From 1c0214b29ddc6d2a048f3f3b8ecb34660a270ca7 Mon Sep 17 00:00:00 2001
From: Christopher Armstrong <christopherada.a@gmail.com>
Date: Mon, 20 Oct 2025 07:26:32 -0400
Subject: [PATCH] du: ignore env zero blocksize

---
 src/uu/du/src/du.rs      | 29 ++++++------
 tests/by-util/test_du.rs | 99 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 115 insertions(+), 13 deletions(-)

diff --git a/src/uu/du/src/du.rs b/src/uu/du/src/du.rs
index c893b06ca..4c29d07d3 100644
--- a/src/uu/du/src/du.rs
+++ b/src/uu/du/src/du.rs
@@ -31,7 +31,7 @@ use uucore::safe_traversal::DirFd;
 use uucore::translate;
 
 use uucore::parser::parse_glob;
-use uucore::parser::parse_size::{ParseSizeError, parse_size_u64};
+use uucore::parser::parse_size::{ParseSizeError, parse_size_non_zero_u64, parse_size_u64};
 use uucore::parser::shortcut_value_parser::ShortcutValueParser;
 use uucore::time::{FormatSystemTimeFallback, format, format_system_time};
 use uucore::{format_usage, show, show_error, show_warning};
@@ -271,23 +271,26 @@ fn get_file_info(path: &Path, _metadata: &Metadata) -> Option<FileInfo> {
     result
 }
 
+fn block_size_from_env() -> Option<u64> {
+    for env_var in ["DU_BLOCK_SIZE", "BLOCK_SIZE", "BLOCKSIZE"] {
+        if let Ok(env_size) = env::var(env_var) {
+            return parse_size_non_zero_u64(&env_size).ok();
+        }
+    }
+
+    None
+}
+
 fn read_block_size(s: Option<&str>) -> UResult<u64> {
     if let Some(s) = s {
         parse_size_u64(s)
             .map_err(|e| USimpleError::new(1, format_error_message(&e, s, options::BLOCK_SIZE)))
+    } else if let Some(bytes) = block_size_from_env() {
+        Ok(bytes)
+    } else if env::var("POSIXLY_CORRECT").is_ok() {
+        Ok(512)
     } else {
-        for env_var in ["DU_BLOCK_SIZE", "BLOCK_SIZE", "BLOCKSIZE"] {
-            if let Ok(env_size) = env::var(env_var) {
-                if let Ok(v) = parse_size_u64(&env_size) {
-                    return Ok(v);
-                }
-            }
-        }
-        if env::var("POSIXLY_CORRECT").is_ok() {
-            Ok(512)
-        } else {
-            Ok(1024)
-        }
+        Ok(1024)
     }
 }
 
diff --git a/tests/by-util/test_du.rs b/tests/by-util/test_du.rs
index 5f8c61396..7c6dcd6c3 100644
--- a/tests/by-util/test_du.rs
+++ b/tests/by-util/test_du.rs
@@ -179,6 +179,105 @@ fn test_du_with_posixly_correct() {
     assert_eq!(expected, result);
 }
 
+#[test]
+fn test_du_zero_env_block_size() {
+    let ts = TestScenario::new(util_name!());
+    let at = &ts.fixtures;
+    let dir = "a";
+
+    at.mkdir(dir);
+    at.write(&format!("{dir}/file"), "some content");
+
+    let expected = ts
+        .ucmd()
+        .arg(dir)
+        .arg("--block-size=1024")
+        .succeeds()
+        .stdout_move_str();
+
+    let result = ts
+        .ucmd()
+        .arg(dir)
+        .env("DU_BLOCK_SIZE", "0")
+        .succeeds()
+        .stdout_move_str();
+
+    assert_eq!(expected, result);
+}
+
+#[test]
+fn test_du_zero_env_block_size_hierarchy() {
+    let ts = TestScenario::new(util_name!());
+    let at = &ts.fixtures;
+    let dir = "a";
+
+    at.mkdir(dir);
+    at.write(&format!("{dir}/file"), "some content");
+
+    let expected = ts
+        .ucmd()
+        .arg(dir)
+        .arg("--block-size=1024")
+        .succeeds()
+        .stdout_move_str();
+
+    let result1 = ts
+        .ucmd()
+        .arg(dir)
+        .env("BLOCK_SIZE", "1")
+        .env("DU_BLOCK_SIZE", "0")
+        .succeeds()
+        .stdout_move_str();
+
+    let result2 = ts
+        .ucmd()
+        .arg(dir)
+        .env("BLOCK_SIZE", "1")
+        .env("BLOCKSIZE", "1")
+        .env("DU_BLOCK_SIZE", "0")
+        .succeeds()
+        .stdout_move_str();
+
+    assert_eq!(expected, result1);
+    assert_eq!(expected, result2);
+}
+
+#[test]
+fn test_du_env_block_size_hierarchy() {
+    let ts = TestScenario::new(util_name!());
+    let at = &ts.fixtures;
+    let dir = "a";
+
+    at.mkdir(dir);
+    at.write(&format!("{dir}/file"), "some content");
+
+    let expected = ts
+        .ucmd()
+        .arg(dir)
+        .arg("--block-size=1")
+        .succeeds()
+        .stdout_move_str();
+
+    let result1 = ts
+        .ucmd()
+        .arg(dir)
+        .env("BLOCK_SIZE", "0")
+        .env("DU_BLOCK_SIZE", "1")
+        .succeeds()
+        .stdout_move_str();
+
+    let result2 = ts
+        .ucmd()
+        .arg(dir)
+        .env("BLOCK_SIZE", "1")
+        .env("BLOCKSIZE", "0")
+        .succeeds()
+        .stdout_move_str();
+
+    assert_eq!(expected, result1);
+    assert_eq!(expected, result2);
+}
+
 #[test]
 fn test_du_non_existing_files() {
     new_ucmd!()