unix: Provide _remove_dir_contents

The implementation is relatively straightforward.  It's a shame that
we need to reach for libc to get the error handling right!

The return type is different to that of Windows's fs:_remove_dir_all.
Unix does not need to canonicalize the path, so doesn't return
a canonicalised path.

This type difference is OK provided both versions typecheck at the
call site, which will appear in a moment.

Right now this code is not used - the caller will appear in the next
commit - so we must temporarily add `#[allow]`.

As discussed, and differently to my v1,
  https://github.com/XAMPPRocky/remove_dir_all/pull/22/files/30791c382ca9535d4fd9758e1b070393bfa6ef3e#diff-cff001b3dd9b58fd8acadc50ffc32f83
I have made remove_dir_contents intolerant of ENOENT.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

Author: ijackson

Cargo.toml

@@ -23,6 +23,9 @@ num_cpus = "1.13"
 rayon = "1.4"
 winapi = {version = "0.3", features = ["std", "errhandlingapi", "winerror", "fileapi", "winbase"]}
 
+[target.'cfg(not(windows))'.dependencies]
+libc = "0.2"
+
 [dev-dependencies]
 doc-comment = "0.3"
 env_logger = "0.8.1"

src/lib.rs

@@ -19,6 +19,9 @@ doctest!("../README.md");
 #[cfg(windows)]
 mod fs;
 
+#[cfg(not(windows))]
+mod unix;
+
 #[cfg(windows)]
 pub use self::fs::remove_dir_all;
 

src/unix.rs

@@ -0,0 +1,23 @@
+#![allow(dead_code)]
+
+use std::fs;
+use std::io;
+use std::path::Path;
+
+fn remove_file_or_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
+    match fs::remove_file(&path) {
+        // Unfortunately, there is no ErrorKind for EISDIR
+        Err(e) if e.raw_os_error() == Some(libc::EISDIR) =>
+            fs::remove_dir_all(&path),
+        r => r,
+    }
+}
+
+pub fn _remove_dir_contents<P: AsRef<Path>>(path: P) -> Result<(), io::Error> {
+    for entry in fs::read_dir(path)? {
+        let entry_path = entry?.path();
+        remove_file_or_dir_all(&entry_path)?;
+    }
+
+    Ok(())
+}