- use RAII idiom

diff --git a/snapper/Btrfs.cc b/snapper/Btrfs.cc
index 0d0d9e0036922a2017c7e3017bd44c98ea1e0736..e69626b3734e6a628ae18fef1ecd966fa4c9e247 100644 (file)
--- a/snapper/Btrfs.cc
+++ b/snapper/Btrfs.cc
@@ -1306,6 +1306,61 @@ namespace snapper
 
 #ifdef ENABLE_ROLLBACK
 
+    class MntTable
+    {
+
+    public:
+
+       MntTable()
+           : table(mnt_new_table())
+       {
+           if (!table)
+               throw runtime_error("mnt_new_table failed");
+
+           mnt_table_enable_comments(table, 1);
+       }
+
+       ~MntTable()
+       {
+           mnt_reset_table(table);
+       }
+
+       void load()
+       {
+           if (mnt_table_parse_fstab(table, "/etc/fstab") != 0)
+               throw runtime_error("mnt_table_parse_fstab failed");
+       }
+
+       void save()
+       {
+           if (mnt_table_replace_file(table, "/etc/fstab") != 0)
+               throw runtime_error("mnt_table_replace_file failed");
+       }
+
+       struct libmnt_fs* find_target(const string& path, int directon)
+       {
+           return mnt_table_find_target(table, path.c_str(), directon);
+       }
+
+       void add_fs(struct libmnt_fs* fs)
+       {
+           if (mnt_table_add_fs(table, fs) != 0)
+               throw runtime_error("mnt_table_add_fs failed");
+       }
+
+       void remove_fs(struct libmnt_fs* fs)
+       {
+           if (mnt_table_remove_fs(table, fs) != 0)
+               throw runtime_error("mnt_table_remove_fs failed");
+       }
+
+    private:
+
+       struct libmnt_table* table;
+
+    };
+
+
     void
     Btrfs::addToFstab() const
     {
@@ -1313,28 +1368,16 @@ namespace snapper
        unsigned long long id = get_id(infos_dir.fd());
        string subvol_option = get_subvolume(infos_dir.fd(), id);
 
-       libmnt_table* table = mnt_new_table();
-       if (!table)
-           throw runtime_error("out of memory");
-
-       mnt_table_enable_comments(table, 1);
-
-       if (mnt_table_parse_fstab(table, "/etc/fstab") != 0)
-           throw runtime_error("mnt_table_parse_fstab failed");
+       MntTable mnt_table;
+       mnt_table.load();
 
-       libmnt_fs* root = mnt_table_find_target(table, subvolume.c_str(), MNT_ITER_FORWARD);
+       libmnt_fs* root = mnt_table.find_target(subvolume, MNT_ITER_FORWARD);
        if (!root)
-       {
-           mnt_reset_table(table);
            throw runtime_error("root entry not found");
-       }
 
        libmnt_fs* snapshots = mnt_copy_fs(NULL, root);
        if (!snapshots)
-       {
-           mnt_reset_table(table);
            throw runtime_error("mnt_copy_fs failed");
-       }
 
        string mountpoint = (subvolume == "/" ? "" : subvolume) +  "/.snapshots";
        mnt_fs_set_target(snapshots, mountpoint.c_str());
@@ -1345,44 +1388,24 @@ namespace snapper
        mnt_fs_set_options(snapshots, options);
        free(options);
 
-       mnt_table_add_fs(table, snapshots);
-
-       if (mnt_table_replace_file(table, "/etc/fstab") != 0)
-       {
-           mnt_reset_table(table);
-           throw runtime_error("mnt_table_replace_file failed");
-       }
-
-       mnt_reset_table(table);
+       mnt_table.add_fs(snapshots);
+       mnt_table.save();
     }
 
 
     void
     Btrfs::removeFromFstab() const
     {
-       libmnt_table* table = mnt_new_table();
-       if (!table)
-           throw runtime_error("out of memory");
-
-       mnt_table_enable_comments(table, 1);
-
-       if (mnt_table_parse_fstab(table, "/etc/fstab") != 0)
-           throw runtime_error("mnt_table_parse_fstab failed");
+       MntTable mnt_table;
+       mnt_table.load();
 
        string mountpoint = (subvolume == "/" ? "" : subvolume) +  "/.snapshots";
-       libmnt_fs* snapshots = mnt_table_find_target(table, mountpoint.c_str(), MNT_ITER_FORWARD);
-       if (snapshots)
-       {
-           mnt_table_remove_fs(table, snapshots);
-
-           if (mnt_table_replace_file(table, "/etc/fstab") != 0)
-           {
-               mnt_reset_table(table);
-               throw runtime_error("mnt_table_replace_file failed");
-           }
-       }
+       libmnt_fs* snapshots = mnt_table.find_target(mountpoint, MNT_ITER_FORWARD);
+       if (!snapshots)
+           return;
 
-       mnt_reset_table(table);
+       mnt_table.remove_fs(snapshots);
+       mnt_table.save();
     }
 
 #endif