[PATCH] guix hash: -g hashes a git repository

[PATCH] guix hash: -g hashes a git repository

[Andy Wingo]

* guix/scripts/hash.scm (show-help, %options): Add -g option.
(guix-hash): Support hashing of Git URLs.
* doc/guix.texi (Invoking guix hash): Document guix hash --git.
---
 doc/guix.texi         | 18 ++++++++++++++++++
 guix/scripts/hash.scm | 37 +++++++++++++++++++++++++++++--------
 2 files changed, 47 insertions(+), 8 deletions(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index 8da82b4d8..7d35d9f45 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -5281,6 +5281,24 @@ $ git clone http://example.org/foo.git
 $ cd foo
 $ guix hash -rx .
 @end example
+
+Hashing a git repository is so common that it has its own alias:
+
+@item --git
+@itemx -g
+Clones the git repository at @var{file} into a temporary directory and
+recursively hashes it, excluding the @file{.git} subdirectory.
+
+For example:
+@example
+$ git clone http://example.org/foo.git
+$ guix hash -g foo
+@end example
+
+Or even:
+@example
+$ guix hash -g http://example.org/foo.git
+@end example
 @end table
 
 @node Invoking guix import
diff --git a/guix/scripts/hash.scm b/guix/scripts/hash.scm
index a048b5346..104a6a864 100644
--- a/guix/scripts/hash.scm
+++ b/guix/scripts/hash.scm
@@ -25,6 +25,7 @@
   #:use-module (guix ui)
   #:use-module (guix scripts)
   #:use-module (guix base16)
+  #:use-module (guix utils)
   #:use-module (ice-9 binary-ports)
   #:use-module (rnrs files)
   #:use-module (ice-9 match)
@@ -52,6 +53,9 @@ and 'hexadecimal' can be used as well).\n"))
   (format #t (_ "
   -x, --exclude-vcs      exclude version control directories"))
   (format #t (_ "
+  -g, --git              clone the git repository at FILE and hash it
+                         (implies -r)"))
+  (format #t (_ "
   -f, --format=FMT       write the hash in the given format"))
   (format #t (_ "
   -r, --recursive        compute the hash on FILE recursively"))
@@ -68,6 +72,10 @@ and 'hexadecimal' can be used as well).\n"))
   (list (option '(#\x "exclude-vcs") #f #f
                 (lambda (opt name arg result)
                   (alist-cons 'exclude-vcs? #t result)))
+        (option '(#\g "git") #f #f
+                (lambda (opt name arg result)
+                  (alist-cons 'git? #t
+                              (alist-cons 'exclude-vcs? #t result))))
         (option '(#\f "format") #t #f
                 (lambda (opt name arg result)
                   (define fmt-proc
@@ -133,18 +141,31 @@ and 'hexadecimal' can be used as well).\n"))
                       (negate vcs-file?)
                       (const #t))))
 
+    (define (recursive-hash file)
+      (let-values (((port get-hash) (open-sha256-port)))
+        (write-file file port #:select? select?)
+        (force-output port)
+        (get-hash)))
+
     (define (file-hash file)
       ;; Compute the hash of FILE.
       ;; Catch and gracefully report possible '&nar-error' conditions.
       (with-error-handling
-        (if (assoc-ref opts 'recursive?)
-            (let-values (((port get-hash) (open-sha256-port)))
-              (write-file file port #:select? select?)
-              (force-output port)
-              (get-hash))
-            (match file
-              ("-" (port-sha256 (current-input-port)))
-              (_   (call-with-input-file file port-sha256))))))
+        (cond
+         ((assoc-ref opts 'git?)
+          (call-with-temporary-directory
+           (lambda (dir)
+             (let ((checkout (in-vicinity dir "git-checkout")))
+               (unless (zero? (system* "git" "clone" "--" file checkout))
+                 (leave (_ "git clone failed~%")))
+               (pk "git" "clone" file checkout)
+               (recursive-hash checkout)))))
+         ((assoc-ref opts 'recursive?)
+          (recursive-hash file))
+         (else
+          (match file
+            ("-" (port-sha256 (current-input-port)))
+            (_   (call-with-input-file file port-sha256)))))))
 
     (match args
       ((file)
-- 
2.12.2

Re: [PATCH] guix hash: -g hashes a git repository

[Ludovic Courtès]

Hello!

Andy Wingo <wingo@igalia.com> skribis:

> * guix/scripts/hash.scm (show-help, %options): Add -g option.
> (guix-hash): Support hashing of Git URLs.
> * doc/guix.texi (Invoking guix hash): Document guix hash --git.

[...]

> +For example:
> +@example
> +$ git clone http://example.org/foo.git
> +$ guix hash -g foo
> +@end example

In this case -g is equivalent to -rx.

> +Or even:
> +@example
> +$ guix hash -g http://example.org/foo.git
> +@end example
>  @end table

This one is indeed simpler.  However, one typically needs to get the
commit id in addition to the hash, so it seems that in practice, most of
the time, we’d still need to do:

  git clone http://…
  cd foo
  git log | head -1
  guix hash -rx .

so we have both the commit id and the content hash.

WDYT?

Thanks,
Ludo’.

Re: [PATCH] guix hash: -g hashes a git repository

[Andy Wingo]

On Tue 04 Apr 2017 14:21, ludo@gnu.org (Ludovic Courtès) writes:

>> +For example:
>> +@example
>> +$ git clone http://example.org/foo.git
>> +$ guix hash -g foo
>> +@end example
>
> In this case -g is equivalent to -rx.

My main use case is when I am in a git checkout that has build products
or other stuff.  Then I can "guix hash -g .".  Easier than making a temp
dir, clone, hash, then delete.

>> +Or even:
>> +@example
>> +$ guix hash -g http://example.org/foo.git
>> +@end example
>>  @end table
>
> This one is indeed simpler.  However, one typically needs to get the
> commit id in addition to the hash, so it seems that in practice, most of
> the time, we’d still need to do:
>
>   git clone http://…
>   cd foo
>   git log | head -1
>   guix hash -rx .
>
> so we have both the commit id and the content hash.
>
> WDYT?

Could be!  Or "git rev-parse HEAD".  I'll do that.

Andy

Re: [PATCH] guix hash: -g hashes a git repository

[Ludovic Courtès]

Andy Wingo <wingo@igalia.com> skribis:

> On Tue 04 Apr 2017 14:21, ludo@gnu.org (Ludovic Courtès) writes:
>
>>> +For example:
>>> +@example
>>> +$ git clone http://example.org/foo.git
>>> +$ guix hash -g foo
>>> +@end example
>>
>> In this case -g is equivalent to -rx.
>
> My main use case is when I am in a git checkout that has build products
> or other stuff.  Then I can "guix hash -g .".  Easier than making a temp
> dir, clone, hash, then delete.

Oh right, I hadn't realized that it would exclude untracked files etc.
Definitely an improvement!

> > so we have both the commit id and the content hash.
> >
> > WDYT?
>
> Could be!  Or "git rev-parse HEAD".  I'll do that.

Awesome.

Thanks,
Ludo’.

Re: [PATCH] guix hash: -g hashes a git repository

[Christopher Allan Webber]

Andy Wingo writes:

> +               (pk "git" "clone" file checkout)
> +               (recursive-hash checkout)))))

One of those cursed pk's made it in here.

Exciting!  Look forward to having this option.