backup: adjust LVM volume size when restoring its content.

Old backup metadata (old qubes.xml) does not contain info about
individual volume sizes. So, extract it from tar header (using verbose
output during restore) and resize volume accordingly.
Without this, restoring volumes larger than default would be impossible.

qubes/backup.py

@@ -26,6 +26,7 @@ import itertools
 import logging
 from qubes.utils import size_to_human
 import sys
+import stat
 import os
 import fcntl
 import subprocess
@@ -931,9 +932,33 @@ class ExtractWorker2(Process):
         debug_msg = filter(msg_re.match, new_lines)
         self.log.debug('tar2_stderr: {}'.format('\n'.join(debug_msg)))
         new_lines = filter(lambda x: not msg_re.match(x), new_lines)
-
+        if self.adjust_output_size:
+            # search for first file size reported by tar, after setting
+            # self.adjust_output_size (so don't look at self.tar2_stderr)
+            # this is used only when extracting single-file archive, so don't
+            #  bother with checking file name
+            file_size_re = re.compile(r"^[^ ]+ [^ ]+/[^ ]+ *([0-9]+) .*")
+            for line in new_lines:
+                match = file_size_re.match(line)
+                if match:
+                    file_size = match.groups()[0]
+                    self.resize_lvm(self.adjust_output_size, file_size)
+                    self.adjust_output_size = None
         self.tar2_stderr += new_lines
 
+    def resize_lvm(self, dev, size):
+        # FIXME: HACK
+        try:
+            subprocess.check_call(
+                ['sudo', 'lvresize', '-f', '-L', str(size) + 'B', dev],
+                stdout=open(os.devnull, 'w'), stderr=subprocess.STDOUT)
+        except subprocess.CalledProcessError as e:
+            if e.returncode == 3:
+                # already at the right size
+                pass
+            else:
+                raise
+
     def run(self):
         try:
             self.__run__()
@@ -966,6 +991,15 @@ class ExtractWorker2(Process):
             # is extracted there
             if dirname in self.relocate:
                 old = old.replace(dirname, self.relocate[dirname], 1)
+            try:
+                stat_buf = os.stat(new)
+                if stat.S_ISBLK(stat_buf.st_mode):
+                    # output file is block device (LVM) - adjust its
+                    # size, otherwise it may fail
+                    # from lack of space
+                    self.resize_lvm(new, stat_buf.st_size)
+            except OSError:  # ENOENT
+                pass
             subprocess.check_call(
                 ['dd', 'if='+old, 'of='+new, 'conv=sparse'])
             os.unlink(old)
@@ -1005,16 +1039,26 @@ class ExtractWorker2(Process):
                             self.handle_dir_relocations(
                                 os.path.dirname(inner_name))
                         self.tar2_current_file = None
+                        self.adjust_output_size = None
 
                 inner_name = os.path.relpath(filename.rstrip('.000'))
                 redirect_stdout = None
                 if self.relocate and inner_name in self.relocate:
                     # TODO: add `dd conv=sparse` when removing tar layer
                     tar2_cmdline = ['tar',
-                        '-%sMOf' % ("t" if self.verify_only else "x"),
+                        '-%sMvvOf' % ("t" if self.verify_only else "x"),
                         self.restore_pipe,
                         inner_name]
                     output_file = self.relocate[inner_name]
+                    try:
+                        stat_buf = os.stat(output_file)
+                        if stat.S_ISBLK(stat_buf.st_mode):
+                            # output file is block device (LVM) - adjust its
+                            # size during extraction, otherwise it may fail
+                            # from lack of space
+                            self.adjust_output_size = output_file
+                    except OSError: # ENOENT
+                        pass
                     redirect_stdout = open(output_file, 'w')
                 elif self.relocate and \
                         os.path.dirname(inner_name) in self.relocate:
@@ -1112,6 +1156,7 @@ class ExtractWorker2(Process):
                 self.tar2_process.terminate()
                 self.tar2_process.wait()
                 self.tar2_process = None
+                self.adjust_output_size = None
                 self.log.error("Error while processing '{}': {}".format(
                     self.tar2_current_file, details))
 
@@ -1136,6 +1181,7 @@ class ExtractWorker2(Process):
                             "\n".join(self.tar2_stderr))))
             else:
                 # Finished extracting the tar file
+                self.collect_tar_output()
                 self.tar2_process = None
                 # if that was whole-directory archive, handle
                 # relocated files now
@@ -1144,6 +1190,7 @@ class ExtractWorker2(Process):
                 if os.path.basename(inner_name) == '.':
                     self.handle_dir_relocations(
                         os.path.dirname(inner_name))
+                self.adjust_output_size = None
 
         self.log.debug("Finished extracting thread")
 
@@ -1188,6 +1235,7 @@ class ExtractWorker3(ExtractWorker2):
                                    "\n  ".join(self.tar2_stderr)))
                     else:
                         # Finished extracting the tar file
+                        self.collect_tar_output()
                         self.tar2_process = None
                         # if that was whole-directory archive, handle
                         # relocated files now
@@ -1197,15 +1245,25 @@ class ExtractWorker3(ExtractWorker2):
                             self.handle_dir_relocations(
                                 os.path.dirname(inner_name))
                         self.tar2_current_file = None
+                        self.adjust_output_size = None
 
                 inner_name = os.path.relpath(filename.rstrip('.000'))
                 redirect_stdout = None
                 if self.relocate and inner_name in self.relocate:
                     # TODO: add dd conv=sparse when removing tar layer
                     tar2_cmdline = ['tar',
-                        '-%sO' % ("t" if self.verify_only else "x"),
+                        '-%svvO' % ("t" if self.verify_only else "x"),
                         inner_name]
                     output_file = self.relocate[inner_name]
+                    try:
+                        stat_buf = os.stat(output_file)
+                        if stat.S_ISBLK(stat_buf.st_mode):
+                            # output file is block device (LVM) - adjust its
+                            # size during extraction, otherwise it may fail
+                            # from lack of space
+                            self.adjust_output_size = output_file
+                    except OSError:  # ENOENT
+                        pass
                     redirect_stdout = open(output_file, 'w')
                 elif self.relocate and \
                         os.path.dirname(inner_name) in self.relocate:
@@ -1293,6 +1351,7 @@ class ExtractWorker3(ExtractWorker2):
                 self.tar2_process.terminate()
                 self.tar2_process.wait()
                 self.tar2_process = None
+                self.adjust_output_size = None
                 self.log.error("Error while processing '{}': {}".format(
                     self.tar2_current_file, details))
 
@@ -1320,6 +1379,7 @@ class ExtractWorker3(ExtractWorker2):
                             "\n".join(self.tar2_stderr))))
             else:
                 # Finished extracting the tar file
+                self.collect_tar_output()
                 self.tar2_process = None
                 # if that was whole-directory archive, handle
                 # relocated files now
@@ -1328,6 +1388,7 @@ class ExtractWorker3(ExtractWorker2):
                 if os.path.basename(inner_name) == '.':
                     self.handle_dir_relocations(
                         os.path.dirname(inner_name))
+                self.adjust_output_size = None
 
         self.log.debug("Finished extracting thread")