From 8237aa9272ce1d13a412b2495cbaa90df38d928b Mon Sep 17 00:00:00 2001
From: Jim Myhrberg <contact@jimeh.me>
Date: Sat, 22 May 2021 20:38:51 +0100
Subject: [PATCH] feat(cli): add "emacs" CLI launcher script to
 Emacs.app/Conents/MacOS/bin

This makes setting up a "emacs" terminal command that works with the
self-contained Emacs.app bundle much simpler, as you just need to add
Emacs.app/Conents/MacOS/bin to your PATH.

For example, if you place Emacs.app in /Applications, add this to your
shell setup:

    if [ -d "/Applications/Emacs.app/Contents/MacOS/bin" ]; then
      export PATH="/Applications/Emacs.app/Contents/MacOS/bin:$PATH"
      alias emacs="emacs -nw" # Always launch "emacs" in terminal mode.
    fi

The launcher script works by figuring out it's own absolute path on
disk, even if you are using a symlink to the script, it will resolve to
correct real path. This allows it to execute the main
Emacs.app/Contents/MacOS/Emacs executable via the correct path, so it
can correctly pick up its dependencies from within the Emacs.app bundle.

Fixes #41
---
 README.md             | 28 ++++++++++++----------------
 build-emacs-for-macos | 13 +++++++++++++
 helper/emacs-cli.bash | 23 +++++++++++++++++++++++
 3 files changed, 48 insertions(+), 16 deletions(-)
 create mode 100755 helper/emacs-cli.bash

diff --git a/README.md b/README.md
index 33b967f..200cf16 100644
--- a/README.md
+++ b/README.md
@@ -111,29 +111,25 @@ All sources as downloaded as tarballs from the
 to get a list of tags/branches available to install, simply check said
 repository.
 
-## Use Self-Contained Emacs.app as `emacs` CLI Tool
+## Use Emacs.app as `emacs` CLI Tool
 
-As the application bundle is self-contained, the main executable needs to be run
-from within the application bundle. This means a simple symlink to
-`Emacs.app/Contents/MacOS/Emacs` will not work. Instead the best approach is to
-create a shell alias called `emacs` pointing to the right place.
+Builds come with a custom `emacs` shell script launcher for use from the command
+line. It makes sure to use the main `Emacs.app/Contents/MacOS/Emacs` executable
+from the correct path, ensuring it finds all the relevant dependencies within
+the Emacs.app bundle.
 
-Personally I use something similar to this:
+To use it, simply add `Emacs.app/Contents/MacOS/bin` to your `PATH`. For
+example, if you place Emacs.app in `/Applications`:
 
 ```bash
-if [ -f "/Applications/Emacs.app/Contents/MacOS/Emacs" ]; then
-  export EMACS="/Applications/Emacs.app/Contents/MacOS/Emacs"
-  alias emacs="$EMACS -nw"
-fi
-
-if [ -f "/Applications/Emacs.app/Contents/MacOS/bin/emacsclient" ]; then
-  alias emacsclient="/Applications/Emacs.app/Contents/MacOS/bin/emacsclient"
+if [ -d "/Applications/Emacs.app/Contents/MacOS/bin" ]; then
+  export PATH="/Applications/Emacs.app/Contents/MacOS/bin:$PATH"
+  alias emacs="emacs -nw" # Always launch "emacs" in terminal mode.
 fi
 ```
 
-Setting the `EMACS` variable to the binary path seems to be a good idea, as some
-tools seems to use it to figure out the path to Emacs' executable, including
-[doom-emacs](https://github.com/hlissner/doom-emacs)' `doom` CLI tool.
+If you want `emacs` in your terminal to launch a GUI instance of Emacs, don't
+use the alias from the above example.
 
 ## Native-Comp
 
diff --git a/build-emacs-for-macos b/build-emacs-for-macos
index 4cd1ea5..5ddd271 100755
--- a/build-emacs-for-macos
+++ b/build-emacs-for-macos
@@ -103,6 +103,7 @@ class Build
 
     app = compile_source(@source_dir)
     symlink_internals(app)
+    add_cli_helper(app)
 
     LibEmbedder.new(app, brew_dir, extra_libs).embed
     GccLibEmbedder.new(app, gcc_info).embed if options[:native_comp]
@@ -373,6 +374,18 @@ class Build
     end
   end
 
+  def add_cli_helper(app)
+    source = File.join(__dir__, 'helper', 'emacs-cli.bash')
+    target = File.join(app, 'Contents', 'MacOS', 'bin', 'emacs')
+    dir = File.dirname(target)
+
+    info "Adding \"emacs\" CLI helper to #{dir}"
+
+    FileUtils.mkdir_p(dir)
+    FileUtils.cp(source, target)
+    FileUtils.chmod('+w', target)
+  end
+
   def archive_filename
     return @archive_filename if @archive_filename
 
diff --git a/helper/emacs-cli.bash b/helper/emacs-cli.bash
new file mode 100755
index 0000000..f8a6ddb
--- /dev/null
+++ b/helper/emacs-cli.bash
@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+
+resolve_link() {
+  "$(type -p greadlink readlink | head -1)" "$1"
+}
+
+abs_dirname() {
+  local path="$1"
+  local name
+  local cwd
+  cwd="$(pwd)"
+
+  while [ -n "$path" ]; do
+    cd "${path%/*}" || exit 1
+    name="${path##*/}"
+    path="$(resolve_link "$name" || true)"
+  done
+
+  pwd
+  cd "$cwd" || exit 1
+}
+
+exec "$(dirname "$(abs_dirname "$0")")/Emacs" "$@"