move pxar binary to separate crate

and move its few remaining proxmox_backup deps out to
pbs-tools

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

pbs-tools/src/fs.rs

@@ -2,9 +2,12 @@
 
 use std::borrow::{Borrow, BorrowMut};
 use std::collections::HashMap;
+use std::fs::File;
 use std::hash::BuildHasher;
+use std::io::{self, BufRead};
 use std::ops::{Deref, DerefMut};
 use std::os::unix::io::{AsRawFd, RawFd};
+use std::path::Path;
 
 use anyhow::{bail, format_err, Error};
 use nix::dir;
@@ -401,3 +404,27 @@ where
 
     result
 }
+
+/// Get an iterator over lines of a file, skipping empty lines and comments (lines starting with a
+/// `#`).
+pub fn file_get_non_comment_lines<P: AsRef<Path>>(
+    path: P,
+) -> Result<impl Iterator<Item = io::Result<String>>, Error> {
+    let path = path.as_ref();
+
+    Ok(io::BufReader::new(
+        File::open(path).map_err(|err| format_err!("error opening {:?}: {}", path, err))?,
+    )
+    .lines()
+    .filter_map(|line| match line {
+        Ok(line) => {
+            let line = line.trim();
+            if line.is_empty() || line.starts_with('#') {
+                None
+            } else {
+                Some(Ok(line.to_string()))
+            }
+        }
+        Err(err) => Some(Err(err)),
+    }))
+}