[PATCH] 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.

Signed-off-by: Roberto A. Foglietta <roberto.foglietta@gmail.com>
---
 meta/classes/deb-dl-dir.bbclass | 41 ++++++++++++++++++---------------
 1 file changed, 23 insertions(+), 18 deletions(-)

diff --git a/meta/classes/deb-dl-dir.bbclass b/meta/classes/deb-dl-dir.bbclass
index 3b1517dc..22de7bf6 100644
--- a/meta/classes/deb-dl-dir.bbclass
+++ b/meta/classes/deb-dl-dir.bbclass
@@ -78,39 +78,44 @@ 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 "${pc}" ] && return 0
+    export tf=$(ls -1 "${pc}"/*.deb | head -n1)
+    [ ! -e "${tf}" ] && return 0
     flock -s "${pc}".lock -c '
         set -e
         printenv | grep -q BB_VERBOSE_LOGS && set -x
 
-        sudo find "${pc}" -type f -iname "*\.deb" -exec \
-            cp -n --no-preserve=owner -t "${rootfs}"/var/cache/apt/archives/ {} +
+        sudo ln -Pf -t "${sc}" "${tf}" 2>/dev/null ||:
+        if [ -r "${tf}" ]; then
+            sudo find "${pc}" -type f -iname "*\.deb" -exec \
+                ln -Pf -t "${sc}" {} +
+        else
+            sudo find "${pc}" -type f -iname "*\.deb" -exec \
+                cp -np owner --reflink=auto -t "${sc}" {} +
+        fi
     '
 }
 
 deb_dl_dir_export() {
     export pc="${DEBDIR}/${2}"
-    export rootfs="${1}"
+    export sc="${1}/var/cache/apt/archives/"
     mkdir -p "${pc}"
+    export tf=$(ls -1 "${sc}"/*.deb | head -n1)
+    [ ! -e "${tf}" ] && return 0
     flock "${pc}".lock -c '
         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 cp -n "${p}" "${pc}"
-        done
+        sudo ln -Pf -t "${pc}" "${tf}" 2>/dev/null ||:
+        if [ -r "${tf}" ]; then
+            sudo find "${sc}" -maxdepth 1 -type f -iname '*\.deb' \
+                -exec ln -P -t "${pc}" {} + 2>/dev/null ||:
+        else
+            sudo find "${sc}" -maxdepth 1 -type f -iname '*\.deb' \
+                -exec cp -n --reflink=auto -t "${pc}" {} +
+        fi
         sudo chown -R $(id -u):$(id -g) "${pc}"
     '
 }
-- 
2.34.1