tools: add file_get_non_comment_lines

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

src/tools.rs

@@ -5,8 +5,7 @@ use std::any::Any;
 use std::collections::HashMap;
 use std::hash::BuildHasher;
 use std::fs::{File, OpenOptions};
-use std::io::ErrorKind;
-use std::io::Read;
+use std::io::{self, BufRead, ErrorKind, Read};
 use std::os::unix::io::{AsRawFd, RawFd};
 use std::path::Path;
 use std::time::Duration;
@@ -572,3 +571,27 @@ pub const DEFAULT_ENCODE_SET: &AsciiSet = &percent_encoding::CONTROLS // 0..1f a
     .add(b'?')
     .add(b'{')
     .add(b'}');
+
+/// 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)),
+    }))
+}