Internally use widestring crate and CString similar extension for managing null terminated utf16 strings (#9)

Author: mveril

Cargo.lock

@@ -9,15 +9,16 @@ version = "0.58"
 features = ["Win32_Foundation", "Win32_System", "Win32_Networking_WinSock"]
 
 [dependencies]
-wslplugins-sys = { path = "../wslplugins-sys" }
-typed-path = ">0.1"
 bitflags = { version = ">0.1.0", optional = true }
-flagset = { version = ">0.1.0", optional = true }
 enumflags2 = { version = ">0.5", optional = true }
+flagset = { version = ">0.1.0", optional = true }
 log = { version = "*", optional = true }
 log-instrument = { version = "*", optional = true }
-wslplugins-macro = { path = "../wslplugins-macro", optional = true }
 thiserror = "2.0.7"
+typed-path = ">0.1"
+widestring = { version = "1", features = ["alloc"] }
+wslplugins-macro = { path = "../wslplugins-macro", optional = true }
+wslplugins-sys = { path = "../wslplugins-sys" }
 
 [dependencies.semver]
 version = ">0.1"

wslplugins-rs/Cargo.toml

@@ -3,20 +3,20 @@ extern crate wslplugins_sys;
 use super::Error;
 use super::Result;
 use crate::api::errors::require_update_error::Result as UpReqResult;
-use crate::utils::{cstring_from_str, encode_wide_null_terminated};
+use crate::cstring_ext::CstringExt;
 use crate::wsl_session_information::WSLSessionInformation;
 #[cfg(feature = "log-instrument")]
 use log_instrument::instrument;
-use std::ffi::{CString, OsStr, OsString};
+use std::ffi::{CString, OsStr};
 use std::fmt::Debug;
 use std::iter::once;
 use std::mem::MaybeUninit;
 use std::net::TcpStream;
 use std::os::windows::io::FromRawSocket;
 use std::os::windows::raw::SOCKET;
 use std::path::Path;
-use std::str::FromStr;
 use typed_path::Utf8UnixPath;
+use widestring::U16CString;
 use windows::Win32::Networking::WinSock::SOCKET as WinSocket;
 use windows::{
     core::{Result as WinResult, GUID, PCSTR, PCWSTR},
@@ -99,13 +99,10 @@ impl ApiV1 {
         read_only: bool,
         name: &OsStr,
     ) -> WinResult<()> {
-        let encoded_windows_path = encode_wide_null_terminated(windows_path.as_ref().as_os_str());
-        let encoded_linux_path = encode_wide_null_terminated(
-            OsString::from_str(linux_path.as_ref().as_str())
-                .unwrap()
-                .as_os_str(),
-        );
-        let encoded_name = encode_wide_null_terminated(name);
+        let encoded_windows_path =
+            U16CString::from_os_str_truncate(windows_path.as_ref().as_os_str());
+        let encoded_linux_path = U16CString::from_str_truncate(linux_path.as_ref().as_str());
+        let encoded_name = U16CString::from_os_str_truncate(name);
         let result = unsafe {
             self.0.MountFolder.unwrap_unchecked()(
                 session.id(),
@@ -163,7 +160,10 @@ impl ApiV1 {
             .copied()
             .chain(once(0))
             .collect();
-        let c_args: Vec<CString> = args.iter().map(|&arg| cstring_from_str(arg)).collect();
+        let c_args: Vec<CString> = args
+            .iter()
+            .map(|&arg| CString::from_str_truncate(arg))
+            .collect();
         let mut args_ptrs: Vec<PCSTR> = c_args
             .iter()
             .map(|arg| PCSTR::from_raw(arg.as_ptr() as *const u8))
@@ -188,8 +188,10 @@ impl ApiV1 {
     /// Set the error message to display to the user if the VM or distribution creation fails.
     #[cfg_attr(feature = "log-instrument", instrument)]
     pub(crate) fn plugin_error(&self, error: &OsStr) -> WinResult<()> {
-        let error_vec = encode_wide_null_terminated(error);
-        unsafe { self.0.PluginError.unwrap_unchecked()(PCWSTR::from_raw(error_vec.as_ptr())).ok() }
+        let error_utf16 = U16CString::from_os_str_truncate(error);
+        unsafe {
+            self.0.PluginError.unwrap_unchecked()(PCWSTR::from_raw(error_utf16.as_ptr())).ok()
+        }
     }
 
     /// Execute a program in a user distribution
@@ -242,7 +244,10 @@ impl ApiV1 {
             .chain(once(0))
             .collect();
         let path_ptr = PCSTR::from_raw(c_path.as_ptr());
-        let c_args: Vec<CString> = args.iter().map(|&arg| cstring_from_str(arg)).collect();
+        let c_args: Vec<CString> = args
+            .iter()
+            .map(|&arg| CString::from_str_truncate(arg))
+            .collect();
         let mut args_ptrs: Vec<PCSTR> = c_args
             .iter()
             .map(|arg| PCSTR::from_raw(arg.as_ptr() as *const u8))

wslplugins-rs/src/api/api_v1.rs

@@ -0,0 +1,59 @@
+use std::ffi::CString;
+
+pub(crate) trait CstringExt {
+    /// Creates a `CString` from a string slice, truncating at the first null byte if present.
+    fn from_str_truncate(value: &str) -> Self;
+}
+
+impl CstringExt for CString {
+    fn from_str_truncate(value: &str) -> Self {
+        let bytes = value.as_bytes();
+        let truncated_bytes = match bytes.iter().position(|&b| b == 0) {
+            Some(pos) => &bytes[..pos],
+            None => bytes,
+        };
+        // SAFETY: `truncated_bytes` is guaranteed not to contain null bytes.
+        unsafe { Self::from_vec_unchecked(truncated_bytes.to_vec()) }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::ffi::CString;
+
+    #[test]
+    fn test_from_str_truncate_no_null() {
+        let input = "Hello, world!";
+        let cstring = CString::from_str_truncate(input);
+        assert_eq!(cstring.to_str().unwrap(), input);
+    }
+
+    #[test]
+    fn test_from_str_truncate_with_null() {
+        let input = "Hello\0world!";
+        let cstring = CString::from_str_truncate(input);
+        assert_eq!(cstring.to_str().unwrap(), "Hello");
+    }
+
+    #[test]
+    fn test_from_str_truncate_empty() {
+        let input = "";
+        let cstring = CString::from_str_truncate(input);
+        assert_eq!(cstring.to_str().unwrap(), "");
+    }
+
+    #[test]
+    fn test_from_str_truncate_null_only() {
+        let input = "\0";
+        let cstring = CString::from_str_truncate(input);
+        assert_eq!(cstring.to_str().unwrap(), "");
+    }
+
+    #[test]
+    fn test_from_str_truncate_null_in_middle() {
+        let input = "Rust\0is awesome!";
+        let cstring = CString::from_str_truncate(input);
+        assert_eq!(cstring.to_str().unwrap(), "Rust");
+    }
+}

wslplugins-rs/src/cstring_ext.rs

@@ -41,6 +41,7 @@ pub mod api;
 
 // Internal modules for managing specific WSL features.
 mod core_distribution_information;
+pub(crate) mod cstring_ext;
 mod distribution_information;
 mod offline_distribution_information;
 mod utils;

wslplugins-rs/src/lib.rs

@@ -1,66 +1,5 @@
-//! # String Encoding Utilities
-//!
-//! This module provides utility functions to handle string encoding conversions, specifically for:
-//! - Encoding `OsStr` as wide, null-terminated UTF-16 strings.
-//! - Creating `CString` instances from Rust strings, filtering out null bytes.
-
-use std::ffi::{CString, OsStr};
-use std::os::windows::ffi::OsStrExt;
-
-pub fn encode_wide_null_terminated(input: &OsStr) -> Vec<u16> {
-    input
-        .encode_wide()
-        .filter(|&c| c != 0)
-        .chain(Some(0))
-        .collect()
-}
-
-pub fn cstring_from_str(input: &str) -> CString {
-    let filtered_input: Vec<u8> = input.bytes().filter(|&c| c != 0).collect();
-    unsafe { CString::from_vec_unchecked(filtered_input) }
-}
-
 #[cfg(test)]
 pub(crate) fn test_transparence<T, U>() {
     assert_eq!(align_of::<T>(), align_of::<U>());
     assert_eq!(size_of::<T>(), size_of::<U>());
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use std::ffi::OsString;
-
-    /// Tests `encode_wide_null_terminated` with a string containing no null characters.
-    #[test]
-    fn test_encode_wide_null_terminated_no_nulls() {
-        let input = OsString::from("Hello");
-        let expected: Vec<u16> = "Hello\0".encode_utf16().collect();
-        assert_eq!(encode_wide_null_terminated(&input), expected);
-    }
-
-    /// Tests `encode_wide_null_terminated` with a string containing null characters.
-    #[test]
-    fn test_encode_wide_null_terminated_with_nulls() {
-        let input = OsString::from("Hel\0lo");
-        let expected: Vec<u16> = "Hello\0".encode_utf16().collect();
-        assert_eq!(encode_wide_null_terminated(&input), expected);
-    }
-
-    /// Tests `cstring_from_str` with a string containing no null characters.
-    #[test]
-    fn test_cstring_from_str_no_nulls() {
-        let input = "Hello";
-        let cstring = cstring_from_str(input);
-        assert_eq!(cstring.to_str().unwrap(), input);
-    }
-
-    /// Tests `cstring_from_str` with a string containing null characters.
-    #[test]
-    fn test_cstring_from_str_with_nulls() {
-        let input = "Hel\0lo";
-        let cstring = cstring_from_str(input);
-        let expected = "Hello".as_bytes();
-        assert_eq!(cstring.into_bytes(), expected);
-    }
-}