config: defend on '/etc/target/backup' directory

Currently we do not create '/etc/target/backup/' while we expect the directory
to be presented by package (rpm).

If for some reason '/etc/target/backup' is not available, say may be a
unintentional deletion or use of targetcli which is compiled from source,
we see below errors on up on saveconfig command,

Case 1: No '/etc/target/backup/' dir

$ targetcli / saveconfig
Could not create backup file /etc/target/backup/saveconfig-20171215-15:26:48.json: No such file or directory.
Configuration saved to /etc/target/saveconfig.json

Case 2: No '/etc/target/' dir

$ targetcli / saveconfig
Could not create backup file /etc/target/backup/saveconfig-20171215-15:27:42.json: No such file or directory.
[Errno 2] No such file or directory: '/etc/target/saveconfig.json.temp'

This patch tries to create '/etc/target/backup' directory tree in case if it
is absent.

Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>

1 files changed, 29 insertions, 21 deletions

diff --git a/targetcli/ui_root.py b/targetcli/ui_root.py
index 8bc8521..33bb948 100644
--- a/targetcli/ui_root.py
+++ b/targetcli/ui_root.py
@@ -78,30 +78,38 @@ class UIRoot(UINode):
                 datetime.now().strftime("%Y%m%d-%H:%M:%S") + ".json"
             backupfile = backup_dir + "/" + backup_name
             backup_error = None
-            try:
-                shutil.copy(savefile, backupfile)
-            except IOError as ioe:
-                backup_error = ioe.strerror or "Unknown error"
 
-            if backup_error == None:
-                # Kill excess backups
+            if not os.path.exists(backup_dir):
+                try:
+                    os.makedirs(backup_dir);
+                except OSError as exe:
+                    raise ExecutionError("Cannot create backup directory [%s] %s." % (backup_dir, exc.strerror))
+
+            if os.path.exists(savefile):
                 try:
-                    with open(universal_prefs_file) as prefs:
-                        backups = [line for line in prefs.read().splitlines() if re.match('^kept_backups\s*=', line)]
-                        kept_backups = int(backups[0].split('=')[1].strip())
-                except:
-                    kept_backups = default_kept_backups
-
-                backups = sorted(glob(os.path.dirname(savefile) + "/backup/*.json"))
-                files_to_unlink = list(reversed(backups))[kept_backups:]
-                for f in files_to_unlink:
-                    with ignored(IOError):
-                        os.unlink(f)
-
-                self.shell.log.info("Last %d configs saved in %s." % \
+                    shutil.copy(savefile, backupfile)
+                except IOError as ioe:
+                    backup_error = ioe.strerror or "Unknown error"
+
+                if backup_error == None:
+                    # Kill excess backups
+                    try:
+                        with open(universal_prefs_file) as prefs:
+                            backups = [line for line in prefs.read().splitlines() if re.match('^kept_backups\s*=', line)]
+                            kept_backups = int(backups[0].split('=')[1].strip())
+                    except:
+                        kept_backups = default_kept_backups
+
+                    backups = sorted(glob(os.path.dirname(savefile) + "/backup/*.json"))
+                    files_to_unlink = list(reversed(backups))[kept_backups:]
+                    for f in files_to_unlink:
+                        with ignored(IOError):
+                            os.unlink(f)
+
+                    self.shell.log.info("Last %d configs saved in %s." % \
                                         (kept_backups, backup_dir))
-            else:
-                self.shell.log.warning("Could not create backup file %s: %s." % \
+                else:
+                    self.shell.log.warning("Could not create backup file %s: %s." % \
                                            (backupfile, backup_error))
 
         self.rtsroot.save_to_file(savefile)