feat:添加symlink系统调用 (#984)

* 添加symlink系统调用

* 修改FATInode的dname的获取逻辑

* 修改fat对Dname的处理，分离dname和inode缓存的key

---------

Co-authored-by: sparkzky <sparkhhhhhhhhh@outlook.com>
Co-authored-by: longjin <longjin@DragonOS.org>

user/apps/test-symlink/Makefile

@@ -0,0 +1,56 @@
+TOOLCHAIN=
+RUSTFLAGS=
+
+ifdef DADK_CURRENT_BUILD_DIR
+# 如果是在dadk中编译，那么安装到dadk的安装目录中
+	INSTALL_DIR = $(DADK_CURRENT_BUILD_DIR)
+else
+# 如果是在本地编译，那么安装到当前目录下的install目录中
+	INSTALL_DIR = ./install
+endif
+
+ifeq ($(ARCH), x86_64)
+	export RUST_TARGET=x86_64-unknown-linux-musl
+else ifeq ($(ARCH), riscv64)
+	export RUST_TARGET=riscv64gc-unknown-linux-gnu
+else 
+# 默认为x86_86，用于本地编译
+	export RUST_TARGET=x86_64-unknown-linux-musl
+endif
+
+run:
+	RUSTFLAGS=$(RUSTFLAGS) cargo $(TOOLCHAIN) run --target $(RUST_TARGET)
+
+build:
+	RUSTFLAGS=$(RUSTFLAGS) cargo $(TOOLCHAIN) build --target $(RUST_TARGET)
+
+clean:
+	RUSTFLAGS=$(RUSTFLAGS) cargo $(TOOLCHAIN) clean --target $(RUST_TARGET)
+
+test:
+	RUSTFLAGS=$(RUSTFLAGS) cargo $(TOOLCHAIN) test --target $(RUST_TARGET)
+
+doc:
+	RUSTFLAGS=$(RUSTFLAGS) cargo $(TOOLCHAIN) doc --target $(RUST_TARGET)
+
+fmt:
+	RUSTFLAGS=$(RUSTFLAGS) cargo $(TOOLCHAIN) fmt
+
+fmt-check:
+	RUSTFLAGS=$(RUSTFLAGS) cargo $(TOOLCHAIN) fmt --check
+
+run-release:
+	RUSTFLAGS=$(RUSTFLAGS) cargo $(TOOLCHAIN) run --target $(RUST_TARGET) --release
+
+build-release:
+	RUSTFLAGS=$(RUSTFLAGS) cargo $(TOOLCHAIN) build --target $(RUST_TARGET) --release
+
+clean-release:
+	RUSTFLAGS=$(RUSTFLAGS) cargo $(TOOLCHAIN) clean --target $(RUST_TARGET) --release
+
+test-release:
+	RUSTFLAGS=$(RUSTFLAGS) cargo $(TOOLCHAIN) test --target $(RUST_TARGET) --release
+
+.PHONY: install
+install:
+	RUSTFLAGS=$(RUSTFLAGS) cargo $(TOOLCHAIN) install --target $(RUST_TARGET) --path . --no-track --root $(INSTALL_DIR) --force