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| 1 | +// SPDX-License-Identifier: AGPL-3.0-or-later |
| 2 | + |
| 3 | +// Package hooks owns the bare-repo hook installation contract used by |
| 4 | +// the push pipeline (S14). pre-receive and post-receive are tiny shell |
| 5 | +// shims that re-invoke shithubd. They're symlinks so a binary upgrade |
| 6 | +// doesn't require touching every repo's hooks directory. |
| 7 | +// |
| 8 | +// Why shell shims and not direct symlinks to the binary: git invokes |
| 9 | +// the hook with stdin piped and a particular cwd, and the shim lets us |
| 10 | +// preserve the env (the SHITHUB_* vars set by S12/S13) while routing |
| 11 | +// to a stable subcommand interface. The shim is generated once at |
| 12 | +// install time; we don't depend on its file path matching the binary. |
| 13 | +package hooks |
| 14 | + |
| 15 | +import ( |
| 16 | + "fmt" |
| 17 | + "os" |
| 18 | + "path/filepath" |
| 19 | +) |
| 20 | + |
| 21 | +// SupportedHooks is the canonical list of hooks the push pipeline owns. |
| 22 | +// Add new hook names here and they'll be installed on every repo init. |
| 23 | +var SupportedHooks = []string{"pre-receive", "post-receive"} |
| 24 | + |
| 25 | +// Install (re)installs every supported hook on the bare repo at gitDir. |
| 26 | +// shithubdPath is the absolute path to the shithubd binary the shim |
| 27 | +// should invoke. Permissions are forced to 0o755 (owner: rwx; group + |
| 28 | +// other: rx) — git refuses to run hooks lacking the executable bit. |
| 29 | +// |
| 30 | +// Install is idempotent: re-running on a repo that already has up-to- |
| 31 | +// date hooks is a no-op. If a hook file exists but doesn't match the |
| 32 | +// expected shim, it's overwritten. |
| 33 | +func Install(gitDir, shithubdPath string) error { |
| 34 | + hooksDir := filepath.Join(gitDir, "hooks") |
| 35 | + if err := os.MkdirAll(hooksDir, 0o755); err != nil { |
| 36 | + return fmt.Errorf("hooks: mkdir %s: %w", hooksDir, err) |
| 37 | + } |
| 38 | + for _, name := range SupportedHooks { |
| 39 | + path := filepath.Join(hooksDir, name) |
| 40 | + body := shim(shithubdPath, name) |
| 41 | + if err := writeAtomic(path, body, 0o755); err != nil { |
| 42 | + return fmt.Errorf("hooks: write %s: %w", path, err) |
| 43 | + } |
| 44 | + } |
| 45 | + return nil |
| 46 | +} |
| 47 | + |
| 48 | +// shim is the body of the wrapper script git executes. It exec's into |
| 49 | +// shithubd, replacing itself so signals (and the exit code) propagate |
| 50 | +// cleanly. Stdin is the pkt-line stream git passes the hook; we forward |
| 51 | +// it untouched. |
| 52 | +func shim(shithubdPath, hookName string) string { |
| 53 | + return fmt.Sprintf(`#!/bin/sh |
| 54 | +# Generated by shithubd hooks.Install. Do not edit by hand — re-run |
| 55 | +# 'shithubd hooks reinstall' if the binary path changes. |
| 56 | +exec %q hook %s "$@" |
| 57 | +`, shithubdPath, hookName) |
| 58 | +} |
| 59 | + |
| 60 | +// writeAtomic writes body to path via a same-directory tmpfile + rename |
| 61 | +// so a partial write can never expose an unbootable hook to git. |
| 62 | +func writeAtomic(path string, body string, mode os.FileMode) error { |
| 63 | + dir := filepath.Dir(path) |
| 64 | + tmp, err := os.CreateTemp(dir, ".shithub-hook-*") |
| 65 | + if err != nil { |
| 66 | + return err |
| 67 | + } |
| 68 | + tmpName := tmp.Name() |
| 69 | + defer func() { |
| 70 | + // If rename succeeded the file is gone and Remove is a no-op error |
| 71 | + // we can swallow. |
| 72 | + _ = os.Remove(tmpName) |
| 73 | + }() |
| 74 | + if _, err := tmp.WriteString(body); err != nil { |
| 75 | + _ = tmp.Close() |
| 76 | + return err |
| 77 | + } |
| 78 | + if err := tmp.Chmod(mode); err != nil { |
| 79 | + _ = tmp.Close() |
| 80 | + return err |
| 81 | + } |
| 82 | + if err := tmp.Close(); err != nil { |
| 83 | + return err |
| 84 | + } |
| 85 | + return os.Rename(tmpName, path) |
| 86 | +} |