From 1f554739fd937e0699aae6efcc56248acd89aaf2 Mon Sep 17 00:00:00 2001
From: Logic769 <tiancongyu769@outlook.com>
Date: Fri, 30 Oct 2026 05:45:50 +0800
Subject: [PATCH 1/2] mktemp: treat an empty TMPDIR as unset

---
 src/uu/mktemp/src/mktemp.rs  | 18 +++++++--------
 tests/by-util/test_mktemp.rs | 43 ++++++++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 10 deletions(-)

diff --git a/src/uu/mktemp/src/mktemp.rs b/src/uu/mktemp/src/mktemp.rs
index 64281e5756a..79810117643 100644
--- a/src/uu/mktemp/src/mktemp.rs
+++ b/src/uu/mktemp/src/mktemp.rs
@@ -131,22 +131,20 @@ impl Options {
                 (tmpdir, OsString::from(template))
             }
             Some(template) => {
-                let tmpdir = if let Some(tmpdir) = env::var_os(TMPDIR_ENV_VAR)
+                let tmpdir = if let Some(tmpdir) =
+                    env::var_os(TMPDIR_ENV_VAR).filter(|val| !val.is_empty())
                     && matches.get_flag(OPT_T)
                 {
+                    // A non-empty `$TMPDIR` has priority over `-p` when
+                    // `-t` is given. An empty `$TMPDIR` is treated as
+                    // unset, so `-p` or the system default is used instead.
                     Some(PathBuf::from(tmpdir))
                 } else if tmpdir.is_some() {
                     tmpdir
                 } else if matches.get_flag(OPT_T) || matches.contains_id(OPT_TMPDIR) {
-                    // If --tmpdir is given without an argument, or -t is given
-                    // export in TMPDIR
-                    #[cfg(target_os = "wasi")]
-                    // WASI's `std::env::temp_dir()` unconditionally panics
-                    let default_tmp_dir = env::var_os(TMPDIR_ENV_VAR)
-                        .map_or_else(|| PathBuf::from(FALLBACK_TMPDIR), PathBuf::from);
-                    #[cfg(not(target_os = "wasi"))]
-                    let default_tmp_dir = env::temp_dir();
-                    Some(default_tmp_dir)
+                    // If --tmpdir is given without an argument, or -t is given,
+                    // export in TMPDIR.
+                    Some(get_tmpdir_env_or_default())
                 } else {
                     None
                 };
diff --git a/tests/by-util/test_mktemp.rs b/tests/by-util/test_mktemp.rs
index ca93e30b466..b40163d5603 100644
--- a/tests/by-util/test_mktemp.rs
+++ b/tests/by-util/test_mktemp.rs
@@ -937,6 +937,49 @@ fn test_empty_tmpdir_env_var() {
     }
 }
 
+#[test]
+#[cfg_attr(wasi_runner, ignore = "WASI sandbox: host paths not visible")]
+fn test_empty_tmpdir_env_var_with_template() {
+    #[cfg(not(any(windows, target_os = "android")))]
+    {
+        let scene = TestScenario::new(util_name!());
+        let pathname = scene.fixtures.as_string();
+
+        // An empty `$TMPDIR` must be treated as unset, so `-t` and
+        // `--tmpdir` fall back to the system default temporary directory.
+        for args in [
+            vec!["-t", TEST_TEMPLATE1],
+            vec!["--tmpdir", TEST_TEMPLATE1],
+            vec!["-d", "-t", TEST_TEMPLATE1],
+        ] {
+            let result = scene.ucmd().env(TMPDIR, "").args(&args).succeeds();
+            let path = PathBuf::from(result.stdout_str().trim());
+            assert!(
+                path.starts_with("/tmp"),
+                "expected a path under /tmp, got {path:?}",
+            );
+            if args.contains(&"-d") {
+                let _ = std::fs::remove_dir(&path);
+            } else {
+                let _ = std::fs::remove_file(&path);
+            }
+        }
+
+        // `-p` must take precedence over the empty `$TMPDIR`.
+        let result = scene
+            .ucmd()
+            .env(TMPDIR, "")
+            .args(&["-p", &pathname, "-t", TEST_TEMPLATE1])
+            .succeeds();
+        let path = PathBuf::from(result.stdout_str().trim());
+        assert!(
+            path.starts_with(&pathname),
+            "expected a path under {pathname}, got {path:?}",
+        );
+        let _ = std::fs::remove_file(&path);
+    }
+}
+
 #[test]
 fn test_nonexistent_dir_prefix() {
     #[cfg(not(windows))]

From 83583d622e55e1965aeee486d88c97cddb0765d1 Mon Sep 17 00:00:00 2001
From: Logic769 <tiancongyu769@outlook.com>
Date: Mon, 2 Nov 2026 10:12:05 +0800
Subject: [PATCH 2/2] test(mktemp): check created path type instead of
 arguments

---
 tests/by-util/test_mktemp.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/by-util/test_mktemp.rs b/tests/by-util/test_mktemp.rs
index b40163d5603..72b3b640ffc 100644
--- a/tests/by-util/test_mktemp.rs
+++ b/tests/by-util/test_mktemp.rs
@@ -958,7 +958,7 @@ fn test_empty_tmpdir_env_var_with_template() {
                 path.starts_with("/tmp"),
                 "expected a path under /tmp, got {path:?}",
             );
-            if args.contains(&"-d") {
+            if path.is_dir() {
                 let _ = std::fs::remove_dir(&path);
             } else {
                 let _ = std::fs::remove_file(&path);