rust/library/std/src/sys_common/fs.rs

#![allow(dead_code)] // not used on all platforms

use crate::fs;
use crate::io::{self, Error, ErrorKind};
use crate::path::Path;

pub(crate) const NOT_FILE_ERROR: Error = Error::new_const(
    ErrorKind::InvalidInput,
    &"the source path is neither a regular file nor a symlink to a regular file",
);

pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
    let mut reader = fs::File::open(from)?;
    let metadata = reader.metadata()?;

    if !metadata.is_file() {
        return Err(NOT_FILE_ERROR);
    }

    let mut writer = fs::File::create(to)?;
    let perm = metadata.permissions();

    let ret = io::copy(&mut reader, &mut writer)?;
    writer.set_permissions(perm)?;
    Ok(ret)
}

pub fn remove_dir_all(path: &Path) -> io::Result<()> {
    let filetype = fs::symlink_metadata(path)?.file_type();
    if filetype.is_symlink() { fs::remove_file(path) } else { remove_dir_all_recursive(path) }
}

fn remove_dir_all_recursive(path: &Path) -> io::Result<()> {
    for child in fs::read_dir(path)? {
        let child = child?;
        if child.file_type()?.is_dir() {
            remove_dir_all_recursive(&child.path())?;
        } else {
            fs::remove_file(&child.path())?;
        }
    }
    fs::remove_dir(path)
}