Add tool for diffing channel generations

1 files changed, 102 insertions, 0 deletions

diff --git a/nix-script-channel-diff-generations.sh b/nix-script-channel-diff-generations.sh
new file mode 100755
index 0000000..5e65397
--- /dev/null
+++ b/nix-script-channel-diff-generations.sh
@@ -0,0 +1,102 @@
+#!/usr/bin/env bash
+
+source $(dirname ${BASH_SOURCE[0]})/nix-utils.sh
+
+usage() {
+    cat <<EOS >&2
+    $(help_synopsis "${BASH_SOURCE[0]}" "[-g <command>] [-w <path>] [-n <generations>] [-h]")
+
+    -g <command>        | Use this command instead of 'diff --name-only' (currently no support for multi-word args)
+    -w <path>           | Path to working-copy of nixpkgs git repo, default: $RC_NIXPKGS
+    -n <generations>    | Generations to show diff in form a..b
+    -h                  | Show this help and exit
+
+$(help_end)
+EOS
+}
+
+GEN_A=
+GEN_B=
+WC=$RC_NIXPKGS
+GIT="diff --name-only"
+
+explain() {
+    stdout $*
+    $*
+}
+
+while getopts "g:w:n:h" OPTION
+do
+    case $OPTION in
+        g)
+            GIT=$OPTARG
+            dbg "GIT = $GIT"
+            ;;
+
+        w)
+            WC=$OPTARG
+            dbg "WC = $WC"
+            ;;
+
+        n)
+            GEN_A=$(echo $OPTARG | cut -d "." -f 1)
+            GEN_B=$(echo $OPTARG | cut -d "." -f 3)
+
+            [[ -z "$GEN_A" || -z "$GEN_B" ]] && \
+                stderr "Parsing error for '$OPTARG'" && usage && exit 1
+
+            dbg "GEN_A = $GEN_A"
+            dbg "GEN_B = $GEN_B"
+            ;;
+
+        h)
+            usage
+            exit 1
+            ;;
+    esac
+done
+
+[[ -z "$GEN_A" || -z "$GEN_B" ]] && \
+    stderr "No generation information" && usage && exit 1
+
+pathof() {
+    echo "/nix/var/nix/profiles/per-user/root/channels-$1-link/nixos/nixpkgs/.version-suffix"
+}
+
+version_string() {
+    local path=$(pathof $1)
+    local version=$(cat $path)
+
+    [[ -z "$version" ]] && \
+        stderr "No commit version information for generation $1" && exit 1
+
+    echo $version
+
+}
+
+commit_for() {
+    echo $(version_string $1) | cut -d . -f 2
+}
+
+__git() {
+    explain git --git-dir="$WC/.git" --work-tree="$WC" $*
+}
+
+A=$(commit_for $GEN_A)
+B=$(commit_for $GEN_B)
+
+stdout "A = $A"
+stdout "B = $B"
+
+[[ "$A" -eq "$B" ]] && \
+    echo "Same hash for both generations. There won't be a diff" && exit 1
+
+if [[ -z "$WC" ]]
+then
+    echo "$A..$B"
+else
+    __git $GIT "$A..$B"
+fi
+
+stdout "Ready"
+