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https://github.com/garrytan/gstack.git
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garrytan
337d34fe16
Codex's sandbox mounts .git read-only, so gstack-wtree's git add -A could not write blobs and /review lost its start capture. gstack-review-log now creates a private 0700 object directory under TMPDIR, passes it to gstack-wtree (which writes new objects there with the common-dir object store, resolved before exporting, as an alternate, so linked worktrees work), exposes it to the bindReview/checkSharedLibsReuse consumers that read the tree and blobs, and removes it on EXIT/INT/TERM after they finish. gstack-wtree prints one stderr line and exits 1 on a failed write or unwritable TMPDIR instead of printing a partial hash; review-log no longer swallows that line. Standalone gstack-wtree keeps writing to the repository store so git diff between saved snapshots (/ship) still works.
96 lines
4.9 KiB
Bash
Executable File
96 lines
4.9 KiB
Bash
Executable File
#!/usr/bin/env bash
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# gstack-wtree — print a working-tree CONTENT fingerprint (a git tree hash).
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#
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# Builds a temp index, stages the full working tree into it (`git add -A`, so
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# .gitignore'd scratch stays out and UNTRACKED source is included), and prints
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# `git write-tree` of that index. Properties that make this the right
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# staleness fingerprint, vs `git rev-parse HEAD^{tree}`:
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#
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# - Committing identical content does NOT change the fingerprint, so a
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# record made on a dirty tree stays valid after the exact same content is
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# committed (the /ship Step 5 -> Step 16 case).
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# - Untracked new source files DO change the fingerprint, so "tests passed"
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# can't stay FRESH after a new file appears.
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# - Rebase/amend/squash that preserve content do not change it.
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#
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# Performance: the temp index is seeded by COPYING the real index (git writes
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# it atomically via rename, so the copy is a consistent snapshot). That
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# preserves the stat cache, so `git add -A` only re-hashes files whose stat
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# changed — measured 40x faster than a `read-tree HEAD` seed, which zeroes
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# stat data and forces a full re-hash of every tracked file. Both seeds
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# produce the identical write-tree hash. Fallback: `read-tree HEAD` when the
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# index copy is unavailable (fresh repo, exotic index).
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#
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# The real repo index is never touched. Run standalone, staged blobs land in
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# the object store as unreachable objects and get gc'd like stash churn (the
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# CONTENT of untracked, non-ignored files enters .git/objects until gc — the
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# same property `git stash -u` has), so `git diff <tree> <tree>` between saved
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# snapshots works. With GSTACK_WTREE_OBJECT_DIR set (gstack-review-log, E4),
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# new objects go to that private directory instead, with the repository's
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# object store as an alternate: the fingerprint works under a read-only .git
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# (Codex's sandbox), and the caller owns the directory's lifetime because its
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# consumers read the tree afterwards. Exit 1 outside a git repo, in a repo with
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# no commits, or when a write fails (one stderr line names the cause) — callers
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# treat that as "no fingerprint"; a partial hash is never printed.
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set -euo pipefail
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TOP=$(git rev-parse --show-toplevel 2>/dev/null) || exit 1
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# Resolve the REAL index path BEFORE exporting GIT_INDEX_FILE — with the env
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# var set, `git rev-parse --git-path index` returns the temp index itself and
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# the stat-cache seed silently self-copies into a dead fast path.
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REAL_INDEX=$(git -C "$TOP" rev-parse --git-path index 2>/dev/null || true)
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# Same for the object store: the common dir's objects (linked worktrees share
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# it), resolved to an absolute path before GIT_OBJECT_DIRECTORY is exported.
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REAL_OBJECTS=$(git -C "$TOP" rev-parse --git-path objects 2>/dev/null || true)
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OBJ_DIR="${GSTACK_WTREE_OBJECT_DIR:-}"
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if [ -n "$OBJ_DIR" ] && [ ! -d "$OBJ_DIR" ]; then
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echo "gstack-wtree: private object directory $OBJ_DIR does not exist" >&2
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exit 1
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fi
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TMPIDX=$(mktemp "${TMPDIR:-/tmp}/gstack-wtree-XXXXXX" 2>/dev/null) || {
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echo "gstack-wtree: cannot create a temp index under ${TMPDIR:-/tmp}; set TMPDIR to a writable directory" >&2
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exit 1
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}
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trap 'rm -f "$TMPIDX"' EXIT
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trap 'exit 130' INT TERM
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export GIT_INDEX_FILE="$TMPIDX"
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# Resolve relative --git-path output against the repo root.
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case "$REAL_INDEX" in
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""|/*) ;;
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*) REAL_INDEX="$TOP/$REAL_INDEX" ;;
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esac
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case "$REAL_OBJECTS" in
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""|/*) ;;
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*) REAL_OBJECTS="$TOP/$REAL_OBJECTS" ;;
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esac
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if [ -n "$OBJ_DIR" ]; then
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export GIT_OBJECT_DIRECTORY="$OBJ_DIR"
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export GIT_ALTERNATE_OBJECT_DIRECTORIES="$REAL_OBJECTS${GIT_ALTERNATE_OBJECT_DIRECTORIES:+:$GIT_ALTERNATE_OBJECT_DIRECTORIES}"
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fi
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if [ -n "$REAL_INDEX" ] && [ -f "$REAL_INDEX" ] && cp "$REAL_INDEX" "$TMPIDX" 2>/dev/null; then
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# Carry the real index's mtime onto the copy. Git's racy-git protection
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# re-hashes any entry whose cached mtime is not older than the index file
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# itself; `cp` stamps the copy "now", which silently marks every entry
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# non-racy and lets a same-size rewrite in the same second as the original
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# `git add` keep its stale stat-cache entry — the content change vanishes
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# from the fingerprint. touch -r restores the original racy window.
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# #2687 hardening: a FAILED touch silently reopened that exact hole (the
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# copy keeps its "now" stamp). Fall through to the HEAD seed instead —
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# slower, but every entry gets re-hashed, so the fingerprint stays honest.
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if ! touch -r "$REAL_INDEX" "$TMPIDX" 2>/dev/null; then
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rm -f "$TMPIDX" 2>/dev/null || true
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git -C "$TOP" read-tree HEAD 2>/dev/null || exit 1
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fi
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else
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git -C "$TOP" read-tree HEAD 2>/dev/null || exit 1
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fi
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if ! ERR=$(git -C "$TOP" add -A 2>&1 >/dev/null); then
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echo "gstack-wtree: cannot stage the working tree: $(printf '%s' "$ERR" | head -1)" >&2
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exit 1
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fi
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if ! TREE=$(git -C "$TOP" write-tree 2>&1) || ! printf '%s' "$TREE" | grep -Eqx '[0-9a-f]{40}|[0-9a-f]{64}'; then
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echo "gstack-wtree: cannot write the tree: $(printf '%s' "$TREE" | head -1)" >&2
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exit 1
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fi
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printf '%s\n' "$TREE"
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