[bug#69780] [PATCH 3/4] git authenticate: Install pre-push and post-checkout hooks.

[Ludovic Courtès]

* guix/scripts/git/authenticate.scm (install-hooks): New procedure.
(guix-git-authenticate): Use it.
* doc/guix.texi (Invoking guix git authenticate): Document it.

Change-Id: I4464a33193186e85b476a12740e54412bd58429c
---
 doc/guix.texi                     |  5 ++++
 guix/scripts/git/authenticate.scm | 43 ++++++++++++++++++++++++++++++-
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index ac0766b98c..b1672803c0 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -7624,6 +7624,11 @@ Invoking guix git authenticate
 guix git authenticate [@var{options}@dots{}]
 @end example
 
+The first run also attempts to install pre-push and post-checkout hooks,
+such that @command{guix git authenticate} is invoked as soon as you run
+@command{git push}, @command{git checkout}, and related commands; it
+does not overwrite preexisting hooks though.
+
 The options below allow you to fine-tune the process.
 
 @table @code
diff --git a/guix/scripts/git/authenticate.scm 
b/guix/scripts/git/authenticate.scm
index 36e1aa6228..13e1de3099 100644
--- a/guix/scripts/git/authenticate.scm
+++ b/guix/scripts/git/authenticate.scm
@@ -129,6 +129,46 @@ (define* (record-configuration repository
   (info (G_ "introduction and keyring configuration recorded in '~a'~%")
         config-file))
 
+(define (install-hooks repository)
+  "Attempt to install in REPOSITORY pre-push and update hooks that invoke
+'guix git authenticate'.  Bail out if one of these already exists."
+  (define directory
+    (repository-directory repository))
+
+  (define pre-push-hook
+    (in-vicinity directory "hooks/pre-push"))
+
+  (define post-checkout-hook
+    (in-vicinity directory "hooks/post-checkout"))
+
+  (if (or (file-exists? pre-push-hook)
+          (file-exists? post-checkout-hook))
+      (begin
+        (warning (G_ "not overriding pre-existing hooks '~a' and '~a'~%")
+                 pre-push-hook post-checkout-hook)
+        (display-hint (G_ "Consider running @command{guix git authenticate}
+from your pre-push and update hooks so your repository is automatically
+authenticated before you push or receive updates.")))
+      (begin
+        (call-with-output-file pre-push-hook
+          (lambda (port)
+            (format port "#!/bin/sh
+set -e
+while read local_ref local_oid remote_ref remote_oid
+do
+  guix git authenticate --end=\"$local_ref\"
+done\n")
+            (chmod port #o755)))
+        (call-with-output-file post-checkout-hook
+          (lambda (port)
+            (format port "#!/bin/sh
+oldrev=\"$1\"
+newrev=\"$2\"
+exec guix git authenticate --end=\"$newrev\"\n")
+            (chmod port #o755)))
+        (info (G_ "installed hooks '~a' and '~a'~%")
+              pre-push-hook post-checkout-hook))))
+
 (define (show-stats stats)
   "Display STATS, an alist containing commit signing stats as returned by
 'authenticate-repository'."
@@ -250,7 +290,8 @@ (define (guix-git-authenticate . args)
        (unless (configured? repository)
          (record-configuration repository
                                #:commit commit #:signer signer
-                               #:keyring-reference keyring))
+                               #:keyring-reference keyring)
+         (install-hooks repository))
 
        (when (and show-stats? (not (null? stats)))
          (show-stats stats))))))
-- 
2.41.0