[elbe-devel] [PATCH] pkgutils: care about version numbers of packages

[Torben Hohn]

The current python-apt workaround code always downloads the last package
mentioned in the Packages file for a given package name. This is not
always the latest package.
This implements a minimalisic version comparision that is able to
download the latest elbe-bootstrap package and therefore fixes the
issue mentioned on github with the id #145.

However this will not work for all version strings that are allowed
in Debian.

This should be backported to elbe-2.x because as mentioned in #145
the issue is hard to decode.

Signed-off-by: Torben Hohn <torben.hohn at linutronix.de>
---
 elbepack/pkgutils.py | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/elbepack/pkgutils.py b/elbepack/pkgutils.py
index 02c6d995..84675a9c 100644
--- a/elbepack/pkgutils.py
+++ b/elbepack/pkgutils.py
@@ -21,6 +21,8 @@ import hashlib
 from tempfile import mkdtemp
 
 from elbepack.shellhelper import CommandError, system
+from itertools import izip_longest
+from pkg_resources import parse_version as V
 
 try:
     from apt_pkg import TagFile
@@ -89,6 +91,19 @@ def get_initrd_pkg(prj, defs):
     return initrdname
 
 
+def version_ge(ver_a, ver_b):
+    for a,b in izip_longest( ver_a.split('+'), ver_b.split('+') ):
+        if a is None:
+            return False
+        if b is None:
+            return True
+        if V(a) < V(b):
+            return False
+
+    # when we come here
+    # the 2 versions are probably equal
+    return True
+
 def get_url(arch, suite, target_pkg, mirror, comp='main'):
     try:
         pack_url = "%s/dists/%s/%s/binary-%s/Packages" % (
@@ -99,9 +114,19 @@ def get_url(arch, suite, target_pkg, mirror, comp='main'):
         packages = [x for x in packages if x.startswith("Filename")]
         packages = [x for x in packages if x.find(target_pkg) != -1]
 
-        tmp = packages.pop()
-        urla = tmp.split()
+        # detect package with latest version number
+        latest_version_str = '0+deb0u0+jessie0'
+        latest_version_pos = 0
+        cnt = 0
+        for x in packages:
+            # extract version from path/name_version_arch
+            version = x.split('_')[1]
+            if version_ge(version, latest_version_str):
+                latest_version_str = version
+                latest_version_pos = cnt
+        urla = packages[latest_version_pos].split()
         url = "%s/%s" % (mirror.replace("LOCALMACHINE", "localhost"), urla[1])
+
     except IOError:
         url = ""
     except IndexError:
-- 
2.11.0