Prevent future potential UB in unix wrapper for getpwuid() (#104)

src/os/unix.rs

@@ -236,7 +236,6 @@ fn getpwuid(name: Name) -> Result<OsString> {
     const BUF_SIZE: usize = 16_384; // size from the man page
     let mut buffer = mem::MaybeUninit::<[u8; BUF_SIZE]>::uninit();
     let mut passwd = mem::MaybeUninit::<PassWd>::uninit();
-    let mut _passwd = mem::MaybeUninit::<*mut PassWd>::uninit();
 
     // Get PassWd `struct`.
     let passwd = unsafe {
@@ -249,6 +248,7 @@ fn getpwuid(name: Name) -> Result<OsString> {
             target_os = "openbsd",
         ))]
         {
+            let mut _passwd = mem::MaybeUninit::<*mut PassWd>::uninit();
             let ret = getpwuid_r(
                 geteuid(),
                 passwd.as_mut_ptr(),
@@ -266,6 +266,7 @@ fn getpwuid(name: Name) -> Result<OsString> {
             if _passwd.is_null() {
                 return Err(super::err_null_record());
             }
+            passwd.assume_init()
         }
 
         #[cfg(target_os = "illumos")]
@@ -280,9 +281,8 @@ fn getpwuid(name: Name) -> Result<OsString> {
             if ret.is_null() {
                 return Err(Error::last_os_error());
             }
+            passwd.assume_init()
         }
-
-        passwd.assume_init()
     };
 
     // Extract names.