uucore(windows): rewrite fsext with safe Win32 wrappers, real free space and mount paths; df(windows): resolve paths by mount prefix

src/uu/df/src/filesystem.rs

@@ -8,7 +8,9 @@
 //! filesystem mounted at a particular directory. It also includes
 //! information on amount of space available and amount of space used.
 // spell-checker:ignore canonicalized
-use std::{ffi::OsString, path::Path};
+use std::ffi::OsString;
+#[cfg(unix)]
+use std::path::Path;
 
 use uucore::fsext::{FsUsage, MountInfo};
 
@@ -59,6 +61,7 @@ pub(crate) enum FsError {
 ///
 /// * [`Path::canonicalize`]
 /// * [`MountInfo::mount_dir`]
+#[cfg(unix)]
 fn mount_info_from_path<P>(
     mounts: &[MountInfo],
     path: P,
@@ -128,6 +131,7 @@ impl Filesystem {
     /// * [`Path::canonicalize`]
     /// * [`MountInfo::mount_dir`]
     ///
+    #[cfg(unix)]
     pub(crate) fn from_path<P>(mounts: &[MountInfo], path: P) -> Result<Self, FsError>
     where
         P: AsRef<Path>,
@@ -141,7 +145,7 @@ impl Filesystem {
     }
 }
 
-#[cfg(test)]
+#[cfg(all(test, unix))]
 mod tests {
 
     mod mount_info_from_path {

src/uu/df/src/platform/windows.rs

@@ -3,7 +3,9 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 
-//! Windows backend of `df`: volume usage probes and the `-i` notice.
+// spell-checker:ignore SUBST
+
+//! Windows backend of `df`: volume usage probes, path resolution and the `-i` notice.
 
 use std::ffi::OsString;
 use std::path::Path;
@@ -21,13 +23,7 @@ pub(crate) fn sync() {}
 
 /// Usage of the filesystem at `mount_info`, `None` if it cannot be queried.
 pub(crate) fn fs_usage(mount_info: &MountInfo) -> Option<FsUsage> {
-    let stat_path = if mount_info.mount_dir.is_empty() {
-        // On windows, we expect the volume id
-        mount_info.dev_id.as_ref()
-    } else {
-        mount_info.mount_dir.as_os_str()
-    };
-    FsUsage::new(Path::new(stat_path)).ok()
+    FsUsage::new(Path::new(&mount_info.mount_dir)).ok()
 }
 
 /// Find and create the filesystem from the given mount.
@@ -39,7 +35,9 @@ pub(crate) fn filesystem_from_mount(
     Filesystem::new(mount.clone(), file).ok_or(FsError::MountMissing)
 }
 
-/// Find and create the filesystem that contains `path` through the mount table.
+/// Find and create the filesystem that contains `path`: the mount with the
+/// longest directory prefixing it, or, when the mount table does not list it
+/// (UNC paths, unreadable table), the volume root the OS reports for it.
 pub(crate) fn filesystem_for_path<P>(
     mounts: &[MountInfo],
     _use_fallback: bool,
@@ -48,7 +46,23 @@ pub(crate) fn filesystem_for_path<P>(
 where
     P: AsRef<Path>,
 {
-    Filesystem::from_path(mounts, path)
+    let path = path.as_ref();
+    let file = path.as_os_str().to_owned();
+    // Not `canonicalize`: it resolves SUBST drives and junctions away and
+    // yields `\\?\` prefixes that never match a mount directory.
+    let absolute = std::path::absolute(path).map_err(|_| FsError::InvalidPath)?;
+    absolute.metadata().map_err(|_| FsError::InvalidPath)?;
+    let longest = mounts
+        .iter()
+        .filter(|m| absolute.starts_with(&m.mount_dir))
+        .max_by_key(|m| m.mount_dir.len());
+    let mount_info = if let Some(mount_info) = longest {
+        mount_info.clone()
+    } else {
+        let root = uucore::fs::volume_path_name(&absolute).map_err(|_| FsError::MountMissing)?;
+        MountInfo::from_mount_dir(root.into_os_string())
+    };
+    Filesystem::new(mount_info, Some(file)).ok_or(FsError::MountMissing)
 }
 
 /// `-i` is not supported: say so and stop successfully.

src/uucore/Cargo.toml

@@ -119,7 +119,9 @@ windows-sys = { workspace = true, optional = true, default-features = false, fea
   "Win32_Storage_FileSystem",
   "Win32_Foundation",
   "Win32_Globalization",
+  "Win32_NetworkManagement_WNet",
   "Win32_System_Console",
+  "Win32_System_Diagnostics_Debug",
   "Win32_System_IO",
   "Win32_System_Ioctl",
   "Win32_System_JobObjects",
@@ -144,7 +146,7 @@ entries = ["libc", "rustix/fs", "rustix/process"]
 extendedbigdecimal = ["bigdecimal", "num-traits"]
 fast-inc = []
 fs = ["dunce", "libc", "rustix/fs", "windows-sys"]
-fsext = ["libc", "windows-sys", "bstr"]
+fsext = ["libc", "windows-sys", "bstr", "wide"]
 fsxattr = ["xattr", "itertools", "libc"]
 hardware = []
 lines = []