = SettingsItemManager::ValidateName(in_name.pointer);
+    if (R_FAILED(rc)) {
+        return rc;
+    }
+    
+    rc = SettingsItemManager::ValidateKey(in_key.pointer);
+    if (R_FAILED(rc)) {
+        return rc;
+    }
+    
     if (in_name.num_elements < SET_MAX_NAME_SIZE) {
         strncpy(name, in_name.pointer, in_name.num_elements);
     } else {
@@ -56,13 +67,32 @@ Result SetSysMitmService::GetSettingsItemValueSize(Out<u64> out_size, InPointer<
         strncpy(key, in_key.pointer, SET_MAX_NAME_SIZE-1);
     }
     
-    return setsysGetSettingsItemValueSize(name, key, out_size.GetPointer());
+    rc = SettingsItemManager::GetValueSize(name, key, out_size.GetPointer());
+    if (R_FAILED(rc)) {
+        rc = setsysGetSettingsItemValueSize(name, key, out_size.GetPointer());
+    }
+
+    return rc;
 }
 
 Result SetSysMitmService::GetSettingsItemValue(Out<u64> out_size, OutBuffer<u8> out_value, InPointer<char> in_name, InPointer<char> in_key) {
     char name[SET_MAX_NAME_SIZE] = {0};
     char key[SET_MAX_NAME_SIZE] = {0};
     
+    Result rc = SettingsItemManager::ValidateName(in_name.pointer);
+    if (R_FAILED(rc)) {
+        return rc;
+    }
+    
+    rc = SettingsItemManager::ValidateKey(in_key.pointer);
+    if (R_FAILED(rc)) {
+        return rc;
+    }
+    
+    if (out_value.buffer == nullptr) {
+        return 0x19A69;
+    }
+    
     if (in_name.num_elements < SET_MAX_NAME_SIZE) {
         strncpy(name, in_name.pointer, in_name.num_elements);
     } else {
@@ -75,7 +105,13 @@ Result SetSysMitmService::GetSettingsItemValue(Out<u64> out_size, OutBuffer<u8>
         strncpy(key, in_key.pointer, SET_MAX_NAME_SIZE-1);
     }
     
-    return setsysGetSettingsItemValue(name, key, out_value.buffer, out_value.num_elements);
+    rc = SettingsItemManager::GetValue(name, key, out_value.buffer, out_value.num_elements, out_size.GetPointer());
+    
+    if (R_FAILED(rc)) {
+        rc = setsysGetSettingsItemValueFwd(this->forward_service.get(), name, key, out_value.buffer, out_value.num_elements, out_size.GetPointer());
+    }
+
+    return rc;
 }
 
 Result SetSysMitmService::GetEdid(OutPointerWithServerSize<SetSysEdid, 0x1> out) {

stratosphere/set_mitm/source/setsys_settings_items.cpp

@@ -0,0 +1,305 @@
+/*
+ * Copyright (c) 2018 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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 <http://www.gnu.org/licenses/>.
+ */
+
+#include <mutex>
+#include <algorithm>
+#include <map>
+#include <string>
+#include <utility>
+#include <switch.h>
+#include <strings.h>
+#include <ctype.h>
+
+#include "setsys_settings_items.hpp"
+#include "ini.h"
+
+struct SettingsItemValue {
+    size_t size;
+    u8 *data;
+};
+
+std::map<std::string, SettingsItemValue> g_settings_items;
+
+static bool g_threw_fatal = false;
+static HosThread g_fatal_thread;
+
+static void FatalThreadFunc(void *arg) {
+    Result rc = (Result)((uintptr_t)arg);
+    fatalSimple(rc);
+}
+
+static bool IsCorrectFormat(const char *str, size_t len) {
+    if (len > 0 && str[len - 1] == '.') {
+        return false;
+    }
+
+    for (size_t i = 0; i < len; i++) {
+        const char c = *(str++);
+
+        if ('a' <= c && c <= 'z') {
+            continue;
+        }
+
+        if ('0' <= c && c <= '9') {
+            continue;
+        }
+
+        if (c == '-' || c == '.' || c == '_') {
+            continue;
+        }
+
+        return false;
+    }
+
+    return true;
+}
+
+Result SettingsItemManager::ValidateName(const char *name, size_t max_size) {
+    if (name == nullptr) {
+        return 0x19269;
+    }
+    
+    const size_t name_len = strnlen(name, std::min(max_size, MaxNameLength + 1));
+    if (name_len == 0) {
+        return 0x1BA69;
+    } else if (name_len > MaxNameLength) {
+        return 0x1E269;
+    }
+    
+    if (!IsCorrectFormat(name, name_len)) {
+        return 0x20A69;
+    }
+    
+    return 0x0;
+}
+
+Result SettingsItemManager::ValidateName(const char *name) {
+    return ValidateName(name, MaxNameLength + 1);
+}
+
+Result SettingsItemManager::ValidateKey(const char *key, size_t max_size) {
+    if (key == nullptr) {
+        return 0x19469;
+    }
+    
+    const size_t key_len = strnlen(key, std::min(max_size, MaxKeyLength + 1));
+    if (key_len == 0) {
+        return 0x1BC69;
+    } else if (key_len > MaxKeyLength) {
+        return 0x1E469;
+    }
+    
+    if (!IsCorrectFormat(key, key_len)) {
+        return 0x20C69;
+    }
+    
+    return 0x0;
+}
+
+Result SettingsItemManager::ValidateKey(const char *key) {
+    return ValidateKey(key, MaxKeyLength + 1);
+}
+
+static bool IsHexadecimal(const char *str) {
+    while (*str) {
+        if (isxdigit(*str)) {
+            str++;
+        } else {
+            return false;
+        }
+    }
+    return true;
+}
+
+static char hextoi(char c) {
+    if ('a' <= c && c <= 'f') return c - 'a' + 0xA;
+    if ('A' <= c && c <= 'F') return c - 'A' + 0xA;
+    if ('0' <= c && c <= '9') return c - '0';
+    return 0;
+}
+
+static Result ParseValue(const char *name, const char *key, const char *val_tup) {
+    const char *delimiter = strchr(val_tup, '!');
+    const char *value_str = delimiter + 1;
+    const char *type = val_tup;
+    
+    if (delimiter == NULL) {
+        return 0x20E69;
+    }
+    
+    while (isspace(*type) && type != delimiter) {
+        type++;
+    }
+    
+    size_t type_len = delimiter - type;
+    size_t value_len = strlen(value_str);
+    if (delimiter == NULL || value_len == 0 || type_len == 0) {
+        return 0x20E69;
+    }
+    
+    std::string kv = std::string(name) + "!" + std::string(key);
+    SettingsItemValue value;
+    
+    if (strncasecmp(type, "str", type_len) == 0 || strncasecmp(type, "string", type_len) == 0) {
+        /* String */
+        value.size = value_len + 1;
+        value.data = reinterpret_cast<u8 *>(strdup(value_str));
+        if (value.data == nullptr) {
+            return 0xCC69;
+        }
+    } else if (strncasecmp(type, "hex", type_len) == 0 || strncasecmp(type, "bytes", type_len) == 0) {
+        /* hex */
+        if (value_len % 2 || !IsHexadecimal(value_str)) {
+            return 0x20E69;
+        }
+        value.size = value_len / 2;
+        u8 *data = reinterpret_cast<u8 *>(malloc(value.size));
+        if (data == nullptr) {
+            return 0xCC69;
+        }
+        
+        memset(data, 0, value.size);
+        for (size_t i = 0; i < value_len; i++) {
+            data[i >> 1] |= hextoi(value_str[i]) << (4 * (i & 1)); 
+        }
+        
+        value.data = data;
+    }  else if (strncasecmp(type, "u8", type_len) == 0) {
+        /* u8 */
+        value.size = sizeof(u8);
+        u8 *data = reinterpret_cast<u8 *>(malloc(value.size));
+        if (data == nullptr) {
+            return 0xCC69;
+        }
+        *data = (u8)(strtoul(value_str, nullptr, 0));
+        value.data = reinterpret_cast<u8 *>(data);
+    } else if (strncasecmp(type, "u16", type_len) == 0) {
+        /* u16 */
+        value.size = sizeof(u16);
+        u16 *data = reinterpret_cast<u16 *>(malloc(value.size));
+        if (data == nullptr) {
+            return 0xCC69;
+        }
+        *data = (u16)(strtoul(value_str, nullptr, 0));
+        value.data = reinterpret_cast<u8 *>(data);
+    } else if (strncasecmp(type, "u32", type_len) == 0) {
+        /* u32 */
+        value.size = sizeof(u32);
+        u32 *data = reinterpret_cast<u32 *>(malloc(value.size));
+        if (data == nullptr) {
+            return 0xCC69;
+        }
+        *data = (u32)(strtoul(value_str, nullptr, 0));
+        value.data = reinterpret_cast<u8 *>(data);
+    } else if (strncasecmp(type, "u64", type_len) == 0) {
+        /* u64 */
+        value.size = sizeof(u64);
+        u64 *data = reinterpret_cast<u64 *>(malloc(value.size));
+        if (data == nullptr) {
+            return 0xCC69;
+        }
+        *data = (u64)(strtoul(value_str, nullptr, 0));
+        value.data = reinterpret_cast<u8 *>(data);
+    } else {
+        return 0x20E69;
+    }
+    
+    g_settings_items[kv] = value;
+    return 0x0;
+}
+
+static int SettingsItemIniHandler(void *user, const char *name, const char *key, const char *value) {
+    Result rc = *(reinterpret_cast<Result *>(user));
+    ON_SCOPE_EXIT { *(reinterpret_cast<Result *>(user)) = rc; };
+    
+    if (R_SUCCEEDED(rc)) {
+        rc = SettingsItemManager::ValidateName(name);
+    }
+    if (R_SUCCEEDED(rc)) {
+        rc = SettingsItemManager::ValidateKey(name);
+    }
+    if (R_SUCCEEDED(rc)) {
+        rc = ParseValue(name, key, value);
+    }
+    
+    return R_SUCCEEDED(rc) ? 1 : 0;
+}
+
+void SettingsItemManager::RefreshConfiguration() {
+    /* Mount the SD Card. */
+    Result rc = fsInitialize();
+    if (R_SUCCEEDED(rc)) {
+        rc = fsdevMountSdmc();
+    }
+    if (R_FAILED(rc)) {
+        fatalSimple(MAKERESULT(Module_Libnx, LibnxError_InitFail_FS));
+    }
+    
+    /* When we're done, we should stop talking to FS. */
+    ON_SCOPE_EXIT {
+        fsdevUnmountAll();
+        fsExit();
+    };
+    
+    /* Open, parse config file. */
+    {
+        FILE *config = fopen("sdmc:/atmosphere/system_settings.ini", "r");
+        if (config == NULL) {
+            return;
+        }
+        ON_SCOPE_EXIT { fclose(config); };
+        
+        Result rc = 0;
+        ini_parse_file(config, SettingsItemIniHandler, &rc);
+        
+        /* Report error if we encountered one. */
+        if (R_FAILED(rc) && !g_threw_fatal) {
+            g_threw_fatal = true;
+            g_fatal_thread.Initialize(&FatalThreadFunc, reinterpret_cast<void *>(rc), 0x1000, 49);
+            g_fatal_thread.Start();
+        }
+    }
+}
+
+Result SettingsItemManager::GetValueSize(const char *name, const char *key, u64 *out_size) {
+    std::string kv = std::string(name) + "!" + std::string(key);
+    
+    auto it = g_settings_items.find(kv);
+    if (it == g_settings_items.end()) {
+        return 0x1669;
+    }
+    
+    *out_size = it->second.size;
+    return 0x0;
+}
+
+Result SettingsItemManager::GetValue(const char *name, const char *key, void *out, size_t max_size, u64 *out_size) {
+    std::string kv = std::string(name) + "!" + std::string(key);
+    
+    auto it = g_settings_items.find(kv);
+    if (it == g_settings_items.end()) {
+        return 0x1669;
+    }
+    
+    size_t copy_size = it->second.size;
+    if (max_size < copy_size) {
+        copy_size = max_size;
+    }
+    *out_size = copy_size;
+    
+    memcpy(out, it->second.data, copy_size);
+    return 0x0;
+}

stratosphere/set_mitm/source/setsys_settings_items.hpp

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2018 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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 <http://www.gnu.org/licenses/>.
+ */
+ 
+#pragma once
+#include <switch.h>
+#include <stratosphere.hpp>
+
+
+class SettingsItemManager {
+    public:
+        static constexpr size_t MaxNameLength = 64; 
+        static constexpr size_t MaxKeyLength = 64;
+    public:
+        static Result ValidateName(const char *name, size_t max_size);
+        static Result ValidateName(const char *name);
+        
+        static Result ValidateKey(const char *key, size_t max_size);
+        static Result ValidateKey(const char *key);
+
+        static void RefreshConfiguration();
+        static Result GetValueSize(const char *name, const char *key, u64 *out_size);
+        static Result GetValue(const char *name, const char *key, void *out, size_t max_size, u64 *out_size);
+};

stratosphere/set_mitm/source/setsys_shim.c

@@ -14,6 +14,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <string.h>
 #include <switch.h>
 #include "setsys_shim.h"
 
@@ -50,3 +51,50 @@ Result setsysGetEdidFwd(Service* s, SetSysEdid* out) {
 
     return rc;
 }
+
+Result setsysGetSettingsItemValueFwd(Service *s, const char *name, const char *item_key, void *value_out, size_t value_out_size, u64 *size_out) {
+    char send_name[SET_MAX_NAME_SIZE];
+    char send_item_key[SET_MAX_NAME_SIZE];
+    
+    memset(send_name, 0, SET_MAX_NAME_SIZE);
+    memset(send_item_key, 0, SET_MAX_NAME_SIZE);
+    strncpy(send_name, name, SET_MAX_NAME_SIZE-1);
+    strncpy(send_item_key, item_key, SET_MAX_NAME_SIZE-1);
+
+    IpcCommand c;
+    ipcInitialize(&c);
+    ipcAddSendStatic(&c, send_name, SET_MAX_NAME_SIZE, 0);
+    ipcAddSendStatic(&c, send_item_key, SET_MAX_NAME_SIZE, 0);
+    ipcAddRecvBuffer(&c, value_out, value_out_size, 0);
+
+    struct {
+        u64 magic;
+        u64 cmd_id;
+    } *raw;
+
+    raw = serviceIpcPrepareHeader(s, &c, sizeof(*raw));
+
+    raw->magic = SFCI_MAGIC;
+    raw->cmd_id = 38;
+
+    Result rc = serviceIpcDispatch(s);
+
+    if (R_SUCCEEDED(rc)) {
+        IpcParsedCommand r;
+        struct {
+            u64 magic;
+            u64 result;
+            u64 size_out;
+        } *resp;
+
+        serviceIpcParse(s, &r, sizeof(*resp));
+        resp = r.Raw;
+
+        rc = resp->result;
+        if (R_SUCCEEDED(rc)) {
+            *size_out = resp->size_out;
+        }
+    }
+
+    return rc;
+}

stratosphere/set_mitm/source/setsys_shim.h

@@ -17,6 +17,7 @@ typedef struct {
 
 /* Command forwarders. */
 Result setsysGetEdidFwd(Service* s, SetSysEdid* out);
+Result setsysGetSettingsItemValueFwd(Service* s, const char *name, const char *item_key, void *value_out, size_t value_out_size, u64 *size_out);
 
 #ifdef __cplusplus
 }