Refactor try_from and try_into error handing.

.vscode/settings.json

@@ -0,0 +1,7 @@
+{
+    "editor.formatOnSave": true,
+    "rust-client.disableRustup": false,
+    "rust.target": "x86_64-pc-windows-gnu",
+    //"rust.sysroot": "/home/marcin/.rustup/toolchains/stable-x86_64-pc-windows-gnu/",
+    "rust.all_targets": false
+}

src/helpers.rs

@@ -6,5 +6,5 @@ pub(crate) fn systemtime_to_timestamp(st: SystemTime) -> Result<u64> {
         .map_err(|_| Error::EINVAL)? // date earlier than UNIX_EPOCH
         .as_nanos()
         .try_into()
-        .map_err(|_| Error::EOVERFLOW) // u128 doesn't fit into u64
+        .map_err(Into::into) // u128 doesn't fit into u64
 }

src/hostcalls_impl/misc.rs

@@ -29,7 +29,7 @@ pub(crate) fn args_get(
 
         argv.push(arg_ptr);
 
-        let len = wasm32::uintptr_t::try_from(arg_bytes.len()).map_err(|_| Error::EOVERFLOW)?;
+        let len = wasm32::uintptr_t::try_from(arg_bytes.len())?;
         argv_buf_offset = argv_buf_offset.checked_add(len).ok_or(Error::EOVERFLOW)?;
     }
 
@@ -87,7 +87,7 @@ pub(crate) fn environ_get(
 
         environ.push(env_ptr);
 
-        let len = wasm32::uintptr_t::try_from(env_bytes.len()).map_err(|_| Error::EOVERFLOW)?;
+        let len = wasm32::uintptr_t::try_from(env_bytes.len())?;
         environ_buf_offset = environ_buf_offset
             .checked_add(len)
             .ok_or(Error::EOVERFLOW)?;

src/sys/unix/host_impl.rs

@@ -187,8 +187,8 @@ pub(crate) fn filestat_from_nix(
     }
 
     let filetype = nix::sys::stat::SFlag::from_bits_truncate(filestat.st_mode);
-    let dev = host::__wasi_device_t::try_from(filestat.st_dev).map_err(|_| Error::EOVERFLOW)?;
+    let dev = host::__wasi_device_t::try_from(filestat.st_dev)?;
-    let ino = host::__wasi_inode_t::try_from(filestat.st_ino).map_err(|_| Error::EOVERFLOW)?;
+    let ino = host::__wasi_inode_t::try_from(filestat.st_ino)?;
     let st_atim = filestat_to_timestamp(filestat.st_atime as u64, filestat.st_atime_nsec as u64)?;
     let st_ctim = filestat_to_timestamp(filestat.st_ctime as u64, filestat.st_ctime_nsec as u64)?;
     let st_mtim = filestat_to_timestamp(filestat.st_mtime as u64, filestat.st_mtime_nsec as u64)?;

src/sys/unix/hostcalls_impl/fs.rs

@@ -4,7 +4,7 @@ use super::fs_helpers::*;
 use crate::helpers::systemtime_to_timestamp;
 use crate::hostcalls_impl::PathGet;
 use crate::sys::host_impl::{self, errno_from_nix};
-use crate::{host, Result, Error};
+use crate::{host, Error, Result};
 use nix::libc::{self, c_long, c_void};
 use std::convert::TryInto;
 use std::ffi::CString;
@@ -51,8 +51,8 @@ pub(crate) fn fd_advise(
     {
         use nix::fcntl::{posix_fadvise, PosixFadviseAdvice};
 
-        let offset = offset.try_into().map_err(|_| Error::EOVERFLOW)?;
+        let offset = offset.try_into()?;
-        let len = len.try_into().map_err(|_| Error::EOVERFLOW)?;
+        let len = len.try_into()?;
         let host_advice = match advice {
             host::__WASI_ADVICE_DONTNEED => PosixFadviseAdvice::POSIX_FADV_DONTNEED,
             host::__WASI_ADVICE_SEQUENTIAL => PosixFadviseAdvice::POSIX_FADV_SEQUENTIAL,
@@ -102,10 +102,8 @@ pub(crate) fn path_create_directory(resolved: PathGet) -> Result<()> {
 
 pub(crate) fn path_link(resolved_old: PathGet, resolved_new: PathGet) -> Result<()> {
     use nix::libc::linkat;
-    let old_path_cstr =
+    let old_path_cstr = CString::new(resolved_old.path().as_bytes()).map_err(|_| Error::EILSEQ)?;
-        CString::new(resolved_old.path().as_bytes()).map_err(|_| Error::EILSEQ)?;
+    let new_path_cstr = CString::new(resolved_new.path().as_bytes()).map_err(|_| Error::EILSEQ)?;
-    let new_path_cstr =
-        CString::new(resolved_new.path().as_bytes()).map_err(|_| Error::EILSEQ)?;
 
     // Not setting AT_SYMLINK_FOLLOW fails on most filesystems
     let atflags = libc::AT_SYMLINK_FOLLOW;
@@ -305,10 +303,8 @@ pub(crate) fn path_readlink(resolved: PathGet, buf: &mut [u8]) -> Result<usize>
 
 pub(crate) fn path_rename(resolved_old: PathGet, resolved_new: PathGet) -> Result<()> {
     use nix::libc::renameat;
-    let old_path_cstr =
+    let old_path_cstr = CString::new(resolved_old.path().as_bytes()).map_err(|_| Error::EILSEQ)?;
-        CString::new(resolved_old.path().as_bytes()).map_err(|_| Error::EILSEQ)?;
+    let new_path_cstr = CString::new(resolved_new.path().as_bytes()).map_err(|_| Error::EILSEQ)?;
-    let new_path_cstr =
-        CString::new(resolved_new.path().as_bytes()).map_err(|_| Error::EILSEQ)?;
 
     let res = unsafe {
         renameat(
@@ -332,14 +328,10 @@ pub(crate) fn fd_filestat_get_impl(file: &std::fs::File) -> Result<host::__wasi_
     Ok(host::__wasi_filestat_t {
         st_dev: metadata.dev(),
         st_ino: metadata.ino(),
-        st_nlink: metadata
+        st_nlink: metadata.nlink().try_into()?, // u64 doesn't fit into u32
-            .nlink()
-            .try_into()?, // u64 doesn't fit into u32
         st_size: metadata.len(),
         st_atim: systemtime_to_timestamp(metadata.accessed()?)?,
-        st_ctim: metadata
+        st_ctim: metadata.ctime().try_into()?, // i64 doesn't fit into u64
-            .ctime()
-            .try_into()?, // i64 doesn't fit into u64
         st_mtim: systemtime_to_timestamp(metadata.modified()?)?,
         st_filetype: filetype(file, &metadata)?,
     })
@@ -432,7 +424,7 @@ pub(crate) fn path_filestat_set_times(
     };
 
     let atim = if set_atim_now {
-        let st_atim = st_atim.try_into().map_err(|_| Error::EOVERFLOW)?;
+        let st_atim = st_atim.try_into()?;
         TimeSpec::nanoseconds(st_atim)
     } else if set_atim_now {
         timespec_now()
@@ -441,7 +433,7 @@ pub(crate) fn path_filestat_set_times(
     };
 
     let mtim = if set_mtim {
-        let st_mtim = st_mtim.try_into().map_err(|_| Error::EOVERFLOW)?;
+        let st_mtim = st_mtim.try_into()?;
         TimeSpec::nanoseconds(st_mtim)
     } else if set_atim_now {
         timespec_now()
@@ -458,8 +450,7 @@ pub(crate) fn path_symlink(old_path: &str, resolved: PathGet) -> Result<()> {
     use nix::libc::symlinkat;
 
     let old_path_cstr = CString::new(old_path.as_bytes()).map_err(|_| Error::EILSEQ)?;
-    let new_path_cstr =
+    let new_path_cstr = CString::new(resolved.path().as_bytes()).map_err(|_| Error::EILSEQ)?;
-        CString::new(resolved.path().as_bytes()).map_err(|_| Error::EILSEQ)?;
 
     let res = unsafe {
         symlinkat(