sync: Verify that the files can be opened

Cargo.lock

@@ -2834,6 +2834,7 @@ version = "0.0.15"
 dependencies = [
  "clap",
  "libc",
+ "nix",
  "uucore",
  "winapi",
 ]

src/uu/sync/Cargo.toml

@@ -19,6 +19,9 @@ clap = { version = "3.2", features = ["wrap_help", "cargo"] }
 libc = "0.2.132"
 uucore = { version=">=0.0.15", package="uucore", path="../../uucore", features=["wide"] }
 
+[target.'cfg(any(target_os = "linux", target_os = "android"))'.dependencies]
+nix = "0.25"
+
 [target.'cfg(target_os = "windows")'.dependencies]
 winapi = { version = "0.3", features = ["errhandlingapi", "fileapi", "handleapi", "std", "winbase", "winerror"] }
 

src/uu/sync/src/sync.rs

@@ -10,6 +10,12 @@
 extern crate libc;
 
 use clap::{crate_version, Arg, Command};
+#[cfg(any(target_os = "linux", target_os = "android"))]
+use nix::errno::Errno;
+#[cfg(any(target_os = "linux", target_os = "android"))]
+use nix::fcntl::{open, OFlag};
+#[cfg(any(target_os = "linux", target_os = "android"))]
+use nix::sys::stat::Mode;
 use std::path::Path;
 use uucore::display::Quotable;
 use uucore::error::{UResult, USimpleError};
@@ -174,11 +180,40 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     }
 
     for f in &files {
-        if !Path::new(&f).exists() {
-            return Err(USimpleError::new(
-                1,
-                format!("cannot stat {}: No such file or directory", f.quote()),
-            ));
+        // Use the Nix open to be able to set the NONBLOCK flags for fifo files
+        #[cfg(any(target_os = "linux", target_os = "android"))]
+        {
+            match open(Path::new(&f), OFlag::O_NONBLOCK, Mode::empty()) {
+                Ok(_) => {}
+                Err(e) => {
+                    if e == Errno::ENOENT {
+                        return Err(USimpleError::new(
+                            1,
+                            format!("cannot stat {}: No such file or directory", f.quote()),
+                        ));
+                    }
+                    if e == Errno::EACCES {
+                        if Path::new(&f).is_dir() {
+                            return Err(USimpleError::new(
+                                1,
+                                format!("error opening {}: Permission denied", f.quote()),
+                            ));
+                        } else {
+                            // ignore the issue
+                            // ./target/debug/coreutils sync --data file
+                        }
+                    }
+                }
+            }
+        }
+        #[cfg(not(any(target_os = "linux", target_os = "android")))]
+        {
+            if !Path::new(&f).exists() {
+                return Err(USimpleError::new(
+                    1,
+                    format!("cannot stat {}: No such file or directory", f.quote()),
+                ));
+            }
         }
     }
 

tests/by-util/test_sync.rs

@@ -52,3 +52,32 @@ fn test_sync_data_but_not_file() {
         .fails()
         .stderr_contains("sync: --data needs at least one argument");
 }
+
+#[cfg(any(target_os = "linux", target_os = "android"))]
+#[cfg(feature = "chmod")]
+#[test]
+fn test_sync_no_permission_dir() {
+    let ts = TestScenario::new(util_name!());
+    let at = &ts.fixtures;
+    let dir = "foo";
+    at.mkdir_all(dir);
+
+    ts.ccmd("chmod").arg("0").arg(dir).succeeds();
+    let result = ts.ucmd().arg("--data").arg(dir).fails();
+    result.stderr_contains("sync: error opening 'foo': Permission denied");
+    let result = ts.ucmd().arg(dir).fails();
+    result.stderr_contains("sync: error opening 'foo': Permission denied");
+}
+
+#[cfg(not(target_os = "windows"))]
+#[cfg(feature = "chmod")]
+#[test]
+fn test_sync_no_permission_file() {
+    let ts = TestScenario::new(util_name!());
+    let at = &ts.fixtures;
+    let f = "file";
+    at.touch(f);
+
+    ts.ccmd("chmod").arg("0200").arg(f).succeeds();
+    ts.ucmd().arg(f).succeeds();
+}