### Check existing issues - [x] I've verified that this bug isn't described by any existing issues. ### Bug description Generated hooks, e.g. a part writing to `$CRAFT_PRIME/snap/hooks/<name>` are not properly staged in the final Snap, leaving the `#!/bin/true` stubs. When `snapcraft.yaml` declares a `hooks` section, stubs with `#!/bin/true` is written in `meta/hooks/<name>` during the `setup_assets(..., copy_hooks_and_gui=False) -> setup_hooks() -> _ensure_hook()` call as the hooks are not yet generated. The generated hooks are supposed to replace the stubs in `_materialize_extra_assets() -> provision_hooks(prime_dir, overwrite=False)`. However, because the stub now occupies the path, the generated hooks are not copied. Two conditions are required to trigger this: 1. `snapcraft.yaml` declares a `hooks` section (needed for hook plugs) 2. a part produces `snap/hooks/<name>` -- what `snap-helpers write-hooks` does This is observed in Snapcraft 9.1.x. Previous Snapcraft versions 9.0.x do not have this bug. Most likely caused by #6379 and #6385. Same issue came and fixed in the past: #3386 and #3837. ### Steps to reproduce Using this helper script: ```sh #!/bin/bash # Reproducer: snapcraft discards a part-generated hook, shipping a # "#!/bin/true" stub in meta/hooks/<name> so the hook never runs. # # ./repro-hooks.sh reproduce the bug # ./repro-hooks.sh --no-hooks control: drop the `hooks:` section # ./repro-hooks.sh --fix workaround applied in override-prime # # Builds a throwaway snap in a temp dir; nothing is installed. set -euo pipefail FIX=0; NO_HOOKS=0 for arg in "$@"; do case "$arg" in --fix) FIX=1 ;; --no-hooks) NO_HOOKS=1 ;; -h|--help) sed -n '2,12p' "$0"; exit 0 ;; *) echo "usage: $0 [--fix] [--no-hooks]" >&2; exit 2 ;; esac done command -v snapcraft >/dev/null || { echo "snapcraft not found" >&2; exit 1; } command -v unsquashfs >/dev/null || { echo "unsquashfs not found (apt install squashfs-tools)" >&2; exit 1; } WORK="$(mktemp -d)"; trap 'rm -rf "$WORK"' EXIT mkdir -p "$WORK/snap" # Two conditions are required to trigger this, and the script lets you remove # either one: # 1. snapcraft.yaml declares a `hooks:` section (needed for hook plugs) # 2. a part produces snap/hooks/<name> -- what `snap-helpers write-hooks` does { cat <<'YAML' name: hookstub-repro base: core26 version: "0.1" summary: part-generated hook replaced by a stub description: part-generated hook replaced by a stub grade: stable confinement: strict apps: hello: command: bin/hello YAML [ "$NO_HOOKS" = 0 ] && cat <<'YAML' hooks: configure: plugs: [network] YAML cat <<'YAML' parts: app: plugin: nil override-build: | mkdir -p $CRAFT_PART_INSTALL/bin printf '#!/bin/sh\necho hello\n' > $CRAFT_PART_INSTALL/bin/hello chmod 755 $CRAFT_PART_INSTALL/bin/hello # A part generating a hook into snap/hooks/, as snap-helpers does. mkdir -p $CRAFT_PART_INSTALL/snap/hooks printf '#!/bin/sh\necho REAL_HOOK_RAN\n' > $CRAFT_PART_INSTALL/snap/hooks/configure chmod 755 $CRAFT_PART_INSTALL/snap/hooks/configure YAML [ "$FIX" = 1 ] && cat <<'YAML' override-prime: | craftctl default # Write the wrappers before metadata generation, so _ensure_hook() finds # meta/hooks/<name> already present and returns early. for hook in "$CRAFT_PRIME"/snap/hooks/*; do [ -f "$hook" ] || continue name="$(basename "$hook")" mkdir -p "$CRAFT_PRIME/meta/hooks" printf '#!/bin/sh\nexec "$SNAP/snap/hooks/%s" "$@"\n' "$name" \ > "$CRAFT_PRIME/meta/hooks/$name" chmod 755 "$CRAFT_PRIME/meta/hooks/$name" done YAML } > "$WORK/snap/snapcraft.yaml" printf '\n== snapcraft version\n'; snapcraft --version 2>/dev/null | head -1 printf '\n== building (hooks-section=%s, fix=%s)\n' "$((1-NO_HOOKS))" "$FIX" ( cd "$WORK" && snapcraft --use-lxd --verbosity=quiet ) SNAP="$(ls "$WORK"/*.snap)" printf '\n== snap/hooks/configure (what the part generated)\n' unsquashfs -cat "$SNAP" snap/hooks/configure 2>/dev/null | sed 's/^/ /' || echo " (absent)" printf '\n== meta/hooks/configure (what snapd actually runs)\n' unsquashfs -cat "$SNAP" meta/hooks/configure 2>/dev/null | sed 's/^/ /' || echo " (absent)" printf '\n' if unsquashfs -cat "$SNAP" meta/hooks/configure 2>/dev/null | grep -q '/bin/true'; then echo ">> REPRODUCED: meta/hooks/configure is a #!/bin/true stub; the hook never runs." exit 1 else echo ">> Real hook shipped (expected behaviour)." fi ``` ### Environment Build on Noble with Snapcraft version 9.1.1.