From 910b70849b38ddcdc00bc33402c6bd0b67e990db Mon Sep 17 00:00:00 2001
From: Alexander Wainwright <code@figtree.dev>
Date: Mon, 14 Jul 2025 17:48:32 +1000
Subject: [PATCH] Add cardboard function

---
 alex/fish/functions/cardboard.fish | 93 ++++++++++++++++++++++++++++++
 alex/home.nix                      |  1 +
 2 files changed, 94 insertions(+)
 create mode 100644 alex/fish/functions/cardboard.fish

diff --git a/alex/fish/functions/cardboard.fish b/alex/fish/functions/cardboard.fish
new file mode 100644
index 0000000..5a0dda3
--- /dev/null
+++ b/alex/fish/functions/cardboard.fish
@@ -0,0 +1,93 @@
+function cardboard
+    set -l mnt_option
+    set -l display_help
+
+    for arg in $argv
+        switch $arg
+            case '-h' '--help'
+                set display_help 1
+            case '*'
+                set mnt_option $arg
+        end
+    end
+
+    if test "$display_help"
+        echo "Usage: cardboard [directory] [-h | --help]"
+        echo ""
+        echo "Mounts a tmpfs with read-write permissions for the user calling it and no permissions for anyone else."
+        echo "Automatically changes the current working directory to the mounted tmpfs directory."
+        echo ""
+        echo "Options:"
+        echo "  -h, --help    Show this help message and exit"
+        echo ""
+        echo "To unmount the tmpfs and return to your home directory, run 'uncardboard'."
+        echo "To securely delete all files inside the mount directory, run 'shred-cardboard'."
+        echo "To list the files that would be shredded without actually deleting them, run 'shred-cardboard-dry-run'."
+        return
+    end
+
+    set user (whoami)
+
+    if test -n "$mnt_option"
+        set mnt_dir $mnt_option
+    else
+        set mnt_dir "/home/$user/mnt/ramfs"
+    end
+
+    set -gx CARDBOARD_MOUNT_DIR $mnt_dir
+
+    if mount | grep -q " $mnt_dir "
+        echo "A tmpfs is already mounted at $mnt_dir."
+        return
+    end
+
+    mkdir -p $mnt_dir
+
+    # Mount the tmpfs so its root directory is owned by the current user
+    sudo mount -t tmpfs -o size=512M,mode=700,uid=(id -u),gid=(id -g) tmpfs $mnt_dir
+
+    cd $mnt_dir
+
+    function uncardboard
+        if test -z "$CARDBOARD_MOUNT_DIR"
+            echo "No cardboard mount directory found."
+            return
+        end
+
+        if test "$PWD" = "$CARDBOARD_MOUNT_DIR"
+            cd /home/$user
+        end
+
+        sudo umount $CARDBOARD_MOUNT_DIR
+    end
+
+    function shred-cardboard
+        if test -z "$CARDBOARD_MOUNT_DIR"
+            echo "No cardboard mount directory found."
+            return
+        end
+
+        if test "$PWD" = "$CARDBOARD_MOUNT_DIR"
+            echo "Please change to a different directory before running shred-cardboard."
+            return
+        end
+
+        echo "Shredding all files in $CARDBOARD_MOUNT_DIR..."
+        find $CARDBOARD_MOUNT_DIR -type f -exec shred -u -v {} \;
+        echo "All files in $CARDBOARD_MOUNT_DIR have been securely deleted."
+    end
+
+    function shred-cardboard-dry-run
+        if test -z "$CARDBOARD_MOUNT_DIR"
+            echo "No cardboard mount directory found."
+            return
+        end
+
+        echo "Files that would be shredded in $CARDBOARD_MOUNT_DIR:"
+        find $CARDBOARD_MOUNT_DIR -type f
+    end
+
+    echo "To unmount the tmpfs and return to your home directory, run 'uncardboard'."
+    echo "To securely delete all files inside the mount directory, run 'shred-cardboard'."
+    echo "To list the files that would be shredded without actually deleting them, run 'shred-cardboard-dry-run'."
+end
diff --git a/alex/home.nix b/alex/home.nix
index c0c7a60..d83e090 100644
--- a/alex/home.nix
+++ b/alex/home.nix
@@ -174,6 +174,7 @@
   programs.fish = {
     enable = true;
     interactiveShellInit = ''
+      source ~/.config/fish/functions/cardboard.fish
       source ~/.config/fish/functions/bangbang.fish
       source ~/.config/fish/functions/borg-h.fish