AK: Make MappedFile heap-allocated and ref-counted

Let's adapt this class a bit better to how it's actually being used.

Instead of having valid/invalid states and storing an error in case
it's invalid, a MappedFile is now always valid, and the factory
function that creates it will return an OSError if mapping fails.

Libraries/LibGfx/BMPLoader.cpp

@@ -179,10 +179,10 @@ static RefPtr<Bitmap> load_bmp_impl(const u8*, size_t);
 
 RefPtr<Gfx::Bitmap> load_bmp(const StringView& path)
 {
-    MappedFile mapped_file(path);
-    if (!mapped_file.is_valid())
+    auto file_or_error = MappedFile::map(path);
+    if (file_or_error.is_error())
         return nullptr;
-    auto bitmap = load_bmp_impl((const u8*)mapped_file.data(), mapped_file.size());
+    auto bitmap = load_bmp_impl((const u8*)file_or_error.value()->data(), file_or_error.value()->size());
     if (bitmap)
         bitmap->set_mmap_name(String::formatted("Gfx::Bitmap [{}] - Decoded BMP: {}", bitmap->size(), LexicalPath::canonicalized_path(path)));
     return bitmap;

Libraries/LibGfx/BitmapFont.cpp

@@ -27,7 +27,6 @@
 #include "BitmapFont.h"
 #include "Bitmap.h"
 #include "Emoji.h"
-#include <AK/MappedFile.h>
 #include <AK/StdLibExtras.h>
 #include <AK/StringBuilder.h>
 #include <AK/Utf32View.h>
@@ -174,15 +173,15 @@ size_t BitmapFont::glyph_count_by_type(FontTypes type)
 
 RefPtr<BitmapFont> BitmapFont::load_from_file(const StringView& path)
 {
-    MappedFile mapped_file(path);
-    if (!mapped_file.is_valid())
+    auto file_or_error = MappedFile::map(path);
+    if (file_or_error.is_error())
         return nullptr;
 
-    auto font = load_from_memory((const u8*)mapped_file.data());
+    auto font = load_from_memory((const u8*)file_or_error.value()->data());
     if (!font)
         return nullptr;
 
-    font->m_mapped_file = move(mapped_file);
+    font->m_mapped_file = file_or_error.release_value();
     return font;
 }
 

Libraries/LibGfx/BitmapFont.h

@@ -128,7 +128,7 @@ private:
 
     unsigned* m_rows { nullptr };
     u8* m_glyph_widths { nullptr };
-    MappedFile m_mapped_file;
+    RefPtr<MappedFile> m_mapped_file;
 
     u8 m_glyph_width { 0 };
     u8 m_glyph_height { 0 };

Libraries/LibGfx/GIFLoader.cpp

@@ -107,10 +107,10 @@ struct GIFLoadingContext {
 
 RefPtr<Gfx::Bitmap> load_gif(const StringView& path)
 {
-    MappedFile mapped_file(path);
-    if (!mapped_file.is_valid())
+    auto file_or_error = MappedFile::map(path);
+    if (file_or_error.is_error())
         return nullptr;
-    GIFImageDecoderPlugin gif_decoder((const u8*)mapped_file.data(), mapped_file.size());
+    GIFImageDecoderPlugin gif_decoder((const u8*)file_or_error.value()->data(), file_or_error.value()->size());
     auto bitmap = gif_decoder.bitmap();
     if (bitmap)
         bitmap->set_mmap_name(String::formatted("Gfx::Bitmap [{}] - Decoded GIF: {}", bitmap->size(), LexicalPath::canonicalized_path(path)));

Libraries/LibGfx/ICOLoader.cpp

@@ -116,10 +116,10 @@ struct ICOLoadingContext {
 
 RefPtr<Gfx::Bitmap> load_ico(const StringView& path)
 {
-    MappedFile mapped_file(path);
-    if (!mapped_file.is_valid())
+    auto file_or_error = MappedFile::map(path);
+    if (file_or_error.is_error())
         return nullptr;
-    ICOImageDecoderPlugin decoder((const u8*)mapped_file.data(), mapped_file.size());
+    ICOImageDecoderPlugin decoder((const u8*)file_or_error.value()->data(), file_or_error.value()->size());
     auto bitmap = decoder.bitmap();
     if (bitmap)
         bitmap->set_mmap_name(String::formatted("Gfx::Bitmap [{}] - Decoded ICO: {}", bitmap->size(), LexicalPath::canonicalized_path(path)));

Libraries/LibGfx/JPGLoader.cpp

@@ -1320,12 +1320,10 @@ static RefPtr<Gfx::Bitmap> load_jpg_impl(const u8* data, size_t data_size)
 
 RefPtr<Gfx::Bitmap> load_jpg(const StringView& path)
 {
-    MappedFile mapped_file(path);
-    if (!mapped_file.is_valid()) {
+    auto file_or_error = MappedFile::map(path);
+    if (file_or_error.is_error())
         return nullptr;
-    }
-
-    auto bitmap = load_jpg_impl((const u8*)mapped_file.data(), mapped_file.size());
+    auto bitmap = load_jpg_impl((const u8*)file_or_error.value()->data(), file_or_error.value()->size());
     if (bitmap)
         bitmap->set_mmap_name(String::formatted("Gfx::Bitmap [{}] - Decoded JPG: {}", bitmap->size(), LexicalPath::canonicalized_path(path)));
     return bitmap;

Libraries/LibGfx/PNGLoader.cpp

@@ -193,10 +193,10 @@ static bool process_chunk(Streamer&, PNGLoadingContext& context);
 
 RefPtr<Gfx::Bitmap> load_png(const StringView& path)
 {
-    MappedFile mapped_file(path);
-    if (!mapped_file.is_valid())
+    auto file_or_error = MappedFile::map(path);
+    if (file_or_error.is_error())
         return nullptr;
-    auto bitmap = load_png_impl((const u8*)mapped_file.data(), mapped_file.size());
+    auto bitmap = load_png_impl((const u8*)file_or_error.value()->data(), file_or_error.value()->size());
     if (bitmap)
         bitmap->set_mmap_name(String::formatted("Gfx::Bitmap [{}] - Decoded PNG: {}", bitmap->size(), LexicalPath::canonicalized_path(path)));
     return bitmap;

Libraries/LibGfx/PortableImageLoaderCommon.h

@@ -294,12 +294,10 @@ static RefPtr<Gfx::Bitmap> load_impl(const u8* data, size_t data_size)
 template<typename TContext>
 static RefPtr<Gfx::Bitmap> load(const StringView& path)
 {
-    MappedFile mapped_file(path);
-    if (!mapped_file.is_valid()) {
+    auto file_or_error = MappedFile::map(path);
+    if (file_or_error.is_error())
         return nullptr;
-    }
-
-    auto bitmap = load_impl<TContext>((const u8*)mapped_file.data(), mapped_file.size());
+    auto bitmap = load_impl<TContext>((const u8*)file_or_error.value()->data(), file_or_error.value()->size());
     if (bitmap)
         bitmap->set_mmap_name(String::formatted("Gfx::Bitmap [{}] - Decoded {}: {}",
             bitmap->size(),