gh-copilot: add auto-updating

pkgs/by-name/gh/gh-copilot/package.nix

···
     runHook postInstall
   '';
 
+  passthru.updateScript = ./update.sh;
+
   meta = {
     changelog = "https://github.com/github/gh-copilot/releases/tag/v${finalAttrs.version}";
     description = "Ask for assistance right in your terminal.";

pkgs/by-name/gh/gh-copilot/update.sh

···
+#!/usr/bin/env nix-shell
+#!nix-shell -i bash -p curl jq common-updater-scripts nix-prefetch
+
+set -euo pipefail
+set -x
+
+ROOT="$(dirname "$(readlink -f "$0")")"
+NIX_DRV="$ROOT/package.nix"
+if [ ! -f "$NIX_DRV" ]; then
+  echo "ERROR: cannot find gh-copilot in $ROOT"
+  exit 1
+fi
+
+fetch_arch() {
+  VER="$1"; ARCH="$2"
+  URL="https://github.com/github/gh-copilot/releases/download/v${VER}/${ARCH}";
+  nix-prefetch "{ stdenv, fetchzip }:
+stdenv.mkDerivation rec {
+  pname = \"vere\"; version = \"${VER}\";
+  src = fetchurl { url = \"$URL\"; };
+}
+"
+}
+
+replace_sha() {
+  # https://stackoverflow.com/a/38470458/22235705
+  sed -rziE "s@($1[^\n]*\n[^\n]*hash = )\"sha256-.{44}\";@\1\"$2\";@" "$NIX_DRV"
+}
+
+VERE_VER=$(curl https://api.github.com/repos/github/gh-copilot/releases/latest | jq .tag_name)
+VERE_VER=$(echo $VERE_VER | sed -e 's/^"v//' -e 's/"$//') # transform "v1.0.2" into 1.0.2
+
+VERE_LINUX_X64_SHA256=$(fetch_arch "$VERE_VER" "linux-amd64")
+VERE_LINUX_AARCH64_SHA256=$(fetch_arch "$VERE_VER" "linux-arm64")
+VERE_DARWIN_X64_SHA256=$(fetch_arch "$VERE_VER" "darwin-amd64")
+VERE_DARWIN_AARCH64_SHA256=$(fetch_arch "$VERE_VER" "darwin-arm64")
+
+sed -i "s/version = \".*\"/version = \"$VERE_VER\"/" "$NIX_DRV"
+
+replace_sha "linux-amd64" "$VERE_LINUX_X64_SHA256"
+replace_sha "linux-arm64" "$VERE_LINUX_AARCH64_SHA256"
+replace_sha "darwin-amd64" "$VERE_DARWIN_X64_SHA256"
+replace_sha "darwin-arm64" "$VERE_DARWIN_AARCH64_SHA256"