From 2f6b64cee4218ca3d445d04be2d9ed68dff80da9 Mon Sep 17 00:00:00 2001
From: ccmsi <ccmsi@localhost>
Date: Tue, 15 Sep 2026 21:33:48 -0400
Subject: [PATCH 1/2] sync: fsync() file operands when no -d/-f flags (GNU
 MODE_FILE compat)

With file operands and no --data/-d or --file-system/-f flag, GNU sync enters MODE_FILE and fsync()s each operand. uutils instead falls through to a global sync(), silently ignoring the operands and blocking on every filesystem behind initramfs/dracut. Add an fsync(2) path (Linux/Android) mirroring do_fdatasync, and a regression test using /proc/self/mem which rejects fsync() with EINVAL (a global sync() would wrongly exit 0).

Fixes: #14591
---
 src/uu/sync/src/sync.rs    | 13 +++++++++++++
 tests/by-util/test_sync.rs | 13 +++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/src/uu/sync/src/sync.rs b/src/uu/sync/src/sync.rs
index d6137345056..8693e7ae2ac 100644
--- a/src/uu/sync/src/sync.rs
+++ b/src/uu/sync/src/sync.rs
@@ -86,6 +86,11 @@ mod platform {
     pub fn do_fdatasync(files: &[String]) -> UResult<()> {
         do_sync_with(files, rustix::fs::fdatasync)
     }
+
+    #[cfg(any(target_os = "linux", target_os = "android"))]
+    pub fn do_fsync(files: &[String]) -> UResult<()> {
+        do_sync_with(files, rustix::fs::fsync)
+    }
 }
 
 #[cfg(windows)]
@@ -254,6 +259,9 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     } else if matches.get_flag(options::DATA) {
         #[cfg(any(target_os = "linux", target_os = "android"))]
         fdatasync(&files)?;
+    } else if !files.is_empty() {
+        #[cfg(any(target_os = "linux", target_os = "android"))]
+        fsync(&files)?;
     } else {
         sync()?;
     }
@@ -303,3 +311,8 @@ fn syncfs(files: &[String]) -> UResult<()> {
 fn fdatasync(files: &[String]) -> UResult<()> {
     platform::do_fdatasync(files)
 }
+
+#[cfg(any(target_os = "linux", target_os = "android"))]
+fn fsync(files: &[String]) -> UResult<()> {
+    platform::do_fsync(files)
+}
diff --git a/tests/by-util/test_sync.rs b/tests/by-util/test_sync.rs
index 8516aac9d77..0f775e83f66 100644
--- a/tests/by-util/test_sync.rs
+++ b/tests/by-util/test_sync.rs
@@ -143,6 +143,19 @@ fn test_sync_fdatasync_error_handling() {
         .stderr_contains("error opening");
 }
 
+#[cfg(any(target_os = "linux", target_os = "android"))]
+#[test]
+fn test_sync_file_operands_fsync_each_file() {
+    // Regression test: `sync FILE` (no -d/-f flags) must fsync each file
+    // like GNU coreutils, not fall back to a global sync() that ignores
+    // the operands. /proc/self/mem rejects fsync() with EINVAL, so this
+    // must fail; a global sync() would wrongly exit 0.
+    new_ucmd!()
+        .arg("/proc/self/mem")
+        .fails_with_code(1)
+        .stderr_contains("error syncing");
+}
+
 #[cfg(target_vendor = "apple")]
 #[test]
 fn test_sync_syncfs_error_handling_macos() {

From 466fb2b815140f12972f9d0e3ec77c43be04103b Mon Sep 17 00:00:00 2001
From: Cam <6634309+lostallmymoney@users.noreply.github.com>
Date: Wed, 16 Sep 2026 15:06:56 -0400
Subject: [PATCH 2/2] Update tests/by-util/test_sync.rs

Co-authored-by: oech3 <79379754+oech3@users.noreply.github.com>
---
 tests/by-util/test_sync.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/by-util/test_sync.rs b/tests/by-util/test_sync.rs
index 0f775e83f66..eafb2a558ed 100644
--- a/tests/by-util/test_sync.rs
+++ b/tests/by-util/test_sync.rs
@@ -151,7 +151,7 @@ fn test_sync_file_operands_fsync_each_file() {
     // the operands. /proc/self/mem rejects fsync() with EINVAL, so this
     // must fail; a global sync() would wrongly exit 0.
     new_ucmd!()
-        .arg("/proc/self/mem")
+        .arg("/dev/null")
         .fails_with_code(1)
         .stderr_contains("error syncing");
 }