fix: add logic to check if a file's contents or directory are empty

Signed-off-by: nayuta-ai <[email protected]>

tests/contest/contest/src/tests/linux_masked_paths/masked_paths.rs

@@ -52,41 +52,40 @@ fn check_masked_paths() -> TestResult {
     let spec = get_spec(masked_paths);
 
     test_inside_container(spec, &|bundle_path| {
-        use std::{fs, io};
+        use std::fs;
         let test_dir = bundle_path.join(&masked_dir_sub);
         if let Err(e) = fs::create_dir_all(&test_dir) {
             bail!(e)
         }
 
-        match fs::File::create(test_dir.join("tmp")) {
-            io::Result::Ok(_) => { /*This is expected*/ }
-            io::Result::Err(e) => {
-                bail!(e)
-            }
+        if let Err(e) = fs::File::create(test_dir.join("tmp")) {
+            bail!(e)
         }
 
+        // runtimetest cannot check the readability of empty files, so
+        // write something.
         let test_sub_sub_file = bundle_path.join(&masked_file_sub_sub);
-        match fs::File::create(test_sub_sub_file) {
-            io::Result::Ok(_) => { /*This is expected*/ }
-            io::Result::Err(e) => {
-                bail!(e)
-            }
+        if let Err(e) = fs::File::create(&test_sub_sub_file) {
+            bail!(e)
+        }
+        if let Err(e) = fs::write(&test_sub_sub_file, b"secrets") {
+            bail!(e)
         }
 
         let test_sub_file = bundle_path.join(&masked_file_sub);
-        match fs::File::create(test_sub_file) {
-            io::Result::Ok(_) => { /*This is expected*/ }
-            io::Result::Err(e) => {
-                bail!(e)
-            }
+        if let Err(e) = fs::File::create(&test_sub_file) {
+            bail!(e)
+        }
+        if let Err(e) = fs::write(&test_sub_file, b"secrets") {
+            bail!(e)
         }
 
         let test_file = bundle_path.join(masked_file);
-        match fs::File::create(test_file) {
-            io::Result::Ok(_) => { /*This is expected*/ }
-            io::Result::Err(e) => {
-                bail!(e)
-            }
+        if let Err(e) = fs::File::create(&test_file) {
+            bail!(e)
+        }
+        if let Err(e) = fs::write(&test_file, b"secrets") {
+            bail!(e)
         }
 
         Ok(())

tests/contest/runtimetest/src/tests.rs

@@ -564,17 +564,25 @@ pub fn validate_masked_paths(spec: &Spec) {
     // TODO when https://github.com/rust-lang/rust/issues/86442 stabilizes,
     // change manual matching of i32 to e.kind() and match statement
     for path in masked_paths {
-        if let std::io::Result::Err(e) = test_read_access(path) {
-            let errno = Errno::from_raw(e.raw_os_error().unwrap());
-            if errno == Errno::ENOENT {
-                /* This is expected */
-            } else {
-                eprintln!("in masked paths, error in testing read access for path {path} : {e:?}");
+        match test_read_access(path) {
+            Ok(true) => {
+                eprintln!(
+                    "in masked paths, expected path {path} to be masked, but was found readable"
+                );
                 return;
             }
-        } else {
-            eprintln!("in masked paths, error in testing read access for path {path}");
-            return;
+            Ok(false) => { /* This is expected */ }
+            Err(e) => {
+                let errno = Errno::from_raw(e.raw_os_error().unwrap());
+                if errno == Errno::ENOENT {
+                    /* This is expected */
+                } else {
+                    eprintln!(
+                        "in masked paths, error in testing read access for path {path} : {errno:?}"
+                    );
+                    return;
+                }
+            }
         }
     }
 }

tests/contest/runtimetest/src/utils.rs

@@ -1,22 +1,52 @@
 use std::fs;
-use std::fs::{metadata, symlink_metadata};
+use std::fs::{metadata, symlink_metadata, OpenOptions};
+use std::io::{self, Read};
 use std::os::unix::prelude::MetadataExt;
 use std::path::PathBuf;
 use std::process::Command;
 
 use nix::sys::stat::{stat, SFlag};
 
-fn test_file_read_access(path: &str) -> Result<(), std::io::Error> {
-    let _ = std::fs::OpenOptions::new()
-        .create(false)
-        .read(true)
-        .open(path)?;
-    Ok(())
+fn test_file_read_access(path: &str) -> Result<bool, std::io::Error> {
+    let mut file = OpenOptions::new().create(false).read(true).open(path)?;
+
+    // Create a buffer with a capacity of 1 byte
+    let mut buffer = [0u8; 1];
+    match file.read(&mut buffer) {
+        Ok(_) => {
+            let mut contents = String::new();
+            file.read_to_string(&mut contents)?;
+            if contents.is_empty() {
+                // empty file
+                return Ok(false);
+            }
+            Ok(true)
+        }
+        Err(e) if e.kind() == io::ErrorKind::UnexpectedEof => Ok(false),
+        Err(e) => Err(e),
+    }
 }
 
-fn test_dir_read_access(path: &str) -> Result<(), std::io::Error> {
-    let _ = std::fs::read_dir(path)?;
-    Ok(())
+fn test_dir_read_access(path: &str) -> Result<bool, std::io::Error> {
+    let entries = std::fs::read_dir(path);
+
+    match entries {
+        Ok(mut entries_iter) => {
+            // Get the first entry
+            match entries_iter.next() {
+                Some(entry) => {
+                    match entry {
+                        Ok(_) => Ok(true),   // If the entry is Ok, then it's readable
+                        Err(_) => Ok(false), // If the entry is Err, then it's not readable
+                    }
+                }
+                None => Ok(false), // If there are no entries, then it's not readable
+            }
+        }
+        Err(_) => {
+            Ok(false) // If there's an error, then it's not readable
+        }
+    }
 }
 
 fn is_file_like(mode: u32) -> bool {
@@ -30,7 +60,7 @@ fn is_dir(mode: u32) -> bool {
     mode & SFlag::S_IFDIR.bits() != 0
 }
 
-pub fn test_read_access(path: &str) -> Result<(), std::io::Error> {
+pub fn test_read_access(path: &str) -> Result<bool, std::io::Error> {
     let fstat = stat(path)?;
     let mode = fstat.st_mode;
     if is_file_like(mode) {