diff --git a/crates/c-api/src/wasi.rs b/crates/c-api/src/wasi.rs
index a3b3ef8e8444..39e133d7748f 100644
--- a/crates/c-api/src/wasi.rs
+++ b/crates/c-api/src/wasi.rs
@@ -200,62 +200,85 @@ enum WasiInstance {
     Snapshot0(WasiSnapshot0),
 }
 
-macro_rules! config_to_builder {
-    ($builder:ident, $config:ident) => {{
-        let mut builder = $builder::new();
-
-        if $config.inherit_args {
-            builder.inherit_args();
-        } else if !$config.args.is_empty() {
-            builder.args($config.args);
-        }
-
-        if $config.inherit_env {
-            builder.inherit_env();
-        } else if !$config.env.is_empty() {
-            builder.envs($config.env);
-        }
-
-        if $config.inherit_stdin {
-            builder.inherit_stdin();
-        } else if let Some(file) = $config.stdin {
-            builder.stdin(file);
-        }
-
-        if $config.inherit_stdout {
-            builder.inherit_stdout();
-        } else if let Some(file) = $config.stdout {
-            builder.stdout(file);
-        }
-
-        if $config.inherit_stderr {
-            builder.inherit_stderr();
-        } else if let Some(file) = $config.stderr {
-            builder.stderr(file);
-        }
-
-        for preopen in $config.preopens {
-            builder.preopened_dir(preopen.0, preopen.1);
-        }
-
-        builder
-    }};
-}
-
 fn create_snapshot0_instance(store: &Store, config: wasi_config_t) -> Result<WasiInstance, String> {
+    let mut builder = WasiSnapshot0CtxBuilder::new();
+    if config.inherit_args {
+        builder.inherit_args();
+    } else if !config.args.is_empty() {
+        builder.args(config.args);
+    }
+    if config.inherit_env {
+        builder.inherit_env();
+    } else if !config.env.is_empty() {
+        builder.envs(config.env);
+    }
+    if config.inherit_stdin {
+        builder.inherit_stdin();
+    } else if let Some(file) = config.stdin {
+        builder.stdin(file);
+    }
+    if config.inherit_stdout {
+        builder.inherit_stdout();
+    } else if let Some(file) = config.stdout {
+        builder.stdout(file);
+    }
+    if config.inherit_stderr {
+        builder.inherit_stderr();
+    } else if let Some(file) = config.stderr {
+        builder.stderr(file);
+    }
+    for preopen in config.preopens {
+        builder.preopened_dir(preopen.0, preopen.1);
+    }
     Ok(WasiInstance::Snapshot0(WasiSnapshot0::new(
         store,
-        config_to_builder!(WasiSnapshot0CtxBuilder, config)
-            .build()
-            .map_err(|e| e.to_string())?,
+        builder.build().map_err(|e| e.to_string())?,
     )))
 }
 
+fn wasi_preview_builder(config: wasi_config_t) -> Result<WasiPreview1CtxBuilder> {
+    use std::convert::TryFrom;
+    use wasi_common::OsOther;
+    let mut builder = WasiPreview1CtxBuilder::new();
+    if config.inherit_args {
+        builder.inherit_args();
+    } else if !config.args.is_empty() {
+        builder.args(config.args);
+    }
+    if config.inherit_env {
+        builder.inherit_env();
+    } else if !config.env.is_empty() {
+        builder.envs(config.env);
+    }
+    if config.inherit_stdin {
+        builder.inherit_stdin();
+    } else if let Some(file) = config.stdin {
+        builder.stdin(OsOther::try_from(file)?);
+    }
+    if config.inherit_stdout {
+        builder.inherit_stdout();
+    } else if let Some(file) = config.stdout {
+        builder.stdout(OsOther::try_from(file)?);
+    }
+    if config.inherit_stderr {
+        builder.inherit_stderr();
+    } else if let Some(file) = config.stderr {
+        builder.stderr(OsOther::try_from(file)?);
+    }
+    for preopen in config.preopens {
+        builder.preopened_dir(preopen.0, preopen.1);
+    }
+    Ok(builder)
+}
+
 fn create_preview1_instance(store: &Store, config: wasi_config_t) -> Result<WasiInstance, String> {
     Ok(WasiInstance::Preview1(WasiPreview1::new(
         store,
-        config_to_builder!(WasiPreview1CtxBuilder, config)
-            .build()
+        wasi_preview_builder(config)
+            .and_then(|mut b| {
+                let b = b.build()?;
+                Ok(b)
+            })
             .map_err(|e| e.to_string())?,
     )))
 }
diff --git a/crates/test-programs/tests/wasm_tests/runtime.rs b/crates/test-programs/tests/wasm_tests/runtime.rs
index 0157a9c61400..a2c4a8f6bdd7 100644
--- a/crates/test-programs/tests/wasm_tests/runtime.rs
+++ b/crates/test-programs/tests/wasm_tests/runtime.rs
@@ -1,7 +1,8 @@
 use anyhow::{bail, Context};
+use std::convert::TryFrom;
 use std::fs::File;
 use std::path::Path;
-use wasi_common::VirtualDirEntry;
+use wasi_common::{OsOther, VirtualDirEntry};
 use wasmtime::{Instance, Module, Store};
 
 #[derive(Clone, Copy, Debug)]
@@ -46,7 +47,9 @@ pub fn instantiate(
     // where `stdin` is never ready to be read. In some CI systems, however,
     // stdin is closed which causes tests to fail.
     let (reader, _writer) = os_pipe::pipe()?;
-    builder.stdin(reader_to_file(reader));
+    let file = reader_to_file(reader);
+    let handle = OsOther::try_from(file).context("failed to create OsOther from PipeReader")?;
+    builder.stdin(handle);
     let snapshot1 = wasmtime_wasi::Wasi::new(&store, builder.build()?);
     let module = Module::new(&store, &data).context("failed to create wasm module")?;
     let imports = module
diff --git a/crates/wasi-common/src/ctx.rs b/crates/wasi-common/src/ctx.rs
index 895c96ad6f17..3121cb14623c 100644
--- a/crates/wasi-common/src/ctx.rs
+++ b/crates/wasi-common/src/ctx.rs
@@ -47,7 +47,7 @@ type WasiCtxBuilderResult<T> = std::result::Result<T, WasiCtxBuilderError>;
 
 enum PendingEntry {
     Thunk(fn() -> io::Result<Box<dyn Handle>>),
-    OsHandle(File),
+    Handle(Box<dyn Handle>),
 }
 
 impl std::fmt::Debug for PendingEntry {
@@ -58,7 +58,7 @@ impl std::fmt::Debug for PendingEntry {
                 "PendingEntry::Thunk({:p})",
                 f as *const fn() -> io::Result<Box<dyn Handle>>
             ),
-            Self::OsHandle(f) => write!(fmt, "PendingEntry::OsHandle({:?})", f),
+            Self::Handle(handle) => write!(fmt, "PendingEntry::Handle({:p})", handle),
         }
     }
 }
@@ -247,21 +247,21 @@ impl WasiCtxBuilder {
         self
     }
 
-    /// Provide a File to use as stdin
-    pub fn stdin(&mut self, file: File) -> &mut Self {
-        self.stdin = Some(PendingEntry::OsHandle(file));
+    /// Provide a `Handle` to use as stdin
+    pub fn stdin<T: Handle + 'static>(&mut self, handle: T) -> &mut Self {
+        self.stdin = Some(PendingEntry::Handle(Box::new(handle)));
         self
     }
 
-    /// Provide a File to use as stdout
-    pub fn stdout(&mut self, file: File) -> &mut Self {
-        self.stdout = Some(PendingEntry::OsHandle(file));
+    /// Provide a `Handle` to use as stdout
+    pub fn stdout<T: Handle + 'static>(&mut self, handle: T) -> &mut Self {
+        self.stdout = Some(PendingEntry::Handle(Box::new(handle)));
         self
     }
 
-    /// Provide a File to use as stderr
-    pub fn stderr(&mut self, file: File) -> &mut Self {
-        self.stderr = Some(PendingEntry::OsHandle(file));
+    /// Provide a `Handle` to use as stderr
+    pub fn stderr<T: Handle + 'static>(&mut self, handle: T) -> &mut Self {
+        self.stderr = Some(PendingEntry::Handle(Box::new(handle)));
         self
     }
 
@@ -368,9 +368,8 @@ impl WasiCtxBuilder {
                         .insert(entry)
                         .ok_or(WasiCtxBuilderError::TooManyFilesOpen)?
                 }
-                PendingEntry::OsHandle(f) => {
-                    let handle = OsOther::try_from(f)?;
-                    let handle = EntryHandle::new(handle);
+                PendingEntry::Handle(handle) => {
+                    let handle = EntryHandle::from(handle);
                     let entry = Entry::new(handle);
                     entries
                         .insert(entry)
diff --git a/crates/wasi-common/src/entry.rs b/crates/wasi-common/src/entry.rs
index eb311a7b10b2..ba9e90c16089 100644
--- a/crates/wasi-common/src/entry.rs
+++ b/crates/wasi-common/src/entry.rs
@@ -8,6 +8,7 @@ use std::rc::Rc;
 pub(crate) struct EntryHandle(Rc<dyn Handle>);
 
 impl EntryHandle {
+    #[allow(dead_code)]
     pub(crate) fn new<T: Handle + 'static>(handle: T) -> Self {
         Self(Rc::new(handle))
     }
diff --git a/crates/wasi-common/src/handle.rs b/crates/wasi-common/src/handle.rs
index 21a0ab4f2c3e..97a841dfac69 100644
--- a/crates/wasi-common/src/handle.rs
+++ b/crates/wasi-common/src/handle.rs
@@ -6,38 +6,49 @@ use std::io::{self, SeekFrom};
 
 /// Represents rights of a `Handle`, either already held or required.
 #[derive(Debug, Copy, Clone)]
-pub(crate) struct HandleRights {
+pub struct HandleRights {
     pub(crate) base: Rights,
     pub(crate) inheriting: Rights,
 }
 
 impl HandleRights {
-    pub(crate) fn new(base: Rights, inheriting: Rights) -> Self {
+    /// Creates new `HandleRights` instance from `base` and `inheriting` rights.
+    pub fn new(base: Rights, inheriting: Rights) -> Self {
         Self { base, inheriting }
     }
 
-    /// Create new `HandleRights` instance from `base` rights only, keeping
+    /// Creates new `HandleRights` instance from `base` rights only, keeping
     /// `inheriting` set to none.
-    pub(crate) fn from_base(base: Rights) -> Self {
+    pub fn from_base(base: Rights) -> Self {
         Self {
             base,
             inheriting: Rights::empty(),
         }
     }
 
-    /// Create new `HandleRights` instance with both `base` and `inheriting`
+    /// Creates new `HandleRights` instance with both `base` and `inheriting`
     /// rights set to none.
-    pub(crate) fn empty() -> Self {
+    pub fn empty() -> Self {
         Self {
             base: Rights::empty(),
             inheriting: Rights::empty(),
         }
     }
 
-    /// Check if `other` is a subset of those rights.
-    pub(crate) fn contains(&self, other: &Self) -> bool {
+    /// Checks if `other` is a subset of those rights.
+    pub fn contains(&self, other: &Self) -> bool {
         self.base.contains(&other.base) && self.inheriting.contains(&other.inheriting)
     }
+
+    /// Returns base rights.
+    pub fn base(&self) -> Rights {
+        self.base
+    }
+
+    /// Returns inheriting rights.
+    pub fn inheriting(&self) -> Rights {
+        self.inheriting
+    }
 }
 
 impl fmt::Display for HandleRights {
@@ -50,7 +61,8 @@ impl fmt::Display for HandleRights {
     }
 }
 
-pub(crate) trait Handle {
+// TODO docs
+pub trait Handle {
     fn as_any(&self) -> &dyn Any;
     fn try_clone(&self) -> io::Result<Box<dyn Handle>>;
     fn get_file_type(&self) -> types::Filetype;
diff --git a/crates/wasi-common/src/lib.rs b/crates/wasi-common/src/lib.rs
index 4c0ccf7b4e0a..f9c17841a97a 100644
--- a/crates/wasi-common/src/lib.rs
+++ b/crates/wasi-common/src/lib.rs
@@ -36,5 +36,9 @@ mod virtfs;
 pub mod wasi;
 
 pub use ctx::{WasiCtx, WasiCtxBuilder, WasiCtxBuilderError};
+pub use handle::{Handle, HandleRights};
+pub use sys::osdir::OsDir;
+pub use sys::osfile::OsFile;
+pub use sys::osother::{OsOther, OsOtherExt};
 pub use sys::preopen_dir;
 pub use virtfs::{FileContents, VirtualDirEntry};
diff --git a/crates/wasi-common/src/sys/osdir.rs b/crates/wasi-common/src/sys/osdir.rs
index 29a69e0c106c..9f16b0f2f116 100644
--- a/crates/wasi-common/src/sys/osdir.rs
+++ b/crates/wasi-common/src/sys/osdir.rs
@@ -10,7 +10,7 @@ use std::ops::Deref;
 // TODO could this be cleaned up?
 // The actual `OsDir` struct is OS-dependent, therefore we delegate
 // its definition to OS-specific modules.
-pub(crate) use super::sys_impl::osdir::OsDir;
+pub use super::sys_impl::osdir::OsDir;
 
 impl Deref for OsDir {
     type Target = RawOsHandle;
diff --git a/crates/wasi-common/src/sys/osfile.rs b/crates/wasi-common/src/sys/osfile.rs
index a3491f5432d9..e9ced03fc673 100644
--- a/crates/wasi-common/src/sys/osfile.rs
+++ b/crates/wasi-common/src/sys/osfile.rs
@@ -9,7 +9,7 @@ use std::io::{self, Read, Seek, SeekFrom, Write};
 use std::ops::Deref;
 
 #[derive(Debug)]
-pub(crate) struct OsFile {
+pub struct OsFile {
     rights: Cell<HandleRights>,
     handle: RawOsHandle,
 }
diff --git a/crates/wasi-common/src/sys/osother.rs b/crates/wasi-common/src/sys/osother.rs
index de30a4f2dd0a..42f15c579b09 100644
--- a/crates/wasi-common/src/sys/osother.rs
+++ b/crates/wasi-common/src/sys/osother.rs
@@ -10,7 +10,7 @@ use std::fs::File;
 use std::io::{self, Read, Write};
 use std::ops::Deref;
 
-pub(crate) trait OsOtherExt {
+pub trait OsOtherExt {
     /// Create `OsOther` as `dyn Handle` from null device.
     fn from_null() -> io::Result<Box<dyn Handle>>;
 }
@@ -21,7 +21,7 @@ pub(crate) trait OsOtherExt {
 /// pipe should be encapsulated within this instance _and not_ `OsFile` which represents a regular
 /// OS file.
 #[derive(Debug)]
-pub(crate) struct OsOther {
+pub struct OsOther {
     file_type: Filetype,
     rights: Cell<HandleRights>,
     handle: RawOsHandle,
diff --git a/crates/wasi-common/src/sys/unix/bsd/osdir.rs b/crates/wasi-common/src/sys/unix/bsd/osdir.rs
index 0726ad2ef6ed..7baa1939ed02 100644
--- a/crates/wasi-common/src/sys/unix/bsd/osdir.rs
+++ b/crates/wasi-common/src/sys/unix/bsd/osdir.rs
@@ -6,7 +6,7 @@ use std::io;
 use yanix::dir::Dir;
 
 #[derive(Debug)]
-pub(crate) struct OsDir {
+pub struct OsDir {
     pub(crate) rights: Cell<HandleRights>,
     pub(crate) handle: RawOsHandle,
     // When the client makes a `fd_readdir` syscall on this descriptor,
diff --git a/crates/wasi-common/src/sys/unix/linux/osdir.rs b/crates/wasi-common/src/sys/unix/linux/osdir.rs
index 2fff99ec7bbf..f15d89a4c5f6 100644
--- a/crates/wasi-common/src/sys/unix/linux/osdir.rs
+++ b/crates/wasi-common/src/sys/unix/linux/osdir.rs
@@ -6,7 +6,7 @@ use std::io;
 use yanix::dir::Dir;
 
 #[derive(Debug)]
-pub(crate) struct OsDir {
+pub struct OsDir {
     pub(crate) rights: Cell<HandleRights>,
     pub(crate) handle: RawOsHandle,
 }
diff --git a/crates/wasi-common/src/sys/unix/osdir.rs b/crates/wasi-common/src/sys/unix/osdir.rs
index 47b264208fa5..6c4ba35655fe 100644
--- a/crates/wasi-common/src/sys/unix/osdir.rs
+++ b/crates/wasi-common/src/sys/unix/osdir.rs
@@ -6,7 +6,7 @@ use std::fs::File;
 use std::io;
 use std::os::unix::prelude::{AsRawFd, FromRawFd, IntoRawFd};
 
-pub(crate) use super::sys_impl::osdir::OsDir;
+pub use super::sys_impl::osdir::OsDir;
 
 impl TryFrom<File> for OsDir {
     type Error = io::Error;
diff --git a/crates/wasi-common/src/sys/unix/oshandle.rs b/crates/wasi-common/src/sys/unix/oshandle.rs
index 513e4b7787ae..b706a5bb0f11 100644
--- a/crates/wasi-common/src/sys/unix/oshandle.rs
+++ b/crates/wasi-common/src/sys/unix/oshandle.rs
@@ -3,7 +3,7 @@ use std::io;
 use std::os::unix::prelude::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
 
 #[derive(Debug)]
-pub(crate) struct RawOsHandle(File);
+pub struct RawOsHandle(File);
 
 impl RawOsHandle {
     /// Tries clone `self`.
diff --git a/crates/wasi-common/src/sys/windows/osdir.rs b/crates/wasi-common/src/sys/windows/osdir.rs
index 80cee50bce55..132bdceee433 100644
--- a/crates/wasi-common/src/sys/windows/osdir.rs
+++ b/crates/wasi-common/src/sys/windows/osdir.rs
@@ -8,7 +8,7 @@ use std::io;
 use std::os::windows::prelude::{AsRawHandle, FromRawHandle, IntoRawHandle};
 
 #[derive(Debug)]
-pub(crate) struct OsDir {
+pub struct OsDir {
     pub(crate) rights: Cell<HandleRights>,
     pub(crate) handle: RawOsHandle,
 }
diff --git a/crates/wasi-common/src/sys/windows/oshandle.rs b/crates/wasi-common/src/sys/windows/oshandle.rs
index 89884d03a8d9..74aacb80192b 100644
--- a/crates/wasi-common/src/sys/windows/oshandle.rs
+++ b/crates/wasi-common/src/sys/windows/oshandle.rs
@@ -6,7 +6,7 @@ use std::mem::ManuallyDrop;
 use std::os::windows::prelude::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
 
 #[derive(Debug)]
-pub(crate) struct RawOsHandle(Cell<RawHandle>);
+pub struct RawOsHandle(Cell<RawHandle>);
 
 impl RawOsHandle {
     /// Tries cloning `self`.