patman: Add functions to compress and decompress data

Add utility functions to compress and decompress using lz4 and lzma
algorithms. In the latter case these use the legacy lzma support favoured
by coreboot's CBFS.

No tests are provided as these functions will be tested by the CBFS
tests in a separate patch.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/patman/tools.py

@@ -374,3 +374,69 @@ def ToBytes(string):
     if sys.version_info[0] >= 3:
         return string.encode('utf-8')
     return string
+
+def Compress(indata, algo):
+    """Compress some data using a given algorithm
+
+    Note that for lzma this uses an old version of the algorithm, not that
+    provided by xz.
+
+    This requires 'lz4' and 'lzma_alone' tools. It also requires an output
+    directory to be previously set up, by calling PrepareOutputDir().
+
+    Args:
+        indata: Input data to compress
+        algo: Algorithm to use ('none', 'gzip', 'lz4' or 'lzma')
+
+    Returns:
+        Compressed data
+    """
+    if algo == 'none':
+        return indata
+    fname = GetOutputFilename('%s.comp.tmp' % algo)
+    WriteFile(fname, indata)
+    if algo == 'lz4':
+        data = Run('lz4', '--no-frame-crc', '-c', fname, binary=True)
+    # cbfstool uses a very old version of lzma
+    elif algo == 'lzma':
+        outfname = GetOutputFilename('%s.comp.otmp' % algo)
+        Run('lzma_alone', 'e', fname, outfname, '-lc1', '-lp0', '-pb0', '-d8')
+        data = ReadFile(outfname)
+    elif algo == 'gzip':
+        data = Run('gzip', '-c', fname, binary=True)
+    else:
+        raise ValueError("Unknown algorithm '%s'" % algo)
+    return data
+
+def Decompress(indata, algo):
+    """Decompress some data using a given algorithm
+
+    Note that for lzma this uses an old version of the algorithm, not that
+    provided by xz.
+
+    This requires 'lz4' and 'lzma_alone' tools. It also requires an output
+    directory to be previously set up, by calling PrepareOutputDir().
+
+    Args:
+        indata: Input data to decompress
+        algo: Algorithm to use ('none', 'gzip', 'lz4' or 'lzma')
+
+    Returns:
+        Compressed data
+    """
+    if algo == 'none':
+        return indata
+    fname = GetOutputFilename('%s.decomp.tmp' % algo)
+    with open(fname, 'wb') as fd:
+        fd.write(indata)
+    if algo == 'lz4':
+        data = Run('lz4', '-dc', fname, binary=True)
+    elif algo == 'lzma':
+        outfname = GetOutputFilename('%s.decomp.otmp' % algo)
+        Run('lzma_alone', 'd', fname, outfname)
+        data = ReadFile(outfname)
+    elif algo == 'gzip':
+        data = Run('gzip', '-cd', fname, binary=True)
+    else:
+        raise ValueError("Unknown algorithm '%s'" % algo)
+    return data