debian_support: updateFile: support .xz files

https://bugs.debian.org/931533

1 files changed, 31 insertions, 21 deletions

diff --git a/lib/python/debian_support.py b/lib/python/debian_support.py
index b6e5134474..73f6b0f80f 100644
--- a/lib/python/debian_support.py
+++ b/lib/python/debian_support.py
@@ -18,7 +18,7 @@ from __future__ import print_function
 
 """This module implements facilities to deal with Debian-specific metadata."""
 
-import gzip
+import gzip, lzma
 import io
 import json
 import os.path
@@ -28,8 +28,10 @@ import tempfile
 
 try:
     from urllib.request import urlopen
+    from urllib.error import URLError
 except ImportError:
     from urllib2 import urlopen
+    from urllib2.error import URLError
 
 try:
     from cStringIO import StringIO as streamIO
@@ -316,9 +318,6 @@ def patchLines(lines, patches):
         lines[first:last] = args
 
 def replaceFile(lines, local):
-
-    import os.path
-
     local_new = local + '.new'
     new_file = open(local_new, 'w+')
 
@@ -331,32 +330,41 @@ def replaceFile(lines, local):
         if os.path.exists(local_new):
             os.unlink(local_new)
 
-def downloadGunzipLines(remote):
-    """Downloads a file from a remote location and gunzips it.
+def downloadCompressedLines(remote):
+    """Downloads a file from a remote location and uncompresses it.
 
     Returns the lines in the file."""
 
+    if remote.endswith('.gz'):
+        cls = gzip
+    elif remote.endswith('.xz'):
+        cls = lzma
+    else:
+        raise ValueError('file format not supported: %s' % remote)
+
     data = urlopen(remote, timeout=TIMEOUT)
     try:
-        gfile = gzip.GzipFile(fileobj=streamIO(data.read()))
-        try:
-            if sys.version_info.major == 3:
-                return io.TextIOWrapper(gfile).readlines()
-            else:
-                return gfile.readlines()
-        finally:
-            gfile.close()
+        b = io.BytesIO(cls.decompress(data.read()))
+        t = io.TextIOWrapper(b, 'utf-8')
+        return t.readlines()
     finally:
         data.close()
-        
+
+def downloadLines(remote):
+    try:
+        return downloadCompressedLines(remote + '.xz')
+    except URLError:
+        return downloadCompressedLines(remote + '.gz')
+
 def downloadFile(remote, local):
-    """Copies a gzipped remote file to the local system.
+    """Copies a compressed remote file to the local system.
 
-    remote - URL, without the .gz suffix
+    remote - URL, without compression suffix
     local - name of the local file
     """
-    
-    lines = downloadGunzipLines(remote + '.gz')
+
+    lines = downloadLines(remote)
+
     replaceFile(lines, local)
     return lines
 
@@ -440,8 +448,10 @@ def updateFile(remote, local, verbose=None):
         if verbose:
             print("updateFile: downloading patch " + repr(patch_name))
         try:
-            patch_contents = downloadGunzipLines(remote + '.diff/' + patch_name
-                                                 + '.gz')
+            # We could remove the extension here and call downloadLines
+            # when diff files come with another compression
+            patch_contents = downloadCompressedLines(remote + '.diff/'
+                                                     + patch_name + '.gz')
         except IOError:
             return downloadFile(remote, local)
         if readLinesSHA1(patch_contents ) != patch_hashes[patch_name]: