chore(flake): enable nix flake support

.envrc

@@ -0,0 +1 @@
+use flake .#

flake.nix

@@ -0,0 +1,67 @@
+{
+  description = "Only Provide the support of qemu";
+
+  inputs = {
+    nixpkgs.url      = "github:NixOS/nixpkgs/nixos-unstable";
+    rust-overlay.url = "github:oxalica/rust-overlay";
+    rust-overlay.inputs.nixpkgs.follows = "nixpkgs";
+    flake-utils.url  = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, rust-overlay, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        overlays = [ 
+          (import rust-overlay)
+          (_: super: {
+            rust-toolchain =
+              let
+                rust = super.rust-bin;
+              in
+              if builtins.pathExists ./rust-toolchain.toml then
+                rust.fromRustupToolchainFile ./rust-toolchain.toml
+              else if builtins.pathExists ./rust-toolchain then
+                rust.fromRustupToolchainFile ./rust-toolchain
+              else
+                # rust.nightly.latest.default;
+                # The rust-toolchain when i make this file, which maybe change
+                (rust.nightly.latest.default.override {
+                  extensions = [ "rust-src" "llvm-tools-preview" "rustfmt" "clippy" "cargo" ];
+                  targets = [ "x86_64-unknown-linux-gnu" ];
+                });
+          })
+        ];
+        pkgs = import nixpkgs {
+          inherit system overlays;
+        };
+      in {
+        devShells.default = with pkgs; mkShell {
+          buildInputs = [
+            # Require of repos
+            gnumake
+
+            # Require of rust-overlay
+            openssl
+            pkg-config
+            eza
+            fd
+
+            # Development Tools
+            ripgrep
+            zellij
+            fzf
+
+            rust-toolchain
+          ];
+
+          shellHook = ''
+            alias ls=eza
+            alias find=fd
+
+            export RUSTUP_DIST_SERVER=https://mirrors.ustc.edu.cn/rust-static
+            export RUSTUP_UPDATE_ROOT=https://mirrors.ustc.edu.cn/rust-static/rustup
+          '';
+        };
+      }
+    );
+}