fix: make ci/container/container-run.sh work when the checkout is a git worktree

ci/container/build-ic.sh

@@ -10,7 +10,11 @@ if [ "${BUILD_IC_NESTED:-}" == 1 ]; then
 fi
 export BUILD_IC_NESTED=1
 
-export ROOT_DIR="$(git rev-parse --show-toplevel)"
+# Assign, then export: `export X="$(...)"` swallows the command
+# substitution's exit status, so a failing git would leave X empty and
+# `set -e` would not notice.
+ROOT_DIR="$(git rev-parse --show-toplevel)"
+export ROOT_DIR
 
 # This script needs to be run inside the ic-build container
 # If it isn't, we drop into the correct container.
@@ -105,7 +109,8 @@ if [ -n "$(git status --porcelain)" ]; then
     exit 1
 fi
 
-export VERSION="$(git rev-parse HEAD)"
+VERSION="$(git rev-parse HEAD)"
+export VERSION
 
 BAZEL_TARGETS=()
 

ci/container/container-run.sh

@@ -205,6 +205,40 @@ RUNTIME_RUN_ARGS=(
     --mount type=tmpfs,target="/tmp/containers" # expected by ic-os build
 )
 
+# When the checkout is a linked git worktree, its `.git` is a *file* holding an
+# absolute path to an admin directory under the main checkout's `.git`, i.e. a
+# path outside the checkout. Mounting only the checkout leaves that pointer
+# dangling, so every `git` call inside the container fails -- including the
+# `$(git rev-parse --show-toplevel)` that several ci scripts rely on. Mount the
+# main checkout's `.git` at the very same absolute path so the pointer resolves.
+if [ -f "${REPO_ROOT}/.git" ]; then
+    GIT_COMMON_DIR="$(git rev-parse --git-common-dir)"
+    GIT_COMMON_DIR="$(cd "$GIT_COMMON_DIR" && pwd)" # may be relative
+    case "$GIT_COMMON_DIR" in
+        "$REPO_ROOT" | "$REPO_ROOT"/*)
+            : # inside the checkout already, covered by the mount above
+            ;;
+        *)
+            eprintln "Checkout is a git worktree, also mounting '$GIT_COMMON_DIR'"
+            RUNTIME_RUN_ARGS+=(
+                --mount type=bind,source="${GIT_COMMON_DIR}",target="${GIT_COMMON_DIR}"
+
+                # Each worktree admin directory holds a back-pointer to its
+                # worktree's *host* path, and those paths do not exist in the
+                # container (this checkout lives at $WORKDIR, the others are not
+                # mounted at all), so git considers every worktree prunable here.
+                # That is harmless for reading, but `git gc` -- which git runs
+                # automatically after commit/fetch/... -- prunes worktrees as
+                # part of its job and would delete the host's admin directories.
+                # Turn auto gc off; an explicit `git gc` remains the user's call.
+                -e GIT_CONFIG_COUNT=1
+                -e GIT_CONFIG_KEY_0=gc.auto
+                -e GIT_CONFIG_VALUE_0=0
+            )
+            ;;
+    esac
+fi
+
 # Privilege/isolation flags required by the IC-OS guest build, per runtime.
 if [ "$RUNTIME" = docker ]; then
     # Under docker the IC-OS build runs (rootless) podman *inside* this

ci/container/get-image-tag.sh

@@ -2,7 +2,9 @@
 
 set -eEuo pipefail
 
-cd "$(git rev-parse --show-toplevel)"
+# Assign first: `cd "$(...)"` would silently `cd ""` (exit 0) if git failed.
+REPO_ROOT="$(git rev-parse --show-toplevel)"
+cd "$REPO_ROOT"
 
 INPUT_FILES=(
     ci/container/Dockerfile

ci/scripts/rust-lint.sh

@@ -1,7 +1,12 @@
 #!/usr/bin/env bash
 set -xeuo pipefail
 
-cd "${CI_PROJECT_DIR:-$(git rev-parse --show-toplevel)}"
+# Note the assignment: `cd "$(git rev-parse ...)"` would `cd ""` and *succeed*
+# (bash returns 0 for a null directory operand) if git failed, silently turning
+# this script into a no-op that lints nothing and exits 0. An assignment, in
+# contrast, takes the command substitution's exit status, so `set -e` fires.
+REPO_ROOT="${CI_PROJECT_DIR:-$(git rev-parse --show-toplevel)}"
+cd "$REPO_ROOT"
 
 cargo fmt -- --check