[PATCH] tests/functional/qemu_test: Use Python hashlib instead of external programs

[Thomas Huth <thuth@redhat.com>]

Some systems (like OpenBSD) do not have the sha256sum or sha512sum programs
installed by default. Use the Python hashlib instead so we don't have to
rely on the external programs.

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 tests/functional/qemu_test/asset.py | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/tests/functional/qemu_test/asset.py b/tests/functional/qemu_test/asset.py
index d3be2aff82..3ec429217e 100644
--- a/tests/functional/qemu_test/asset.py
+++ b/tests/functional/qemu_test/asset.py
@@ -43,15 +43,21 @@ def _check(self, cache_file):
         if self.hash is None:
             return True
         if len(self.hash) == 64:
-            sum_prog = 'sha256sum'
+            hl = hashlib.sha256()
         elif len(self.hash) == 128:
-            sum_prog = 'sha512sum'
+            hl = hashlib.sha512()
         else:
             raise Exception("unknown hash type")
 
-        checksum = subprocess.check_output(
-            [sum_prog, str(cache_file)]).split()[0]
-        return self.hash == checksum.decode("utf-8")
+        # Calculate the hash of the file:
+        with open(cache_file, 'rb') as file:
+            while True:
+                chunk = file.read(1 << 20)
+                if not chunk:
+                    break
+                hl.update(chunk)
+
+        return  hl.hexdigest()
 
     def valid(self):
         return self.cache_file.exists() and self._check(self.cache_file)
-- 
2.46.0