feat(sterni/mblog): add package to read maildirs r/3719

Change-Id: I7be8d8b7d12bb194712aa26f3ddad74340357779
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5070
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>

3 files changed, 25 insertions, 0 deletions

diff --git a/users/sterni/mblog/default.nix b/users/sterni/mblog/default.nix
index 16ae573ba78c..1c2776ec9250 100644
--- a/users/sterni/mblog/default.nix
+++ b/users/sterni/mblog/default.nix
@@ -5,6 +5,7 @@ depot.nix.buildLisp.program {
 
   srcs = [
     ./packages.lisp
+    ./maildir.lisp
     ./transformer.lisp
     ./note.lisp
     ./cli.lisp
diff --git a/users/sterni/mblog/maildir.lisp b/users/sterni/mblog/maildir.lisp
new file mode 100644
index 000000000000..aca014203e29
--- /dev/null
+++ b/users/sterni/mblog/maildir.lisp
@@ -0,0 +1,17 @@
+(in-package :maildir)
+(declaim (optimize (safety 3)))
+
+(defun list (dir)
+  "Returns a list of pathnames to messages in a maildir. The messages are
+  returned in no guaranteed order. Note that this function doesn't fully
+  implement the behavior prescribed by maildir(5): It only looks at `cur`
+  and `new` and won't clean up `tmp` nor move files from `new` to `cur`,
+  since it is strictly read-only."
+  (flet ((subdir-contents (subdir)
+           (directory
+            (merge-pathnames
+             (make-pathname :directory `(:relative ,subdir)
+                            :name :wild :type :wild)
+             dir))))
+    (mapcan #'subdir-contents '("cur" "new"))))
+
diff --git a/users/sterni/mblog/packages.lisp b/users/sterni/mblog/packages.lisp
index ca2e41b6827f..a58aad27d11b 100644
--- a/users/sterni/mblog/packages.lisp
+++ b/users/sterni/mblog/packages.lisp
@@ -1,3 +1,10 @@
+(defpackage :maildir
+  (:use :common-lisp)
+  (:shadow :list)
+  (:export :list)
+  (:documentation
+   "Very incomplete package for dealing with maildir(5)."))
+
 (defpackage :mblog
   (:use
    :common-lisp