Re: [PATCH v2 2/2] wireless-regdb: make scripts compatible with Python 3

[Seth Forshee <seth.forshee@canonical.com>]

On Sun, Feb 04, 2018 at 12:36:54AM +0100, Matthias Schiffer wrote:
> When playing with the generation scripts for OpenWrt development, I noticed
> that these scripts still required Python 2. Future-proof them by replacing
> deprecated functions with new Python 3 compatible variants. The result
> works with both Python 2.7 and Python 3.x; older Python 2.x releases are
> not supported anymore.
> 
> regulatory.db and regulatory.bin are unchanged and reproducible across
> Python versions. Note that there is no stable release of m2crypto for
> Python 3 yet; I used the current development branch for testing.

I can't say I'm all that knowledgable about Python 2 to Python 3
conversion, but as far as I can tell this looks okay. It does seem to
work for me running with both Python 2 and Python 3.

One question below though, mostly just to satisfy my curiousity.

> Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
> ---
> 
> v2: explicitly open input file with UTF-8 encoding; otherwise the scripts
> will fail without a UTF-8 locale set in the environment
> 
> 
>  db2bin.py  | 22 ++++++++---------
>  db2fw.py   | 28 +++++++++++-----------
>  dbparse.py | 81 +++++++++++++++++++++++++++++++++++++-------------------------
>  3 files changed, 74 insertions(+), 57 deletions(-)
> 
> diff --git a/db2bin.py b/db2bin.py
> index ae5f064..28cd7d2 100755
> --- a/db2bin.py
> +++ b/db2bin.py
> @@ -1,6 +1,6 @@
>  #!/usr/bin/env python
>  
> -from cStringIO import StringIO
> +from io import BytesIO, open
>  import struct
>  import hashlib
>  from dbparse import DBParser
> @@ -10,21 +10,21 @@ MAGIC = 0x52474442
>  VERSION = 19
>  
>  if len(sys.argv) < 3:
> -    print 'Usage: %s output-file input-file [key-file]' % sys.argv[0]
> +    print('Usage: %s output-file input-file [key-file]' % sys.argv[0])
>      sys.exit(2)
>  
>  def create_rules(countries):
>      result = {}
> -    for c in countries.itervalues():
> +    for c in countries.values():
>          for rule in c.permissions:
>              result[rule] = 1
> -    return result.keys()
> +    return list(result)

Here and elsewhere, to get a list of the keys from a dictionary, we use
list(dict). Experimentally I find this works, but I haven't been able to
find anything which actually tells me that this is the defined behavior,
and examples seem to prefer list(dict.keys()). I'm curious why this is
guaranteed to provide a lsit of dictionary keys, and why you've done
that rather than list(dict.keys()) (I'll grant that the scripts
elsewhere use list(dict), so maybe you were just being consistent with
that).

>  def create_collections(countries):
>      result = {}
> -    for c in countries.itervalues():
> +    for c in countries.values():
>          result[c.permissions] = 1
> -    return result.keys()
> +    return list(result)
>  
>  
>  def be32(output, val):
> @@ -49,9 +49,9 @@ class PTR(object):
>          return self._offset
>  
>  p = DBParser()
> -countries = p.parse(file(sys.argv[2]))
> +countries = p.parse(open(sys.argv[2], 'r', encoding='utf-8'))
>  
> -countrynames = countries.keys()
> +countrynames = list(countries)
>  countrynames.sort()
>  
>  power = []
> @@ -67,7 +67,7 @@ rules.sort()
>  collections = create_collections(countries)
>  collections.sort()
>  
> -output = StringIO()
> +output = BytesIO()
>  
>  # struct regdb_file_header
>  be32(output, MAGIC)
> @@ -118,7 +118,7 @@ reg_country_ptr.set()
>  for alpha2 in countrynames:
>      coll = countries[alpha2]
>      # struct regdb_file_reg_country
> -    output.write(struct.pack('>ccxBI', str(alpha2[0]), str(alpha2[1]), coll.dfs_region, reg_rules_collections[coll.permissions]))
> +    output.write(struct.pack('>BBxBI', alpha2[0], alpha2[1], coll.dfs_region, reg_rules_collections[coll.permissions]))
>  
>  
>  if len(sys.argv) > 3:
> @@ -143,5 +143,5 @@ if len(sys.argv) > 3:
>  else:
>      siglen.set(0)
>  
> -outfile = open(sys.argv[1], 'w')
> +outfile = open(sys.argv[1], 'wb')
>  outfile.write(output.getvalue())
> diff --git a/db2fw.py b/db2fw.py
> index 630e4d6..91b88d3 100755
> --- a/db2fw.py
> +++ b/db2fw.py
> @@ -1,6 +1,6 @@
>  #!/usr/bin/env python
>  
> -from cStringIO import StringIO
> +from io import BytesIO, open
>  import struct
>  import hashlib
>  from dbparse import DBParser
> @@ -10,21 +10,21 @@ MAGIC = 0x52474442
>  VERSION = 20
>  
>  if len(sys.argv) < 3:
> -    print 'Usage: %s output-file input-file' % sys.argv[0]
> +    print('Usage: %s output-file input-file' % sys.argv[0])
>      sys.exit(2)
>  
>  def create_rules(countries):
>      result = {}
> -    for c in countries.itervalues():
> +    for c in countries.values():
>          for rule in c.permissions:
>              result[rule] = 1
> -    return result.keys()
> +    return list(result)
>  
>  def create_collections(countries):
>      result = {}
> -    for c in countries.itervalues():
> +    for c in countries.values():
>          result[(c.permissions, c.dfs_region)] = 1
> -    return result.keys()
> +    return list(result)
>  
>  
>  def be32(output, val):
> @@ -58,26 +58,26 @@ class PTR(object):
>          return self._written
>  
>  p = DBParser()
> -countries = p.parse(file(sys.argv[2]))
> +countries = p.parse(open(sys.argv[2], 'r', encoding='utf-8'))
>  rules = create_rules(countries)
>  rules.sort()
>  collections = create_collections(countries)
>  collections.sort()
>  
> -output = StringIO()
> +output = BytesIO()
>  
>  # struct regdb_file_header
>  be32(output, MAGIC)
>  be32(output, VERSION)
>  
>  country_ptrs = {}
> -countrynames = countries.keys()
> +countrynames = list(countries)
>  countrynames.sort()
>  for alpha2 in countrynames:
>      coll = countries[alpha2]
> -    output.write(struct.pack('>cc', str(alpha2[0]), str(alpha2[1])))
> +    output.write(struct.pack('>BB', alpha2[0], alpha2[1]))
>      country_ptrs[alpha2] = PTR(output)
> -output.write('\x00' * 4)
> +output.write(b'\x00' * 4)
>  
>  reg_rules = {}
>  flags = 0
> @@ -104,8 +104,8 @@ for reg_rule in rules:
>          cac_timeout = 0
>      if cac_timeout:
>          rule_len += 2
> -    output.write(struct.pack('>BBHIII', rule_len, flags, power_rule.max_eirp * 100,
> -                             freq_range.start * 1000, freq_range.end * 1000, freq_range.maxbw * 1000,
> +    output.write(struct.pack('>BBHIII', rule_len, flags, int(power_rule.max_eirp * 100),
> +                             int(freq_range.start * 1000), int(freq_range.end * 1000), int(freq_range.maxbw * 1000),
>                               ))
>      if cac_timeout:
>          output.write(struct.pack('>H', cac_timeout))
> @@ -129,5 +129,5 @@ for coll in collections:
>  for alpha2 in countrynames:
>      assert country_ptrs[alpha2].written
>  
> -outfile = open(sys.argv[1], 'w')
> +outfile = open(sys.argv[1], 'wb')
>  outfile.write(output.getvalue())
> diff --git a/dbparse.py b/dbparse.py
> index b735b6a..d73d1bd 100755
> --- a/dbparse.py
> +++ b/dbparse.py
> @@ -1,5 +1,7 @@
>  #!/usr/bin/env python
>  
> +from builtins import bytes
> +from functools import total_ordering
>  import sys, math
>  
>  # must match <linux/nl80211.h> enum nl80211_reg_rule_flags
> @@ -25,6 +27,7 @@ dfs_regions = {
>      'DFS-JP':		3,
>  }
>  
> +@total_ordering
>  class FreqBand(object):
>      def __init__(self, start, end, bw, comments=None):
>          self.start = start
> @@ -32,41 +35,49 @@ class FreqBand(object):
>          self.maxbw = bw
>          self.comments = comments or []
>  
> -    def __cmp__(self, other):
> -        s = self
> -        o = other
> -        if not isinstance(o, FreqBand):
> -            return False
> -        return cmp((s.start, s.end, s.maxbw), (o.start, o.end, o.maxbw))
> +    def _as_tuple(self):
> +        return (self.start, self.end, self.maxbw)
> +
> +    def __eq__(self, other):
> +        return (self._as_tuple() == other._as_tuple())
> +
> +    def __ne__(self, other):
> +        return not (self == other)
> +
> +    def __lt__(self, other):
> +        return (self._as_tuple() < other._as_tuple())
>  
>      def __hash__(self):
> -        s = self
> -        return hash((s.start, s.end, s.maxbw))
> +        return hash(self._as_tuple())
>  
>      def __str__(self):
>          return '<FreqBand %.3f - %.3f @ %.3f>' % (
>                    self.start, self.end, self.maxbw)
>  
> +@total_ordering
>  class PowerRestriction(object):
>      def __init__(self, max_ant_gain, max_eirp, comments = None):
>          self.max_ant_gain = max_ant_gain
>          self.max_eirp = max_eirp
>          self.comments = comments or []
>  
> -    def __cmp__(self, other):
> -        s = self
> -        o = other
> -        if not isinstance(o, PowerRestriction):
> -            return False
> -        return cmp((s.max_ant_gain, s.max_eirp),
> -                   (o.max_ant_gain, o.max_eirp))
> +    def _as_tuple(self):
> +        return (self.max_ant_gain, self.max_eirp)
>  
> -    def __str__(self):
> -        return '<PowerRestriction ...>'
> +    def __eq__(self, other):
> +        return (self._as_tuple() == other._as_tuple())
> +
> +    def __ne__(self, other):
> +        return not (self == other)
> +
> +    def __lt__(self, other):
> +        return (self._as_tuple() < other._as_tuple())
>  
>      def __hash__(self):
> -        s = self
> -        return hash((s.max_ant_gain, s.max_eirp))
> +        return hash(self._as_tuple())
> +
> +    def __str__(self):
> +        return '<PowerRestriction ...>'
>  
>  class DFSRegionError(Exception):
>      def __init__(self, dfs_region):
> @@ -76,6 +87,7 @@ class FlagError(Exception):
>      def __init__(self, flag):
>          self.flag = flag
>  
> +@total_ordering
>  class Permission(object):
>      def __init__(self, freqband, power, flags):
>          assert isinstance(freqband, FreqBand)
> @@ -92,10 +104,14 @@ class Permission(object):
>      def _as_tuple(self):
>          return (self.freqband, self.power, self.flags)
>  
> -    def __cmp__(self, other):
> -        if not isinstance(other, Permission):
> -            return False
> -        return cmp(self._as_tuple(), other._as_tuple())
> +    def __eq__(self, other):
> +        return (self._as_tuple() == other._as_tuple())
> +
> +    def __ne__(self, other):
> +        return not (self == other)
> +
> +    def __lt__(self, other):
> +        return (self._as_tuple() < other._as_tuple())
>  
>      def __hash__(self):
>          return hash(self._as_tuple())
> @@ -104,12 +120,12 @@ class Country(object):
>      def __init__(self, dfs_region, permissions=None, comments=None):
>          self._permissions = permissions or []
>          self.comments = comments or []
> -	self.dfs_region = 0
> +        self.dfs_region = 0
>  
> -	if dfs_region:
> -		if not dfs_region in dfs_regions:
> -		    raise DFSRegionError(dfs_region)
> -		self.dfs_region = dfs_regions[dfs_region]
> +        if dfs_region:
> +            if not dfs_region in dfs_regions:
> +                raise DFSRegionError(dfs_region)
> +            self.dfs_region = dfs_regions[dfs_region]
>  
>      def add(self, perm):
>          assert isinstance(perm, Permission)
> @@ -248,6 +264,7 @@ class DBParser(object):
>          for cname in cnames:
>              if len(cname) != 2:
>                  self._warn("country '%s' not alpha2" % cname)
> +            cname = bytes(cname, 'ascii')
>              if not cname in self._countries:
>                  self._countries[cname] = Country(dfs_region, comments=self._comments)
>              self._current_countries[cname] = self._countries[cname]
> @@ -304,9 +321,9 @@ class DBParser(object):
>          p = self._power[pname]
>          try:
>              perm = Permission(b, p, flags)
> -        except FlagError, e:
> +        except FlagError as e:
>              self._syntax_error("Invalid flag '%s'" % e.flag)
> -        for cname, c in self._current_countries.iteritems():
> +        for cname, c in self._current_countries.items():
>              if perm in c:
>                  self._warn('Rule "%s, %s" added to "%s" twice' % (
>                                bname, pname, cname))
> @@ -360,7 +377,7 @@ class DBParser(object):
>  
>          countries = self._countries
>          bands = {}
> -        for k, v in self._bands.iteritems():
> +        for k, v in self._bands.items():
>              if k in self._bands_used:
>                  bands[self._banddup[k]] = v
>                  continue
> @@ -369,7 +386,7 @@ class DBParser(object):
>                  self._lineno = self._bandline[k]
>                  self._warn('Unused band definition "%s"' % k)
>          power = {}
> -        for k, v in self._power.iteritems():
> +        for k, v in self._power.items():
>              if k in self._power_used:
>                  power[self._powerdup[k]] = v
>                  continue
> -- 
> 2.16.1
>