ipkg-build: use deterministic timestamps in ipk tarballs

As a follow-up to r46026, this commit sets the modification
times of files inside the tarballs to deterministic values.
It uses the date of the last git or svn commit and falls
back to the old behavior if those are not available.

Signed-off-by: Reiner Herrmann <reiner@reiner-h.de>

SVN-Revision: 46360

scripts/ipkg-build

@@ -13,8 +13,19 @@ version=1.0
 FIND="$(which find)"
 FIND="${FIND:-$(which gfind)}"
 TAR="${TAR:-$(which tar)}"
+SVN="$(which svn)"
+GIT="$(which git)"
 export GZIP="-n"
 
+# look up date of last commit
+if [ -d "$TOPDIR/.git" ]; then
+	TIMESTAMP=$($GIT log -1 -s --format=%ci)
+elif [ -d "$TOPDIR/.svn" ]; then
+	TIMESTAMP=$($SVN info "$TOPDIR" | sed -n "s/^Last Changed Date: \(.*\)/\1/p")
+else
+	TIMESTAMP=$(date)
+fi
+
 ipkg_extract_value() {
 	sed -e "s/^[^:]*:[[:space:]]*//"
 }
@@ -128,20 +139,20 @@ mkdir $tmp_dir
 
 echo $CONTROL > $tmp_dir/tarX
 # Preserve permissions (-p) when creating data.tar.gz as non-root user
-( cd $pkg_dir && $TAR $ogargs -X $tmp_dir/tarX --format=gnu -czpf $tmp_dir/data.tar.gz . )
+( cd $pkg_dir && $TAR $ogargs -X $tmp_dir/tarX --format=gnu -czpf $tmp_dir/data.tar.gz --mtime="$TIMESTAMP" . )
 
 installed_size=`stat -c "%s" $tmp_dir/data.tar.gz`
 sed -i -e "s/^Installed-Size: .*/Installed-Size: $installed_size/" \
 	$pkg_dir/$CONTROL/control
 
-( cd $pkg_dir/$CONTROL && $TAR $ogargs --format=gnu -czf $tmp_dir/control.tar.gz . )
+( cd $pkg_dir/$CONTROL && $TAR $ogargs --format=gnu -czf $tmp_dir/control.tar.gz --mtime="$TIMESTAMP" . )
 rm $tmp_dir/tarX
 
 echo "2.0" > $tmp_dir/debian-binary
 
 pkg_file=$dest_dir/${pkg}_${version}_${arch}.ipk
 rm -f $pkg_file
-( cd $tmp_dir && $TAR --format=gnu -zcf $pkg_file ./debian-binary ./data.tar.gz ./control.tar.gz )
+( cd $tmp_dir && $TAR --format=gnu -zcf $pkg_file --mtime="$TIMESTAMP" ./debian-binary ./data.tar.gz ./control.tar.gz )
 
 rm $tmp_dir/debian-binary $tmp_dir/data.tar.gz $tmp_dir/control.tar.gz
 rmdir $tmp_dir