wsl2: wsl no longer differs in output

refactor `is_wsl` to `is_wsl_1` and `is_wsl_2`

On my tests with wsl2 ubuntu2004 all tests pass without special cases

I moved wsl detection into uucore so that it can be shared instead of duplicated

I moved `parse_mode` into uucode as it seemed to fit there better and anyway requires libc feature

tests/by-util/test_chgrp.rs

@@ -1,5 +1,6 @@
 use crate::common::util::*;
 use rust_users::*;
+use uucore;
 
 #[test]
 fn test_invalid_option() {
@@ -104,7 +105,7 @@ fn test_reference() {
     // skip for root or MS-WSL
     // * MS-WSL is bugged (as of 2019-12-25), allowing non-root accounts su-level privileges for `chgrp`
     // * for MS-WSL, succeeds and stdout == 'group of /etc retained as root'
-    if !(get_effective_gid() == 0 || is_wsl()) {
+    if !(get_effective_gid() == 0 || uucore::os::is_wsl_1()) {
         new_ucmd!()
             .arg("-v")
             .arg("--reference=/etc/passwd")

tests/by-util/test_date.rs

@@ -4,6 +4,7 @@ use self::regex::Regex;
 use crate::common::util::*;
 #[cfg(all(unix, not(target_os = "macos")))]
 use rust_users::*;
+use uucore;
 
 #[test]
 fn test_date_email() {
@@ -159,7 +160,7 @@ fn test_date_set_invalid() {
 #[test]
 #[cfg(all(unix, not(target_os = "macos")))]
 fn test_date_set_permissions_error() {
-    if !(get_effective_uid() == 0 || is_wsl()) {
+    if !(get_effective_uid() == 0 || uucore::os::is_wsl_1()) {
         let (_, mut ucmd) = at_and_ucmd!();
         let result = ucmd.arg("--set").arg("2020-03-11 21:45:00+08:00").fails();
         let result = result.no_stdout();

tests/by-util/test_du.rs

@@ -1,4 +1,5 @@
 use crate::common::util::*;
+use uucore;
 
 const SUB_DIR: &str = "subdir/deeper";
 const SUB_DIR_LINKS: &str = "subdir/links";
@@ -52,7 +53,7 @@ fn _du_basics_subdir(s: String) {
 #[cfg(all(not(target_vendor = "apple"), not(target_os = "windows")))]
 fn _du_basics_subdir(s: String) {
     // MS-WSL linux has altered expected output
-    if !is_wsl() {
+    if !uucore::os::is_wsl_1() {
         assert_eq!(s, "8\tsubdir/deeper\n");
     } else {
         assert_eq!(s, "0\tsubdir/deeper\n");
@@ -96,7 +97,7 @@ fn _du_soft_link(s: String) {
 #[cfg(all(not(target_vendor = "apple"), not(target_os = "windows")))]
 fn _du_soft_link(s: String) {
     // MS-WSL linux has altered expected output
-    if !is_wsl() {
+    if !uucore::os::is_wsl_1() {
         assert_eq!(s, "16\tsubdir/links\n");
     } else {
         assert_eq!(s, "8\tsubdir/links\n");
@@ -128,7 +129,7 @@ fn _du_hard_link(s: String) {
 #[cfg(all(not(target_vendor = "apple"), not(target_os = "windows")))]
 fn _du_hard_link(s: String) {
     // MS-WSL linux has altered expected output
-    if !is_wsl() {
+    if !uucore::os::is_wsl_1() {
         assert_eq!(s, "16\tsubdir/links\n");
     } else {
         assert_eq!(s, "8\tsubdir/links\n");
@@ -156,7 +157,7 @@ fn _du_d_flag(s: String) {
 #[cfg(all(not(target_vendor = "apple"), not(target_os = "windows")))]
 fn _du_d_flag(s: String) {
     // MS-WSL linux has altered expected output
-    if !is_wsl() {
+    if !uucore::os::is_wsl_1() {
         assert_eq!(s, "28\t./subdir\n36\t./\n");
     } else {
         assert_eq!(s, "8\t./subdir\n8\t./\n");

tests/by-util/test_logname.rs

@@ -1,5 +1,6 @@
 use crate::common::util::*;
 use std::env;
+use uucore;
 
 #[test]
 fn test_normal() {
@@ -13,7 +14,7 @@ fn test_normal() {
     for (key, value) in env::vars() {
         println!("{}: {}", key, value);
     }
-    if (is_ci() || is_wsl()) && result.stderr.contains("error: no login name") {
+    if (is_ci() || uucore::os::is_wsl_1()) && result.stderr.contains("error: no login name") {
         // ToDO: investigate WSL failure
         // In the CI, some server are failing to return logname.
         // As seems to be a configuration issue, ignoring it

tests/common/util.rs

@@ -40,22 +40,6 @@ pub fn is_ci() -> bool {
         .eq_ignore_ascii_case("true")
 }
 
-/// Test if the program is running under WSL
-// ref: <https://github.com/microsoft/WSL/issues/4555> @@ <https://archive.is/dP0bz>
-// ToDO: test on WSL2 which likely doesn't need special handling; plan change to `is_wsl_1()` if WSL2 is less needy
-pub fn is_wsl() -> bool {
-    #[cfg(target_os = "linux")]
-    {
-        if let Ok(b) = std::fs::read("/proc/sys/kernel/osrelease") {
-            if let Ok(s) = std::str::from_utf8(&b) {
-                let a = s.to_ascii_lowercase();
-                return a.contains("microsoft") || a.contains("wsl");
-            }
-        }
-    }
-    false
-}
-
 /// Read a test scenario fixture, returning its bytes
 fn read_scenario_fixture<S: AsRef<OsStr>>(tmpd: &Option<Rc<TempDir>>, file_rel_path: S) -> Vec<u8> {
     let tmpdir_path = tmpd.as_ref().unwrap().as_ref().path();