linux-rt: add update script

pkgs/os-specific/linux/kernel/update-rt.sh

@@ -0,0 +1,77 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# To update all rt kernels run: ./update-rt.sh
+
+# To update just one ./linux-rt-5.X.nix run: ./update-rt.sh ./linux-rt-5.X.nix
+
+# To add a new kernel branch 5.Y run: ./update-rt.sh ./linux-rt-5.Y.nix
+# (with nonexistent .nix file) and update all-packages.nix.
+
+# To commit run with: env COMMIT=1
+
+mirror=https://kernel.org/pub/linux/kernel
+
+main() {
+    if [ $# -ge 1 ]; then
+        update-if-needed "$1"
+    else
+        update-all-if-needed
+    fi
+}
+
+update-all-if-needed() {
+    for f in "$(dirname "$0")"/linux-rt-*.nix; do
+        update-if-needed "$f"
+    done
+}
+
+file-version() {
+    file="$1" # e.g. ./linux-rt-5.4.nix
+    if [ -e "$file" ]; then
+        grep ' version = ' "$file" | grep -o '[0-9].[^"]*'
+    fi
+}
+
+latest-rt-version() {
+    branch="$1" # e.g. 5.4
+    curl -sL "$mirror/projects/rt/$branch/sha256sums.asc" |
+        sed -ne '/.patch.xz/ { s/.*patch-\(.*\).patch.xz/\1/; p; q }'
+}
+
+update-if-needed() {
+    file="$1" # e.g. ./linux-rt-5.4.nix (created if does not exist)
+    branch=$(basename "$file" .nix) # e.g. linux-rt-5.4
+    branch=${branch#linux-rt-} # e.g. 5.4
+    cur=$(file-version "$file") # e.g. 5.4.59-rt36 or empty
+    new=$(latest-rt-version "$branch") # e.g. 5.4.61-rt37
+    kversion=${new%-*} # e.g. 5.4.61
+    major=${branch%.*} # e.g 5
+    nixattr="linux-rt_${branch/./_}"
+    if [ "$new" = "$cur" ]; then
+        echo "$nixattr: $cur (up-to-date)"
+        return
+    fi
+    khash=$(nix-prefetch-url "$mirror/v${major}.x/linux-${kversion}.tar.xz")
+    phash=$(nix-prefetch-url "$mirror/projects/rt/${branch}/older/patch-${new}.patch.xz")
+    if [ "$cur" ]; then
+        msg="$nixattr: $cur -> $new"
+    else
+        msg="$nixattr: init at $new"
+        prev=$(ls "$(dirname "$0")"/linux-rt-*.nix | tail -1)
+        cp "$prev" "$file"
+        cur=$(file-version "$file")
+    fi
+    echo "$msg"
+    sed -i "$file" \
+        -e "s/$cur/$new/" \
+        -e "s|kernel/v[0-9]*|kernel/v$major|" \
+        -e "1,/.patch.xz/ s/sha256 = .*/sha256 = \"$khash\";/" \
+        -e "1,/.patch.xz/! s/sha256 = .*/sha256 = \"$phash\";/"
+    if [ "${COMMIT:-}" ]; then
+        git add "$file"
+        git commit -m "$msg"
+    fi
+}
+
+return 2>/dev/null || main "$@"

pkgs/os-specific/linux/kernel/update.sh

@@ -58,6 +58,9 @@ ls $NIXPKGS/pkgs/os-specific/linux/kernel | while read FILE; do
   echo "Updated $OLDVER -> $V"
 done
 
+# Update linux-rt
+COMMIT=1 $NIXPKGS/pkgs/os-specific/linux/kernel/update-rt.sh
+
 # Update linux-libre
 COMMIT=1 $NIXPKGS/pkgs/os-specific/linux/kernel/update-libre.sh