From 9f4556182568fe84fb5aa11902d8b7b33dbb752c Mon Sep 17 00:00:00 2001
From: Henrik Lissner <henrik@lissner.net>
Date: Tue, 18 Aug 2020 18:45:37 -0400
Subject: [PATCH] bin/doom: inhibit POSIX errors during postscript

Some doom commands will generate a temporary script at
~/.emacs.d/.local/.doom.sh so that it can run an arbitrary shell command
after the current invocation of bin/doom ends. Very useful for, say,
restarting the currently running doom command after a destructive
operation, like updating Doom's source code, tangling your literate
config, or for launching arbitrary programs, like a new instance of
Emacs. This is necessary because elisp lacks an execv implementation.

However, for some folks, .doom.sh wasn't executing at all. This meant:

1. Some `doom upgrade`s would upgrade Doom itself but never move on to
   the second step of the process: updating its packages.
2. Literate config users could tangle their configs on `doom sync`, but
   the actual syncing process would never happen (#3746).
3. `doom run` would do nothing.

I hadn't realized /bin/sh runs bash in POSIX mode (at least, on systems
where /bin/sh = bash, like nixOS or macOS). In POSIX mode the script
will abort the if a builtin command (like export) returns a non-zero
exit code. Since .doom.sh is basically a bunch of exports followed by an
arbitrary command, and there are some environment variables
that can trigger validation errors (like UID triggering a "read-only
variable" error), we have a problem.

Hopefully addresses #3746
---
 core/core-cli.el | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/core/core-cli.el b/core/core-cli.el
index 2e31515d1..a8cc89ab5 100644
--- a/core/core-cli.el
+++ b/core/core-cli.el
@@ -172,17 +172,18 @@ COMMAND, and passes ARGS to it."
 (defun doom-cli--execute-after (lines)
   (let ((post-script (concat doom-local-dir ".doom.sh"))
         (coding-system-for-write 'utf-8)
-        (coding-system-for-read  'utf-8))
+        (coding-system-for-read  'utf-8)
+        (delimiter "--%EOF%--"))
     (with-temp-file post-script
-      (insert "#!/usr/bin/env sh\n"
-              (save-match-data
+      (insert (save-match-data
                 (cl-loop for env in process-environment
                          if (string-match "^\\([a-zA-Z0-9_]+\\)=\\(.+\\)$" env)
-                         concat (format "export %s=%s;\n"
+                         concat (format "%s=%s \\\n"
                                         (match-string 1 env)
                                         (shell-quote-argument (match-string 2 env)))))
-              (format "\nexport PATH=\"%s:$PATH\"\n" (concat doom-emacs-dir "bin/"))
-              "\n[ -x \"$0\" ] && rm -f \"$0\"\n"
+              (format "PATH=\"%s:$PATH\" \\\n" (concat doom-emacs-dir "bin/"))
+              "/usr/bin/env sh <<" delimiter "\n"
+              "rm -f " (shell-quote-argument post-script) "\n"
               (if (stringp lines)
                   lines
                 (string-join
@@ -191,7 +192,7 @@ COMMAND, and passes ARGS to it."
                               collect (mapconcat #'shell-quote-argument (remq nil line) " "))
                    (list (mapconcat #'shell-quote-argument (remq nil lines) " ")))
                  "\n"))
-              "\n"))
+              "\n" delimiter "\n"))
     (set-file-modes post-script #o700)))
 
 (defun doom-cli-execute-lines-after (&rest lines)