windows-sys: bump & replace SHGetFolderPathW with SHGetKnownFolderPath

Cargo.toml

@@ -18,4 +18,4 @@ home = "0.5"
 
 # We should keep this in sync with the `home` crate.
 [target.'cfg(windows)'.dependencies]
-windows-sys = { version = "0.48", features = ["Win32_Foundation", "Win32_UI_Shell"] }
+windows-sys = { version = "0.59", features = ["Win32_Foundation", "Win32_System_Com", "Win32_UI_Shell"] }

src/app_strategy/windows.rs

@@ -5,7 +5,7 @@ use std::path::{Path, PathBuf};
 /// This strategy follows Windows’ conventions. It seems that all Windows GUI apps, and some command-line ones follow this pattern. The specification is available [here](https://docs.microsoft.com/en-us/windows/win32/shell/knownfolderid).
 ///
 /// This initial example removes all the relevant environment variables to show the strategy’s use of the:
-/// - (on Windows) SHGetFolderPathW API.
+/// - (on Windows) SHGetKnownFolderPath API.
 /// - (on non-Windows) Windows default directories.
 ///
 /// ```

src/base_strategy/windows.rs

@@ -5,7 +5,7 @@ use crate::HomeDirError;
 /// This strategy follows Windows’ conventions. It seems that all Windows GUI apps, and some command-line ones follow this pattern. The specification is available [here](https://docs.microsoft.com/en-us/windows/win32/shell/knownfolderid).
 ///
 /// This initial example removes all the relevant environment variables to show the strategy’s use of the:
-/// - (on Windows) SHGetFolderPathW API.
+/// - (on Windows) SHGetKnownFolderPath API.
 /// - (on non-Windows) Windows default directories.
 ///
 /// ```
@@ -108,8 +108,6 @@ pub struct Windows {
     home_dir: PathBuf,
 }
 
-// Ref: /~https://github.com/rust-lang/cargo/blob/home-0.5.5/crates/home/src/windows.rs
-// We should keep this code in sync with the above.
 impl Windows {
     /// Create a new Windows BaseStrategy
     pub fn new() -> Result<Self, HomeDirError> {
@@ -125,39 +123,56 @@ impl Windows {
             .or_else(|| Self::dir_crt(env))
     }
 
-    #[cfg(all(windows, target_vendor = "uwp"))]
+    // Ref: /~https://github.com/rust-lang/cargo/blob/home-0.5.11/crates/home/src/windows.rs
+    // We should keep this code in sync with the above.
+    #[cfg(all(windows, not(target_vendor = "uwp")))]
     fn dir_crt(env: &'static str) -> Option<PathBuf> {
         use std::ffi::OsString;
         use std::os::windows::ffi::OsStringExt;
-
-        use windows_sys::Win32::Foundation::{MAX_PATH, S_OK};
-        use windows_sys::Win32::UI::Shell::{SHGetFolderPathW, CSIDL_APPDATA, CSIDL_LOCAL_APPDATA};
-
-        let csidl = match env {
-            "APPDATA" => CSIDL_APPDATA,
-            "LOCALAPPDATA" => CSIDL_LOCAL_APPDATA,
-            _ => return None,
+        use std::ptr;
+        use std::slice;
+
+        use windows_sys::Win32::Foundation::S_OK;
+        use windows_sys::Win32::System::Com::CoTaskMemFree;
+        use windows_sys::Win32::UI::Shell::{
+            FOLDERID_LocalAppData, FOLDERID_RoamingAppData, SHGetKnownFolderPath,
+            KF_FLAG_DONT_VERIFY,
         };
 
         extern "C" {
             fn wcslen(buf: *const u16) -> usize;
         }
 
+        let folder_id = match env {
+            "APPDATA" => FOLDERID_RoamingAppData,
+            "LOCALAPPDATA" => FOLDERID_LocalAppData,
+            _ => return None,
+        };
+
         unsafe {
-            let mut path: Vec<u16> = Vec::with_capacity(MAX_PATH as usize);
-            match SHGetFolderPathW(0, csidl, 0, 0, path.as_mut_ptr()) {
+            let mut path = ptr::null_mut();
+            match SHGetKnownFolderPath(
+                &folder_id,
+                KF_FLAG_DONT_VERIFY as u32,
+                std::ptr::null_mut(),
+                &mut path,
+            ) {
                 S_OK => {
-                    let len = wcslen(path.as_ptr());
-                    path.set_len(len);
-                    let s = OsString::from_wide(&path);
+                    let path_slice = slice::from_raw_parts(path, wcslen(path));
+                    let s = OsString::from_wide(path_slice);
+                    CoTaskMemFree(path.cast());
                     Some(PathBuf::from(s))
                 }
-                _ => None,
+                _ => {
+                    // Free any allocated memory even on failure. A null ptr is a no-op for `CoTaskMemFree`.
+                    CoTaskMemFree(path.cast());
+                    None
+                }
             }
         }
     }
 
-    #[cfg(not(all(windows, target_vendor = "uwp")))]
+    #[cfg(not(all(windows, not(target_vendor = "uwp"))))]
     fn dir_crt(_env: &'static str) -> Option<PathBuf> {
         None
     }