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stack/packages/mosaic/framework/tools/git/push-guard.sh
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feat(git): push-guard — refuse verifications satisfied by the null case (closes #975) (#974)
2026-07-31 03:35:24 +00:00

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#!/usr/bin/env bash
# push-guard.sh - Mechanical guards against verifications that PASS when the
# thing they verify never happened.
#
# WHY THIS EXISTS
# ---------------
# Three independent incidents, one shape:
# 1. An agent's "PUSH VERIFIED" step compared local HEAD to the remote ref and
# reported success. The commit had ABORTED, so local trivially equalled
# remote. The guard could not distinguish "pushed" from "committed nothing".
# 2. An agent chained a push after a FAILED commit, ran on stale state, and
# pushed an EMPTY commit carrying an unrelated commit's message.
# 3. An agent committed unresolved conflict markers into 70 generated files and
# pushed invalid JSON to a default branch.
#
# All three are the same defect: a check whose success condition is satisfied by
# the null case. This script asserts the POSITIVE fact (a new object exists, the
# remote MOVED, the content parses) rather than the absence of an error.
#
# DESIGN RULES (do not relax these)
# * Every check exits NON-ZERO and names what failed. There is deliberately no
# --warn-only / --soft flag: a guard that can degrade to a warning is the
# fail-open we are trying to remove.
# * Checks are fail-CLOSED. `set -euo pipefail` means an unexpected git or
# network error aborts non-zero rather than falling through to "OK".
# * Nothing is skipped silently. A check with no applicable inputs says so on
# stdout instead of contributing a quiet green.
#
# EXIT CODES
# 0 all requested checks passed
# 2 conflict markers present, or the index has unmerged paths
# 3 staged JSON does not parse
# 4 push verification failed (remote did not move, or moved elsewhere)
# 5 nothing staged / empty commit — the null case, refused
# 6 NO JSON DECISION — no --json-path and no usable .push-guard.json
# 64 usage error
#
# Dependencies: bash 4.4+, git, python3.
set -euo pipefail
readonly EX_OK=0
readonly EX_CONFLICT=2
readonly EX_JSON=3
readonly EX_PUSH=4
readonly EX_NULL=5
readonly EX_CONFIG=6
readonly EX_USAGE=64
# Repo-level configuration. Its ABSENCE is refused, not defaulted — see
# resolve_json_config() for why.
readonly CONFIG_FILE=".push-guard.json"
# Conflict-marker detection.
#
# We match `<<<<<<<`, `>>>>>>>` and the diff3 `|||||||` marker, each anchored at
# column 0 and required to be followed by a space or end-of-line (real markers
# are exactly seven characters plus an optional ref label).
#
# We deliberately do NOT match a bare `=======` line. It is the one marker that
# collides with ordinary prose — reStructuredText section underlines and ASCII
# rules use it constantly — and a guard that fires on documentation gets switched
# off, which costs more than the miss. Every genuine conflict git writes contains
# `<<<<<<<` and `>>>>>>>` as well, so requiring those loses no real detection.
readonly MARKER_PATTERNS=(
-e '^<<<<<<<( |$)'
-e '^>>>>>>>( |$)'
-e '^[|]{7}( |$)'
)
log() { printf '%s\n' "$*"; }
fail() {
local code="$1"; shift
printf '\n' >&2
printf 'PUSH-GUARD FAILED: %s\n' "$1" >&2
shift
local line
for line in "$@"; do printf ' %s\n' "$line" >&2; done
printf '\n' >&2
exit "$code"
}
usage() {
cat <<'EOF'
Usage:
push-guard.sh check-staged [--json-path <pathspec>]...
[--allow-invalid-json <pathspec>]...
push-guard.sh push --remote <remote> --branch <branch> [--since-head <sha>]
[-- <extra git push args>...]
push-guard.sh --help
Subcommands:
check-staged Run pre-commit content guards against the STAGED index:
(a) no unmerged index paths, no conflict markers
(c) staged JSON under the nominated paths parses
Refuses to pass when nothing is staged (exit 5).
Check (c) requires an EXPLICIT decision — either --json-path,
or .push-guard.json. Saying nothing is refused (exit 6).
push Perform a push and prove it HAPPENED:
- HEAD is a non-empty commit (differs from its parent)
- with --since-head: HEAD advanced past that sha
- the remote ref MOVED, and now equals local HEAD
Capturing the remote ref BEFORE the push is what makes
"remote == local" meaningful; without it the assertion is
satisfied by having pushed nothing.
Options:
--json-path <pathspec> Git pathspec of generated/serialized JSON to
parse-check, e.g. 'data/**/*.json'. Repeatable.
Opt-in on purpose: many real .json files are
JSONC (tsconfig) or templates and do NOT parse
strictly. Nominate the generated ones. Satisfies
the decision requirement on its own; overrides a
config opt-out (loudly).
--allow-invalid-json <pathspec> Exempt a path from the JSON parse check
(for deliberate malformed-input fixtures).
Exemptions are printed, never silent.
--since-head <sha> HEAD before your commit step. Asserts a new
commit object was actually created.
--remote <name> Remote to push to.
--branch <name> Branch to push.
Repo config (.push-guard.json, at the repository root):
{"json_paths": ["data/**/*.json"], "allow_invalid_json": ["fixtures/*"]}
— nominate generated JSON for parse-checking.
{"json_check": "none", "reason": "no generated JSON in this repo"}
— opt out. The reason is REQUIRED and is printed on every run.
An opt-out is only accepted from this file, never from a command-line flag: a
committed reason can be read in a diff, an absent flag cannot be reviewed at all.
An invalid config is refused outright rather than treated as absent.
There is no flag to downgrade a failure to a warning. That is intentional.
EOF
}
require_repo() {
git rev-parse --show-toplevel >/dev/null 2>&1 \
|| fail "$EX_USAGE" "not inside a git repository"
cd "$(git rev-parse --show-toplevel)"
}
# ---------------------------------------------------------------- check-staged
# staged_files_z <array-name> [pathspec...]
#
# THE FAIL-OPEN THIS FUNCTION EXISTS TO REMOVE:
# mapfile -d '' -t files < <(git diff ...)
# observes MAPFILE's exit status, never the producer's. When git diff dies -- a
# bad pathspec, a corrupt index -- mapfile cheerfully reads zero bytes and
# succeeds, and the caller then reports that silence as "nothing to check".
#
# `set -o pipefail` does NOT cover this. pipefail applies to PIPELINES; a process
# substitution is an asynchronous child whose status is never collected. That is
# the precise reason every `cmd | cmd` in this file is safe and both `< <(cmd)`
# constructs were not -- a distinction worth stating, because "we set pipefail"
# reads like whole-file coverage and is not.
#
# Both callers now route through here, so the category is gone rather than the
# two known instances being patched.
staged_files_z() {
local -n _out="$1"; shift
local tmp err status=0
tmp="$(mktemp)"; err="$(mktemp)"
if (( $# )); then
git diff --cached --name-only --diff-filter=ACM --no-renames -z \
-- "$@" >"$tmp" 2>"$err" || status=$?
else
git diff --cached --name-only --diff-filter=ACM --no-renames -z \
>"$tmp" 2>"$err" || status=$?
fi
if (( status != 0 )); then
local msg; msg="$(tr '\n' ' ' <"$err")"
rm -f "$tmp" "$err"
fail "$EX_CONFIG" \
"CANNOT ENUMERATE STAGED FILES — git diff exited $status" \
"git said: ${msg:-(no message)}" \
"" \
"Refusing to report a result. An enumeration that failed returns no" \
"files, which is indistinguishable from a clean tree — reporting that" \
"as OK would be a silent pass on an unexamined index."
fi
_out=()
mapfile -d '' -t _out <"$tmp"
rm -f "$tmp" "$err"
}
check_unmerged() {
local unmerged
unmerged="$(git ls-files --unmerged | awk '{print $4}' | sort -u)"
if [[ -n "$unmerged" ]]; then
mapfile -t paths <<<"$unmerged"
fail "$EX_CONFLICT" \
"the index has UNMERGED paths — a merge/rebase is still in progress" \
"${paths[@]}" \
"" \
"Resolve the conflict and 'git add' the result. Do not commit past this."
fi
log " ok index has no unmerged paths"
}
check_conflict_markers() {
local -a files=("$@")
local hits
# git grep --cached searches the INDEX (what will actually be committed),
# not the working tree.
#
# -a (treat every blob as text), NOT -I (skip binary). -I honours git's
# binary classification, which includes an explicit `.gitattributes` `binary`
# attribute. A repo that marks a path binary would have its staged conflict
# markers silently skipped while the summary still counted the file as
# scanned — a clean pass AND a false count. Verified reproducible. The cost
# of -a is that a genuine binary blob could theoretically emit a noisy match
# line; a false alarm is recoverable, a silent miss is not.
# -E is load-bearing: git grep defaults to BASIC regex, in which '(', '|'
# and '{7}' are literal characters. Without it these patterns match nothing
# and the check reports a clean pass over a file full of markers. That
# failure was caught by the needle, not by review.
#
# Exit status is discriminated, NOT swallowed. git grep returns 1 for "no
# match" and >=2 for a real error (bad pathspec, unreadable index). A blanket
# '|| true' would turn a broken scan into "ok, no conflict markers" — the
# same fail-open in the guard's own error handling.
local status=0
hits="$(git grep --cached -a -n -E "${MARKER_PATTERNS[@]}" -- "${files[@]}")" || status=$?
if (( status > 1 )); then
fail "$EX_CONFLICT" \
"git grep FAILED (exit $status) — the conflict scan did not run" \
"Refusing to report a clean result from a scan that did not complete."
fi
if [[ -n "$hits" ]]; then
mapfile -t lines <<<"$hits"
fail "$EX_CONFLICT" \
"staged content contains unresolved CONFLICT MARKERS" \
"${lines[@]}" \
"" \
"These are staged and would be committed verbatim."
fi
log " ok no conflict markers in ${#files[@]} staged file(s)"
}
# JSON parse check.
#
# SCOPE IS OPT-IN, AND THAT IS A MEASURED DECISION, NOT LAZINESS.
# The first draft checked every staged *.json. Run against a real repository that
# turned out to be 17 of 119 tracked .json files failing a strict parse — all of
# them legitimate: every tsconfig*.json is JSONC (comments are legal there) and
# the CA templates are Go templates that merely carry a .json suffix. An
# on-by-default check would have fired on ~14% of this repo's JSON, and a guard
# that cries wolf gets routed around until the bypass is habitual — which is
# worse than no guard, because the bypass then also covers the true positives.
#
# So the caller nominates the generated/serialized paths this check is FOR, as
# git pathspecs (git, not bash, expands them — '**' works correctly).
#
# WHAT SAYING NOTHING NOW COSTS YOU
# ---------------------------------
# The first release announced "JSON check NOT REQUESTED" and continued. That was
# visible rather than silent, which is better — but it is still an ABSENCE, and
# an absence is not reviewable. Nobody reads a line that has printed correctly
# ten thousand times. A repo that needed the check and never wired it up stayed
# unprotected forever, and nothing ever failed.
#
# The decision is now MANDATORY and must come from one of two places:
# * turning the check ON — --json-path on the command line, or "json_paths"
# in .push-guard.json
# * turning the check OFF — ONLY "json_check": "none" in .push-guard.json,
# which REQUIRES a non-empty "reason"
# Saying nothing at all is refused (exit 6).
#
# The asymmetry is deliberate. Turning a check on is safe from anywhere. Turning
# one OFF is confined to a committed file because that is the only form a human
# can review: you can read a reason in a diff, and you cannot review the fact
# that nobody typed a flag. An opt-out that lives in an ad-hoc command line is
# just the old fail-open with extra steps.
# The config parser, held as a string rather than an inline heredoc.
#
# A `<<'PY'` heredoc INSIDE a $( ) command substitution makes bash emit
# warning: command substitution: 1 unterminated here-document
# on every single run. It still executed, every needle stayed green and the
# static linter stayed clean — the warning goes to stderr and broke no
# assertion. It surfaced only when the guard was run against a real
# repository. A tool built to refuse quiet output was quietly polluting
# stderr; needle 'z1' now asserts the guard emits no warnings at all.
#
# `read -d ''` returns non-zero at EOF without finding a NUL, which is the
# NORMAL path when slurping a heredoc — hence `|| true`. That is the one
# shape where it does not mask a real error, unlike the `git grep || true`
# this codebase already removed once.
IFS='' read -r -d '' CONFIG_PARSER <<'PY' || true
import json, sys
path = sys.argv[1]
try:
with open(path) as fh:
cfg = json.load(fh)
except Exception as exc:
sys.stderr.write("does not parse: %s" % exc)
sys.exit(2)
if not isinstance(cfg, dict):
sys.stderr.write("must contain a JSON object, got %s" % type(cfg).__name__)
sys.exit(2)
def clean_list(name, value):
if not isinstance(value, list):
sys.stderr.write('"%s" must be an array' % name)
sys.exit(2)
for item in value:
if not isinstance(item, str) or not item.strip():
sys.stderr.write('"%s" must contain only non-empty strings' % name)
sys.exit(2)
# Tabs/newlines would be mangled by the tab-delimited handoff below.
# Reject them explicitly rather than silently truncating a pathspec.
if "\t" in item or "\n" in item:
sys.stderr.write('"%s" entry contains a tab or newline: %r' % (name, item))
sys.exit(2)
return value
mode = cfg.get("json_check")
paths = cfg.get("json_paths")
allow = cfg.get("allow_invalid_json", [])
if mode is not None and mode != "none":
sys.stderr.write('"json_check" must be "none" if present, got %r' % (mode,))
sys.exit(2)
if mode == "none":
if paths:
sys.stderr.write('"json_check": "none" and "json_paths" are mutually exclusive')
sys.exit(2)
reason = cfg.get("reason")
if not isinstance(reason, str) or not reason.strip():
sys.stderr.write('"json_check": "none" REQUIRES a non-empty "reason"')
sys.exit(2)
print("MODE\tnone")
print("REASON\t%s" % reason.strip().replace("\t", " ").replace("\n", " "))
sys.exit(0)
if paths is None:
sys.stderr.write(
'states no decision — needs "json_paths", '
'or "json_check": "none" with a "reason"'
)
sys.exit(2)
clean_list("json_paths", paths)
if not paths:
sys.stderr.write('"json_paths" must not be empty')
sys.exit(2)
clean_list("allow_invalid_json", allow)
print("MODE\tcheck")
for item in paths:
print("JPATH\t%s" % item)
for item in allow:
print("ALLOW\t%s" % item)
PY
resolve_json_config() {
local cfg out status=0
cfg="$(git rev-parse --show-toplevel)/$CONFIG_FILE"
if [[ ! -f "$cfg" ]]; then
CFG_MODE="absent"
return 0
fi
# A malformed config must REFUSE, never degrade to "treat as absent". That
# fallback would rebuild precisely the fail-open this gate closes: a typo in
# the config would silently disable the check it was written to enable.
out="$(python3 -c "$CONFIG_PARSER" "$cfg" 2>&1)" || status=$?
if (( status != 0 )); then
fail "$EX_CONFIG" \
"$CONFIG_FILE is INVALID — $out" \
"" \
"Refusing to run. A config that does not parse is not the same as no" \
"config: treating it as absent would silently disable the very check" \
"this file was written to enable."
fi
local key val
while IFS=$'\t' read -r key val; do
case "$key" in
MODE) CFG_MODE="$val" ;;
REASON) CFG_REASON="$val" ;;
JPATH) CFG_PATHS+=("$val") ;;
ALLOW) CFG_ALLOW+=("$val") ;;
esac
done <<<"$out"
# ------------------------------------------------------------------
# THE ASYMMETRY, ENFORCED RATHER THAN INTENDED.
# ON may come from anywhere: turning a check on needs no review.
# OFF must come from a COMMITTED object, because the entire argument for
# requiring a written reason was that a reason is reviewable in a diff
# while an absence is not. An opt-out honoured from an untracked
# working-tree file is not reviewable either -- it is an ad-hoc local
# bypass wearing a config file's clothes, and it defeats the design.
# So the OFF decision is re-read from HEAD and the working tree gets no
# vote in it. A committed ON flipped to OFF locally is likewise refused.
# ------------------------------------------------------------------
[[ "$CFG_MODE" == "none" ]] || return 0
local rel cmode cblob cout cstatus=0
rel="$(git ls-files --full-name --error-unmatch -- "$cfg" 2>/dev/null)" || rel=""
if [[ -z "$rel" ]]; then
fail "$EX_CONFIG" \
"OPT-OUT IS NOT REVIEWABLE — $CONFIG_FILE is not tracked in git" \
"recorded reason was: ${CFG_REASON:-(none)}" \
"" \
"The opt-out requires a written reason precisely so it shows up in a" \
"diff. An untracked file shows up in nobody's review, so honouring it" \
"would rebuild the unreviewable bypass this design exists to prevent." \
"" \
"Commit $CONFIG_FILE, then run again. Turning the check ON needs no" \
"commit; only turning it OFF does."
fi
# A COMMITTED SYMLINK (mode 120000) is a mutable target: the reviewed blob
# is a path, and what it points at can change without any diff at all.
cmode="$(git ls-tree HEAD -- "$rel" 2>/dev/null | awk '{print $1}')"
if [[ -z "$cmode" ]]; then
fail "$EX_CONFIG" \
"OPT-OUT IS NOT REVIEWABLE — $CONFIG_FILE is staged but not yet in HEAD" \
"recorded reason was: ${CFG_REASON:-(none)}" \
"" \
"A staged-but-uncommitted opt-out has not been through review either." \
"Commit it first."
fi
if [[ "$cmode" == "120000" ]]; then
fail "$EX_CONFIG" \
"OPT-OUT IS NOT REVIEWABLE — $CONFIG_FILE is a committed SYMLINK" \
"" \
"The reviewed object would be a path, not a decision: what it points" \
"at can be changed later without producing any diff. Commit the" \
"config as a regular file."
fi
cblob="$(git show "HEAD:$rel" 2>/dev/null)" || cblob=""
cout="$(printf '%s' "$cblob" | python3 -c "$CONFIG_PARSER" /dev/stdin 2>&1)" || cstatus=$?
if (( cstatus != 0 )); then
fail "$EX_CONFIG" \
"COMMITTED $CONFIG_FILE is INVALID — $cout" \
"" \
"The working tree opts out, but the committed version does not parse," \
"so there is no reviewable decision to honour."
fi
local cmode_val="" creason=""
while IFS=$'\t' read -r key val; do
case "$key" in
MODE) cmode_val="$val" ;;
REASON) creason="$val" ;;
esac
done <<<"$cout"
if [[ "$cmode_val" != "none" ]]; then
fail "$EX_CONFIG" \
"LOCAL-ONLY OPT-OUT — the working tree turns the JSON check OFF but" \
"HEAD does not (committed decision: $cmode_val)" \
"working-tree reason: ${CFG_REASON:-(none)}" \
"" \
"An uncommitted edit that disables a committed check is exactly the" \
"unreviewable bypass this guard refuses. Commit the change if it is" \
"real; revert it if it was a local convenience."
fi
# Print the COMMITTED reason, never the working tree's: the reason anyone
# can actually review is the one in the object.
CFG_REASON="$creason"
}
check_staged_json() {
local -a checked=() skipped=()
local f err
local -a pathspec=()
resolve_json_config
if (( ${#JSON_PATHS[@]} == 0 )); then
case "$CFG_MODE" in
absent)
fail "$EX_CONFIG" \
"NO JSON DECISION — no --json-path, and no $CONFIG_FILE" \
"" \
"This guard will not run without an explicit decision about" \
"staged-JSON validation. Create $CONFIG_FILE with EITHER:" \
"" \
' {"json_paths": ["data/**/*.json"]}' \
"" \
"or, if this repo genuinely has no generated JSON:" \
"" \
' {"json_check": "none", "reason": "<why>"}' \
"" \
"The reason is mandatory so the opt-out is recorded and" \
"reviewable in the diff, instead of being an absence nobody sees."
;;
none)
log " -- JSON check OPTED OUT in $CONFIG_FILE — recorded reason: $CFG_REASON"
return 0
;;
check)
JSON_PATHS=(${CFG_PATHS[@]+"${CFG_PATHS[@]}"})
ALLOW_INVALID_JSON+=(${CFG_ALLOW[@]+"${CFG_ALLOW[@]}"})
log " .. JSON paths from $CONFIG_FILE: ${JSON_PATHS[*]}"
;;
esac
else
# An explicit --json-path turns the check ON, so it satisfies the decision
# requirement by itself. If the config opted out, the nomination WINS and
# says so loudly — resolving a contradiction toward more checking is the
# only safe direction, but silently ignoring a committed opt-out would
# hide a real disagreement.
case "$CFG_MODE" in
none)
log " !! $CONFIG_FILE opts out of the JSON check, but --json-path was"
log " !! given — honouring the nomination and checking anyway."
;;
check)
JSON_PATHS+=(${CFG_PATHS[@]+"${CFG_PATHS[@]}"})
ALLOW_INVALID_JSON+=(${CFG_ALLOW[@]+"${CFG_ALLOW[@]}"})
;;
esac
fi
# Normalize to :(glob) magic. WITHOUT it, git's default pathspec matching
# makes 'data/**/*.json' require at least one intermediate directory, so it
# matches data/sub/b.json but SILENTLY SKIPS data/a.json. The obvious
# spelling would then deliver partial coverage with no warning — a
# quiet-underscan, which is the same family of defect as a quiet pass.
# Pathspecs that already carry explicit magic (leading ':') are left alone.
for f in "${JSON_PATHS[@]}"; do
[[ "$f" == :* ]] && pathspec+=("$f") || pathspec+=(":(glob)$f")
done
for f in ${ALLOW_INVALID_JSON[@]+"${ALLOW_INVALID_JSON[@]}"}; do
[[ "$f" == :* ]] && pathspec+=("$f") || pathspec+=(":(exclude,glob)$f")
skipped+=("$f")
done
local -a files=()
staged_files_z files "${pathspec[@]}"
for f in ${files[@]+"${files[@]}"}; do
[[ "$f" == *.json ]] || continue
if ! err="$(git show ":$f" | python3 -c '
import json, sys
try:
json.load(sys.stdin)
except Exception as exc:
sys.stderr.write(str(exc))
sys.exit(1)
' 2>&1)"; then
fail "$EX_JSON" \
"staged JSON does not parse: $f" \
"$err" \
"" \
"A serialization error from a generator is a STOP, not something to commit past."
fi
checked+=("$f")
done
for f in ${skipped[@]+"${skipped[@]}"}; do
log " -- JSON check EXEMPTED by --allow-invalid-json: $f"
done
if (( ${#checked[@]} == 0 )); then
log " -- no staged .json under ${JSON_PATHS[*]} — JSON check not applicable"
else
log " ok ${#checked[@]} staged .json file(s) under ${JSON_PATHS[*]} parse"
fi
}
cmd_check_staged() {
require_repo
log "push-guard: checking staged content"
check_unmerged
# --no-renames is load-bearing, NOT cosmetic. Git detects renames by default
# (diff.renames=true since 2.9), so a `git mv` plus a small edit is reported
# as ONE 'R' entry — which --diff-filter=ACM DOES NOT MATCH. The renamed file
# becomes invisible to every content check: staged conflict markers sail
# through and the guard prints "staged content OK". Verified reproducible at
# 97% similarity with an ordinary co-staged file present. --no-renames
# decomposes each rename back into D + A so the new path is always seen.
# (Adding R to the filter also works, but --name-only -z emits two paths for
# a rename and is ambiguous to parse — this removes the category instead.)
#
# SECOND INSTANCE OF THE SAME DEFECT, found by sweeping for the construct
# rather than fixing only the one that was reported. This one failed CLOSED
# (zero files hit "NOTHING IS STAGED"), so it was never a security hole --
# but it reported a confident WRONG DIAGNOSIS, sending anyone debugging it
# at their index instead of at the failing git invocation.
local -a files=()
staged_files_z files
if (( ${#files[@]} == 0 )); then
fail "$EX_NULL" \
"NOTHING IS STAGED" \
"About to commit, but the index is identical to HEAD." \
"" \
"This is the null case: a commit here is empty, and any later" \
"'verified' step would be asserting against content that does not exist."
fi
check_conflict_markers "${files[@]}"
check_staged_json "${files[@]}"
log "push-guard: staged content OK"
}
# ------------------------------------------------------------------------ push
remote_sha() {
# Empty output means the branch does not exist on the remote yet.
# A network/auth failure makes ls-remote non-zero, which set -e turns into an
# abort — the guard never treats an unreachable remote as "unchanged".
git ls-remote "$1" "refs/heads/$2" | awk 'NR==1{print $1}'
}
cmd_push() {
require_repo
local remote="" branch="" since_head=""
local -a extra=()
while (( $# )); do
case "$1" in
--remote) remote="${2:-}"; shift 2 ;;
--branch) branch="${2:-}"; shift 2 ;;
--since-head) since_head="${2:-}"; shift 2 ;;
--) shift; extra=("$@"); break ;;
*) fail "$EX_USAGE" "unknown argument to push: $1" ;;
esac
done
[[ -n "$remote" && -n "$branch" ]] \
|| fail "$EX_USAGE" "push requires --remote and --branch"
local head
head="$(git rev-parse HEAD)"
log "push-guard: verifying push of $head -> $remote/$branch"
# (1) Did a new commit actually get created?
if [[ -n "$since_head" ]]; then
git rev-parse --verify --quiet "${since_head}^{commit}" >/dev/null \
|| fail "$EX_USAGE" \
"--since-head is not a commit in this repository: $since_head" \
"" \
"Cannot verify advancement against a start point that does not exist."
if [[ "$head" == "$since_head" ]]; then
fail "$EX_NULL" \
"HEAD DID NOT ADVANCE — no commit was created" \
"HEAD is still $head" \
"" \
"Your commit step failed and execution continued on stale state." \
"Pushing now would publish something you did not just build."
fi
# INEQUALITY IS NOT ADVANCEMENT. "different from where I started" is
# satisfied by checking out any unrelated commit -- including one that
# existed long before this session -- which would let pre-existing work
# be published as something just built. The claim being made is that new
# commits were created ON TOP OF the recorded start point, and only
# ancestry states that.
if ! git merge-base --is-ancestor "$since_head" "$head"; then
fail "$EX_NULL" \
"HEAD IS NOT A DESCENDANT of the recorded start point" \
"start: $since_head" \
"head : $head" \
"" \
"HEAD differs from the start point but does not build on it, so" \
"this is a checkout of other history rather than work you just" \
"created. Being different is not the same as having advanced."
fi
log " ok HEAD advanced ${since_head:0:9} -> ${head:0:9} (descendant)"
fi
# (2) Is that commit non-empty?
# EXEMPTING BY PARENT COUNT WAS A FAIL-OPEN. An empty root commit sailed
# through "emptiness check not applicable" and was then reported as a
# CONFIRMED PUSH -- directly contradicting the non-empty requirement this
# step exists to enforce. Root and merge commits do have well-defined
# emptiness; the original code declined to define it, which is not the same
# as it being undefined.
local parents
parents="$(git rev-list --parents -n 1 HEAD | wc -w)"
if (( parents == 2 )); then # sha + exactly one parent
if git diff --quiet HEAD^ HEAD; then
fail "$EX_NULL" \
"HEAD IS AN EMPTY COMMIT — it changes nothing against its parent" \
"commit $head" \
"" \
"An empty commit carrying a real message is indistinguishable" \
"from real work in the log. Refusing to push it."
fi
log " ok HEAD is a non-empty commit"
elif (( parents > 2 )); then
# A merge is empty when its tree matches EVERY parent: it then carries
# no content of its own and no integration either.
local p all_same=yes
for p in $(git rev-list --parents -n 1 HEAD | cut -d' ' -f2-); do
git diff --quiet "$p" HEAD || { all_same=no; break; }
done
if [[ "$all_same" == yes ]]; then
fail "$EX_NULL" \
"HEAD IS AN EMPTY MERGE — its tree is identical to every parent" \
"commit $head" \
"" \
"It integrates nothing and introduces nothing. Refusing to push it."
fi
log " ok HEAD is a non-empty merge commit"
else
# A root commit has no parent, so emptiness is measured against the
# empty tree: it is empty when it adds no paths at all.
if [[ -z "$(git diff-tree --root -r --name-only --no-commit-id HEAD)" ]]; then
fail "$EX_NULL" \
"HEAD IS AN EMPTY ROOT COMMIT — it introduces no files" \
"commit $head" \
"" \
"A root commit is empty when it adds nothing against the empty" \
"tree. Refusing to push it."
fi
log " ok HEAD is a non-empty root commit"
fi
# (3) Capture the remote BEFORE. This is the step whose absence made the
# original "PUSH VERIFIED" a false positive.
local before after
before="$(remote_sha "$remote" "$branch")"
log " .. remote before: ${before:-<branch does not exist>}"
git push "$remote" "HEAD:refs/heads/$branch" ${extra[@]+"${extra[@]}"}
after="$(remote_sha "$remote" "$branch")"
log " .. remote after: ${after:-<absent>}"
# (4) The remote must now equal local HEAD...
if [[ "$after" != "$head" ]]; then
fail "$EX_PUSH" \
"REMOTE DOES NOT MATCH LOCAL HEAD after push" \
"local HEAD: $head" \
"remote $branch: ${after:-<absent>}" \
"" \
"The push did not land what you are holding."
fi
# (5) ...AND it must have MOVED to get there. Without this, a push that
# transferred nothing passes step (4) trivially.
if [[ "$after" == "$before" ]]; then
fail "$EX_PUSH" \
"REMOTE DID NOT MOVE — nothing was actually pushed" \
"remote was already at $after before this push ran" \
"" \
"'remote == local' is satisfied by having pushed nothing. That is" \
"the false positive this guard exists to catch: the work you think" \
"you just published was already there, or was never committed."
fi
log "push-guard: PUSH CONFIRMED ${before:0:9}${before:+ }-> ${after:0:9}"
}
# ------------------------------------------------------------------------ main
ALLOW_INVALID_JSON=()
JSON_PATHS=()
CFG_MODE="absent"
CFG_REASON=""
CFG_PATHS=()
CFG_ALLOW=()
main() {
(( $# )) || { usage; exit "$EX_USAGE"; }
local sub="$1"; shift
case "$sub" in
check-staged)
while (( $# )); do
case "$1" in
--json-path) JSON_PATHS+=("${2:-}"); shift 2 ;;
--allow-invalid-json) ALLOW_INVALID_JSON+=("${2:-}"); shift 2 ;;
*) fail "$EX_USAGE" "unknown argument to check-staged: $1" ;;
esac
done
cmd_check_staged
;;
push) cmd_push "$@" ;;
-h|--help) usage ;;
*) usage; exit "$EX_USAGE" ;;
esac
# Explicit: the only way to reach here is with every requested check passed.
exit "$EX_OK"
}
main "$@"