65 lines
2.7 KiB
Bash
Executable File
65 lines
2.7 KiB
Bash
Executable File
#!/bin/sh
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# Mosaic push guard (row 211, #426). Installed as pre-push in the common
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# .git/hooks by `scripts/install-git-hooks.sh`; never edit the installed copy.
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# For each ref git is about to push, it refuses a delete and any update whose
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# remote tip isn't an ancestor of the local tip: a force-push or a +refspec.
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# It refuses any change to an existing tag, and an object name that isn't 40
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# or 64 hex characters. A new ref passes. It fetches nothing, so a remote tip
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# that isn't in this repository refuses. Any failure of the check refuses too.
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# `git push --no-verify` skips this hook; Gitea's branch protection is the
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# guard that holds (ops-01). Canon: never force-push.
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refused=0
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refuse() {
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echo "mosaic push guard: refused: $*" >&2
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refused=1
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}
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zero() {
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case "$1" in *[!0]*) return 1 ;; esac
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return 0
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}
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idlen() { # $1: an object name. True at 40 (SHA-1) or 64 (SHA-256) characters.
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[ "${#1}" -eq 40 ] || [ "${#1}" -eq 64 ]
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}
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while read -r lref lsha rref rsha extra || [ -n "${lref:-}" ]; do
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if [ -z "${rsha:-}" ] || [ -n "${extra:-}" ]; then
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refuse "unreadable ref line from git: $lref ${lsha:-} ${rref:-} ${rsha:-} ${extra:-}"
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continue
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fi
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case "$lsha$rsha" in
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*[!0-9a-f]*) refuse "$rref: a ref line with a non-hex object name (local $lsha, remote $rsha)"; continue ;;
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esac
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if ! idlen "$lsha" || ! idlen "$rsha"; then
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refuse "$rref: a ref line with an object name that isn't 40 or 64 hex characters (local $lsha, remote $rsha)"
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continue
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fi
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if zero "$lsha"; then
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refuse "$rref: a delete (remote $rsha); seat branches are never deleted by push"
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continue
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fi
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if zero "$rsha"; then
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continue
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fi
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# An existing tag never changes. A new tag object on the same commit, or
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# a tag moved to a descendant, would pass the ancestor check below.
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if [ "${rref#refs/tags/}" != "$rref" ] && [ "$lsha" != "$rsha" ]; then
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refuse "$rref: an existing tag can't be moved or replaced (remote $rsha, local $lsha); push a new tag instead"
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continue
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fi
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if ! git cat-file -e "$rsha^{commit}" 2>/dev/null; then
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refuse "$rref: the remote tip $rsha isn't in this repository; fetch first, then push again"
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continue
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fi
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git merge-base --is-ancestor "$rsha" "$lsha" 2>/dev/null
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rc=$?
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case $rc in
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0) ;;
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1) refuse "$rref: not a fast-forward; remote $rsha isn't an ancestor of local $lsha (a force-push or a rewritten branch)" ;;
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*) refuse "$rref: the ancestor check failed (exit $rc) for remote $rsha and local $lsha" ;;
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esac
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done
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if [ "$refused" != 0 ]; then
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echo "mosaic push guard: nothing was pushed; a pushed branch only moves forward (canon: never force-push)" >&2
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exit 1
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fi
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exit 0
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