[PATCH] Map git objects to buildchroot

[Alexander Smirnov <asmirnov@ilbers.de>]

Hi Christian,

The patch above has 2 major issues:

1. It mounts ${GITDIR} to buildchroot during package building. This variable
is static, so it's the same for each recipe. This means that if several
packages are building in parallel, the folder ${BUILDCHROOT_DIR}/${GITDIR}
could be mounted/unmounted while there is active I/O operation by another
package. To be honest, I don't know what could happen, but believe in worst
case.

2. Using host configuration in buildchroot could lead to some problems.
Lets consider the following example:
 - User override ${DL_DIR} to point it to local cache, let's say: /home/builder/XXX
 - Isar uses  the following path to build package YYY: /home/builder/YYY
 - If XXX equals YYY, you will probably experience some problems, because your source
   tree will be overriden by incorect mount.

So I'd see the more generic solution like patch below:

8<--

dpkg-base: Map git objects to buildchroot

This patch mounts git repository to buildchroot into the respective folder:

 /git/$REPO_NAME

Also it updates git alternative to correctly point to objects in buildchroot.

Signed-off-by: Alexander Smirnov <asmirnov@ilbers.de>
---
 meta/classes/dpkg-base.bbclass | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/meta/classes/dpkg-base.bbclass b/meta/classes/dpkg-base.bbclass
index 35af6d5..147cfce 100644
--- a/meta/classes/dpkg-base.bbclass
+++ b/meta/classes/dpkg-base.bbclass
@@ -19,12 +19,25 @@ dpkg_runbuild() {
 
 # Wrap the function dpkg_runbuild with the bind mount for buildroot
 do_build() {
+    if [ -d ${WORKDIR}/git/.git ]; then
+        OBJ_PATH=$(cat ${WORKDIR}/git/.git/objects/info/alternates)
+        REPO_PATH=$(dirname $OBJ_PATH)
+        REPO_NAME=$(basename $REPO_PATH)
+        sudo mkdir -p ${BUILDCHROOT_DIR}/git/$REPO_NAME
+        sudo mount --bind $REPO_PATH ${BUILDCHROOT_DIR}/git/$REPO_NAME
+        echo "/git/$REPO_NAME/objects" > ${WORKDIR}/git/.git/objects/info/alternates
+    fi
+
     mkdir -p ${BUILDROOT}
     sudo mount --bind ${WORKDIR} ${BUILDROOT}
     _do_build_cleanup() {
         ret=$?
         sudo umount ${BUILDROOT} 2>/dev/null || true
         sudo rmdir ${BUILDROOT} 2>/dev/null || true
+        if [ -d ${WORKDIR}/git/.git ]; then
+            sudo umount ${BUILDCHROOT_DIR}/git/$REPO_NAME
+            sudo rm -rf ${BUILDCHROOT_DIR}/git/$REPO_NAME
+        fi
         (exit $ret) || bb_exit_handler
     }
     trap '_do_build_cleanup' EXIT
-- 
2.9.5