[PATCH] dpkg: Make mount buildroot reliable

[Anton Mikanovich <amikan@ilbers.de>]

We use mounting for several tasks. Mounting and unmounting is performed
in shell scripts. If a command fails before unmounting, the directories
remain mounted.

Implement exception handling around the scripts to ensure that
unmounting is performed also in case of script failure. The number of
unmounting attempts has been limited to avoid infinite loops.

Signed-off-by: Anton Mikanovich <amikan@ilbers.de>
---
 meta/classes/dpkg-base.bbclass | 93 +++++++++++++++++++---------------
 meta/classes/dpkg-gbp.bbclass  |  8 +--
 meta/classes/dpkg.bbclass      | 14 +++--
 3 files changed, 64 insertions(+), 51 deletions(-)

diff --git a/meta/classes/dpkg-base.bbclass b/meta/classes/dpkg-base.bbclass
index 5c7bddc..544ee36 100644
--- a/meta/classes/dpkg-base.bbclass
+++ b/meta/classes/dpkg-base.bbclass
@@ -54,13 +54,7 @@ addtask patch before do_adjust_git
 
 SRC_APT ?= ""
 
-do_apt_fetch() {
-    if [ -z "${@d.getVar("SRC_APT", True).strip()}" ]; then
-        return 0
-    fi
-    rm -rf ${S}
-    dpkg_do_mounts
-    E="${@ isar_export_proxies(d)}"
+fetch_apt() {
     sudo -E chroot ${BUILDCHROOT_DIR} /usr/bin/apt-get update \
         -o Dir::Etc::SourceList="sources.list.d/isar-apt.list" \
         -o Dir::Etc::SourceParts="-" \
@@ -72,8 +66,27 @@ do_apt_fetch() {
         sudo -E chroot --userspec=$( id -u ):$( id -g ) ${BUILDCHROOT_DIR} \
             sh -c 'cp /downloads/deb-src/"$1"/"$2"/* ${PP} && cd ${PP} && apt-get -y --only-source source "$2"' my_script "${DISTRO}" "${uri}"
     done
+}
+
+python do_apt_fetch() {
+    import glob
+    import shutil
+
+    src_apt = d.getVar("SRC_APT", True)
+    if not src_apt:
+        return 0
 
-    dpkg_undo_mounts
+    srcsubdir = d.getVar('S', True)
+    if os.path.exists(srcsubdir):
+        shutil.rmtree(srcsubdir)
+
+    dpkg_do_mounts(d)
+    try:
+        isar_export_proxies(d)
+        buildchroot = d.getVar('BUILDCHROOT_DIR', True)
+        bb.build.exec_func("fetch_apt", d)
+    finally:
+        dpkg_undo_mounts(d)
 }
 
 addtask apt_fetch after do_unpack before do_patch
@@ -118,25 +131,23 @@ do_prepare_build[deptask] = "do_deploy_deb"
 
 BUILDROOT = "${BUILDCHROOT_DIR}/${PP}"
 
-dpkg_do_mounts() {
-    mkdir -p ${BUILDROOT}
-    sudo mount --bind ${WORKDIR} ${BUILDROOT}
-
-    buildchroot_do_mounts
-}
-
-dpkg_undo_mounts() {
-    i=1
-    while ! sudo umount ${BUILDROOT}; do
-        sleep 0.1
-        i=`expr $i + 1`
-        if [ $i -gt 100 ]; then
-            bbwarn "${BUILDROOT}: Couldn't unmount, retrying..."
-            i=1
-        fi
-    done
-    sudo rmdir ${BUILDROOT}
-}
+def dpkg_do_mounts(d):
+    buildroot = d.getVar('BUILDROOT', True)
+    workdir = d.getVar("WORKDIR", True)
+    os.makedirs(buildroot, exist_ok=True)
+    os.system('sudo mount --bind %s %s' % (workdir, buildroot))
+    bb.build.exec_func("buildchroot_do_mounts", d)
+
+def dpkg_undo_mounts(d):
+    buildroot = d.getVar('BUILDROOT', True)
+    for i in range(200):
+        if not os.system('sudo umount %s' % buildroot):
+            os.rmdir(buildroot)
+            return
+        if i % 100 == 0:
+            bb.warn("%s: Couldn't unmount, retrying..." % buildroot)
+        time.sleep(0.1)
+    bb.fatal("Couldn't unmount, exiting...")
 
 # Placeholder for actual dpkg_runbuild() implementation
 dpkg_runbuild() {
@@ -146,10 +157,12 @@ dpkg_runbuild() {
 python do_dpkg_build() {
     lock = bb.utils.lockfile(d.getVar("REPO_ISAR_DIR") + "/isar.lock",
                              shared=True)
-    bb.build.exec_func("dpkg_do_mounts", d)
-    bb.build.exec_func("dpkg_runbuild", d)
-    bb.build.exec_func("dpkg_undo_mounts", d)
-    bb.utils.unlockfile(lock)
+    dpkg_do_mounts(d)
+    try:
+        bb.build.exec_func("dpkg_runbuild", d)
+    finally:
+        dpkg_undo_mounts(d)
+        bb.utils.unlockfile(lock)
 }
 
 addtask dpkg_build before do_build
@@ -193,16 +206,16 @@ python do_devshell() {
     oe_lib_path = os.path.join(d.getVar('LAYERDIR_core'), 'lib')
     sys.path.insert(0, oe_lib_path)
 
-    bb.build.exec_func('dpkg_do_mounts', d)
-
-    isar_export_proxies(d)
-
-    buildchroot = d.getVar('BUILDCHROOT_DIR')
-    pp_pps = os.path.join(d.getVar('PP'), d.getVar('PPS'))
-    termcmd = "sudo -E chroot {0} sh -c 'cd {1}; $SHELL -i'"
-    oe_terminal(termcmd.format(buildchroot, pp_pps), "Isar devshell", d)
+    dpkg_do_mounts(d)
+    try:
+        isar_export_proxies(d)
 
-    bb.build.exec_func('dpkg_undo_mounts', d)
+        buildchroot = d.getVar('BUILDCHROOT_DIR')
+        pp_pps = os.path.join(d.getVar('PP'), d.getVar('PPS'))
+        termcmd = "sudo -E chroot {0} sh -c 'cd {1}; $SHELL -i'"
+        oe_terminal(termcmd.format(buildchroot, pp_pps), "Isar devshell", d)
+    finally:
+        dpkg_undo_mounts(d)
 }
 
 addtask devshell after do_prepare_build
diff --git a/meta/classes/dpkg-gbp.bbclass b/meta/classes/dpkg-gbp.bbclass
index d956e8c..20d2d4c 100644
--- a/meta/classes/dpkg-gbp.bbclass
+++ b/meta/classes/dpkg-gbp.bbclass
@@ -12,12 +12,7 @@ PATCHTOOL ?= "git"
 GBP_DEPENDS ?= "git-buildpackage pristine-tar"
 GBP_EXTRA_OPTIONS ?= "--git-pristine-tar"
 
-do_install_builddeps_append() {
-    dpkg_do_mounts
-    distro="${DISTRO}"
-    if [ ${ISAR_CROSS_COMPILE} -eq 1 ]; then
-       distro="${HOST_DISTRO}"
-    fi
+builddeps_install_append() {
     deb_dl_dir_import "${BUILDCHROOT_DIR}" "${distro}"
     sudo -E chroot ${BUILDCHROOT_DIR} \
         apt-get install -y -o Debug::pkgProblemResolver=yes \
@@ -26,7 +21,6 @@ do_install_builddeps_append() {
     sudo -E chroot ${BUILDCHROOT_DIR} \
         apt-get install -y -o Debug::pkgProblemResolver=yes \
                         --no-install-recommends ${GBP_DEPENDS}
-    dpkg_undo_mounts
 }
 
 dpkg_runbuild_prepend() {
diff --git a/meta/classes/dpkg.bbclass b/meta/classes/dpkg.bbclass
index 4e7c2f7..29e2b89 100644
--- a/meta/classes/dpkg.bbclass
+++ b/meta/classes/dpkg.bbclass
@@ -6,9 +6,7 @@ inherit dpkg-base
 PACKAGE_ARCH ?= "${DISTRO_ARCH}"
 
 # Install build dependencies for package
-do_install_builddeps() {
-    dpkg_do_mounts
-    E="${@ isar_export_proxies(d)}"
+builddeps_install() {
     distro="${DISTRO}"
     if [ ${ISAR_CROSS_COMPILE} -eq 1 ]; then
        distro="${HOST_DISTRO}"
@@ -19,7 +17,15 @@ do_install_builddeps() {
     deb_dl_dir_export "${BUILDCHROOT_DIR}" "${distro}"
     sudo -E chroot ${BUILDCHROOT_DIR} /isar/deps.sh \
         ${PP}/${PPS} ${PACKAGE_ARCH}
-    dpkg_undo_mounts
+}
+
+python do_install_builddeps() {
+    dpkg_do_mounts(d)
+    isar_export_proxies(d)
+    try:
+        bb.build.exec_func("builddeps_install", d)
+    finally:
+        dpkg_undo_mounts(d)
 }
 
 addtask install_builddeps after do_prepare_build before do_dpkg_build
-- 
2.20.1