[PATCH v3] deb-dl-dir: Fallback to copying when import-export

[Uladzimir Bely <ubely@ilbers.de>]

By default, hardlinks are used when doing DL_DIR import and export.
This fails if DL_DIR's filesystem differs from TMPDIR's one.

Fallback to file copying (with lower performance and huge disk usage)
in this case.

Also rework sudo using when import/export by preferring "sudo/while"
approach instead of "while/sudo" (less spam in system logs).

Signed-off-by: Uladzimir Bely <ubely@ilbers.de>
---
 meta/classes/deb-dl-dir.bbclass | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

Changes since v2:
 - Reworked sudo usage approach from "while/sudo" to "sudo/while".

Changes since v1:
 - Try create handrlink first and then copy if failed. It should better
handle hardlink issues that may happen even on the same partition.

diff --git a/meta/classes/deb-dl-dir.bbclass b/meta/classes/deb-dl-dir.bbclass
index 7db25251..ca2a1ee2 100644
--- a/meta/classes/deb-dl-dir.bbclass
+++ b/meta/classes/deb-dl-dir.bbclass
@@ -81,20 +81,24 @@ deb_dl_dir_import() {
     export rootfs="${1}"
     sudo mkdir -p "${rootfs}"/var/cache/apt/archives/
     [ ! -d "${pc}" ] && return 0
-    flock -s "${pc}".lock -c '
+    flock -s "${pc}".lock sudo -Es << 'EOSUDO'
         set -e
         printenv | grep -q BB_VERBOSE_LOGS && set -x
 
-        sudo find "${pc}" -type f -iname "*\.deb" -exec \
-            ln -Pf -t "${rootfs}"/var/cache/apt/archives/ {} +
-    '
+        find "${pc}" -type f -iname "*\.deb" |\
+        while read p; do
+            ln -Pf -t "${rootfs}"/var/cache/apt/archives/ "$p" 2>/dev/null ||
+                cp -n --no-preserve=owner -t "${rootfs}"/var/cache/apt/archives/ "$p"
+        done
+EOSUDO
 }
 
 deb_dl_dir_export() {
     export pc="${DEBDIR}/${2}"
     export rootfs="${1}"
+    export owner=$(id -u):$(id -g)
     mkdir -p "${pc}"
-    flock "${pc}".lock -c '
+    flock "${pc}".lock sudo -Es << 'EOSUDO'
         set -e
         printenv | grep -q BB_VERBOSE_LOGS && set -x
 
@@ -109,8 +113,9 @@ deb_dl_dir_export() {
             if [ -n "$package" ]; then
                 cmp --silent "$package" "$p" && continue
             fi
-            sudo ln -Pf "${p}" "${pc}"
+            ln -Pf "${p}" "${pc}" 2>/dev/null ||
+                cp -n "${p}" "${pc}"
         done
-        sudo chown -R $(id -u):$(id -g) "${pc}"
-    '
+        chown -R ${owner} "${pc}"
+EOSUDO
 }
-- 
2.20.1