add lzma compression

needs python 3.3+, on 3.2 it won't be available.

borg/archiver.py

@@ -641,12 +641,14 @@ Type "Yes I am sure" if you understand this and want to continue.\n""")
                                help='select compression algorithm and level, by giving a number: '
                                     '0 == no compression [default], '
                                     '1..9 == zlib level 1..9, '
-                                    '10 == lz4. '
+                                    '10 == lz4, '
+                                    '20-29 == lzma level 0..9.'
                                     'Alternatively, you can also give a name and optionally additional args: '
                                     'null == no compression, '
                                     'zlib == zlib (default level 6), '
                                     'zlib,0 .. zlib,9 == zlib (with level 0..9), '
-                                    'lz4 == lz4.')
+                                    'lz4 == lz4, '
+                                    'lzma,0 .. lzma,9 == lzma (with level 0..9).')
         subparser.add_argument('archive', metavar='ARCHIVE',
                                type=location_validator(archive=True),
                                help='archive to create')

borg/compress.pyx

@@ -1,4 +1,8 @@
 import zlib
+try:
+    import lzma
+except ImportError:
+    lzma = None
 
 cdef extern from "lz4.h":
     int LZ4_compress_limitedOutput(const char* source, char* dest, int inputSize, int maxOutputSize) nogil
@@ -104,6 +108,29 @@ cdef class LZ4(CompressorBase):
         return dest[:osize]
 
 
+class LZMA(CompressorBase):
+    """
+    lzma compression / decompression (python 3.3+ stdlib)
+    """
+    ID = b'\x02\x00'
+    name = 'lzma'
+
+    def __init__(self, level=6, **kwargs):
+        super().__init__(**kwargs)
+        self.level = level
+        if lzma is None:
+            raise ValueError('No lzma support found.')
+
+    def compress(self, data):
+        # we do not need integrity checks in lzma, we do that already
+        data = lzma.compress(data, preset=self.level, check=lzma.CHECK_NONE)
+        return super().compress(data)
+
+    def decompress(self, data):
+        data = super().decompress(data)
+        return lzma.decompress(data)
+
+
 class ZLIB(CompressorBase):
     """
     zlib compression / decompression (python stdlib)
@@ -137,8 +164,9 @@ COMPRESSOR_TABLE = {
     CNULL.name: CNULL,
     LZ4.name: LZ4,
     ZLIB.name: ZLIB,
+    LZMA.name: LZMA,
 }
-COMPRESSOR_LIST = [LZ4, CNULL, ZLIB, ]  # check fast stuff first
+COMPRESSOR_LIST = [LZ4, CNULL, ZLIB, LZMA, ]  # check fast stuff first
 
 def get_compressor(name, **kwargs):
     cls = COMPRESSOR_TABLE[name]

borg/helpers.py

@@ -302,13 +302,15 @@ def CompressionSpec(s):
             return dict(name='zlib', level=compression)
         if compression == 10:
             return dict(name='lz4')
+        if 20 <= compression <= 29:
+            return dict(name='lzma', level=compression-20)
         raise ValueError
     except ValueError:
         # --compression algo[,...]
         name = compression
         if name in ('null', 'lz4', ):
             return dict(name=name)
-        if name == 'zlib':
+        if name in ('zlib', 'lzma', ):
             if count < 2:
                 level = 6  # default compression level in py stdlib
             elif count == 2:
@@ -317,7 +319,7 @@ def CompressionSpec(s):
                     raise ValueError
             else:
                 raise ValueError
-            return dict(name='zlib', level=level)
+            return dict(name=name, level=level)
         raise ValueError
 
 

borg/testsuite/compress.py

@@ -1,4 +1,8 @@
 import zlib
+try:
+    import lzma
+except ImportError:
+    lzma = None
 
 import pytest
 
@@ -6,7 +10,7 @@ from ..compress import get_compressor, Compressor, CNULL, ZLIB, LZ4
 
 
 buffer = bytes(2**16)
-data = b'fooooooooobaaaaaaaar'
+data = b'fooooooooobaaaaaaaar' * 10
 params = dict(name='zlib', level=6, buffer=buffer)
 
 
@@ -46,6 +50,16 @@ def test_zlib():
     assert data == Compressor(**params).decompress(cdata)  # autodetect
 
 
+def test_lzma():
+    if lzma is None:
+        pytest.skip("No lzma support found.")
+    c = get_compressor(name='lzma')
+    cdata = c.compress(data)
+    assert len(cdata) < len(data)
+    assert data == c.decompress(cdata)
+    assert data == Compressor(**params).decompress(cdata)  # autodetect
+
+
 def test_autodetect_invalid():
     with pytest.raises(ValueError):
         Compressor(**params).decompress(b'\xff\xfftotalcrap')
@@ -68,13 +82,20 @@ def test_zlib_compat():
 
 
 def test_compressor():
-    for params in [
+    params_list = [
         dict(name='null', buffer=buffer),
         dict(name='lz4', buffer=buffer),
         dict(name='zlib', level=0, buffer=buffer),
         dict(name='zlib', level=6, buffer=buffer),
         dict(name='zlib', level=9, buffer=buffer),
-    ]:
+    ]
+    if lzma:
+        params_list += [
+            dict(name='lzma', level=0, buffer=buffer),
+            dict(name='lzma', level=6, buffer=buffer),
+            dict(name='lzma', level=9, buffer=buffer),
+        ]
+    for params in params_list:
         c = Compressor(**params)
         assert data == c.decompress(c.compress(data))