file-install modules: Don't destroy original before we know we have a…

… backup.

This was revealed by the `test_file_update_module` in integration,
which puts a file in the way of the directory. If it fails that early,
we should not delete the original, since we never created a backup.

More commonly, this problem would happen if there was no space for the
backup, which would obviously be disastrous. So also make sure we have
a *complete* backup.

Changelog: Title

Signed-off-by: Kristian Amlie <kristian.amlie@northern.tech>

support/modules/file-tree-install

@@ -26,21 +26,27 @@ case "$STATE" in
         test "$dest_dir" = "/" && \
             echo "Error: destination dir is '/', install not supported." && exit 1
         mkdir -p $dest_dir
-        tar -cf ${prev_files_tar} -C ${dest_dir} .
+        if ! tar -cf ${prev_files_tar} -C ${dest_dir} .
+        then
+            ret=$?
+            # Make sure there is no half-backup lying around.
+            rm -f ${prev_files_tar}
+            exit $ret
+        fi
         rm -rf ${dest_dir}
         mkdir -p ${dest_dir}
         tar -xf ${update_files_tar} -C ${dest_dir}
         ;;
 
     ArtifactRollback)
+        test -f $prev_files_tar || exit 0
         dest_dir=$(cat $dest_dir_file)
         test -z "$dest_dir" && \
             echo "Fatal error: dest_dir is undefined." && exit 1
         test "$dest_dir" = "/" && \
             echo "Info: destination dir is '/', not performing rollback." && exit 0
         rm -rf ${dest_dir}
         mkdir -p ${dest_dir}
-        test -f $prev_files_tar || exit 0
         tar -xf ${prev_files_tar} -C ${dest_dir}
         ;;
 esac

support/modules/single-file-install

@@ -26,17 +26,26 @@ case "$STATE" in
             echo "Fatal error: dest_dir or filename are undefined." && exit 1
         mkdir -p $dest_dir
         mkdir -p $tmp_dest_dir
-        test -f ${dest_dir}/${filename} && cp ${dest_dir}/${filename} ${tmp_dest_dir}
+        if test -f ${dest_dir}/${filename}
+        then
+            if ! cp ${dest_dir}/${filename} ${tmp_dest_dir}
+            then
+                ret=$?
+                # Make sure there is no half-backup lying around.
+                rm -rf ${tmp_dest_dir}
+                exit $ret
+            fi
+        fi
         cp "$FILES"/files/$filename ${dest_dir}/${filename}
         ;;
 
     ArtifactRollback)
+        test -f $tmp_dest_dir/$filename || exit 0
         dest_dir=$(cat $dest_dir_file)
         filename=$(cat $filename_file)
         test -z "$dest_dir" -o -z "$filename" && \
             echo "Fatal error: dest_dir or filename are undefined." && exit 1
         rm ${dest_dir}/${filename}
-        test -f $tmp_dest_dir/$filename || exit 0
         cp $tmp_dest_dir/$filename ${dest_dir}/${filename}
         ;;
 esac