Clean up fd_renumber

build.rs

@@ -134,6 +134,7 @@ cfg_if::cfg_if! {
                     "big_random_buf" => false,
                     "sched_yield" => false,
                     "file_pread_pwrite" => false,
+                    "renumber" => false,
                     _ => true,
                 }
             } else {

src/ctx.rs

@@ -152,6 +152,10 @@ impl WasiCtx {
             .and_then(|ctx| ctx.build())
     }
 
+    pub fn contains_fd_entry(&self, fd: host::__wasi_fd_t) -> bool {
+        self.fds.contains_key(&fd)
+    }
+
     pub fn get_fd_entry(
         &self,
         fd: host::__wasi_fd_t,

src/fdentry.rs

@@ -13,6 +13,36 @@ pub enum Descriptor {
     Stderr,
 }
 
+impl Descriptor {
+    pub fn is_file(&self) -> bool {
+        match self {
+            Descriptor::File(_) => true,
+            _ => false,
+        }
+    }
+
+    pub fn is_stdin(&self) -> bool {
+        match self {
+            Descriptor::Stdin => true,
+            _ => false,
+        }
+    }
+
+    pub fn is_stdout(&self) -> bool {
+        match self {
+            Descriptor::Stdout => true,
+            _ => false,
+        }
+    }
+
+    pub fn is_stderr(&self) -> bool {
+        match self {
+            Descriptor::Stderr => true,
+            _ => false,
+        }
+    }
+}
+
 #[derive(Debug)]
 pub struct FdObject {
     pub file_type: host::__wasi_filetype_t,

src/hostcalls/fs.rs

@@ -1,7 +1,7 @@
 #![allow(non_camel_case_types)]
 use super::return_enc_errno;
 use crate::ctx::WasiCtx;
-use crate::fdentry::Descriptor;
+use crate::fdentry::{Descriptor, FdEntry};
 use crate::memory::*;
 use crate::sys::{errno_from_host, host_impl, hostcalls_impl};
 use crate::{host, wasm32};
@@ -244,12 +244,38 @@ pub fn fd_renumber(
     let from = dec_fd(from);
     let to = dec_fd(to);
 
-    let ret = match hostcalls_impl::fd_renumber(wasi_ctx, from, to) {
-        Ok(()) => host::__WASI_ESUCCESS,
-        Err(e) => e,
+    if !wasi_ctx.contains_fd_entry(from) || !wasi_ctx.contains_fd_entry(to) {
+        return return_enc_errno(host::__WASI_EBADF);
+    }
+
+    // Don't allow renumbering over a pre-opened resource.
+    // TODO: Eventually, we do want to permit this, once libpreopen in
+    // userspace is capable of removing entries from its tables as well.
+    if wasi_ctx.fds[&from].preopen_path.is_some() || wasi_ctx.fds[&to].preopen_path.is_some() {
+        return return_enc_errno(host::__WASI_ENOTSUP);
+    }
+
+    // check if stdio fds
+    // TODO should we renumber stdio fds?
+    if !wasi_ctx.fds[&from].fd_object.descriptor.is_file()
+        || !wasi_ctx.fds[&to].fd_object.descriptor.is_file()
+    {
+        return return_enc_errno(host::__WASI_EBADF);
+    }
+
+    let fe_from_dup = if let Descriptor::File(f) = &*wasi_ctx.fds[&from].fd_object.descriptor {
+        match FdEntry::duplicate(f) {
+            Ok(fe) => fe,
+            Err(e) => return return_enc_errno(e),
+        }
+    } else {
+        return return_enc_errno(host::__WASI_EBADF);
     };
 
-    return_enc_errno(ret)
+    wasi_ctx.fds.insert(to, fe_from_dup);
+    wasi_ctx.fds.remove(&from);
+
+    return_enc_errno(host::__WASI_ESUCCESS)
 }
 
 #[wasi_common_cbindgen]

src/sys/unix/hostcalls_impl/fs.rs

@@ -27,39 +27,6 @@ pub(crate) fn fd_pwrite(file: &File, buf: &[u8], offset: host::__wasi_filesize_t
         .map_err(|e| e.raw_os_error().map_or(host::__WASI_EIO, errno_from_host))
 }
 
-pub(crate) fn fd_renumber(
-    wasi_ctx: &mut WasiCtx,
-    from: host::__wasi_fd_t,
-    to: host::__wasi_fd_t,
-) -> Result<()> {
-    let fe_from = match wasi_ctx.fds.get(&from) {
-        Some(fe_from) => fe_from,
-        None => return Err(host::__WASI_EBADF),
-    };
-    let fe_to = match wasi_ctx.fds.get(&to) {
-        Some(fe_to) => fe_to,
-        None => return Err(host::__WASI_EBADF),
-    };
-
-    // Don't allow renumbering over a pre-opened resource.
-    // TODO: Eventually, we do want to permit this, once libpreopen in
-    // userspace is capable of removing entries from its tables as well.
-    if fe_from.preopen_path.is_some() || fe_to.preopen_path.is_some() {
-        return Err(host::__WASI_ENOTSUP);
-    }
-
-    let rawfd_from = fe_from.fd_object.descriptor.as_raw_fd();
-    let rawfd_to = fe_to.fd_object.descriptor.as_raw_fd();
-
-    if let Err(e) = nix::unistd::dup2(rawfd_from, rawfd_to) {
-        return Err(host_impl::errno_from_nix(e.as_errno().unwrap()));
-    }
-
-    let _ = wasi_ctx.fds.remove(&(rawfd_from as host::__wasi_fd_t));
-
-    Ok(())
-}
-
 pub(crate) fn fd_seek(
     fd_entry: &FdEntry,
     offset: host::__wasi_filedelta_t,

src/sys/windows/hostcalls_impl/fs.rs

@@ -46,14 +46,6 @@ pub(crate) fn fd_pwrite(file: &File, buf: &[u8], offset: host::__wasi_filesize_t
         .map_err(|err| err.raw_os_error().map_or(host::__WASI_EIO, errno_from_host))
 }
 
-pub(crate) fn fd_renumber(
-    wasi_ctx: &mut WasiCtx,
-    from: host::__wasi_fd_t,
-    to: host::__wasi_fd_t,
-) -> Result<()> {
-    unimplemented!("fd_renumber")
-}
-
 pub(crate) fn fd_seek(
     fd_entry: &FdEntry,
     offset: host::__wasi_filedelta_t,