[gnome-continuous-yocto/gnomeostree-3.28-rocko: 821/8267] image/image_types.bbclass: fix fatal error during cpio debugfs creation

[Emmanuele Bassi <ebassi src gnome org>]

commit 9ac4c8b11cd28cc1d343f9b2a91a6666febe246d
Author: André Draszik <adraszik tycoint com>
Date:   Fri Jun 10 16:11:38 2016 +0100

    image/image_types.bbclass: fix fatal error during cpio debugfs creation
    
    If /init is just a symlink to /sbin/init, debugfs creation
    fails with the following error:
    
    ERROR: Error: The image creation script '<...>/debugfs.create_image.cpio' returned 1:
    touch: cannot touch '<...>/cpio_append/init': Permission denied
    WARNING: exit code 1 from a shell command.
    
    ERROR: Function failed: do_rootfs
    
    The reason is that IMAGE_CMD_cpio() is run twice on the same
    WORKDIR. The first run creates a symlink in WORKDIR/cpio_append/init
    to point to /sbin/init, while the 2nd run then tries to 'touch'
    that link, which will fail, of course since /sbin/init is not
    usually writable by non-root users.
    
    Fix this by providing knowledge to the IMAGE_CMD_xxx() scripts
    with regards to the fact that they are being executed in the
    context of debugfs creation. The IMAGE_CMD_cpio() can now be
    intelligent in the sense that it can avoid all additional symlink
    handling during the debugfs run. The symlinks do not need to
    be part of the debugfs, so we can skip that part altogether
    in that case.
    
    (From OE-Core rev: 659ae1d7df28115429f6f31450fad6d1f86e3031)
    
    Signed-off-by: André Draszik <adraszik tycoint com>
    Signed-off-by: Ross Burton <ross burton intel com>
    Signed-off-by: Richard Purdie <richard purdie linuxfoundation org>

 meta/classes/image.bbclass       |    1 +
 meta/classes/image_types.bbclass |   19 +++++++++++++------
 2 files changed, 14 insertions(+), 6 deletions(-)
---
diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
index 9f4c83f..65ce6bb 100644
--- a/meta/classes/image.bbclass
+++ b/meta/classes/image.bbclass
@@ -287,6 +287,7 @@ def setup_debugfs_variables(d):
     d.appendVar('IMAGE_ROOTFS', '-dbg')
     d.appendVar('IMAGE_LINK_NAME', '-dbg')
     d.appendVar('IMAGE_NAME','-dbg')
+    d.setVar('IMAGE_BUILDING_DEBUGFS', 'true')
     debugfs_image_fstypes = d.getVar('IMAGE_FSTYPES_DEBUGFS', True)
     if debugfs_image_fstypes:
         d.setVar('IMAGE_FSTYPES', debugfs_image_fstypes)
diff --git a/meta/classes/image_types.bbclass b/meta/classes/image_types.bbclass
index ea45809..72e8ed3 100644
--- a/meta/classes/image_types.bbclass
+++ b/meta/classes/image_types.bbclass
@@ -101,13 +101,20 @@ IMAGE_CMD_tar = "${IMAGE_CMD_TAR} -cvf ${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}${IMAGE_
 do_image_cpio[cleandirs] += "${WORKDIR}/cpio_append"
 IMAGE_CMD_cpio () {
        (cd ${IMAGE_ROOTFS} && find . | cpio -o -H newc 
> ${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.cpio)
-       if [ ! -L ${IMAGE_ROOTFS}/init -a ! -e ${IMAGE_ROOTFS}/init ]; then
-               if [ -L ${IMAGE_ROOTFS}/sbin/init -o -e ${IMAGE_ROOTFS}/sbin/init ]; then
-                       ln -sf /sbin/init ${WORKDIR}/cpio_append/init
-               else
-                       touch ${WORKDIR}/cpio_append/init
+       # We only need the /init symlink if we're building the real
+       # image. The -dbg image doesn't need it! By being clever
+       # about this we also avoid 'touch' below failing, as it
+       # might be trying to touch /sbin/init on the host since both
+       # the normal and the -dbg image share the same WORKDIR
+       if [ "${IMAGE_BUILDING_DEBUGFS}" != "true" ]; then
+               if [ ! -L ${IMAGE_ROOTFS}/init ] && [ ! -e ${IMAGE_ROOTFS}/init ]; then
+                       if [ -L ${IMAGE_ROOTFS}/sbin/init ] || [ -e ${IMAGE_ROOTFS}/sbin/init ]; then
+                               ln -sf /sbin/init ${WORKDIR}/cpio_append/init
+                       else
+                               touch ${WORKDIR}/cpio_append/init
+                       fi
+                       (cd  ${WORKDIR}/cpio_append && echo ./init | cpio -oA -H newc -F 
${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.cpio)
                fi
-               (cd  ${WORKDIR}/cpio_append && echo ./init | cpio -oA -H newc -F 
${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.cpio)
        fi
 }