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) 2006, 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 _uname = os.uname()
  26
  27 os_ranks = {
  28 #       'Linux' : 3,            # Linux (lots of systems support emulation)
  29         None : 2,               # Any OS
  30         _uname[0] : 1,          # Current OS
  31 }
  32
  33 # All chosen machine-specific implementations must come from the same group
  34 # Unlisted archs are in group 0
  35 machine_groups = {
  36         'x86_64': 64,
  37         'ppc64': 64,
  38 }
  39
  40 def _get_machine_ranks(target_machine):
  41         # Binaries compiled for _this_machine are best...
  42         machine_ranks = {target_machine : 0}
  43
  44         # If target_machine appears in the first column of this table, all
  45         # following machine types on the line will also run on this one
  46         # (earlier ones preferred):
  47         _machine_matrix = {
  48                 'i486': ['i386'],
  49                 'i586': ['i486', 'i386'],
  50                 'i686': ['i586', 'i486', 'i386'],
  51                 'x86_64': ['i686', 'i586', 'i486', 'i386'],
  52                 'ppc64': ['ppc32'],
  53         }
  54         for supported in _machine_matrix.get(target_machine, []):
  55                 machine_ranks[supported] = len(machine_ranks)
  56
  57         # At the lowest priority, try a machine-independant implementation
  58         machine_ranks[None] = len(machine_ranks)
  59         return machine_ranks
  60
  61 machine_ranks = _get_machine_ranks(_uname[-1])
  62 #print machine_ranks
  63
  64 class Architecture:
  65         """A description of an architecture. Use by L{solver} to make sure it chooses
  66         compatible versions.
  67         @ivar os_ranks: supported operating systems and their desirability
  68         @type os_ranks: {str: int}
  69         @ivar machine_ranks: supported CPU types and their desirability
  70         @type machine_ranks: {str: int}
  71         @ivar child_arch: architecture for dependencies (usually C{self})
  72         @type child_arch: L{Architecture}"""
  73         def __init__(self, os_ranks, machine_ranks):
  74                 self.os_ranks = os_ranks
  75                 self.machine_ranks = machine_ranks
  76                 self.child_arch = self
  77
  78         def __str__(self):
  79                 return "<Arch: %s %s>" % (self.os_ranks, self.machine_ranks)
  80
  81 class SourceArchitecture(Architecture):
  82         """Matches source code that creates binaries for a particular architecture.
  83         Note that the L{child_arch} here is the binary; source code depends on binary tools,
  84         not on other source packages.
  85         """
  86         def __init__(self, binary_arch):
  87                 Architecture.__init__(self, binary_arch.os_ranks, {'src': 1})
  88                 self.child_arch = binary_arch
  89
  90 def get_host_architecture():
  91         """Get an Architecture that matches implementations that will run on the host machine.
  92         @rtype: L{Architecture}"""
  93         return Architecture(os_ranks, machine_ranks)
  94
  95 def get_architecture(os, machine):
  96         """Get an Architecture that matches binaries that will work on the given system.
  97         @param os: OS type, or None for host's type
  98         @param machine: CPU type, or None for host's type
  99         @return: an Architecture object
 100         @rtype: L{Architecture}"""
 101
 102         if os:
 103                 target_os_ranks = {
 104                         os : 1,         # Perfer binaries for target OS
 105                         None : 2,       # Otherwise, generic OS is fine
 106                 }
 107         else:
 108                 target_os_ranks = os_ranks
 109         if machine:
 110                 target_machine_ranks = _get_machine_ranks(machine)
 111         else:
 112                 target_machine_ranks = machine_ranks
 113         return Architecture(target_os_ranks, target_machine_ranks)