df(windows): fix Avail/Use% by using number_of_free_clusters for bavail (#7461)

Author: naoNao89

src/uucore/src/lib/features/fsext.rs

@@ -683,7 +683,9 @@ impl FsUsage {
             //  Total number of free blocks.
             bfree: number_of_free_clusters as u64,
             //  Total number of free blocks available to non-privileged processes.
-            bavail: 0,
+            // Windows: 'bavail' should reflect free clusters available to non-privileged processes.
+            // See: https://github.com/uutils/coreutils/issues/7461
+            bavail: number_of_free_clusters as u64,
             bavail_top_bit_set: ((bytes_per_sector as u64) & (1u64.rotate_right(1))) != 0,
             // Total number of file nodes (inodes) on the file system.
             files: 0, // Not available on windows

tests/by-util/test_df.rs

@@ -973,3 +973,23 @@ fn test_nonexistent_file() {
         .stderr_is("df: does-not-exist: No such file or directory\n")
         .stdout_is("File\n.\n");
 }
+
+#[test]
+#[cfg(target_os = "windows")]
+fn test_windows_avail_column_not_zero() {
+    // Regression test for issue #7461: Avail column should not be 0 on Windows
+    let output = new_ucmd!()
+        .args(&["--output=avail"])
+        .succeeds()
+        .stdout_str_lossy();
+
+    let lines: Vec<&str> = output.lines().skip(1).collect();
+    assert!(!lines.is_empty(), "Should have at least one filesystem");
+
+    // At least one filesystem should have non-zero avail
+    let has_non_zero = lines.iter().any(|line| {
+        line.trim().parse::<u64>().map(|v| v > 0).unwrap_or(false)
+    });
+
+    assert!(has_non_zero, "At least one filesystem should have non-zero available space");
+}