3 files changed, 84 insertions, 0 deletions

diff --git a/nix/default.nix b/nix/default.nix
index 1c0105f..a40d8f6 100644
--- a/nix/default.nix
+++ b/nix/default.nix
@@ -7,4 +7,5 @@ in rec {
   rebuild-system = pkgs.callPackage ./rebuild-system.nix {};
   pulseaudio-ctl = pkgs.callPackage ./pulseaudio-ctl.nix {};
   monitor-uucp = pkgs.callPackage ./monitor-uucp.nix {};
+  rolling-directory = pkgs.callPackage ./rolling-directory.nix {};
 }
diff --git a/nix/rolling-directory.nix b/nix/rolling-directory.nix
new file mode 100644
index 0000000..bb5dd53
--- /dev/null
+++ b/nix/rolling-directory.nix
@@ -0,0 +1,25 @@
+{ stdenv
+, zsh, coreutils, findutils, gawk, inotify-tools
+}:
+
+stdenv.mkDerivation rec {
+  name = "rolling-directory-${version}";
+  version = "0.2";
+  src = ../rolling-directory;
+
+  phases = [ "buildPhase" "installPhase" ];
+
+  inherit zsh coreutils findutils gawk;
+  inotify = inotify-tools;
+
+  buildPhase = ''
+    substituteAll $src rolling-directory
+  '';
+
+  installPhase = ''
+    mkdir -p $out/bin
+
+    install -m 755 -t $out/bin \
+      rolling-directory
+  '';
+}
diff --git a/rolling-directory b/rolling-directory
new file mode 100644
index 0000000..d85f8b7
--- /dev/null
+++ b/rolling-directory
@@ -0,0 +1,58 @@
+#!@zsh@/bin/zsh
+
+set -e
+
+PATH=@coreutils@/bin:@findutils@/bin:@gawk@/bin:@inotify@/bin:$PATH
+
+dir=${1:A}
+maxSize=$(numfmt --from=auto --to=none -- $2)
+shift 2
+
+[[ -d "${dir}" ]] || exit 2
+[[ "${maxSize}" = <-> ]] || exit 2
+
+typeset -a findExtra
+findExtra=(-not -path ${dir}/CACHEDIR.TAG)
+
+resize() {
+    echo "Resizing ${dir} to below $(numfmt --to=iec-i --suffix=B -- ${maxSize})..." >&2
+
+    while [[ $(du -xbs ${dir} | awk '{ print $1; }') -gt $maxSize ]]; do
+        find ${dir} -xdev -type f \( ${findExtra} \) -print0 | \
+            xargs -r0 -- stat --printf '%W %Y %Z %X %n\0' | \
+            sort -t '\0' -z | \
+            awk -F '\0' '{ gsub("^\\S+\\s+\\S+\\s+\\S+\\s+\\S+\\s+", "", $1); printf "%s\0", $1; }' | \
+            xargs -r0 -- rm -v
+    done
+
+    find ${dir} -xdev -xtype l -print0 | xargs -r0 -- rm -v
+    find ${dir} -xdev -type d \( -not -path ${dir} \) -empty -print0 | xargs -r0 -- rmdir -v
+}
+
+case "${1}" in
+    monitor)
+        shift
+
+        typeset -a inotifyExtra
+        inotifyExtra=()
+
+        if [[ "${1}" = <-> ]]; then
+            inotifyExtra=(-t "${1}")
+            shift
+        fi
+        
+        while
+            resize
+            inotifywait -qq -r ${dir} ${inotifyExtra} \
+                        -e modify \
+                        -e close_write \
+                        -e moved_to \
+                        -e move_self \
+                        -e create
+            true
+        do :; done
+    ;;
+    *)
+        resize
+    ;;
+esac