[emacs] Add magit key loading

emacs/.config/doom/config.el

@@ -439,3 +439,36 @@ Always open the result in `eww`."
 
 ;; Bind globally to C-c l
 (global-set-key (kbd "C-c l") #'life-scrobble-url)
+
+(after! magit
+  (defvar my/ssh-key-injector-script
+    (expand-file-name "~/.local/bin/inject-ssh-keys-from-pass"))
+
+  (defun my/ssh-agent-has-keys-p (&rest _ignore)
+    "Non-nil if ssh-agent currently has at least one identity loaded."
+    (eq 0 (call-process "ssh-add" nil nil nil "-l")))
+
+  (defun my/ensure-ssh-keys-loaded (&rest _ignore)
+    "Ensure ssh-agent has keys loaded; if not, run injector script."
+    (unless (my/ssh-agent-has-keys-p)
+      (unless (file-executable-p my/ssh-key-injector-script)
+        (user-error "SSH injector script not executable: %s" my/ssh-key-injector-script))
+      (let ((buf (get-buffer-create "*ssh-key-injector*")))
+        (with-current-buffer buf (erase-buffer))
+        (let ((exit (call-process-shell-command my/ssh-key-injector-script nil buf t)))
+          (unless (eq exit 0)
+            (display-buffer buf)
+            (user-error "SSH key injection failed (see *ssh-key-injector*)"))))))
+
+  ;; IMPORTANT: remove then re-add, so we don't keep an old advised function object around
+  (advice-remove 'magit-status #'my/ensure-ssh-keys-loaded)
+  (advice-add 'magit-status :before #'my/ensure-ssh-keys-loaded)
+
+  ;; optional:
+  (advice-remove 'magit-fetch  #'my/ensure-ssh-keys-loaded)
+  (advice-add    'magit-fetch  :before #'my/ensure-ssh-keys-loaded)
+  (advice-remove 'magit-push   #'my/ensure-ssh-keys-loaded)
+  (advice-add    'magit-push   :before #'my/ensure-ssh-keys-loaded)
+  (advice-remove 'magit-pull   #'my/ensure-ssh-keys-loaded)
+  (advice-add    'magit-pull   :before #'my/ensure-ssh-keys-loaded))
+