[PATCH] Updated documentation of hooks in git-receive-pack.

[PATCH] Updated documentation of hooks in git-receive-pack.

[Jan Hudec]

Added documentation of pre-receive and post-receive hooks and updated
documentation of update and post-update hooks.

Signed-off-by: Jan Hudec <bulb@ucw.cz>
---

Recent question on the mailing-list made me to look at the post-receive hook
in the Documentation/hooks.txt, only to find it is not mentioned there at
all.

I looked up all the hooks and how they are called in receive-pack.c and
updated the documentation for them. Please review and apply.

Feel free to suggest syntactic or semantic fixes; I am not a native English
speaker, so there may well be some.

Regards,

Jan

 Documentation/hooks.txt |   84 ++++++++++++++++++++++++++++++++++++++++++----
 1 files changed, 76 insertions(+), 8 deletions(-)

diff --git a/Documentation/hooks.txt b/Documentation/hooks.txt
index b083290..e36cf44 100644
--- a/Documentation/hooks.txt
+++ b/Documentation/hooks.txt
@@ -90,6 +90,37 @@ parameter, and is invoked after a commit is made.
 This hook is meant primarily for notification, and cannot affect
 the outcome of `git-commit`.
 
+[[pre-receive]]
+pre-receive
+-----------
+
+This hook is invoked by `git-receive-pack` on the remote repository,
+which happens when a `git push` is done on a local repository.
+Just before starting to update refs on the remote repository, the
+pre-receive hook is invoked.  Its exit status determines the success
+or failure of the update.
+
+This hook executes once for the receive operation. It takes no
+arguments, but for each ref to be updated it receives on standard
+input a line of the format:
+
+  <old-value> SP <new-value> SP <ref-name> NL
+
+where `<old-value>` is the old object name stored in the ref,
+`<new-value>` is the new object name to be stored in the ref and
+`<ref-name>` is the full name of the ref.
+
+If the hook exits with non-zero status, none of the refs will be
+updated. If the hook returs zero, updating of individual refs can
+still be prevented by the <<update,'update'>> hook.
+
+The standard output of this hook is sent to `stderr`, so if you
+want to report something to the `git-send-pack` on the other end,
+you can simply `echo` your messages.
+
+There is no default 'pre-receive' hook.
+
+[[update]]
 update
 ------
 
@@ -108,7 +139,7 @@ three parameters:
 
 A zero exit from the update hook allows the ref to be updated.
 Exiting with a non-zero status prevents `git-receive-pack`
-from updating the ref.
+from updating that ref.
 
 This hook can be used to prevent 'forced' update on certain refs by
 making sure that the object name is a commit object that is a
@@ -117,7 +148,8 @@ That is, to enforce a "fast forward only" policy.
 
 It could also be used to log the old..new status.  However, it
 does not know the entire set of branches, so it would end up
-firing one e-mail per ref when used naively, though.
+firing one e-mail per ref when used naively, though.  The
+<<post-receive,'post-receive'>> hook is more suited to that.
 
 Another use suggested on the mailing list is to use this hook to
 implement access control which is finer grained than the one
@@ -127,9 +159,45 @@ The standard output of this hook is sent to `stderr`, so if you
 want to report something to the `git-send-pack` on the other end,
 you can simply `echo` your messages.
 
-The default 'update' hook, when enabled, demonstrates how to
-send out a notification e-mail.
+The default 'update' hook, when enabled--and with
+`hooks.allowunannotated` config option turned on--prevents
+unannotated tags to be pushed.
 
+[[post-receive]]
+post-receive
+------------
+
+This hook is invoked by `git-receive-pack` on the remote repository,
+which happens when a `git push` is done on a local repository.
+It executes on the remote repository once after all the refs have
+been updated.
+
+This hook executes once for the receive operation.  It takes no
+arguments, but for each ref that was updated it receives on standard
+input a line of the format:
+
+  <old-value> SP <new-value> SP <ref-name> NL
+
+on stdin, where `<old-value>` is the old object name stored in the
+ref, `<new-value>` is the new object name to be stored in the ref and
+`<ref-name>` is the full name of the ref.
+
+This hook cannot affect the outcome of `git-receive-pack`, as it's
+called after the real work is done.
+
+This superceedes the [[post-update]] hook in that it actually get's
+both old and new values of all the refs.
+
+The standard output of this hook is sent to `stderr`, so if you
+want to report something to the `git-send-pack` on the other end,
+you can simply `echo` your messages.
+
+The default 'post-receive' hook is empty, but there is
+a script `post-receive-email` provided in the `contrib/hooks`
+directory in git distribution, which implements sending commit
+emails.
+
+[[post-update]]
 post-update
 -----------
 
@@ -146,7 +214,8 @@ the outcome of `git-receive-pack`.
 
 The 'post-update' hook can tell what are the heads that were pushed,
 but it does not know what their original and updated values are,
-so it is a poor place to do log old..new.
+so it is a poor place to do log old..new. See
+<<post-receive,'post-receive'>> hook above for a better one.
 
 When enabled, the default 'post-update' hook runs
 `git-update-server-info` to keep the information used by dumb
@@ -154,6 +223,5 @@ transports (e.g., HTTP) up-to-date.  If you are publishing
 a git repository that is accessible via HTTP, you should
 probably enable this hook.
 
-The standard output of this hook is sent to `/dev/null`; if you
-want to report something to the `git-send-pack` on the other end,
-you can redirect your output to your `stderr`.
+Both standard output and standard error output are forwarded to
+`git-send-pack` on the other end.
-- 
1.5.1.4

Re: [PATCH] Updated documentation of hooks in git-receive-pack.

[Junio C Hamano]

Jan Hudec <bulb@ucw.cz> writes:

> Added documentation of pre-receive and post-receive hooks and updated
> documentation of update and post-update hooks.
>
> Signed-off-by: Jan Hudec <bulb@ucw.cz>

Thanks, much appreciated.  Domain ucw.cz sounds familiar; are
you close by to Pasky?

> +[[pre-receive]]
> +pre-receive
>...
> +This hook executes once for the receive operation. It takes no
> +arguments, but for each ref to be updated it receives on standard
> +input a line of the format:
> +
> +  <old-value> SP <new-value> SP <ref-name> NL
> +
> +where `<old-value>` is the old object name stored in the ref,
> +`<new-value>` is the new object name to be stored in the ref and
> +`<ref-name>` is the full name of the ref.

s/NL/LF/
When creating a new ref, `<old-value>` is 40 `0`.

> +If the hook exits with non-zero status, none of the refs will be
> +updated. If the hook returs zero, updating of individual refs can
> +still be prevented by the <<update,'update'>> hook.

s/returs/exits with/

> +The standard output of this hook is sent to `stderr`, so if you
> +want to report something to the `git-send-pack` on the other end,
> +you can simply `echo` your messages.

I think "sent to stderr" is a implementation detail between
receive-pack and hook scripts.  I would just keep the "if you
want to..." part.

> +[[post-receive]]
> +post-receive
> +------------
> +
> +This hook is invoked by `git-receive-pack` on the remote repository,
> +which happens when a `git push` is done on a local repository.
> +It executes on the remote repository once after all the refs have
> +been updated.
> +
> +This hook executes once for the receive operation.  It takes no
> +arguments, but for each ref that was updated it receives on standard
> +input a line of the format:
> +
> +  <old-value> SP <new-value> SP <ref-name> NL
> +
> +on stdin, where `<old-value>` is the old object name stored in the
> +ref, `<new-value>` is the new object name to be stored in the ref and
> +`<ref-name>` is the full name of the ref.

Maybe

	It takes no arguments, but gets the same information as
	the `pre-receive` hook does on its standard input.

to avoid the duplicated description.

> +This hook cannot affect the outcome of `git-receive-pack`, as it's
> +called after the real work is done.
> +
> +This superceedes the [[post-update]] hook in that it actually get's
> +both old and new values of all the refs.

s/superceedes/supersedes/

> +The standard output of this hook is sent to `stderr`, so if you
> +want to report something to the `git-send-pack` on the other end,
> +you can simply `echo` your messages.

Ditto.

> +[[post-update]]
>  post-update
>  -----------
>  
> @@ -146,7 +214,8 @@ the outcome of `git-receive-pack`.
>  
>  The 'post-update' hook can tell what are the heads that were pushed,
>  but it does not know what their original and updated values are,
> -so it is a poor place to do log old..new.
> +so it is a poor place to do log old..new. See
> +<<post-receive,'post-receive'>> hook above for a better one.

Instead of just passing 'a better one' judgement without
rationale, it is more helpful to explain why the newer ones are
recommended, so that the reader can agree to it.

        In general, `post-receive` hook is preferred when the hook needs
        to decide its acion on the status of the entire set of refs
        being updated, as this hook is called once per ref, with
        information only on a single ref at a time.

Re: [PATCH] Updated documentation of hooks in git-receive-pack.

[Jan Hudec]

[-- Attachment #1: Type: text/plain, Size: 3371 bytes --]

On Sat, May 12, 2007 at 12:27:52 -0700, Junio C Hamano wrote:
> Jan Hudec <bulb@ucw.cz> writes:
> 
> > Added documentation of pre-receive and post-receive hooks and updated
> > documentation of update and post-update hooks.
> >
> > Signed-off-by: Jan Hudec <bulb@ucw.cz>
> 
> Thanks, much appreciated.  Domain ucw.cz sounds familiar; are
> you close by to Pasky?

Studied the same faculty.

> [...]
> > +The standard output of this hook is sent to `stderr`, so if you
> > +want to report something to the `git-send-pack` on the other end,
> > +you can simply `echo` your messages.
> 
> I think "sent to stderr" is a implementation detail between
> receive-pack and hook scripts.  I would just keep the "if you
> want to..." part.

It's actually original wording from description of 'update'. I think just
leaving out the stderr thing is not right, because it's important that both
stdout and stderr go to the same place. I'll change it to:

  Both standard output and error output are forwarded to `git-send-pack` on
  the other end, so you can simply `echo` messages for the user.

> > +[[post-receive]]
> > +post-receive
> > +------------
> > +
> > +This hook is invoked by `git-receive-pack` on the remote repository,
> > +which happens when a `git push` is done on a local repository.
> > +It executes on the remote repository once after all the refs have
> > +been updated.
> > +
> > +This hook executes once for the receive operation.  It takes no
> > +arguments, but for each ref that was updated it receives on standard
> > +input a line of the format:
> > +
> > +  <old-value> SP <new-value> SP <ref-name> NL
> > +
> > +on stdin, where `<old-value>` is the old object name stored in the
> > +ref, `<new-value>` is the new object name to be stored in the ref and
> > +`<ref-name>` is the full name of the ref.
> 
> Maybe
> 
> 	It takes no arguments, but gets the same information as
> 	the `pre-receive` hook does on its standard input.
> 
> to avoid the duplicated description.

Makes sense.

> > +[[post-update]]
> >  post-update
> >  -----------
> >  
> > @@ -146,7 +214,8 @@ the outcome of `git-receive-pack`.
> >  
> >  The 'post-update' hook can tell what are the heads that were pushed,
> >  but it does not know what their original and updated values are,
> > -so it is a poor place to do log old..new.
> > +so it is a poor place to do log old..new. See
> > +<<post-receive,'post-receive'>> hook above for a better one.
> 
> Instead of just passing 'a better one' judgement without
> rationale, it is more helpful to explain why the newer ones are
> recommended, so that the reader can agree to it.
> 
>         In general, `post-receive` hook is preferred when the hook needs
>         to decide its acion on the status of the entire set of refs
>         being updated, as this hook is called once per ref, with
>         information only on a single ref at a time.

Yes, it's probably better. Though in this case the post-update hook should be
really obsoleted. It takes names of all updated refs on command-line, which
is unlikely to fail on linux, but might fail on Windows where the
command-line lenght is much more limited. But for now I'll just mention that
the other hook does have the information this one does not.

-- 
						 Jan 'Bulb' Hudec <bulb@ucw.cz>

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[PATCH] Updated documentation of hooks in git-receive-pack.

[Jan Hudec]

Added documentation of pre-receive and post-receive hooks and updated
documentation of update and post-update hooks.

Signed-off-by: Jan Hudec <bulb@ucw.cz>
---

Resubmitting the patch including the changes based on review.

 Documentation/hooks.txt |   90 +++++++++++++++++++++++++++++++++++++++++------
 1 files changed, 79 insertions(+), 11 deletions(-)

diff --git a/Documentation/hooks.txt b/Documentation/hooks.txt
index b083290..db23dc4 100644
--- a/Documentation/hooks.txt
+++ b/Documentation/hooks.txt
@@ -90,6 +90,38 @@ parameter, and is invoked after a commit is made.
 This hook is meant primarily for notification, and cannot affect
 the outcome of `git-commit`.
 
+[[pre-receive]]
+pre-receive
+-----------
+
+This hook is invoked by `git-receive-pack` on the remote repository,
+which happens when a `git push` is done on a local repository.
+Just before starting to update refs on the remote repository, the
+pre-receive hook is invoked.  Its exit status determines the success
+or failure of the update.
+
+This hook executes once for the receive operation. It takes no
+arguments, but for each ref to be updated it receives on standard
+input a line of the format:
+
+  <old-value> SP <new-value> SP <ref-name> NL
+
+where `<old-value>` is the old object name stored in the ref,
+`<new-value>` is the new object name to be stored in the ref and
+`<ref-name>` is the full name of the ref. When creating a new ref,
+the `<old-value>` is 40 `0`.
+
+If the hook exits with non-zero status, none of the refs will be
+updated. If the hook exits with zero, updating of individual refs can
+still be prevented by the <<update,'update'>> hook.
+
+Both standard output and standard error output are forwarded to
+`git-send-pack` on the other end, so you can simply `echo` messages
+for the user.
+
+There is no default 'pre-receive' hook.
+
+[[update]]
 update
 ------
 
@@ -108,7 +140,8 @@ three parameters:
 
 A zero exit from the update hook allows the ref to be updated.
 Exiting with a non-zero status prevents `git-receive-pack`
-from updating the ref.
+from updating that ref. When creating a new ref,
+<old-value> is 40 `0`.
 
 This hook can be used to prevent 'forced' update on certain refs by
 making sure that the object name is a commit object that is a
@@ -117,19 +150,51 @@ That is, to enforce a "fast forward only" policy.
 
 It could also be used to log the old..new status.  However, it
 does not know the entire set of branches, so it would end up
-firing one e-mail per ref when used naively, though.
+firing one e-mail per ref when used naively, though.  The
+<<post-receive,'post-receive'>> hook is more suited to that.
 
 Another use suggested on the mailing list is to use this hook to
 implement access control which is finer grained than the one
 based on filesystem group.
 
-The standard output of this hook is sent to `stderr`, so if you
-want to report something to the `git-send-pack` on the other end,
-you can simply `echo` your messages.
+Both standard output and standard error output are forwarded to
+`git-send-pack` on the other end, so you can simply `echo` messages
+for the user.
+
+The default 'update' hook, when enabled--and with
+`hooks.allowunannotated` config option turned on--prevents
+unannotated tags to be pushed.
+
+[[post-receive]]
+post-receive
+------------
+
+This hook is invoked by `git-receive-pack` on the remote repository,
+which happens when a `git push` is done on a local repository.
+It executes on the remote repository once after all the refs have
+been updated.
+
+This hook executes once for the receive operation.  It takes no
+arguments, but receives the same input as the
+<<pre-receive,'pre-receive'>> hook.
+
+This hook cannot affect the outcome of `git-receive-pack`, as it's
+called after the real work is done.
+
+This supersedes the <<post-update,'post-update'>> hook in that it
+get's both old and new values of all the refs in addition to their
+names.
+
+Both standard output and standard error output are forwarded to
+`git-send-pack` on the other end, so you can simply `echo` messages
+for the user.
 
-The default 'update' hook, when enabled, demonstrates how to
-send out a notification e-mail.
+The default 'post-receive' hook is empty, but there is
+a script `post-receive-email` provided in the `contrib/hooks`
+directory in git distribution, which implements sending commit
+emails.
 
+[[post-update]]
 post-update
 -----------
 
@@ -146,7 +211,10 @@ the outcome of `git-receive-pack`.
 
 The 'post-update' hook can tell what are the heads that were pushed,
 but it does not know what their original and updated values are,
-so it is a poor place to do log old..new.
+so it is a poor place to do log old..new. The
+<<post-receive,'post-receive'>> hook does get both original and
+updated values of the refs. You might consider it instead if you need
+them.
 
 When enabled, the default 'post-update' hook runs
 `git-update-server-info` to keep the information used by dumb
@@ -154,6 +222,6 @@ transports (e.g., HTTP) up-to-date.  If you are publishing
 a git repository that is accessible via HTTP, you should
 probably enable this hook.
 
-The standard output of this hook is sent to `/dev/null`; if you
-want to report something to the `git-send-pack` on the other end,
-you can redirect your output to your `stderr`.
+Both standard output and standard error output are forwarded to
+`git-send-pack` on the other end, so you can simply `echo` messages
+for the user.
-- 
1.5.1.4