Keep the old code for win7.

Author: smmalis37

library/std/src/sys/windows/c/windows_sys.lst

@@ -2537,6 +2537,7 @@ Windows.Win32.System.Threading.InitOnceComplete
 Windows.Win32.System.Threading.LPPROC_THREAD_ATTRIBUTE_LIST
 Windows.Win32.System.Threading.LPTHREAD_START_ROUTINE
 Windows.Win32.System.Threading.NORMAL_PRIORITY_CLASS
+Windows.Win32.System.Threading.OpenProcessToken
 Windows.Win32.System.Threading.PROCESS_CREATION_FLAGS
 Windows.Win32.System.Threading.PROCESS_INFORMATION
 Windows.Win32.System.Threading.PROCESS_MODE_BACKGROUND_BEGIN

library/std/src/sys/windows/c/windows_sys.rs

@@ -8,6 +8,14 @@
 
 #![allow(non_snake_case, non_upper_case_globals, non_camel_case_types, dead_code, clippy::all)]
 #[link(name = "advapi32")]
+extern "system" {
+    pub fn OpenProcessToken(
+        processhandle: HANDLE,
+        desiredaccess: TOKEN_ACCESS_MASK,
+        tokenhandle: *mut HANDLE,
+    ) -> BOOL;
+}
+#[link(name = "advapi32")]
 extern "system" {
     #[link_name = "SystemFunction036"]
     pub fn RtlGenRandom(randombuffer: *mut ::core::ffi::c_void, randombufferlength: u32)

library/std/src/sys/windows/os.rs

@@ -318,7 +318,7 @@ pub fn temp_dir() -> PathBuf {
     super::fill_utf16_buf(|buf, sz| unsafe { c::GetTempPath2W(sz, buf) }, super::os2path).unwrap()
 }
 
-#[cfg(not(target_vendor = "uwp"))]
+#[cfg(and(not(target_vendor = "uwp"), not(target_vendor = "win7"))]
 fn home_dir_crt() -> Option<PathBuf> {
     unsafe {
         // Defined in processthreadsapi.h.
@@ -342,6 +342,31 @@ fn home_dir_crt() -> Option<PathBuf> {
     }
 }
 
+#[cfg(target_vendor = "win7")]
+fn home_dir_crt() -> Option<PathBuf> {
+    unsafe {
+        use crate::sys::handle::Handle;
+
+        let me = c::GetCurrentProcess();
+        let mut token = ptr::null_mut();
+        if c::OpenProcessToken(me, c::TOKEN_READ, &mut token) == 0 {
+            return None;
+        }
+        let _handle = Handle::from_raw_handle(token);
+        super::fill_utf16_buf(
+            |buf, mut sz| {
+                match c::GetUserProfileDirectoryW(token, buf, &mut sz) {
+                    0 if api::get_last_error().code != c::ERROR_INSUFFICIENT_BUFFER => 0,
+                    0 => sz,
+                    _ => sz - 1, // sz includes the null terminator
+                }
+            },
+            super::os2path,
+        )
+        .ok()
+    }
+}
+
 #[cfg(target_vendor = "uwp")]
 fn home_dir_crt() -> Option<PathBuf> {
     None