Add tests for mapped directories

Author: william-stacken

spec/fixtures/wasi-fs-p2.wasm

@@ -0,0 +1,2 @@
+[build]
+target = "wasm32-wasip1"

spec/fixtures/wasi-fs.wasm

@@ -0,0 +1,10 @@
+[package]
+name = "wasi-fs"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[workspace]
+
+[dependencies]

spec/fixtures/wasi-fs/.cargo/config.toml

@@ -0,0 +1,14 @@
+Example WASI program used to test WASI preopened directories
+
+To update:
+
+```shell
+cargo build --release && \
+    wasm-opt -O \
+    --enable-bulk-memory \
+    target/wasm32-wasip1/release/wasi-fs.wasm \
+    -o ../wasi-fs.wasm && \
+cargo build --target=wasm32-wasip2 --release && \
+    cp target/wasm32-wasip2/release/wasi-fs.wasm \
+    ../wasi-fs-p2.wasm
+```

spec/fixtures/wasi-fs/Cargo.toml

@@ -0,0 +1,18 @@
+use std::io::{Write, Read};
+use std::fs::File;
+
+fn main() {
+    let args: Vec<String> = std::env::args().collect();
+
+    let counter_file = File::open(&args[1]).expect("failed to open counter file");
+
+    let mut counter_str = String::new();
+    counter_file.take(100).read_to_string(&mut counter_str)
+        .expect("failed to read counter file");
+    let mut counter: u32 = counter_str.trim().parse().expect("failed to parse counter");
+
+    counter += 1;
+
+    let mut counter_file = File::create(&args[1]).expect("failed to create counter file");
+    write!(counter_file, "{}", counter).expect("failed to write counter file");
+}

spec/fixtures/wasi-fs/README.md

@@ -12,9 +12,11 @@ module Wasmtime
       # Compile module only once for speed
       @compiled_wasi_module = @engine.precompile_module(IO.binread("spec/fixtures/wasi-debug.wasm"))
       @compiled_wasi_deterministic_module = @engine.precompile_module(IO.binread("spec/fixtures/wasi-deterministic.wasm"))
+      @compiled_wasi_fs_module = @engine.precompile_module(IO.binread("spec/fixtures/wasi-fs.wasm"))
 
       @compiled_wasi_component = @engine.precompile_component(IO.binread("spec/fixtures/wasi-debug-p2.wasm"))
       @compiled_wasi_deterministic_component = @engine.precompile_component(IO.binread("spec/fixtures/wasi-deterministic-p2.wasm"))
+      @compiled_wasi_fs_component = @engine.precompile_component(IO.binread("spec/fixtures/wasi-fs-p2.wasm"))
     end
 
     describe "Linker.new" do
@@ -233,13 +235,103 @@ module Wasmtime
           end
         end
       end
+
+      it "writes to mapped directory" do
+        Dir.mkdir(tempfile_path("tmp"))
+        File.write(tempfile_path(File.join("tmp", "counter")), "0")
+
+        wasi_config = WasiConfig.new
+          .set_argv(["wasi-fs", "/tmp/counter"])
+          .set_mapped_directory(tempfile_path("tmp"), "/tmp", :all, :all)
+
+        expect { run_fs.call(wasi_config) }.not_to raise_error
+
+        expect(File.read(tempfile_path(File.join("tmp", "counter")))).to eq("1")
+      end
+
+      it "fails to write to mapped directory if not permitted" do
+        Dir.mkdir(tempfile_path("tmp"))
+        File.write(tempfile_path(File.join("tmp", "counter")), "0")
+
+        stderr_str = ""
+        wasi_config = WasiConfig.new
+          .set_argv(["wasi-fs", "/tmp/counter"])
+          .set_stderr_buffer(stderr_str, 40000)
+          .set_mapped_directory(tempfile_path("tmp"), "/tmp", :read, :read)
+
+        expect { run_fs.call(wasi_config) }.to raise_error do |error|
+          expect(error).to be_a(Wasmtime::Error)
+        end
+
+        expect(stderr_str).to match(/failed to create counter file/)
+
+        expect(File.read(tempfile_path(File.join("tmp", "counter")))).to eq("0")
+      end
+
+      it "fails to read from mapped directory if not permitted" do
+        Dir.mkdir(tempfile_path("tmp"))
+        File.write(tempfile_path(File.join("tmp", "counter")), "0")
+
+        stderr_str = ""
+        wasi_config = WasiConfig.new
+          .set_argv(["wasi-fs", "/tmp/counter"])
+          .set_stderr_buffer(stderr_str, 40000)
+          .set_mapped_directory(tempfile_path("tmp"), "/tmp", :mutate, :write)
+
+        expect { run_fs.call(wasi_config) }.to raise_error do |error|
+          expect(error).to be_a(Wasmtime::Error)
+        end
+
+        expect(stderr_str).to match(/failed to open counter file/)
+
+        expect(File.read(tempfile_path(File.join("tmp", "counter")))).to eq("0")
+      end
+
+      it "fails to access non-mapped directories" do
+        Dir.mkdir(tempfile_path("tmp"))
+        File.write(tempfile_path(File.join("tmp", "counter")), "0")
+
+        stderr_str = ""
+        wasi_config = WasiConfig.new
+          .set_argv(["wasi-fs", File.join(tempfile_path("tmp"), "counter")])
+          .set_stderr_buffer(stderr_str, 40000)
+
+        expect { run_fs.call(wasi_config) }.to raise_error do |error|
+          expect(error).to be_a(Wasmtime::Error)
+        end
+
+        expect(stderr_str).to match(/failed to find a pre-opened file descriptor/)
+
+        expect(File.read(tempfile_path(File.join("tmp", "counter")))).to eq("0")
+      end
+
+      it "does not accept an invalid host path" do
+        wasi_config = WasiConfig.new
+          .set_mapped_directory(tempfile_path("tmp"), "/tmp", :all, :all)
+
+        expect { run_fs.call(wasi_config) }.to raise_error do |error|
+          expect(error).to be_a(Wasmtime::Error)
+          # error message is os-specific
+        end
+      end
+
+      it "does not accept invalid permissions" do
+        wasi_config = WasiConfig.new
+          .set_mapped_directory(tempfile_path("tmp"), "/tmp", :mutate, :invalid_permission)
+
+        expect { run_fs.call(wasi_config) }.to raise_error do |error|
+          expect(error).to be_a(Wasmtime::Error)
+          expect(error.message).to match(/Invalid file_perms: invalid_permission. Use one of :read, :write, or :all/)
+        end
+      end
     end
 
     describe "WasiConfig preview 1" do
       it_behaves_like WasiConfig do
         let(:run) { method(:run_wasi_module) }
         let(:wasi_env) { method(:wasi_module_env) }
         let(:run_deterministic) { method(:run_wasi_module_deterministic) }
+        let(:run_fs) { method(:run_wasi_module_fs) }
       end
     end
 
@@ -248,6 +340,7 @@ module Wasmtime
         let(:run) { method(:run_wasi_component) }
         let(:wasi_env) { method(:wasi_component_env) }
         let(:run_deterministic) { method(:run_wasi_component_deterministic) }
+        let(:run_fs) { method(:run_wasi_component_fs) }
       end
     end
 
@@ -272,6 +365,13 @@ def run_wasi_module_deterministic(wasi_config)
         .invoke("_start")
     end
 
+    def run_wasi_module_fs(wasi_config)
+      linker = Linker.new(@engine)
+      WASI::P1.add_to_linker_sync(linker)
+      store = Store.new(@engine, wasi_p1_config: wasi_config)
+      linker.instantiate(store, Module.deserialize(@engine, @compiled_wasi_fs_module)).invoke("_start")
+    end
+
     def wasi_module_env
       stdout_file = tempfile_path("stdout")
 
@@ -318,6 +418,17 @@ def run_wasi_component_deterministic(wasi_config)
       ).call_run(store)
     end
 
+    def run_wasi_component_fs(wasi_config)
+      linker = Component::Linker.new(@engine)
+      WASI::P2.add_to_linker_sync(linker)
+      store = Store.new(@engine, wasi_config: wasi_config)
+      Component::WasiCommand.new(
+        store,
+        Component::Component.deserialize(@engine, @compiled_wasi_fs_component),
+        linker
+      ).call_run(store)
+    end
+
     def tempfile_path(name)
       File.join(tmpdir, name)
     end