[gentoo-dev] vcs-snapshot.eclass: add a way to specify the extraction path

[gentoo-dev] vcs-snapshot.eclass: add a way to specify the extraction path

[William Hubbs]

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All,

I'm finding in working on Go ebuilds, that we are propegating a
src_unpack function that is very similar to the one in vcs-snapshot.

This patch adds an EXTRACT_PATH variable to the vcs-snapshot eclass
which, if set, puts the extracted archives in the specified directory under ${S}.

If it is not set, nothing should happen.

This could be used by other types of ebuilds later, but for now it would
be used by Go ebuilds.

Thoughts?

William


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Index: vcs-snapshot.eclass
===================================================================
RCS file: /var/cvsroot/gentoo-x86/eclass/vcs-snapshot.eclass,v
retrieving revision 1.7
diff -u -B -r1.7 vcs-snapshot.eclass
--- vcs-snapshot.eclass	25 Jul 2013 07:51:16 -0000	1.7
+++ vcs-snapshot.eclass	30 Jul 2015 15:44:55 -0000
@@ -40,6 +40,13 @@
 	*) die "vcs-snapshot.eclass API in EAPI ${EAPI} not yet established."
 esac
 
+# @ECLASS-VARIABLE: EXTRACT_PATH
+# @DESCRIPTION:
+# This is a special purpose variable, mainly used by Go ebuilds, which
+# creates a sub directory under ${S} and stores the extracted archive
+# there. By default, this is empty, and please do not set it in your
+# ebuild unless you know exactly what you are doing.
+
 EXPORT_FUNCTIONS src_unpack
 
 # @FUNCTION: vcs-snapshot_src_unpack
@@ -57,13 +64,19 @@
 	do
 		case "${f}" in
 			*.tar|*.tar.gz|*.tar.bz2|*.tar.xz)
-				local destdir=${WORKDIR}/${f%.tar*}
+				[[ -n $EXTRACT_PATH ]] &&
+					local destdir=${WORKDIR}/${P}/${EXTRACT_PATH} ||
+					local destdir=${WORKDIR}/${f%.tar*}
 
 				debug-print "${FUNCNAME}: unpacking ${f} to ${destdir}"
 
 				# XXX: check whether the directory structure inside is
 				# fine? i.e. if the tarball has actually a parent dir.
-				mkdir "${destdir}" || die
+				if [[ -n ${EXTRACT_PATH} ]]; then
+					mkdir -p "${destdir}" || die
+				else
+					mkdir "${destdir}" || die
+				fi
 				tar -C "${destdir}" -x --strip-components 1 \
 					-f "${DISTDIR}/${f}" || die
 				;;

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Re: [gentoo-dev] vcs-snapshot.eclass: add a way to specify the extraction path

[Mike Gilbert]

On Thu, Jul 30, 2015 at 11:57 AM, William Hubbs <williamh@gentoo.org> wrote:
> All,
>
> I'm finding in working on Go ebuilds, that we are propegating a
> src_unpack function that is very similar to the one in vcs-snapshot.
>
> This patch adds an EXTRACT_PATH variable to the vcs-snapshot eclass
> which, if set, puts the extracted archives in the specified directory under ${S}.
>
> If it is not set, nothing should happen.
>
> This could be used by other types of ebuilds later, but for now it would
> be used by Go ebuilds.
>
> Thoughts?

Can you provide an example of an ebuild in the tree for which this
would be useful?

I'm unclear as to why tarballs are being unpacked in sub-directories of ${S}.

Re: [gentoo-dev] vcs-snapshot.eclass: add a way to specify the extraction path

[Michał Górny]

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Dnia 2015-07-30, o godz. 10:57:46
William Hubbs <williamh@gentoo.org> napisał(a):

> All,
> 
> I'm finding in working on Go ebuilds, that we are propegating a
> src_unpack function that is very similar to the one in vcs-snapshot.
> 
> This patch adds an EXTRACT_PATH variable to the vcs-snapshot eclass
> which, if set, puts the extracted archives in the specified directory under ${S}.
> 
> If it is not set, nothing should happen.
> 
> This could be used by other types of ebuilds later, but for now it would
> be used by Go ebuilds.
> 
> Thoughts?

I'm against it. This doubles the eclass code, adding completely
orthogonal and incompatible behavior.

The goal of this eclass is to provide a relatively simple way of
extracting VCS snapshots and putting them in a predictable locations,
not fitting some random src_unpack() you happen to use.

-- 
Best regards,
Michał Górny
<http://dev.gentoo.org/~mgorny/>

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Re: [gentoo-dev] Jvcs-snapshot.eclass: add a way to specify the extraction path

[William Hubbs]

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On Thu, Jul 30, 2015 at 05:11:20PM -0400, Mike Gilbert wrote:
> On Thu, Jul 30, 2015 at 11:57 AM, William Hubbs <williamh@gentoo.org> wrote:
> > All,
> >
> > I'm finding in working on Go ebuilds, that we are propegating a
> > src_unpack function that is very similar to the one in vcs-snapshot.
> >
> > This patch adds an EXTRACT_PATH variable to the vcs-snapshot eclass
> > which, if set, puts the extracted archives in the specified directory under ${S}.
> >
> > If it is not set, nothing should happen.
> >
> > This could be used by other types of ebuilds later, but for now it would
> > be used by Go ebuilds.
> >
> > Thoughts?
> 
> Can you provide an example of an ebuild in the tree for which this
> would be useful?

Sure,

Take a look at dev-go/go-snappy and most of the dev-go ebuilds.

They use a src_unpack function for the non-live side that is almost
exactly like vcs-snapshot except for the extraction location.

> I'm unclear as to why tarballs are being unpacked in sub-directories of ${S}.
 
For Go software that just uses the Go tools to build, it is easiest to
work with if you treat ${S} as a Go Workspace [1].

I could write my own golang-vcs-snapshot.eclass that does this, but I
thought it would be easier to leverage code that is already in the tree.

William

[1] https://golang.org/doc/code.html#Workspaces

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Re: [gentoo-dev] Jvcs-snapshot.eclass: add a way to specify the extraction path

[Mike Gilbert]

On Fri, Jul 31, 2015 at 10:44 AM, William Hubbs <williamh@gentoo.org> wrote:
> On Thu, Jul 30, 2015 at 05:11:20PM -0400, Mike Gilbert wrote:
>> On Thu, Jul 30, 2015 at 11:57 AM, William Hubbs <williamh@gentoo.org> wrote:
>> > All,
>> >
>> > I'm finding in working on Go ebuilds, that we are propegating a
>> > src_unpack function that is very similar to the one in vcs-snapshot.
>> >
>> > This patch adds an EXTRACT_PATH variable to the vcs-snapshot eclass
>> > which, if set, puts the extracted archives in the specified directory under ${S}.
>> >
>> > If it is not set, nothing should happen.
>> >
>> > This could be used by other types of ebuilds later, but for now it would
>> > be used by Go ebuilds.
>> >
>> > Thoughts?
>>
>> Can you provide an example of an ebuild in the tree for which this
>> would be useful?
>
> Sure,
>
> Take a look at dev-go/go-snappy and most of the dev-go ebuilds.
>
> They use a src_unpack function for the non-live side that is almost
> exactly like vcs-snapshot except for the extraction location.
>
>> I'm unclear as to why tarballs are being unpacked in sub-directories of ${S}.
>
> For Go software that just uses the Go tools to build, it is easiest to
> work with if you treat ${S} as a Go Workspace [1].
>
> I could write my own golang-vcs-snapshot.eclass that does this, but I
> thought it would be easier to leverage code that is already in the tree.

The thing I find a bit awkward here is that vcs-snapshot_src_unpack
will automatically unpack multiple tarballs into separate directories.
As soon as you set EXTRACT_PATH, you break that; all tarballs get
unpacked into a single directory.

I think sharing code often a good thing, but I think some refactoring
is in order before it will be possible here.

Since go does things rather strangely, it may make more since to
maintain your own version of this function in another eclass.