Index: Cargo.toml
==================================================================
--- Cargo.toml
+++ Cargo.toml
@@ -1,8 +1,8 @@
 [package]
 name = "orphanage"
-version = "0.1.3"
+version = "0.1.4"
 edition = "2021"
 license = "0BSD"
 # https://crates.io/category_slugs
 categories = [ "network-programming" ]
 keywords = [ "sqlite", "fs", "path" ]

Index: src/fs.rs
==================================================================
--- src/fs.rs
+++ src/fs.rs
@@ -1,7 +1,8 @@
 use std::{
   fs,
+  io::ErrorKind,
   path::{Path, PathBuf}
 };
 
 use crate::err::Error;
 
@@ -63,6 +64,59 @@
   P: AsRef<Path>
 {
   Ok(pth.as_ref().canonicalize()?)
 }
 
+
+/// Call a closure if `outfile` is outdated (according to the rules of
+/// [`outdated()`] with regards to `infile`.
+///
+/// Returns `Ok(true)` if the closure was called.
+///
+/// # Errors
+/// Errors mirror the behavior of [`outdated()`]'s errors.
+pub fn run_if_outdated<F>(
+  srcfile: impl AsRef<Path>,
+  dstfile: impl AsRef<Path>,
+  f: F
+) -> Result<bool, std::io::Error>
+where
+  F: FnOnce(&Path, &Path)
+{
+  if outdated(&srcfile, &dstfile)? {
+    f(srcfile.as_ref(), dstfile.as_ref());
+    Ok(true)
+  } else {
+    Ok(false)
+  }
+}
+
+/// Returns `true` if `infile` is newer than `outfile` (or if `outfile` doesn't
+/// exist).  Returns `false` otherwise.
+///
+/// # Errors
+/// Returns [`std::io::Error`] if:
+/// - `infile`'s metadata could not be read.
+/// - `outfile`'s metadata could not be read and it is other than
+///   `ErrorKind::NotFound`.
+/// - Either `infile`' or `outfile`'s mtime could not be extracted.
+pub fn outdated(
+  infile: impl AsRef<Path>,
+  outfile: impl AsRef<Path>
+) -> Result<bool, std::io::Error> {
+  let in_md = fs::metadata(infile.as_ref())?;
+  let out_md = match fs::metadata(outfile.as_ref()) {
+    Ok(md) => md,
+    Err(err) if err.kind() == ErrorKind::NotFound => {
+      // If the target file could not be found then treat target as outdated
+      return Ok(true);
+    }
+    Err(e) => Err(e)?
+  };
+
+  let in_mtime = in_md.modified()?;
+  let out_mtime = out_md.modified()?;
+
+  Ok(in_mtime > out_mtime)
+}
+
 // vim: set ft=rust et sw=2 ts=2 sts=2 cinoptions=2 tw=79 :

Index: www/changelog.md
==================================================================
--- www/changelog.md
+++ www/changelog.md
@@ -1,17 +1,30 @@
 # Change Log
 
 ## [Unreleased]
 
-[Details](/vdiff?from=orphanage-0.1.3&to=trunk)
+[Details](/vdiff?from=orphanage-0.1.4&to=trunk)
 
 ### Added
 
 ### Changed
 
 ### Removed
 
+---
+
+## [0.1.4] - 2024-11-22
+
+[Details](/vdiff?from=orphanage-0.1.3&to=orphanage-0.1.4)
+
+### Added
+
+- `fs::outdated()` can be used to detect of a file is "outdated" with regards
+  to another.
+- `fs::run_if_outdated()` can be used to run a closure if a file is "outdated"
+  with regards to another.
+
 ---
 
 ## [0.1.3] - 2024-11-07
 
 [Details](/vdiff?from=orphanage-0.1.2&to=orphanage-0.1.3)