Fix preopened directory mapping to virtual root

This commit fixes the bug where preopening `.` causes the WASI runner to
map it to the virtual root, causing `path_open` to fail.

fixes wasmerio#4361

lib/wasix/src/os/console/mod.rs

@@ -30,6 +30,7 @@ use crate::{
     bin_factory::{spawn_exec, BinFactory, BinaryPackage},
     capabilities::Capabilities,
     os::task::{control_plane::WasiControlPlane, process::WasiProcess},
+    runners::MappedDirectory,
     runtime::{resolver::PackageSpecifier, task_manager::InlineWaker},
     Runtime, SpawnError, WasiEnv, WasiEnvBuilder, WasiRuntimeError,
 };
@@ -225,6 +226,10 @@ impl Console {
             .with_stdin(Box::new(self.stdin.clone()))
             .with_stdout(Box::new(self.stdout.clone()))
             .with_stderr(Box::new(self.stderr.clone()))
+            .with_mapped_directories(vec![MappedDirectory {
+                host: ".".into(),
+                guest: "/mnt/host".to_owned(),
+            }])
             .prepare_webc_env(
                 prog,
                 &wasi_opts,

lib/wasix/src/runners/wasi_common.rs

@@ -48,8 +48,8 @@ impl CommonWasiOptions {
         builder.add_preopen_dir("/")?;
 
         if self.mapped_dirs.iter().all(|m| m.guest != ".") {
-            // The user hasn't mounted "." to anything, so let's map it to "/"
-            builder.add_map_dir(".", "/")?;
+            // The user hasn't mounted "." to anything, so let's map it to "/mnt/host"
+            builder.add_map_dir(".", "/mnt/host")?;
         }
 
         builder.set_fs(Box::new(fs));

lib/wasix/tests/runners.rs

@@ -25,7 +25,11 @@ use webc::Container;
 
 mod wasi {
     use virtual_fs::{AsyncReadExt, AsyncSeekExt};
-    use wasmer_wasix::{bin_factory::BinaryPackage, runners::wasi::WasiRunner, WasiError};
+    use wasmer_wasix::{
+        bin_factory::BinaryPackage,
+        runners::{wasi::WasiRunner, MappedDirectory},
+        WasiError,
+    };
 
     use super::*;
 
@@ -54,6 +58,10 @@ mod wasi {
                 .with_stdin(Box::new(virtual_fs::NullFile::default()))
                 .with_stdout(Box::new(stdout_2) as Box<_>)
                 .with_stderr(Box::new(virtual_fs::NullFile::default()))
+                .with_mapped_directories(vec![MappedDirectory {
+                    host: ".".into(),
+                    guest: "/mnt/host".to_owned(),
+                }])
                 .run_command("wat2wasm", &pkg, Arc::new(rt))
         });
 
@@ -82,6 +90,10 @@ mod wasi {
                 .with_stdin(Box::new(virtual_fs::NullFile::default()))
                 .with_stdout(Box::new(virtual_fs::NullFile::default()))
                 .with_stderr(Box::new(virtual_fs::NullFile::default()))
+                .with_mapped_directories(vec![MappedDirectory {
+                    host: ".".into(),
+                    guest: "/mnt/host".to_owned(),
+                }])
                 .run_command("python", &pkg, Arc::new(rt))
         });