[RFC v2][PATCH 2/3] build-rep: Add helper class

[Alexander Smirnov <asmirnov@ilbers.de>]

Add class that helps to implement build reproducibility. It implements
anonymous function that will get all the Debian dependencies that are
needed for current Isar tree.

Until build reproducibility will be fully implemented, it's disabled by
default. To enable it just set ISAR_BUILD_REP to "1" in local.conf.

Signed-off-by: Alexander Smirnov <asmirnov@ilbers.de>
---
 meta-isar/conf/local.conf.sample                 |  6 +++++
 meta-isar/recipes-app/hello/hello.bb             |  2 ++
 meta/classes/build-rep.bbclass                   | 32 ++++++++++++++++++++++++
 meta/classes/dpkg-base.bbclass                   |  2 ++
 meta/classes/image.bbclass                       |  2 ++
 meta/recipes-devtools/buildchroot/buildchroot.bb |  2 ++
 6 files changed, 46 insertions(+)
 create mode 100644 meta/classes/build-rep.bbclass

diff --git a/meta-isar/conf/local.conf.sample b/meta-isar/conf/local.conf.sample
index 660958f..45b8995 100644
--- a/meta-isar/conf/local.conf.sample
+++ b/meta-isar/conf/local.conf.sample
@@ -162,3 +162,9 @@ BB_NUMBER_THREADS = "4"
 #
 # Number of attempts to try to get reprepro lock for access to apt cache
 REPREPRO_LOCK_ATTEMPTS = "16"
+
+# Isar build reproducibility feature creates local repository which contains
+# copies for all the upstream Debian packages that could be used to build
+# your Isar tree. So fetching them once will guarantee that all the next Isar
+# builds will be identically.
+ISAR_BUILD_REP ?= "0"
diff --git a/meta-isar/recipes-app/hello/hello.bb b/meta-isar/recipes-app/hello/hello.bb
index 44b8bc3..fafda2e 100644
--- a/meta-isar/recipes-app/hello/hello.bb
+++ b/meta-isar/recipes-app/hello/hello.bb
@@ -16,3 +16,5 @@ SRCREV = "ad7065ecc4840cc436bfcdac427386dbba4ea719"
 SRC_DIR = "git"
 
 inherit dpkg
+
+DEBIAN_DEPENDS = "debhelper (>= 9), autotools-dev"
diff --git a/meta/classes/build-rep.bbclass b/meta/classes/build-rep.bbclass
new file mode 100644
index 0000000..ede5a93
--- /dev/null
+++ b/meta/classes/build-rep.bbclass
@@ -0,0 +1,32 @@
+# This software is a part of ISAR.
+# Copyright (C) 2017 Siemens AG
+
+python __anonymous() {
+    rep = d.getVar('ISAR_BUILD_REP', True) or "0"
+    if rep == "0":
+        return
+
+    depsdir = d.getVar('BASE_APT_DIR', True)
+    if depsdir is None:
+        return
+
+    depsdir += '/deps/'
+
+    pn = d.getVar('PN', True)
+
+    if not os.path.exists(depsdir):
+        os.makedirs(depsdir, exist_ok=True)
+
+    if d.getVar('DEBIAN_DEPENDS', True):
+        with open(depsdir + '/' +  pn + '.depends', 'w') as the_file:
+            the_file.write(d.getVar('DEBIAN_DEPENDS', True))
+            the_file.close
+    elif d.getVar('BUILDCHROOT_PREINSTALL', True):
+        with open(depsdir + '/' +  pn + '.preinst', 'w') as the_file:
+            the_file.write(d.getVar('BUILDCHROOT_PREINSTALL', True))
+            the_file.close
+    elif d.getVar('IMAGE_PREINSTALL', True):
+        with open(depsdir + '/' +  pn + '.preinst', 'w') as the_file:
+            the_file.write(d.getVar('IMAGE_PREINSTALL', True))
+            the_file.close
+}
diff --git a/meta/classes/dpkg-base.bbclass b/meta/classes/dpkg-base.bbclass
index 4d220da..bf66e78 100644
--- a/meta/classes/dpkg-base.bbclass
+++ b/meta/classes/dpkg-base.bbclass
@@ -3,6 +3,8 @@
 
 DEBIAN_DEPENDS ?= ""
 
+inherit build-rep
+
 # Add dependency from buildchroot creation
 do_build[depends] = "buildchroot:do_build"
 
diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
index e2cb01b..67f5af8 100644
--- a/meta/classes/image.bbclass
+++ b/meta/classes/image.bbclass
@@ -5,6 +5,8 @@ IMAGE_INSTALL ?= ""
 IMAGE_TYPE    ?= "ext4-img"
 IMAGE_ROOTFS   = "${WORKDIR}/rootfs"
 
+inherit build-rep
+
 def get_image_name(d, name_link):
     S = d.getVar("IMAGE_ROOTFS", True)
     path_link = os.path.join(S, name_link)
diff --git a/meta/recipes-devtools/buildchroot/buildchroot.bb b/meta/recipes-devtools/buildchroot/buildchroot.bb
index 51f9d5d..da18231 100644
--- a/meta/recipes-devtools/buildchroot/buildchroot.bb
+++ b/meta/recipes-devtools/buildchroot/buildchroot.bb
@@ -16,6 +16,8 @@ SRC_URI = "file://multistrap.conf.in \
            file://build.sh"
 PV = "1.0"
 
+inherit build-rep
+
 BUILDCHROOT_PREINSTALL ?= "gcc \
                            make \
                            build-essential \
-- 
2.1.4