tests/functional: add a generalized uncompress helper

There are many types of compression that the tests deal with, and
it makes sense to have a single helper 'uncompress' that can deal
with all.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-ID: <20241217155953.3950506-25-berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/functional/qemu_test/__init__.py

@@ -17,3 +17,4 @@ from .decorators import skipIfMissingCommands, skipIfNotMachine, \
     skipFlakyTest, skipUntrustedTest, skipBigDataTest, \
     skipIfMissingImports
 from .archive import archive_extract
+from .uncompress import uncompress

tests/functional/qemu_test/uncompress.py

@@ -11,6 +11,9 @@ import gzip
 import lzma
 import os
 import shutil
+from urllib.parse import urlparse
+
+from .asset import Asset
 
 
 def gzip_uncompress(gz_path, output_path):
@@ -34,3 +37,47 @@ def lzma_uncompress(xz_path, output_path):
         except:
             os.remove(output_path)
             raise
+
+'''
+@params compressed: filename, Asset, or file-like object to uncompress
+@params uncompressed: filename to uncompress into
+@params format: optional compression format (gzip, lzma)
+
+Uncompresses @compressed into @uncompressed
+
+If @format is None, heuristics will be applied to guess the format
+from the filename or Asset URL. @format must be non-None if @uncompressed
+is a file-like object.
+
+Returns the fully qualified path to the uncompessed file
+'''
+def uncompress(compressed, uncompressed, format=None):
+    if format is None:
+        format = guess_uncompress_format(compressed)
+
+    if format == "xz":
+        lzma_uncompress(str(compressed), uncompressed)
+    elif format == "gz":
+        gzip_uncompress(str(compressed), uncompressed)
+    else:
+        raise Exception(f"Unknown compression format {format}")
+
+'''
+@params compressed: filename, Asset, or file-like object to guess
+
+Guess the format of @compressed, raising an exception if
+no format can be determined
+'''
+def guess_uncompress_format(compressed):
+    if type(compressed) == Asset:
+        compressed = urlparse(compressed.url).path
+    elif type(compressed) != str:
+        raise Exception(f"Unable to guess compression cformat for {compressed}")
+
+    (name, ext) = os.path.splitext(compressed)
+    if ext == ".xz":
+        return "xz"
+    elif ext == ".gz":
+        return "gz"
+    else:
+        raise Exception(f"Unknown compression format for {compressed}")