Replace SHGetFolderPathW with SHGetKnownFolderPath

Author: ChrisDenton

crates/home/Cargo.toml

@@ -17,7 +17,7 @@ repository = "https://github.com/rust-lang/cargo"
 description = "Shared definitions of home directories."
 
 [target.'cfg(windows)'.dependencies]
-windows-sys = { workspace = true, features = ["Win32_Foundation", "Win32_UI_Shell"] }
+windows-sys = { workspace = true, features = ["Win32_Foundation", "Win32_UI_Shell", "Win32_System_Com"] }
 
 [lints]
 workspace = true

crates/home/src/lib.rs

@@ -44,11 +44,11 @@ use std::path::{Path, PathBuf};
 ///
 /// Returns the value of the `USERPROFILE` environment variable if it is set
 /// **and** it is not an empty string. Otherwise, it tries to determine the
-/// home directory by invoking the [`SHGetFolderPathW`][shgfp] function with
-/// [`CSIDL_PROFILE`][csidl].
+/// home directory by invoking the [`SHGetKnownFolderPath`][shgkfp] function with
+/// [`FOLDERID_Profile`][knownfolderid].
 ///
-/// [shgfp]: https://docs.microsoft.com/en-us/windows/win32/api/shlobj_core/nf-shlobj_core-shgetfolderpathw
-/// [csidl]: https://learn.microsoft.com/en-us/windows/win32/shell/csidl
+/// [shgkfp]: https://learn.microsoft.com/en-us/windows/win32/api/shlobj_core/nf-shlobj_core-shgetknownfolderpath
+/// [knownfolderid]: https://learn.microsoft.com/en-us/windows/win32/shell/knownfolderid
 ///
 /// # Examples
 ///

crates/home/src/windows.rs

@@ -2,9 +2,12 @@ use std::env;
 use std::ffi::OsString;
 use std::os::windows::ffi::OsStringExt;
 use std::path::PathBuf;
+use std::ptr;
+use std::slice;
 
-use windows_sys::Win32::Foundation::{MAX_PATH, S_OK};
-use windows_sys::Win32::UI::Shell::{SHGetFolderPathW, CSIDL_PROFILE};
+use windows_sys::Win32::Foundation::S_OK;
+use windows_sys::Win32::System::Com::CoTaskMemFree;
+use windows_sys::Win32::UI::Shell::{FOLDERID_Profile, SHGetKnownFolderPath, KF_FLAG_DONT_VERIFY};
 
 pub fn home_dir_inner() -> Option<PathBuf> {
     env::var_os("USERPROFILE")
@@ -16,15 +19,19 @@ pub fn home_dir_inner() -> Option<PathBuf> {
 #[cfg(not(target_vendor = "uwp"))]
 fn home_dir_crt() -> Option<PathBuf> {
     unsafe {
-        let mut path: Vec<u16> = Vec::with_capacity(MAX_PATH as usize);
-        match SHGetFolderPathW(0, CSIDL_PROFILE as i32, 0, 0, path.as_mut_ptr()) {
+        let mut path = ptr::null_mut();
+        match SHGetKnownFolderPath(&FOLDERID_Profile, KF_FLAG_DONT_VERIFY as u32, 0, &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
+            }
         }
     }
 }

src/cargo/sources/git/known_hosts.rs

@@ -538,7 +538,7 @@ fn user_known_host_location() -> Option<PathBuf> {
     // - OpenSSH (most unix platforms): Uses `pw->pw_dir` from `getpwuid()`.
     //
     // This doesn't do anything close to that. home_dir's behavior is:
-    // - Windows: $USERPROFILE, or SHGetFolderPathW()
+    // - Windows: $USERPROFILE, or SHGetKnownFolderPath()
     // - Unix: $HOME, or getpwuid_r()
     //
     // Since there is a mismatch here, the location returned here might be