Add virtual.map_file

core/mem/virtual/file.odin

@@ -0,0 +1,47 @@
+package mem_virtual
+
+import "core:os"
+
+Mapped_File_Error :: enum {
+	None,
+	Open_Failure,
+	Stat_Failure,
+	Negative_Size,
+	Too_Large_Size,
+	Map_Failure,
+}
+
+Mapped_File_Flag :: enum u32 {
+	Read,
+	Write,
+}
+Mapped_File_Flags :: distinct bit_set[Mapped_File_Flag; u32]
+
+map_file :: proc{
+	map_file_from_path,
+	map_file_from_file_descriptor,
+}
+
+map_file_from_path :: proc(filename: string, flags: Mapped_File_Flags) -> (data: []byte, error: Mapped_File_Error) {
+	fd, err := os.open(filename, os.O_RDWR)
+	if err != 0 {
+		return nil, .Open_Failure
+	}
+	defer os.close(fd)
+
+	return map_file_from_file_descriptor(uintptr(fd), flags)
+}
+
+map_file_from_file_descriptor :: proc(fd: uintptr, flags: Mapped_File_Flags) -> (data: []byte, error: Mapped_File_Error) {
+	size, os_err := os.file_size(os.Handle(fd))
+	if os_err != 0 {
+		return nil, .Stat_Failure
+	}
+	if size < 0 {
+		return nil, .Negative_Size
+	}
+	if size != i64(int(size)) {
+		return nil, .Too_Large_Size
+	}
+	return _map_file(fd, size, flags)
+}