strip UNC prefix on windows paths (vercel/turborepo#3847)

crates/next-dev/Cargo.toml

@@ -42,6 +42,7 @@ rustls-tls = ["next-core/rustls-tls"]
 anyhow = { version = "1.0.47", features = ["backtrace"] }
 clap = { version = "4.0.18", features = ["derive", "env"], optional = true }
 console-subscriber = { version = "0.1.8", optional = true }
+dunce = "1.0.3"
 futures = "0.3.25"
 mime = "0.3.16"
 next-core = { path = "../next-core" }

crates/next-dev/src/lib.rs

@@ -17,6 +17,7 @@ use std::{
 
 use anyhow::{anyhow, Context, Result};
 use devserver_options::DevServerOptions;
+use dunce::canonicalize;
 use next_core::{
     create_app_source, create_page_source, create_web_entry_source, env::load_env,
     manifest::DevManifestContentSource, next_config::load_next_config,
@@ -421,15 +422,15 @@ pub async fn start_server(options: &DevServerOptions) -> Result<()> {
     let dir = options
         .dir
         .as_ref()
-        .map(|dir| dir.canonicalize())
+        .map(|dir| canonicalize(dir))
         .unwrap_or_else(current_dir)
         .context("project directory can't be found")?
         .to_str()
         .context("project directory contains invalid characters")?
         .to_string();
 
     let root_dir = if let Some(root) = options.root.as_ref() {
-        root.canonicalize()
+        canonicalize(root)
             .context("root directory can't be found")?
             .to_str()
             .context("root directory contains invalid characters")?

crates/turbo-tasks-fs/Cargo.toml

@@ -18,6 +18,7 @@ auto-hash-map = { path = "../auto-hash-map" }
 bitflags = "1.3.2"
 bytes = "1.1.0"
 concurrent-queue = "1.2.2"
+dunce = "1.0.3"
 futures = "0.3.25"
 futures-retry = "0.6.0"
 include_dir = { version = "0.7.2", features = ["nightly"] }

crates/turbo-tasks-fs/src/embed/file.rs

@@ -1,15 +1,16 @@
 use std::path::PathBuf;
 
 use anyhow::{Context, Result};
+use dunce::canonicalize;
 
 use crate::{DiskFileSystemVc, File, FileContentVc, FileSystem};
 
 #[turbo_tasks::function]
 pub async fn content_from_relative_path(package_path: &str, path: &str) -> Result<FileContentVc> {
     let package_path = PathBuf::from(package_path);
     let resolved_path = package_path.join(path);
-    let resolved_path = std::fs::canonicalize(&resolved_path)
-        .context("failed to canonicalize embedded file path")?;
+    let resolved_path =
+        canonicalize(&resolved_path).context("failed to canonicalize embedded file path")?;
     let root_path = resolved_path.parent().unwrap();
     let path = resolved_path.file_name().unwrap().to_str().unwrap();
 

crates/turbo-tasks-fs/src/lib.rs

@@ -37,6 +37,7 @@ use std::{
 use anyhow::{anyhow, bail, Context, Result};
 use auto_hash_map::AutoMap;
 use bitflags::bitflags;
+use dunce::simplified;
 use glob::GlobVc;
 use invalidator_map::InvalidatorMap;
 use jsonc_parser::{parse_to_serde_value, ParseOptions};
@@ -58,8 +59,6 @@ use turbo_tasks_hash::hash_xxh3_hash64;
 use util::{join_path, normalize_path, sys_to_unix, unix_to_sys};
 
 use self::{json::UnparseableJson, mutex_map::MutexMap};
-#[cfg(target_family = "windows")]
-use crate::util::is_windows_raw_path;
 use crate::{
     attach::AttachedFileSystemVc,
     retry::{retry_blocking, retry_future},
@@ -270,7 +269,8 @@ impl DiskFileSystem {
     }
 
     pub async fn to_sys_path(&self, fs_path: FileSystemPathVc) -> Result<PathBuf> {
-        let path = Path::new(&self.root);
+        // just in case there's a windows unc path prefix we remove it with `dunce`
+        let path = simplified(Path::new(&self.root));
         let fs_path = fs_path.await?;
         Ok(if fs_path.path.is_empty() {
             path.to_path_buf()
@@ -419,18 +419,11 @@ impl FileSystem for DiskFileSystem {
         // strip the root from the path, it serves two purpose
         // 1. ensure the linked path is under the root
         // 2. strip the root path if the linked path is absolute
-        #[cfg(target_family = "windows")]
-        let result = {
-            let root_path = Path::new(&self.root);
-            if is_windows_raw_path(root_path) && !is_windows_raw_path(&file) {
-                file.strip_prefix(Path::new(&self.root[4..]))
-            } else {
-                file.strip_prefix(root_path)
-            }
-        };
+        //
+        // we use `dunce::simplify` to strip a potential UNC prefix on windows, on any
+        // other OS this gets compiled away
+        let result = simplified(&file).strip_prefix(simplified(Path::new(&self.root)));
 
-        #[cfg(not(target_family = "windows"))]
-        let result = file.strip_prefix(Path::new(&self.root));
         let relative_to_root_path = match result {
             Ok(file) => PathBuf::from(sys_to_unix(&file.to_string_lossy()).as_ref()),
             Err(_) => return Ok(LinkContent::Invalid.cell()),

crates/turbo-tasks-fs/src/util.rs

@@ -1,6 +1,4 @@
 use std::borrow::Cow;
-#[cfg(target_family = "windows")]
-use std::path::Path;
 
 /// Joins two /-separated paths into a normalized path.
 /// Paths are concatenated with /.
@@ -112,16 +110,3 @@ pub fn normalize_request(str: &str) -> String {
     }
     seqments.join("/")
 }
-
-#[cfg(target_family = "windows")]
-/// Checks if the path has the `\\?\` prefix which "tells the Windows APIs to
-/// disable all string parsing and to send the string that follows it straight
-/// to the file system."
-///
-/// See [Win32 File Namespaces](https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file#win32-file-namespaces)
-pub fn is_windows_raw_path(path: impl AsRef<Path>) -> bool {
-    // `Path::new("\\\\?\\D:\\workspace\\turbo-tooling").starts_with("\\\\?\\")` is
-    // `false`.
-    // So we use `String::starts_with` here
-    path.as_ref().to_string_lossy().starts_with("\\\\?\\")
-}