Add custom root support

.github/workflows/test-with-custom-root.yml

@@ -0,0 +1,66 @@
+name: Test with custom root
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+
+  ext2:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python 3.7.7
+      uses: actions/setup-python@v1
+      with:
+        python-version: 3.7.7
+    - name: Install e2fsprogs
+      run: sudo apt-get install e2fsprogs
+    - name: Setup filesystem
+      run: sudo ./test.sh setup ext2
+    - name: Test
+      run: ./test.sh run /test/dir/
+    - name: Clear filesystem
+      run: sudo ./test.sh clear
+
+  ext3:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python 3.7.7
+      uses: actions/setup-python@v1
+      with:
+        python-version: 3.7.7
+    - name: Install e2fsprogs
+      run: sudo apt-get install e2fsprogs
+    - name: Setup filesystem
+      run: sudo ./test.sh setup ext3
+    - name: Test
+      run: ./test.sh run /test/dir/
+    - name: Clear filesystem
+      run: sudo ./test.sh clear
+
+  ext4:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python 3.7.7
+      uses: actions/setup-python@v1
+      with:
+        python-version: 3.7.7
+    - name: Install e2fsprogs
+      run: sudo apt-get install e2fsprogs
+    - name: Setup filesystem
+      run: sudo ./test.sh setup ext4
+    - name: Test
+      run: ./test.sh run /test/dir/
+    - name: Clear filesystem
+      run: sudo ./test.sh clear

README.md

@@ -53,7 +53,7 @@ optional arguments:
 ```
 
 ## Example
-**Create snapshot.** It creates snapshot of filesystem image `data_fs.img` and saves to `data_fs.img.snapshot.out` (if not otherwise specified, using `-o`).
+**Create snapshot.** It creates snapshot of filesystem image `data_fs.img` and saves to `data_fs.img.snapshot.out` (if not otherwise specified, using `-o`). You can specify your own root directory, using `-root /custom`.
 
 ```
 $ ext4-backup-pointers create -i data_fs.img
@@ -83,7 +83,8 @@ from src.utils import generate_snapshot, recover_file
 generate_snapshot(
 	fs="data_fs.img",             # Filesystem image file
 	snapshot_file="snapshot.out", # Path, where will be snapshot metadata file created
-	dirs_max_depth=100            # Max directory traversal depth
+	root_path="/",                # Root directory of backup
+	dirs_max_depth=100            # Max directory traversal depth from root
 )
 recover_file(
 	fs="data_fs.img",             # Filesystem image file

src/console.py

@@ -15,6 +15,7 @@ def create(args):
     snapshot = generate_snapshot(
         fs=args.input,
         snapshot_file=snapshot_file,
+        root_path=args.root_path,
         dirs_max_depth=args.dirs_max_depth
     )
 
@@ -65,6 +66,7 @@ def start():
     parser_create = subparsers.add_parser('create', help='create metadata snapshot')
     parser_create.add_argument('-i', '--input', type=str, help='image of file system', required=True)
     parser_create.add_argument('-o', '--output', type=str, help='metadata snapshot output file', required=False)
+    parser_create.add_argument('-root', '--root-path', type=str, help='root directory of backup', required=False, default='/')
     parser_create.add_argument('-depth', '--dirs-max-depth', type=int, help='maximum depth of directory traversal', required=False, default=100)
     parser_create.set_defaults(func=create) 
 

src/utils.py

@@ -148,34 +148,6 @@ def parse_bitmap(data, total_items=None):
 
     return indexes
 
-# [ 'inode_id': 'physical_addr', ... ]
-def get_inodes_addresses(fs, sb=None):
-    # get blocks
-    bgs = get_block_groups(fs)
-
-    # get inodes with their physical address
-    inodes = {}
-    for bg in bgs:
-        # only initialized inodes
-        if test_block_groups_flag(sb, 'INODE_UNINIT', bg['group']):
-            continue
-
-        # get & parse bitmap
-        bitmap = read_blocks(fs, sb['Block size'], bg['ibitmap'])
-        indexes = parse_bitmap(bitmap, sb['Inodes per group'])
-
-        # get base address for inode table in this bg
-        base_address = bg['itable'] * sb['Block size']
-
-        # loop through used inodes in this bg
-        for index in indexes:
-            inode_id = index + (sb['Inodes per group'] * bg['group']) + 1
-            raw_address = (index * sb['Inode size']) + base_address
-
-            inodes[inode_id] = raw_address
-
-    return inodes
-
 #
 # INODE
 #
@@ -253,6 +225,23 @@ def inode_parse(data):
         'size': join_int32(i_size_high, i_size_lo)
     }
 
+# get inode by inode id
+def get_inode_by_inode_id(fs, sb, inode_id):
+    # get blocks
+    bgs = get_block_groups(fs)
+
+    # get bg where inode is
+    bg_index = (inode_id - 1) // sb['Inodes per group']
+    bg = bgs[bg_index]
+
+    # get offet and addr in itable
+    index = (inode_id - 1) % sb['Inodes per group']
+    inode_addr = (index * sb['Inode size']) + bg['itable'] * sb['Block size']
+
+    # get and parse inode data
+    inode_data = read_blocks(fs, 1, inode_addr, sb['Inode size'])
+    return inode_parse(inode_data)
+
 #
 # EXTENT TREE STRUCTS
 #
@@ -583,6 +572,43 @@ def readdir_from_chunks(fs, sb, chunks, size=None):
     fh.close()
     return entries
 
+# read dir by inode_id
+def readdir(fs, sb, inode_id):
+    inode = get_inode_by_inode_id(fs, sb, inode_id)
+
+    # read all chunks and get dir list
+    size, chunks = inode_to_chunks(fs, sb, inode)
+    dir_list = readdir_from_chunks(fs, sb, chunks, size)
+
+    return dir_list
+
+# get inode id of given path
+def get_inode_id_of_path(fs, sb, dir_path):
+    # split dir to names
+    names = dir_path.split("/")
+    # remove empty strings
+    names = [x for x in names if x]
+
+    inode_id = 2
+    for name in names:
+        entries = readdir(fs, sb, inode_id)
+
+        # find name in entries
+        found_entry = None
+        for entry in entries:
+            if entry['name'] == name:
+                found_entry = entry
+                break
+
+        if found_entry is None:
+            raise Exception('Directory `' + name + '` was not found.')
+
+        # ext3 compatibility
+        assert entry['filetype'] is None or entry['filetype'] == 'S_IFDIR'
+        inode_id = entry['inode']
+
+    return inode_id
+
 #
 # CHECKSUM
 #
@@ -734,31 +760,21 @@ def load_snapshot(file_path):
     return snapshot
 
 # generate snapshot from fs
-def generate_snapshot(fs, snapshot_file, dirs_max_depth=100):
+def generate_snapshot(fs, snapshot_file, dirs_max_depth=100, root_path='/'):
     sb = get_super(fs)
-    inodes = get_inodes_addresses(fs, sb)
 
+    # normalize root path
+    if root_path != '/':
+        if not root_path.endswith('/'):
+            root_path += '/'
+        if not root_path.startswith('/'):
+            root_path = '/' + root_path
+
+    # start indexing from root inode
+    root_inode = get_inode_id_of_path(fs, sb, root_path)
+    inodes = [ { 'prefix': root_path, 'inode': root_inode } ]
+    dir_entries = {}
     files_chunks = {}
-    dirs_chunks = {}
-    for inode_id, inode_addr in inodes.items():
-        inode_data = read_blocks(fs, 1, inode_addr, sb['Inode size'])
-        inode = inode_parse(inode_data)
-
-        # only regular files
-        if inode['filetype'] == 'S_IFREG' and inode_id > 11:
-            size, chunks = inode_to_chunks(fs, sb, inode)
-            files_chunks[inode_id] = size, chunks
-            continue
-
-        # save directories
-        if inode['filetype'] == 'S_IFDIR':
-            size, chunks = inode_to_chunks(fs, sb, inode)
-            dirs_chunks[inode_id] = size, chunks
-            continue
-
-    # root inode is 2
-    inodes = [ { 'prefix': '/', 'inode': 2 } ]
-    entries = {}
 
     # loop through dirs
     for depth in range(dirs_max_depth):
@@ -768,22 +784,29 @@ def generate_snapshot(fs, snapshot_file, dirs_max_depth=100):
         last_inodes, inodes = inodes, []
         for entry in last_inodes:
             prefix = entry['prefix']
-            inode = entry['inode']
+            inode_id = entry['inode']
 
-            if not inode in dirs_chunks:
-                continue
+            # get inode
+            inode = get_inode_by_inode_id(fs, sb, inode_id)
 
-            # pop from dict
-            size, chunks = dirs_chunks[inode]
-            del dirs_chunks[inode]
+            # we are looping only through direcotories
+            assert inode['filetype'] == 'S_IFDIR'
 
+            # get chunks
+            size, chunks = inode_to_chunks(fs, sb, inode)
             for entry in readdir_from_chunks(fs, sb, chunks, size):
                 if entry['name'] == '.' or entry['name'] == '..':
                     continue
 
                 # only regular files
                 if entry['filetype'] == 'S_IFREG':
-                    entries[prefix + entry['name']] = entry['inode']
+                    # save dir entry
+                    dir_entries[prefix + entry['name']] = entry['inode']
+
+                    # save files chunks
+                    inode = get_inode_by_inode_id(fs, sb, entry['inode'])
+                    size, chunks = inode_to_chunks(fs, sb, inode)
+                    files_chunks[entry['inode']] = size, chunks
                     continue
 
                 # add dir to next iteration
@@ -794,7 +817,7 @@ def generate_snapshot(fs, snapshot_file, dirs_max_depth=100):
                     })
 
     save_snapshot(snapshot_file, {
-        'dirs': entries,
+        'dirs': dir_entries,
         'inodes': files_chunks
     })
 

test.sh

@@ -163,8 +163,15 @@ remove_file() {
 # CREATE SNAPSHOT
 #
 snapshot() {
-	ext4-backup-pointers create -i data_fs.img.test -o snapshot.out.test
-	CATCH "[OK] Created snapshot."
+	# set custom root
+	if [ -z "$1" ]; then
+		ROOT="/"
+	else
+		ROOT="$1"
+	fi
+
+	ext4-backup-pointers create -i data_fs.img.test -o snapshot.out.test -root "$ROOT"
+	CATCH "[OK] Created snapshot with root: $ROOT"
 }
 
 #
@@ -223,7 +230,7 @@ case $1 in
 		fi
 		install
 		create_file
-		snapshot
+		snapshot "$2"
 		remove_file
 		restore
 		;;
@@ -253,7 +260,7 @@ case $1 in
 		echo ''
 		echo './test.sh setup [ext4]   # setup test filesystem. (run as root)'
 		echo '                         # - optional: (ext2, ext3, ext4)'
-		echo './test.sh run            # run rests.'
+		echo './test.sh run [/]        # run rests with FS root path.'
 		echo './test.sh clear          # clear test filesystem. (run as root)'
 		echo './test.sh full [ext4]    # create & test & clear. (run as root)'
 		echo '                         # - optional: (ext2, ext3, ext4)'
@@ -262,7 +269,7 @@ case $1 in
 		echo ''
 		echo './test.sh install        # python install src.'
 		echo './test.sh create_file    # create test file.'
-		echo './test.sh snapshot       # create snapshot.'
+		echo './test.sh snapshot [/]   # create snapshot, specify FS root path.'
 		echo './test.sh remove_file    # remove test file.'
 		echo './test.sh restore        # restore removed file from snapshot.'
 		echo ''