Merge pull request #241 from linkmauve/better-loader

Improve the loader a bit

8 files changed, 344 insertions, 352 deletions

diff --git a/src/core/loader/3dsx.cpp b/src/core/loader/3dsx.cpp
index 4d072871a..958dd03e8 100644
--- a/src/core/loader/3dsx.cpp
+++ b/src/core/loader/3dsx.cpp
@@ -13,11 +13,9 @@
 
 #include "3dsx.h"
 
-
 namespace Loader {
 
-
-/** 
+/**
  * File layout:
  * - File header
  * - Code, rodata and data relocation table headers
@@ -46,7 +44,6 @@ enum THREEDSX_Error {
 static const u32 RELOCBUFSIZE = 512;
 
 // File header
-static const u32 THREEDSX_MAGIC = 0x58534433; // '3DSX'
 #pragma pack(1)
 struct THREEDSX_Header
 {
@@ -64,9 +61,9 @@ struct THREEDSX_Header
 struct THREEDSX_RelocHdr
 {
     // # of absolute relocations (that is, fix address to post-relocation memory layout)
-    u32 cross_segment_absolute; 
+    u32 cross_segment_absolute;
     // # of cross-segment relative relocations (that is, 32bit signed offsets that need to be patched)
-    u32 cross_segment_relative; 
+    u32 cross_segment_relative;
     // more?
 
     // Relocations are written in this order:
@@ -88,12 +85,7 @@ struct THREEloadinfo
     u32 seg_sizes[3];
 };
 
-class THREEDSXReader {
-public:
-     static int Load3DSXFile(const std::string& filename, u32 base_addr);
-};
-
-static u32 TranslateAddr(u32 addr, THREEloadinfo *loadinfo, u32* offsets)
+static u32 TranslateAddr(u32 addr, const THREEloadinfo *loadinfo, u32* offsets)
 {
     if (addr < offsets[0])
         return loadinfo->seg_addrs[0] + addr;
@@ -102,12 +94,14 @@ static u32 TranslateAddr(u32 addr, THREEloadinfo *loadinfo, u32* offsets)
     return loadinfo->seg_addrs[2] + addr - offsets[1];
 }
 
-int THREEDSXReader::Load3DSXFile(const std::string& filename, u32 base_addr)
+static THREEDSX_Error Load3DSXFile(FileUtil::IOFile& file, u32 base_addr)
 {
-    FileUtil::IOFile file(filename, "rb");
-    if (!file.IsOpen()) {
+    if (!file.IsOpen())
         return ERROR_FILE;
-    }
+
+    // Reset read pointer in case this file has been read before.
+    file.Seek(0, SEEK_SET);
+
     THREEDSX_Header hdr;
     if (file.ReadBytes(&hdr, sizeof(hdr)) != sizeof(hdr))
         return ERROR_READ;
@@ -136,8 +130,9 @@ int THREEDSXReader::Load3DSXFile(const std::string& filename, u32 base_addr)
     // Read the relocation headers
     u32* relocs = (u32*)(loadinfo.seg_ptrs[2] + hdr.data_seg_size);
 
-    for (u32 current_segment = 0; current_segment < 3; current_segment++) {
-        if (file.ReadBytes(&relocs[current_segment*n_reloc_tables], n_reloc_tables * 4) != n_reloc_tables * 4)
+    for (unsigned current_segment : {0, 1, 2}) {
+        size_t size = n_reloc_tables * 4;
+        if (file.ReadBytes(&relocs[current_segment * n_reloc_tables], size) != size)
             return ERROR_READ;
     }
 
@@ -153,9 +148,9 @@ int THREEDSXReader::Load3DSXFile(const std::string& filename, u32 base_addr)
     memset((char*)loadinfo.seg_ptrs[2] + hdr.data_seg_size - hdr.bss_size, 0, hdr.bss_size);
 
     // Relocate the segments
-    for (u32 current_segment = 0; current_segment < 3; current_segment++) {
-        for (u32 current_segment_reloc_table = 0; current_segment_reloc_table < n_reloc_tables; current_segment_reloc_table++) {
-            u32 n_relocs = relocs[current_segment*n_reloc_tables + current_segment_reloc_table];
+    for (unsigned current_segment : {0, 1, 2}) {
+        for (unsigned current_segment_reloc_table = 0; current_segment_reloc_table < n_reloc_tables; current_segment_reloc_table++) {
+            u32 n_relocs = relocs[current_segment * n_reloc_tables + current_segment_reloc_table];
             if (current_segment_reloc_table >= 2) {
                 // We are not using this table - ignore it because we don't know what it dose
                 file.Seek(n_relocs*sizeof(THREEDSX_Reloc), SEEK_CUR);
@@ -164,29 +159,35 @@ int THREEDSXReader::Load3DSXFile(const std::string& filename, u32 base_addr)
             static THREEDSX_Reloc reloc_table[RELOCBUFSIZE];
 
             u32* pos = (u32*)loadinfo.seg_ptrs[current_segment];
-            u32* end_pos = pos + (loadinfo.seg_sizes[current_segment] / 4);
+            const u32* end_pos = pos + (loadinfo.seg_sizes[current_segment] / 4);
 
             while (n_relocs) {
                 u32 remaining = std::min(RELOCBUFSIZE, n_relocs);
                 n_relocs -= remaining;
 
-                if (file.ReadBytes(reloc_table, remaining*sizeof(THREEDSX_Reloc)) != remaining*sizeof(THREEDSX_Reloc))
+                if (file.ReadBytes(reloc_table, remaining * sizeof(THREEDSX_Reloc)) != remaining * sizeof(THREEDSX_Reloc))
                     return ERROR_READ;
 
-                for (u32 current_inprogress = 0; current_inprogress < remaining && pos < end_pos; current_inprogress++) {
-                    LOG_TRACE(Loader, "(t=%d,skip=%u,patch=%u)\n",
-                        current_segment_reloc_table, (u32)reloc_table[current_inprogress].skip, (u32)reloc_table[current_inprogress].patch);
-                    pos += reloc_table[current_inprogress].skip;
-                    s32 num_patches = reloc_table[current_inprogress].patch;
+                for (unsigned current_inprogress = 0; current_inprogress < remaining && pos < end_pos; current_inprogress++) {
+                    const auto& table = reloc_table[current_inprogress];
+                    LOG_TRACE(Loader, "(t=%d,skip=%u,patch=%u)\n", current_segment_reloc_table,
+                              (u32)table.skip, (u32)table.patch);
+                    pos += table.skip;
+                    s32 num_patches = table.patch;
                     while (0 < num_patches && pos < end_pos) {
                         u32 in_addr = (char*)pos - (char*)&all_mem[0];
                         u32 addr = TranslateAddr(*pos, &loadinfo, offsets);
                         LOG_TRACE(Loader, "Patching %08X <-- rel(%08X,%d) (%08X)\n",
-                            base_addr + in_addr, addr, current_segment_reloc_table, *pos);
+                                  base_addr + in_addr, addr, current_segment_reloc_table, *pos);
                         switch (current_segment_reloc_table) {
-                        case 0: *pos = (addr); break;
-                        case 1: *pos = (addr - in_addr); break;
-                        default: break; //this should never happen
+                        case 0:
+                            *pos = (addr);
+                            break;
+                        case 1:
+                            *pos = (addr - in_addr);
+                            break;
+                        default:
+                            break; //this should never happen
                         }
                         pos++;
                         num_patches--;
@@ -207,28 +208,30 @@ int THREEDSXReader::Load3DSXFile(const std::string& filename, u32 base_addr)
     return ERROR_NONE;
 }
 
-    /// AppLoader_DSX constructor
-    AppLoader_THREEDSX::AppLoader_THREEDSX(const std::string& filename) : filename(filename) {
-    }
+FileType AppLoader_THREEDSX::IdentifyType(FileUtil::IOFile& file) {
+    u32 magic;
+    file.Seek(0, SEEK_SET);
+    if (1 != file.ReadArray<u32>(&magic, 1))
+        return FileType::Error;
 
-    /// AppLoader_DSX destructor
-    AppLoader_THREEDSX::~AppLoader_THREEDSX() {
-    }
+    if (MakeMagic('3', 'D', 'S', 'X') == magic)
+        return FileType::THREEDSX;
 
-    /**
-    * Loads a 3DSX file
-    * @return Success on success, otherwise Error
-    */
-    ResultStatus AppLoader_THREEDSX::Load() {
-        LOG_INFO(Loader, "Loading 3DSX file %s...", filename.c_str());
-        FileUtil::IOFile file(filename, "rb");
-        if (file.IsOpen()) {
-            THREEDSXReader::Load3DSXFile(filename, 0x00100000);
-            Kernel::LoadExec(0x00100000);
-        } else {
-            return ResultStatus::Error;
-        }
-        return ResultStatus::Success;
-    }
+    return FileType::Error;
+}
+
+ResultStatus AppLoader_THREEDSX::Load() {
+    if (is_loaded)
+        return ResultStatus::ErrorAlreadyLoaded;
+
+    if (!file->IsOpen())
+        return ResultStatus::Error;
+
+    Load3DSXFile(*file, 0x00100000);
+    Kernel::LoadExec(0x00100000);
+
+    is_loaded = true;
+    return ResultStatus::Success;
+}
 
 } // namespace Loader
diff --git a/src/core/loader/3dsx.h b/src/core/loader/3dsx.h
index da8836662..a11667400 100644
--- a/src/core/loader/3dsx.h
+++ b/src/core/loader/3dsx.h
@@ -15,18 +15,20 @@ namespace Loader {
 /// Loads an 3DSX file
 class AppLoader_THREEDSX final : public AppLoader {
 public:
-    AppLoader_THREEDSX(const std::string& filename);
-    ~AppLoader_THREEDSX() override;
+    AppLoader_THREEDSX(std::unique_ptr<FileUtil::IOFile>&& file) : AppLoader(std::move(file)) { }
+
+    /**
+     * Returns the type of the file
+     * @param file FileUtil::IOFile open file
+     * @return FileType found, or FileType::Error if this loader doesn't know it
+     */
+    static FileType IdentifyType(FileUtil::IOFile& file);
 
     /**
      * Load the bootable file
      * @return ResultStatus result of function
      */
     ResultStatus Load() override;
-
-private:
-    std::string filename;
-    bool        is_loaded;
 };
 
 } // namespace Loader
diff --git a/src/core/loader/elf.cpp b/src/core/loader/elf.cpp
index 3ca60c072..e7e5df408 100644
--- a/src/core/loader/elf.cpp
+++ b/src/core/loader/elf.cpp
@@ -18,25 +18,25 @@
 
 // File type
 enum ElfType {
-    ET_NONE = 0,
-    ET_REL = 1,
-    ET_EXEC = 2,
-    ET_DYN = 3,
-    ET_CORE = 4,
+    ET_NONE   = 0,
+    ET_REL    = 1,
+    ET_EXEC   = 2,
+    ET_DYN    = 3,
+    ET_CORE   = 4,
     ET_LOPROC = 0xFF00,
     ET_HIPROC = 0xFFFF,
 };
 
 // Machine/Architecture
 enum ElfMachine {
-    EM_NONE = 0,
-    EM_M32 = 1,
+    EM_NONE  = 0,
+    EM_M32   = 1,
     EM_SPARC = 2,
-    EM_386 = 3,
-    EM_68K = 4,
-    EM_88K = 5,
-    EM_860 = 7,
-    EM_MIPS = 8
+    EM_386   = 3,
+    EM_68K   = 4,
+    EM_88K   = 5,
+    EM_860   = 7,
+    EM_MIPS  = 8
 };
 
 // File version
@@ -54,12 +54,6 @@ enum ElfMachine {
 #define EI_PAD     7
 #define EI_NIDENT 16
 
-// Magic number
-#define ELFMAG0 0x7F
-#define ELFMAG1  'E'
-#define ELFMAG2  'L'
-#define ELFMAG3  'F'
-
 // Sections constants
 
 // Section types
@@ -83,10 +77,10 @@ enum ElfMachine {
 // Section flags
 enum ElfSectionFlags
 {
-    SHF_WRITE = 0x1,
-    SHF_ALLOC = 0x2,
+    SHF_WRITE     = 0x1,
+    SHF_ALLOC     = 0x2,
     SHF_EXECINSTR = 0x4,
-    SHF_MASKPROC = 0xF0000000,
+    SHF_MASKPROC  = 0xF0000000,
 };
 
 // Segment types
@@ -100,11 +94,11 @@ enum ElfSectionFlags
 #define PT_LOPROC  0x70000000
 #define PT_HIPROC  0x7FFFFFFF
 
-typedef unsigned int  Elf32_Addr;
+typedef unsigned int   Elf32_Addr;
 typedef unsigned short Elf32_Half;
-typedef unsigned int  Elf32_Off;
-typedef signed   int  Elf32_Sword;
-typedef unsigned int  Elf32_Word;
+typedef unsigned int   Elf32_Off;
+typedef signed   int   Elf32_Sword;
+typedef unsigned int   Elf32_Word;
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 // ELF file header
@@ -188,7 +182,6 @@ private:
 
 public:
     ElfReader(void *ptr);
-    ~ElfReader() { }
 
     u32 Read32(int off) const { return base32[off >> 2]; }
 
@@ -197,7 +190,7 @@ public:
     ElfMachine GetMachine() const { return (ElfMachine)(header->e_machine); }
     u32 GetEntryPoint() const { return entryPoint; }
     u32 GetFlags() const { return (u32)(header->e_flags); }
-    bool LoadInto(u32 vaddr);
+    void LoadInto(u32 vaddr);
     bool LoadSymbols();
 
     int GetNumSegments() const { return (int)(header->e_phnum); }
@@ -229,11 +222,11 @@ public:
 
 ElfReader::ElfReader(void *ptr) {
     base = (char*)ptr;
-    base32 = (u32 *)ptr;
+    base32 = (u32*)ptr;
     header = (Elf32_Ehdr*)ptr;
 
-    segments = (Elf32_Phdr *)(base + header->e_phoff);
-    sections = (Elf32_Shdr *)(base + header->e_shoff);
+    segments = (Elf32_Phdr*)(base + header->e_phoff);
+    sections = (Elf32_Shdr*)(base + header->e_shoff);
 
     entryPoint = header->e_entry;
 
@@ -245,7 +238,7 @@ const char *ElfReader::GetSectionName(int section) const {
         return nullptr;
 
     int name_offset = sections[section].sh_name;
-    char *ptr = (char*)GetSectionDataPtr(header->e_shstrndx);
+    const char* ptr = (char*)GetSectionDataPtr(header->e_shstrndx);
 
     if (ptr)
         return ptr + name_offset;
@@ -253,7 +246,7 @@ const char *ElfReader::GetSectionName(int section) const {
     return nullptr;
 }
 
-bool ElfReader::LoadInto(u32 vaddr) {
+void ElfReader::LoadInto(u32 vaddr) {
     LOG_DEBUG(Loader, "String section: %i", header->e_shstrndx);
 
     // Should we relocate?
@@ -271,20 +264,19 @@ bool ElfReader::LoadInto(u32 vaddr) {
     u32 segment_addr[32];
     u32 base_addr = relocate ? vaddr : 0;
 
-    for (int i = 0; i < header->e_phnum; i++) {
-        Elf32_Phdr *p = segments + i;
+    for (unsigned i = 0; i < header->e_phnum; i++) {
+        Elf32_Phdr* p = segments + i;
         LOG_DEBUG(Loader, "Type: %i Vaddr: %08x Filesz: %i Memsz: %i ", p->p_type, p->p_vaddr,
-            p->p_filesz, p->p_memsz);
+                  p->p_filesz, p->p_memsz);
 
         if (p->p_type == PT_LOAD) {
             segment_addr[i] = base_addr + p->p_vaddr;
             memcpy(Memory::GetPointer(segment_addr[i]), GetSegmentPtr(i), p->p_filesz);
             LOG_DEBUG(Loader, "Loadable Segment Copied to %08x, size %08x", segment_addr[i],
-                p->p_memsz);
+                      p->p_memsz);
         }
     }
     LOG_DEBUG(Loader, "Done loading.");
-    return true;
 }
 
 SectionID ElfReader::GetSectionByName(const char *name, int firstSection) const {
@@ -305,9 +297,9 @@ bool ElfReader::LoadSymbols() {
         const char *stringBase = (const char *)GetSectionDataPtr(stringSection);
 
         //We have a symbol table!
-        Elf32_Sym *symtab = (Elf32_Sym *)(GetSectionDataPtr(sec));
+        Elf32_Sym* symtab = (Elf32_Sym *)(GetSectionDataPtr(sec));
         int numSymbols = sections[sec].sh_size / sizeof(Elf32_Sym);
-        for (int sym = 0; sym < numSymbols; sym++) {
+        for (unsigned sym = 0; sym < numSymbols; sym++) {
             int size = symtab[sym].st_size;
             if (size == 0)
                 continue;
@@ -330,40 +322,38 @@ bool ElfReader::LoadSymbols() {
 
 namespace Loader {
 
-/// AppLoader_ELF constructor
-AppLoader_ELF::AppLoader_ELF(const std::string& filename) : is_loaded(false) {
-    this->filename = filename;
-}
+FileType AppLoader_ELF::IdentifyType(FileUtil::IOFile& file) {
+    u32 magic;
+    file.Seek(0, SEEK_SET);
+    if (1 != file.ReadArray<u32>(&magic, 1))
+        return FileType::Error;
+
+    if (MakeMagic('\x7f', 'E', 'L', 'F') == magic)
+        return FileType::ELF;
 
-/// AppLoader_NCCH destructor
-AppLoader_ELF::~AppLoader_ELF() {
+    return FileType::Error;
 }
 
-/**
- * Loads an NCCH file (e.g. from a CCI, or the first NCCH in a CXI)
- * @param error_string Pointer to string to put error message if an error has occurred
- * @todo Move NCSD parsing out of here and create a separate function for loading these
- * @return True on success, otherwise false
- */
 ResultStatus AppLoader_ELF::Load() {
-    LOG_INFO(Loader, "Loading ELF file %s...", filename.c_str());
-
     if (is_loaded)
         return ResultStatus::ErrorAlreadyLoaded;
 
-    FileUtil::IOFile file(filename, "rb");
+    if (!file->IsOpen())
+        return ResultStatus::Error;
 
-    if (file.IsOpen()) {
-        u32 size = (u32)file.GetSize();
-        std::unique_ptr<u8[]> buffer(new u8[size]);
-        file.ReadBytes(&buffer[0], size);
+    // Reset read pointer in case this file has been read before.
+    file->Seek(0, SEEK_SET);
 
-        ElfReader elf_reader(&buffer[0]);
-        elf_reader.LoadInto(0x00100000);
-        Kernel::LoadExec(elf_reader.GetEntryPoint());
-    } else {
+    u32 size = static_cast<u32>(file->GetSize());
+    std::unique_ptr<u8[]> buffer(new u8[size]);
+    if (file->ReadBytes(&buffer[0], size) != size)
         return ResultStatus::Error;
-    }
+
+    ElfReader elf_reader(&buffer[0]);
+    elf_reader.LoadInto(0x00100000);
+    Kernel::LoadExec(elf_reader.GetEntryPoint());
+
+    is_loaded = true;
     return ResultStatus::Success;
 }
 
diff --git a/src/core/loader/elf.h b/src/core/loader/elf.h
index c221cce6d..b6e6651f5 100644
--- a/src/core/loader/elf.h
+++ b/src/core/loader/elf.h
@@ -15,18 +15,20 @@ namespace Loader {
 /// Loads an ELF/AXF file
 class AppLoader_ELF final : public AppLoader {
 public:
-    AppLoader_ELF(const std::string& filename);
-    ~AppLoader_ELF() override;
+    AppLoader_ELF(std::unique_ptr<FileUtil::IOFile>&& file) : AppLoader(std::move(file)) { }
+
+    /**
+     * Returns the type of the file
+     * @param file FileUtil::IOFile open file
+     * @return FileType found, or FileType::Error if this loader doesn't know it
+     */
+    static FileType IdentifyType(FileUtil::IOFile& file);
 
     /**
      * Load the bootable file
      * @return ResultStatus result of function
      */
     ResultStatus Load() override;
-
-private:
-    std::string filename;
-    bool        is_loaded;
 };
 
 } // namespace Loader
diff --git a/src/core/loader/loader.cpp b/src/core/loader/loader.cpp
index 45cf425df..60460292d 100644
--- a/src/core/loader/loader.cpp
+++ b/src/core/loader/loader.cpp
@@ -19,11 +19,32 @@ namespace Loader {
 
 /**
  * Identifies the type of a bootable file
+ * @param file open file
+ * @return FileType of file
+ */
+static FileType IdentifyFile(FileUtil::IOFile& file) {
+    FileType type;
+
+#define CHECK_TYPE(loader) \
+    type = AppLoader_##loader::IdentifyType(file); \
+    if (FileType::Error != type) \
+        return type;
+
+    CHECK_TYPE(THREEDSX)
+    CHECK_TYPE(ELF)
+    CHECK_TYPE(NCCH)
+
+#undef CHECK_TYPE
+
+    return FileType::Unknown;
+}
+
+/**
+ * Guess the type of a bootable file from its extension
  * @param filename String filename of bootable file
- * @todo (ShizZy) this function sucks... make it actually check file contents etc.
  * @return FileType of file
  */
-FileType IdentifyFile(const std::string &filename) {
+static FileType GuessFromFilename(const std::string& filename) {
     if (filename.size() == 0) {
         LOG_ERROR(Loader, "invalid filename %s", filename.c_str());
         return FileType::Error;
@@ -34,47 +55,74 @@ FileType IdentifyFile(const std::string &filename) {
         return FileType::Unknown;
     std::string extension = Common::ToLower(filename.substr(extension_loc));
 
-    // TODO(bunnei): Do actual filetype checking instead of naively checking the extension
-    if (extension == ".elf") {
+    if (extension == ".elf")
         return FileType::ELF;
-    } else if (extension == ".axf") {
+    else if (extension == ".axf")
         return FileType::ELF;
-    } else if (extension == ".cxi") {
+    else if (extension == ".cxi")
         return FileType::CXI;
-    } else if (extension == ".cci") {
+    else if (extension == ".cci")
         return FileType::CCI;
-    } else if (extension == ".bin") {
+    else if (extension == ".bin")
         return FileType::BIN;
-    } else if (extension == ".3ds") {
+    else if (extension == ".3ds")
         return FileType::CCI;
-    } else if (extension == ".3dsx") {
+    else if (extension == ".3dsx")
         return FileType::THREEDSX;
-    }
     return FileType::Unknown;
 }
 
-/**
- * Identifies and loads a bootable file
- * @param filename String filename of bootable file
- * @return ResultStatus result of function
- */
+static const char* GetFileTypeString(FileType type) {
+    switch (type) {
+    case FileType::CCI:
+        return "NCSD";
+    case FileType::CXI:
+        return "NCCH";
+    case FileType::ELF:
+        return "ELF";
+    case FileType::THREEDSX:
+        return "3DSX";
+    case FileType::BIN:
+        return "raw";
+    case FileType::Error:
+    case FileType::Unknown:
+        return "unknown";
+    }
+}
+
 ResultStatus LoadFile(const std::string& filename) {
-    LOG_INFO(Loader, "Loading file %s...", filename.c_str());
+    std::unique_ptr<FileUtil::IOFile> file(new FileUtil::IOFile(filename, "rb"));
+    if (!file->IsOpen()) {
+        LOG_ERROR(Loader, "Failed to load file %s", filename.c_str());
+        return ResultStatus::Error;
+    }
+
+    FileType type = IdentifyFile(*file);
+    FileType filename_type = GuessFromFilename(filename);
+
+    if (type != filename_type) {
+        LOG_WARNING(Loader, "File %s has a different type than its extension.", filename.c_str());
+        if (FileType::Unknown == type)
+            type = filename_type;
+    }
 
-    switch (IdentifyFile(filename)) {
+    LOG_INFO(Loader, "Loading file %s as %s...", filename.c_str(), GetFileTypeString(type));
+
+    switch (type) {
 
     //3DSX file format...
     case FileType::THREEDSX:
-        return AppLoader_THREEDSX(filename).Load();
+        return AppLoader_THREEDSX(std::move(file)).Load();
 
     // Standard ELF file format...
     case FileType::ELF:
-        return AppLoader_ELF(filename).Load();
+        return AppLoader_ELF(std::move(file)).Load();
 
     // NCCH/NCSD container formats...
     case FileType::CXI:
-    case FileType::CCI: {
-        AppLoader_NCCH app_loader(filename);
+    case FileType::CCI:
+    {
+        AppLoader_NCCH app_loader(std::move(file));
 
         // Load application and RomFS
         if (ResultStatus::Success == app_loader.Load()) {
@@ -88,16 +136,11 @@ ResultStatus LoadFile(const std::string& filename) {
     // Raw BIN file format...
     case FileType::BIN:
     {
-        LOG_INFO(Loader, "Loading BIN file %s...", filename.c_str());
-
-        FileUtil::IOFile file(filename, "rb");
-
-        if (file.IsOpen()) {
-            file.ReadBytes(Memory::GetPointer(Memory::EXEFS_CODE_VADDR), (size_t)file.GetSize());
-            Kernel::LoadExec(Memory::EXEFS_CODE_VADDR);
-        } else {
+        size_t size = (size_t)file->GetSize();
+        if (file->ReadBytes(Memory::GetPointer(Memory::EXEFS_CODE_VADDR), size) != size)
             return ResultStatus::Error;
-        }
+
+        Kernel::LoadExec(Memory::EXEFS_CODE_VADDR);
         return ResultStatus::Success;
     }
 
@@ -106,10 +149,11 @@ ResultStatus LoadFile(const std::string& filename) {
 
     // IdentifyFile could know identify file type...
     case FileType::Unknown:
-
-    default:
+    {
+        LOG_CRITICAL(Loader, "File %s is of unknown type.");
         return ResultStatus::ErrorInvalidFormat;
     }
+    }
     return ResultStatus::Error;
 }
 
diff --git a/src/core/loader/loader.h b/src/core/loader/loader.h
index ec5534d41..7456b019b 100644
--- a/src/core/loader/loader.h
+++ b/src/core/loader/loader.h
@@ -7,6 +7,7 @@
 #include <vector>
 
 #include "common/common.h"
+#include "common/file_util.h"
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 // Loader namespace
@@ -37,10 +38,14 @@ enum class ResultStatus {
     ErrorMemoryAllocationFailed,
 };
 
+static u32 MakeMagic(char a, char b, char c, char d) {
+    return a | b << 8 | c << 16 | d << 24;
+}
+
 /// Interface for loading an application
 class AppLoader : NonCopyable {
 public:
-    AppLoader() { }
+    AppLoader(std::unique_ptr<FileUtil::IOFile>&& file) : file(std::move(file)) { }
     virtual ~AppLoader() { }
 
     /**
@@ -93,14 +98,11 @@ public:
     virtual ResultStatus ReadRomFS(std::vector<u8>& buffer) const {
         return ResultStatus::ErrorNotImplemented;
     }
-};
 
-/**
- * Identifies the type of a bootable file
- * @param filename String filename of bootable file
- * @return FileType of file
- */
-FileType IdentifyFile(const std::string &filename);
+protected:
+    std::unique_ptr<FileUtil::IOFile> file;
+    bool                              is_loaded = false;
+};
 
 /**
  * Identifies and loads a bootable file
diff --git a/src/core/loader/ncch.cpp b/src/core/loader/ncch.cpp
index 0dc21699e..aaaa4d650 100644
--- a/src/core/loader/ncch.cpp
+++ b/src/core/loader/ncch.cpp
@@ -4,8 +4,6 @@
 
 #include <memory>
 
-#include "common/file_util.h"
-
 #include "core/loader/ncch.h"
 #include "core/hle/kernel/kernel.h"
 #include "core/mem_map.h"
@@ -15,8 +13,8 @@
 
 namespace Loader {
 
-static const int kMaxSections   = 8;        ///< Maximum number of sections (files) in an ExeFs
-static const int kBlockSize     = 0x200;    ///< Size of ExeFS blocks (in bytes)
+static const int kMaxSections = 8;        ///< Maximum number of sections (files) in an ExeFs
+static const int kBlockSize   = 0x200;    ///< Size of ExeFS blocks (in bytes)
 
 /**
  * Get the decompressed size of an LZSS compressed ExeFS file
@@ -24,7 +22,7 @@ static const int kBlockSize     = 0x200;    ///< Size of ExeFS blocks (in bytes)
  * @param size Size of compressed buffer
  * @return Size of decompressed buffer
  */
-static u32 LZSS_GetDecompressedSize(u8* buffer, u32 size) {
+static u32 LZSS_GetDecompressedSize(const u8* buffer, u32 size) {
     u32 offset_size = *(u32*)(buffer + size - 4);
     return offset_size + size;
 }
@@ -37,9 +35,9 @@ static u32 LZSS_GetDecompressedSize(u8* buffer, u32 size) {
  * @param decompressed_size Size of decompressed buffer
  * @return True on success, otherwise false
  */
-static bool LZSS_Decompress(u8* compressed, u32 compressed_size, u8* decompressed, u32 decompressed_size) {
-    u8* footer = compressed + compressed_size - 8;
-    u32 buffer_top_and_bottom = *(u32*)footer;
+static bool LZSS_Decompress(const u8* compressed, u32 compressed_size, u8* decompressed, u32 decompressed_size) {
+    const u8* footer = compressed + compressed_size - 8;
+    u32 buffer_top_and_bottom = *reinterpret_cast<const u32*>(footer);
     u32 out = decompressed_size;
     u32 index = compressed_size - ((buffer_top_and_bottom >> 24) & 0xFF);
     u32 stop_index = compressed_size - (buffer_top_and_bottom & 0xFFFFFF);
@@ -47,22 +45,21 @@ static bool LZSS_Decompress(u8* compressed, u32 compressed_size, u8* decompresse
     memset(decompressed, 0, decompressed_size);
     memcpy(decompressed, compressed, compressed_size);
 
-    while(index > stop_index) {
+    while (index > stop_index) {
        u8 control = compressed[--index];
 
-        for(u32 i = 0; i < 8; i++) {
-            if(index <= stop_index)
+        for (unsigned i = 0; i < 8; i++) {
+            if (index <= stop_index)
                 break;
-            if(index <= 0)
+            if (index <= 0)
                 break;
-            if(out <= 0)
+            if (out <= 0)
                 break;
 
-            if(control & 0x80) {
+            if (control & 0x80) {
                 // Check if compression is out of bounds
-                if(index < 2) {
+                if (index < 2)
                     return false;
-                }
                 index -= 2;
 
                 u32 segment_offset = compressed[index] | (compressed[index + 1] << 8);
@@ -71,23 +68,21 @@ static bool LZSS_Decompress(u8* compressed, u32 compressed_size, u8* decompresse
                 segment_offset += 2;
 
                 // Check if compression is out of bounds
-                if(out < segment_size) {
+                if (out < segment_size)
                     return false;
-                }
-                for(u32 j = 0; j < segment_size; j++) {
+
+                for (unsigned j = 0; j < segment_size; j++) {
                     // Check if compression is out of bounds
-                    if(out + segment_offset >= decompressed_size) {
+                    if (out + segment_offset >= decompressed_size)
                         return false;
-                    }
 
-                    u8 data  = decompressed[out + segment_offset];
+                    u8 data = decompressed[out + segment_offset];
                     decompressed[--out] = data;
                 }
             } else {
                 // Check if compression is out of bounds
-                if(out < 1) {
+                if (out < 1)
                     return false;
-                }
                 decompressed[--out] = compressed[--index];
             }
             control <<= 1;
@@ -99,24 +94,21 @@ static bool LZSS_Decompress(u8* compressed, u32 compressed_size, u8* decompresse
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 // AppLoader_NCCH class
 
-/// AppLoader_NCCH constructor
-AppLoader_NCCH::AppLoader_NCCH(const std::string& filename) {
-    this->filename = filename;
-    is_loaded = false;
-    is_compressed = false;
-    entry_point = 0;
-    ncch_offset = 0;
-    exefs_offset = 0;
-}
+FileType AppLoader_NCCH::IdentifyType(FileUtil::IOFile& file) {
+    u32 magic;
+    file.Seek(0x100, SEEK_SET);
+    if (1 != file.ReadArray<u32>(&magic, 1))
+        return FileType::Error;
+
+    if (MakeMagic('N', 'C', 'S', 'D') == magic)
+        return FileType::CCI;
 
-/// AppLoader_NCCH destructor
-AppLoader_NCCH::~AppLoader_NCCH() {
+    if (MakeMagic('N', 'C', 'C', 'H') == magic)
+        return FileType::CXI;
+
+    return FileType::Error;
 }
 
-/**
- * Loads .code section into memory for booting
- * @return ResultStatus result of function
- */
 ResultStatus AppLoader_NCCH::LoadExec() const {
     if (!is_loaded)
         return ResultStatus::ErrorNotLoaded;
@@ -130,189 +122,144 @@ ResultStatus AppLoader_NCCH::LoadExec() const {
     return ResultStatus::Error;
 }
 
-/**
- * Reads an application ExeFS section of an NCCH file into AppLoader (e.g. .code, .logo, etc.)
- * @param name Name of section to read out of NCCH file
- * @param buffer Vector to read data into
- * @return ResultStatus result of function
- */
 ResultStatus AppLoader_NCCH::LoadSectionExeFS(const char* name, std::vector<u8>& buffer) const {
+    if (!file->IsOpen())
+        return ResultStatus::Error;
+
+    LOG_DEBUG(Loader, "%d sections:", kMaxSections);
     // Iterate through the ExeFs archive until we find the .code file...
-    FileUtil::IOFile file(filename, "rb");
-    if (file.IsOpen()) {
-        LOG_DEBUG(Loader, "%d sections:", kMaxSections);
-        for (int i = 0; i < kMaxSections; i++) {
-            // Load the specified section...
-            if (strcmp((const char*)exefs_header.section[i].name, name) == 0) {
-                LOG_DEBUG(Loader, "%d - offset: 0x%08X, size: 0x%08X, name: %s", i,
-                        exefs_header.section[i].offset, exefs_header.section[i].size,
-                        exefs_header.section[i].name);
-
-                s64 section_offset = (exefs_header.section[i].offset + exefs_offset +
-                    sizeof(ExeFs_Header)+ncch_offset);
-                file.Seek(section_offset, 0);
-
-                // Section is compressed...
-                if (i == 0 && is_compressed) {
-                    // Read compressed .code section...
-                    std::unique_ptr<u8[]> temp_buffer;
-                    try {
-                        temp_buffer.reset(new u8[exefs_header.section[i].size]);
-                    } catch (std::bad_alloc&) {
-                        return ResultStatus::ErrorMemoryAllocationFailed;
-                    }
-                    file.ReadBytes(&temp_buffer[0], exefs_header.section[i].size);
-
-                    // Decompress .code section...
-                    u32 decompressed_size = LZSS_GetDecompressedSize(&temp_buffer[0],
-                        exefs_header.section[i].size);
-                    buffer.resize(decompressed_size);
-                    if (!LZSS_Decompress(&temp_buffer[0], exefs_header.section[i].size, &buffer[0],
-                        decompressed_size)) {
-                        return ResultStatus::ErrorInvalidFormat;
-                    }
-                    // Section is uncompressed...
-                }
-                else {
-                    buffer.resize(exefs_header.section[i].size);
-                    file.ReadBytes(&buffer[0], exefs_header.section[i].size);
+    for (unsigned section_number = 0; section_number < kMaxSections; section_number++) {
+        const auto& section = exefs_header.section[section_number];
+
+        // Load the specified section...
+        if (strcmp(section.name, name) == 0) {
+            LOG_DEBUG(Loader, "%d - offset: 0x%08X, size: 0x%08X, name: %s", section_number,
+                      section.offset, section.size, section.name);
+
+            s64 section_offset = (section.offset + exefs_offset + sizeof(ExeFs_Header) + ncch_offset);
+            file->Seek(section_offset, SEEK_SET);
+
+            if (is_compressed) {
+                // Section is compressed, read compressed .code section...
+                std::unique_ptr<u8[]> temp_buffer;
+                try {
+                    temp_buffer.reset(new u8[section.size]);
+                } catch (std::bad_alloc&) {
+                    return ResultStatus::ErrorMemoryAllocationFailed;
                 }
-                return ResultStatus::Success;
+
+                if (file->ReadBytes(&temp_buffer[0], section.size) != section.size)
+                    return ResultStatus::Error;
+
+                // Decompress .code section...
+                u32 decompressed_size = LZSS_GetDecompressedSize(&temp_buffer[0], section.size);
+                buffer.resize(decompressed_size);
+                if (!LZSS_Decompress(&temp_buffer[0], section.size, &buffer[0], decompressed_size))
+                    return ResultStatus::ErrorInvalidFormat;
+            } else {
+                // Section is uncompressed...
+                buffer.resize(section.size);
+                if (file->ReadBytes(&buffer[0], section.size) != section.size)
+                    return ResultStatus::Error;
             }
+            return ResultStatus::Success;
         }
-    } else {
-        LOG_ERROR(Loader, "Unable to read file %s!", filename.c_str());
-        return ResultStatus::Error;
     }
     return ResultStatus::ErrorNotUsed;
 }
 
-/**
- * Loads an NCCH file (e.g. from a CCI, or the first NCCH in a CXI)
- * @param error_string Pointer to string to put error message if an error has occurred
- * @todo Move NCSD parsing out of here and create a separate function for loading these
- * @return True on success, otherwise false
- */
 ResultStatus AppLoader_NCCH::Load() {
-    LOG_INFO(Loader, "Loading NCCH file %s...", filename.c_str());
-
     if (is_loaded)
         return ResultStatus::ErrorAlreadyLoaded;
 
-    FileUtil::IOFile file(filename, "rb");
-    if (file.IsOpen()) {
-        file.ReadBytes(&ncch_header, sizeof(NCCH_Header));
+    if (!file->IsOpen())
+        return ResultStatus::Error;
 
-        // Skip NCSD header and load first NCCH (NCSD is just a container of NCCH files)...
-        if (0 == memcmp(&ncch_header.magic, "NCSD", 4)) {
-            LOG_WARNING(Loader, "Only loading the first (bootable) NCCH within the NCSD file!");
-            ncch_offset = 0x4000;
-            file.Seek(ncch_offset, 0);
-            file.ReadBytes(&ncch_header, sizeof(NCCH_Header));
-        }
+    // Reset read pointer in case this file has been read before.
+    file->Seek(0, SEEK_SET);
 
-        // Verify we are loading the correct file type...
-        if (0 != memcmp(&ncch_header.magic, "NCCH", 4))
-            return ResultStatus::ErrorInvalidFormat;
+    if (file->ReadBytes(&ncch_header, sizeof(NCCH_Header)) != sizeof(NCCH_Header))
+        return ResultStatus::Error;
 
-        // Read ExHeader...
+    // Skip NCSD header and load first NCCH (NCSD is just a container of NCCH files)...
+    if (MakeMagic('N', 'C', 'S', 'D') == ncch_header.magic) {
+        LOG_WARNING(Loader, "Only loading the first (bootable) NCCH within the NCSD file!");
+        ncch_offset = 0x4000;
+        file->Seek(ncch_offset, SEEK_SET);
+        file->ReadBytes(&ncch_header, sizeof(NCCH_Header));
+    }
 
-        file.ReadBytes(&exheader_header, sizeof(ExHeader_Header));
+    // Verify we are loading the correct file type...
+    if (MakeMagic('N', 'C', 'C', 'H') != ncch_header.magic)
+        return ResultStatus::ErrorInvalidFormat;
 
-        is_compressed = (exheader_header.codeset_info.flags.flag & 1) == 1;
-        entry_point = exheader_header.codeset_info.text.address;
+    // Read ExHeader...
 
-        LOG_INFO(Loader, "Name:            %s", exheader_header.codeset_info.name);
-        LOG_DEBUG(Loader, "Code compressed: %s", is_compressed ? "yes" : "no");
-        LOG_DEBUG(Loader, "Entry point:     0x%08X", entry_point);
+    if (file->ReadBytes(&exheader_header, sizeof(ExHeader_Header)) != sizeof(ExHeader_Header))
+        return ResultStatus::Error;
 
-        // Read ExeFS...
+    is_compressed = (exheader_header.codeset_info.flags.flag & 1) == 1;
+    entry_point = exheader_header.codeset_info.text.address;
 
-        exefs_offset = ncch_header.exefs_offset * kBlockSize;
-        u32 exefs_size = ncch_header.exefs_size * kBlockSize;
+    LOG_INFO(Loader, "Name:            %s", exheader_header.codeset_info.name);
+    LOG_DEBUG(Loader, "Code compressed: %s", is_compressed ? "yes" : "no");
+    LOG_DEBUG(Loader, "Entry point:     0x%08X", entry_point);
 
-        LOG_DEBUG(Loader, "ExeFS offset:    0x%08X", exefs_offset);
-        LOG_DEBUG(Loader, "ExeFS size:      0x%08X", exefs_size);
+    // Read ExeFS...
 
-        file.Seek(exefs_offset + ncch_offset, 0);
-        file.ReadBytes(&exefs_header, sizeof(ExeFs_Header));
+    exefs_offset = ncch_header.exefs_offset * kBlockSize;
+    u32 exefs_size = ncch_header.exefs_size * kBlockSize;
 
-        is_loaded = true; // Set state to loaded
+    LOG_DEBUG(Loader, "ExeFS offset:    0x%08X", exefs_offset);
+    LOG_DEBUG(Loader, "ExeFS size:      0x%08X", exefs_size);
 
-        LoadExec(); // Load the executable into memory for booting
+    file->Seek(exefs_offset + ncch_offset, SEEK_SET);
+    if (file->ReadBytes(&exefs_header, sizeof(ExeFs_Header)) != sizeof(ExeFs_Header))
+        return ResultStatus::Error;
 
-        return ResultStatus::Success;
-    } else {
-        LOG_ERROR(Loader, "Unable to read file %s!", filename.c_str());
-    }
-    return ResultStatus::Error;
+    is_loaded = true; // Set state to loaded
+
+    return LoadExec(); // Load the executable into memory for booting
 }
 
-/**
- * Get the code (typically .code section) of the application
- * @param buffer Reference to buffer to store data
- * @return ResultStatus result of function
- */
 ResultStatus AppLoader_NCCH::ReadCode(std::vector<u8>& buffer) const {
     return LoadSectionExeFS(".code", buffer);
 }
 
-/**
- * Get the icon (typically icon section) of the application
- * @param buffer Reference to buffer to store data
- * @return ResultStatus result of function
- */
 ResultStatus AppLoader_NCCH::ReadIcon(std::vector<u8>& buffer) const {
     return LoadSectionExeFS("icon", buffer);
 }
 
-/**
- * Get the banner (typically banner section) of the application
- * @param buffer Reference to buffer to store data
- * @return ResultStatus result of function
- */
 ResultStatus AppLoader_NCCH::ReadBanner(std::vector<u8>& buffer) const {
     return LoadSectionExeFS("banner", buffer);
 }
 
-/**
- * Get the logo (typically logo section) of the application
- * @param buffer Reference to buffer to store data
- * @return ResultStatus result of function
- */
 ResultStatus AppLoader_NCCH::ReadLogo(std::vector<u8>& buffer) const {
     return LoadSectionExeFS("logo", buffer);
 }
 
-/**
- * Get the RomFS of the application
- * @param buffer Reference to buffer to store data
- * @return ResultStatus result of function
- */
 ResultStatus AppLoader_NCCH::ReadRomFS(std::vector<u8>& buffer) const {
-    FileUtil::IOFile file(filename, "rb");
-    if (file.IsOpen()) {
-        // Check if the NCCH has a RomFS...
-        if (ncch_header.romfs_offset != 0 && ncch_header.romfs_size != 0) {
-            u32 romfs_offset = ncch_offset + (ncch_header.romfs_offset * kBlockSize) + 0x1000;
-            u32 romfs_size = (ncch_header.romfs_size * kBlockSize) - 0x1000;
+    if (!file->IsOpen())
+        return ResultStatus::Error;
 
-            LOG_DEBUG(Loader, "RomFS offset:    0x%08X", romfs_offset);
-            LOG_DEBUG(Loader, "RomFS size:      0x%08X", romfs_size);
+    // Check if the NCCH has a RomFS...
+    if (ncch_header.romfs_offset != 0 && ncch_header.romfs_size != 0) {
+        u32 romfs_offset = ncch_offset + (ncch_header.romfs_offset * kBlockSize) + 0x1000;
+        u32 romfs_size = (ncch_header.romfs_size * kBlockSize) - 0x1000;
 
-            buffer.resize(romfs_size);
+        LOG_DEBUG(Loader, "RomFS offset:    0x%08X", romfs_offset);
+        LOG_DEBUG(Loader, "RomFS size:      0x%08X", romfs_size);
 
-            file.Seek(romfs_offset, 0);
-            file.ReadBytes(&buffer[0], romfs_size);
+        buffer.resize(romfs_size);
 
-            return ResultStatus::Success;
-        }
-        LOG_DEBUG(Loader, "NCCH has no RomFS");
-        return ResultStatus::ErrorNotUsed;
-    } else {
-        LOG_ERROR(Loader, "Unable to read file %s!", filename.c_str());
+        file->Seek(romfs_offset, SEEK_SET);
+        if (file->ReadBytes(&buffer[0], romfs_size) != romfs_size)
+            return ResultStatus::Error;
+
+        return ResultStatus::Success;
     }
-    return ResultStatus::Error;
+    LOG_DEBUG(Loader, "NCCH has no RomFS");
+    return ResultStatus::ErrorNotUsed;
 }
 
 u64 AppLoader_NCCH::GetProgramId() const {
diff --git a/src/core/loader/ncch.h b/src/core/loader/ncch.h
index fd9258970..9ae2de99f 100644
--- a/src/core/loader/ncch.h
+++ b/src/core/loader/ncch.h
@@ -5,7 +5,6 @@
 #pragma once
 
 #include "common/common.h"
-#include "common/file_util.h"
 
 #include "core/loader/loader.h"
 
@@ -14,7 +13,7 @@
 
 struct NCCH_Header {
     u8 signature[0x100];
-    char magic[4];
+    u32 magic;
     u32 content_size;
     u8 partition_id[8];
     u16 maker_code;
@@ -147,8 +146,14 @@ namespace Loader {
 /// Loads an NCCH file (e.g. from a CCI, or the first NCCH in a CXI)
 class AppLoader_NCCH final : public AppLoader {
 public:
-    AppLoader_NCCH(const std::string& filename);
-    ~AppLoader_NCCH() override;
+    AppLoader_NCCH(std::unique_ptr<FileUtil::IOFile>&& file) : AppLoader(std::move(file)) { }
+
+    /**
+     * Returns the type of the file
+     * @param file FileUtil::IOFile open file
+     * @return FileType found, or FileType::Error if this loader doesn't know it
+     */
+    static FileType IdentifyType(FileUtil::IOFile& file);
 
     /**
      * Load the application
@@ -213,14 +218,11 @@ private:
      */
     ResultStatus LoadExec() const;
 
-    std::string     filename;
-
-    bool            is_loaded;
-    bool            is_compressed;
+    bool            is_compressed = false;
 
-    u32             entry_point;
-    u32             ncch_offset; // Offset to NCCH header, can be 0 or after NCSD header
-    u32             exefs_offset;
+    u32             entry_point = 0;
+    u32             ncch_offset = 0; // Offset to NCCH header, can be 0 or after NCSD header
+    u32             exefs_offset = 0;
 
     NCCH_Header     ncch_header;
     ExeFs_Header    exefs_header;