git-attest 1.6.0

Sign and verify attestations that a test suite already passed on a tree, so CI can skip it: the library and its command line
Documentation 
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#!/usr/bin/env bash
# A faulty git, for the fixtures that prove a fingerprint is never computed
# from a git that failed. Prepended to PATH by tests/lib.sh's with_faulty_git;
# everything but the injected failure is delegated to the real git, which is
# named in ATTEST_REAL_GIT. ATTEST_FAULT selects the failure:
#
#   ls-tree   print the first record of the listing, then exit 1
#   cat-file  make `cat-file blob …` exit 1 (`-e` and --batch-check untouched)
#   env       for `fetch` and `ls-remote`, append the GIT_TERMINAL_PROMPT and
#             GIT_SSH_COMMAND they run with to ATTEST_FAULT_LOG, then run them
#   hang      `fetch` and `ls-remote` never answer (a host that drops SYNs):
#             only the verifier's own deadline can end them; each call is
#             logged to ATTEST_FAULT_LOG when set, and a fetch first takes
#             the lock of every refspec destination, as a real fetch killed
#             mid-write would leave it
#
# Both implementations spawn `git` from PATH, so one wrapper serves both.
real=${ATTEST_REAL_GIT:?}
case "${ATTEST_FAULT:-}:$*" in
    probe:*) echo attest-faulty-git; exit 0 ;;
    ls-tree:*" ls-tree "*|ls-tree:"ls-tree "*)
        # -z output: records end in NUL. One record, then a failure after it.
        "$real" "$@" | head -c 64
        exit 1 ;;
    cat-file:"cat-file blob "*|cat-file:*" cat-file blob "*)
        exit 1 ;;
    hang:*" fetch "*|hang:*" ls-remote "*|hang:"fetch "*|hang:"ls-remote "*)
        [ -z "${ATTEST_FAULT_LOG:-}" ] || printf 'call\n' >> "$ATTEST_FAULT_LOG"
        for a in "$@"; do
            case $a in
                +*:*) dst=${a#*:}; lock=$("$real" rev-parse --git-path "$dst.lock")
                      mkdir -p "$(dirname "$lock")"; : > "$lock" ;;
            esac
        done
        # exec: the killed pid IS the sleeper, so nothing lingers on a pipe.
        exec sleep 120 ;;
    env:*" fetch "*|env:*" ls-remote "*|env:"fetch "*|env:"ls-remote "*)
        printf '%s|%s\n' "${GIT_TERMINAL_PROMPT-}" "${GIT_SSH_COMMAND-}" >> "${ATTEST_FAULT_LOG:?}" ;;
esac
exec "$real" "$@"