fix: List empty dir should not return error (#67)

* fix: List empty dir should not return error

Signed-off-by: Xuanwo <[email protected]>

* Cleanup errno

Signed-off-by: Xuanwo <[email protected]>

Cargo.toml

@@ -19,10 +19,14 @@ tokio-io = ["tokio"]
 futures-io = { version = "0.3.21", optional = true }
 # hdrs requires at least hadoop 2.3 to work.
 # hadoop 2.2 doesn't handle FileNotFound correctly.
-hdfs-sys = { version = "0.2.0", features = ["hdfs_2_3"] }
+#
+# hdrs requires at least hadoop 2.6 to work.
+# Older version of hadoop doesn't handle errno correctly.
+hdfs-sys = { version = "0.2.0", features = ["hdfs_2_6"] }
 libc = "0.2.124"
 log = "0.4.16"
 tokio = { version = "1.18.0", optional = true }
+errno = "0.2.8"
 
 [dev-dependencies]
 anyhow = "1.0.57"

README.md

@@ -58,6 +58,12 @@ export LD_LIBRARY_PATH=${JAVA_HOME}/lib/server:${LD_LIBRARY_PATH}
 export CLASSPATH=$(find $HADOOP_HOME -iname "*.jar" | xargs echo | tr ' ' ':')
 ```
 
+## Version Requirement
+
+`hdrs` requires at least hadoop 2.3 to work: hadoop 2.2 doesn't handle FileNotFound correctly.
+
+`hdrs` requires at least hadoop 2.6 to work: Older version of hadoop doesn't handle errno correctly. In older versions, hadoop will set errno to `3` if input path is an empty dir.
+
 ## Contributing
 
 Check out the [CONTRIBUTING.md](./CONTRIBUTING.md) guide for more details on getting started with contributing to this project.

src/client.rs

@@ -1,6 +1,7 @@
 use std::ffi::CString;
 use std::{env, fs, io};
 
+use errno::{set_errno, Errno};
 use hdfs_sys::*;
 use log::debug;
 
@@ -54,6 +55,8 @@ impl Client {
     pub fn connect(name_node: &str) -> io::Result<Self> {
         prepare_env()?;
 
+        set_errno(Errno(0));
+
         debug!("connect name node {}", name_node);
 
         let fs = unsafe {
@@ -187,6 +190,8 @@ impl Client {
     /// assert_eq!(fi.unwrap_err().kind(), io::ErrorKind::NotFound)
     /// ```
     pub fn metadata(&self, path: &str) -> io::Result<Metadata> {
+        set_errno(Errno(0));
+
         let hfi = unsafe {
             let p = CString::new(path)?;
             hdfsGetPathInfo(self.fs, p.as_ptr())
@@ -216,6 +221,8 @@ impl Client {
     /// let fis = fs.read_dir("/tmp/hello/");
     /// ```
     pub fn read_dir(&self, path: &str) -> io::Result<Readdir> {
+        set_errno(Errno(0));
+
         let mut entries = 0;
         let hfis = unsafe {
             let p = CString::new(path)?;

tests/main.rs

@@ -39,6 +39,31 @@ fn test_mkdir() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn test_read_dir() -> Result<()> {
+    let _ = env_logger::try_init();
+    dotenv::from_filename(".env").ok();
+
+    if env::var("HDRS_TEST").unwrap_or_default() != "on" {
+        return Ok(());
+    }
+
+    let name_node = env::var("HDRS_NAMENODE")?;
+    let work_dir = env::var("HDRS_WORKDIR").unwrap_or_default();
+
+    let fs = Client::connect(&name_node)?;
+
+    let path = format!("{work_dir}{}", uuid::Uuid::new_v4());
+
+    let _ = fs.create_dir(&path).expect("mkdir should succeed");
+    debug!("read dir {}", path);
+    let readdir = fs.read_dir(&path).expect("readdir should succeed");
+    debug!("readdir: {:?}", readdir);
+    assert_eq!(readdir.len(), 0);
+
+    Ok(())
+}
+
 #[test]
 fn test_file() -> Result<()> {
     use std::io::{Read, Seek, SeekFrom, Write};