From e31eb9a58d62043cdc9ba7db8b6b2dd19f6e1c5d Mon Sep 17 00:00:00 2001
From: gilice <104317939+gilice@users.noreply.github.com>
Date: Tue, 21 Mar 2023 17:30:07 +0100
Subject: [PATCH] dart: Make update script atomic

---
 pkgs/development/compilers/dart/sources.nix |  3 ---
 pkgs/development/compilers/dart/update.sh   | 19 ++++++++-----------
 2 files changed, 8 insertions(+), 14 deletions(-)

diff --git a/pkgs/development/compilers/dart/sources.nix b/pkgs/development/compilers/dart/sources.nix
index 13aaac2bb327..40e25d358477 100644
--- a/pkgs/development/compilers/dart/sources.nix
+++ b/pkgs/development/compilers/dart/sources.nix
@@ -1,5 +1,3 @@
-# This file was generated by ./update.sh.
-# If you do not find a line of three #-s at the end, it is broken and should not be used.
 let version = "2.19.3"; in
 {  fetchurl }: {
   versionUsed = version;
@@ -24,4 +22,3 @@ let version = "2.19.3"; in
     sha256 = "0xksis14ff6bzjvycgxgldg96n88rh42adjyrrhcay2s183vh480";
   };
 }
-###
diff --git a/pkgs/development/compilers/dart/update.sh b/pkgs/development/compilers/dart/update.sh
index c148f09b52a2..87f430cd5d2d 100755
--- a/pkgs/development/compilers/dart/update.sh
+++ b/pkgs/development/compilers/dart/update.sh
@@ -3,7 +3,7 @@
 
 set -euo pipefail
 
-# so if the script fails, debug logs are on stdenv
+# so if the script fails, debug logs are on stderr
 log() {
   >&2 echo "DART_UPDATER: $@"
 }
@@ -13,12 +13,11 @@ NEW_VER_DETAILS=$(curl -sL https://storage.googleapis.com/dart-archive/channels/
 NEW_VER=$(jq -r '.version' <<< "$NEW_VER_DETAILS")
 
 MY_PATH=$(dirname $(realpath "$0"))
-SRC_FILE="$MY_PATH/sources.nix"
+SRC_FILE=$(mktemp)
+
 log "file to write is $SRC_FILE"
 
-PRELUDE="# This file was generated by ./update.sh.
-# If you do not find a line of three #-s at the end, it is broken and should not be used.
-let version = \"$NEW_VER\"; in
+PRELUDE="let version = \"$NEW_VER\"; in
 { fetchurl }: {
   versionUsed = version;"
 echo "$PRELUDE" > "$SRC_FILE"
@@ -54,8 +53,7 @@ write_for_platform() {
 
     echo "$FETCHER" >> $SRC_FILE
   done
-  log "finished for $1
----"
+  log "finished for $1"
 
 }
 
@@ -73,8 +71,7 @@ declare -A LIN_PLATFORMS=( ["x86_64-linux"]="$X8664"
 write_for_platform "DARWIN_PLATFORMS" "macos"
 write_for_platform "LIN_PLATFORMS" "linux"
 
-echo '}
-###' >> $SRC_FILE
+echo '}' >> $SRC_FILE
 
-log "Replacing version in dart/default.nix"
-sed -i "s/$UPDATE_NIX_OLD_VERSION/$NEW_VER/g" "$MY_PATH/default.nix"
+log "moving tempfile to target directory"
+mv "$SRC_FILE" "$MY_PATH/sources.nix"