[PATCH v4] deb-dl-dir class rework to use faster ln -P or fallback to cp

[roberto.foglietta@linuxteam.org]

From: "Roberto A. Foglietta" <roberto.foglietta@gmail.com>

deb-dl-dir, feature: faster when using ln -P otherwise fallback to cp

The original class functions deb_dl_dir_import/export were using cp to
copy debian package to the target rootfs but this approach is quite slow
while using hard link does not work if the destination and source dirs
are not lying on the same filesystem. Thus, ln -P should fallback to cp
when it does not work (which is different from complaining on stderr).

Moreover, these two functions have been reworked to reach a straight
forward and more compact form. In particular, export function was using
bashism to do some kind of comparison which after all is useless
because copying back without overwriting just fulfills that part.

More rework using sudo in a different way plus a corner case
addressingi, in case the spia file exists for some other reasons.

Rebased on the current next and bugfix about checking the destination
not the source file.

Signed-off-by: Roberto A. Foglietta <roberto.foglietta@gmail.com>
---
 meta/classes/deb-dl-dir.bbclass | 53 +++++++++++++++++++--------------
 1 file changed, 30 insertions(+), 23 deletions(-)

diff --git a/meta/classes/deb-dl-dir.bbclass b/meta/classes/deb-dl-dir.bbclass
index 7db25251..2a3c7508 100644
--- a/meta/classes/deb-dl-dir.bbclass
+++ b/meta/classes/deb-dl-dir.bbclass
@@ -78,39 +78,46 @@ debsrc_download() {
 
 deb_dl_dir_import() {
     export pc="${DEBDIR}/${2}"
-    export rootfs="${1}"
-    sudo mkdir -p "${rootfs}"/var/cache/apt/archives/
+    export sc="${1}/var/cache/apt/archives/"
+    sudo mkdir -p "${sc}"
     [ ! -d "${pc}" ] && return 0
-    flock -s "${pc}".lock -c '
+    export tf=$(cd "${pc}"; ls -1 *.deb | head -n1)
+    [ ! -e "${pc}/${tf}" ] && return 0
+    flock -Fs "${pc}".lock sudo -Es << 'EOFSUDO'
         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/ {} +
-    '
+        rm -f "${sc}/${tf}"
+        ln -Pf -t "${sc}" "${pc}/${tf}" 2>/dev/null ||:
+        if [ -r "${sc}/${tf}" ]; then
+            find "${pc}" -type f -iname "*\.deb" -exec \
+                ln -Pf -t "${sc}" {} +
+        else
+            find "${pc}" -type f -iname "*\.deb" -exec \
+                cp -np owner --reflink=auto -t "${sc}" {} +
+        fi
+EOFSUDO
 }
 
 deb_dl_dir_export() {
     export pc="${DEBDIR}/${2}"
-    export rootfs="${1}"
+    export sc="${1}/var/cache/apt/archives/"
     mkdir -p "${pc}"
-    flock "${pc}".lock -c '
+    export tf=$(cd "${sc}"; ls -1 *.deb | head -n1)
+    [ ! -e "${sc}/${tf}" ] && return 0
+    flock -F "${pc}".lock sudo -Es << 'EOFSUDO'
         set -e
         printenv | grep -q BB_VERBOSE_LOGS && set -x
 
-        find "${rootfs}"/var/cache/apt/archives/ \
-            -maxdepth 1 -type f -iname '*\.deb' |\
-        while read p; do
-            # skip files from a previous export
-            [ -f "${pc}/${p##*/}" ] && continue
-            # can not reuse bitbake function here, this is basically
-            # "repo_contains_package"
-            package=$(find "${REPO_ISAR_DIR}"/"${DISTRO}" -name ${p##*/})
-            if [ -n "$package" ]; then
-                cmp --silent "$package" "$p" && continue
-            fi
-            sudo ln -Pf "${p}" "${pc}"
-        done
-        sudo chown -R $(id -u):$(id -g) "${pc}"
-    '
+        rm -f "${pc}/${tf}"
+        ln -Pf -t "${pc}" "${sc}/${tf}" 2>/dev/null ||:
+        if [ -r "${pc}/${tf}" ]; then
+            find "${sc}" -maxdepth 1 -type f -iname '*\.deb' \
+                -exec ln -P -t "${pc}" {} + 2>/dev/null ||:
+        else
+            find "${sc}" -maxdepth 1 -type f -iname '*\.deb' \
+                -exec cp -n --reflink=auto -t "${pc}" {} +
+        fi
+        chown -R $(id -u):$(id -g) "${pc}"
+EOFSUDO
 }
-- 
2.34.1