zeroinstall/injector/arch.py

   1 """
   2 Information about the current system's architecture.
   3
   4 This module provides information about the current system. It is used to determine
   5 whether an implementation is suitable for this machine, and to compare different implementations.
   6
   7 For example, it will indicate that:
   8
   9  - An i486 machine cannot run an i686 binary.
  10  - An i686 machine can run an i486 binary, but would prefer an i586 one.
  11  - A Windows binary cannot run on a Linux machine.
  12
  13 Each dictionary maps from a supported architecture type to a preference level. Lower numbers are
  14 better, Unsupported architectures are not listed at all.
  15 """
  16
  17 # Copyright (C) 2009, Thomas Leonard
  18 # See the README file for details, or visit http://0install.net.
  19
  20 import os
  21
  22 # os_ranks and mapping are mappings from names to how good they are.
  23 # 1 => Native (best)
  24 # Higher numbers are worse but usable.
  25 try:
  26         _uname = os.uname()
  27 except AttributeError:
  28         # No uname. Probably Windows (untested).
  29         import sys
  30         p = sys.platform
  31         if p == 'win32':
  32                 _uname = ('Windows', 'i486')
  33         elif p == 'win64':
  34                 _uname = ('Windows', 'x86_64')
  35         else:
  36                 _uname = (p, 'i486')
  37
  38 os_ranks = {
  39 #       'Linux' : 3,            # Linux (lots of systems support emulation)
  40         None : 2,               # Any OS
  41         _uname[0] : 1,          # Current OS
  42 }
  43
  44 # All chosen machine-specific implementations must come from the same group
  45 # Unlisted archs are in group 0
  46 machine_groups = {
  47         'x86_64': 64,
  48         'ppc64': 64,
  49 }
  50
  51 def _get_machine_ranks(target_machine):
  52         # Binaries compiled for _this_machine are best...
  53         machine_ranks = {target_machine : 0}
  54
  55         # If target_machine appears in the first column of this table, all
  56         # following machine types on the line will also run on this one
  57         # (earlier ones preferred):
  58         _machine_matrix = {
  59                 'i486': ['i386'],
  60                 'i586': ['i486', 'i386'],
  61                 'i686': ['i586', 'i486', 'i386'],
  62                 'x86_64': ['i686', 'i586', 'i486', 'i386'],
  63                 'ppc64': ['ppc32'],
  64         }
  65         for supported in _machine_matrix.get(target_machine, []):
  66                 machine_ranks[supported] = len(machine_ranks)
  67
  68         # At the lowest priority, try a machine-independant implementation
  69         machine_ranks[None] = len(machine_ranks)
  70         return machine_ranks
  71
  72 machine_ranks = _get_machine_ranks(_uname[-1])
  73 #print machine_ranks
  74
  75 class Architecture:
  76         """A description of an architecture. Use by L{solver} to make sure it chooses
  77         compatible versions.
  78         @ivar os_ranks: supported operating systems and their desirability
  79         @type os_ranks: {str: int}
  80         @ivar machine_ranks: supported CPU types and their desirability
  81         @type machine_ranks: {str: int}
  82         @ivar child_arch: architecture for dependencies (usually C{self})
  83         @type child_arch: L{Architecture}"""
  84         def __init__(self, os_ranks, machine_ranks):
  85                 self.os_ranks = os_ranks
  86                 self.machine_ranks = machine_ranks
  87                 self.child_arch = self
  88
  89         def __str__(self):
  90                 return "<Arch: %s %s>" % (self.os_ranks, self.machine_ranks)
  91
  92 class SourceArchitecture(Architecture):
  93         """Matches source code that creates binaries for a particular architecture.
  94         Note that the L{child_arch} here is the binary; source code depends on binary tools,
  95         not on other source packages.
  96         """
  97         def __init__(self, binary_arch):
  98                 Architecture.__init__(self, binary_arch.os_ranks, {'src': 1})
  99                 self.child_arch = binary_arch
 100
 101 def get_host_architecture():
 102         """Get an Architecture that matches implementations that will run on the host machine.
 103         @rtype: L{Architecture}"""
 104         return Architecture(os_ranks, machine_ranks)
 105
 106 def get_architecture(os, machine):
 107         """Get an Architecture that matches binaries that will work on the given system.
 108         @param os: OS type, or None for host's type
 109         @param machine: CPU type, or None for host's type
 110         @return: an Architecture object
 111         @rtype: L{Architecture}"""
 112
 113         if os:
 114                 target_os_ranks = {
 115                         os : 1,         # Perfer binaries for target OS
 116                         None : 2,       # Otherwise, generic OS is fine
 117                 }
 118         else:
 119                 target_os_ranks = os_ranks
 120         if machine:
 121                 target_machine_ranks = _get_machine_ranks(machine)
 122         else:
 123                 target_machine_ranks = machine_ranks
 124         return Architecture(target_os_ranks, target_machine_ranks)