fix default video save directory

Signed-off-by: 21pages <pages21@163.com>

src/platform/linux.rs

@@ -4,6 +4,7 @@ use hbb_common::{allow_err, bail, log};
 use libc::{c_char, c_int, c_void};
 use std::{
     cell::RefCell,
+    path::PathBuf,
     sync::{
         atomic::{AtomicBool, Ordering},
         Arc,
@@ -516,6 +517,17 @@ pub fn get_active_username() -> String {
     get_value_of_seat0(2)
 }
 
+pub fn get_active_user_home() -> Option<PathBuf> {
+    let username = get_active_username();
+    if !username.is_empty() {
+        let home = PathBuf::from(format!("/home/{}", username));
+        if home.exists() {
+            return Some(home);
+        }
+    }
+    None
+}
+
 pub fn is_prelogin() -> bool {
     let n = get_active_userid().len();
     n < 4 && n > 1