############################################################################ # # # ENV.PY # # # # Copyright (C) 2008 - 2011 Ada Core Technologies, Inc. # # # # This program is free software: you can redistribute it and/or modify # # it under the terms of the GNU General Public License as published by # # the Free Software Foundation, either version 3 of the License, or # # (at your option) any later version. # # # # This program is distributed in the hope that it will be useful, # # but WITHOUT ANY WARRANTY; without even the implied warranty of # # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # # GNU General Public License for more details. # # # # You should have received a copy of the GNU General Public License # # along with this program. If not, see # # # ############################################################################ """Global environment handling This package provide a class called Env used to store global information. Env is a singleton so there is in fact only one instance. Here is a description of the functionalities provided by the class: * host, target information retrieval/setting: >>> from gnatpython.env import Env >>> e = Env () >>> print e.target platform: x86-linux machine: barcelona is_hie: False is_host: True triplet: i686-pc-linux-gnu OS name: linux version: suse10.3 is_bareboard: False CPU name: x86 bits: 32 endian: little >>> e.set_target ('ppc-vxw') >>> print e.target.os.name vxworks >>> print e.target.os.version 5.5 * make some info global >>> e = Env () >>> d = Env () >>> e.example_of_global_info = 'hello' >>> print d.example_of_global_info hello * restoring/saving complete environment, including environment variables and current dir >>> e = Env () >>> e.example = 'hello' >>> e.store ('./saved_env') >>> ^D $ gnatpython >>> from gnatpython.env import Env >>> e = Env () >>> e.restore ('./saved_env') >>> print e.example hello """ from gnatpython.arch import Arch import pickle import os def putenv(key, value): """Portable version of os.putenv""" # When a variable is set by os.putenv, os.environ is not updated; # this is a problem, as Env and ex.Run use os.environ to store the # current environment or to spawn a process. This limitation is # documented in the Python Library Reference: # environ # A mapping object representing the string environment. For # example, environ['HOME'] is the pathname of your home directory # (on some platforms), and is equivalent to getenv("HOME") in C. # # This mapping is captured the first time the os module is # imported, typically during Python startup as part of # processing site.py. Changes to the environment made after # this time are not reflected in os.environ, except for # changes made by modifying os.environ directly. # # If the platform supports the putenv() function, this # mapping may be used to modify the environment as well as # query the environment. putenv() will be called # automatically when the mapping is modified. Note: Calling # putenv() directly does not change os.environ, so it's # better to modify os.environ. # ...For this reason, os.environ is prefered to os.putenv here. os.environ[key] = value def getenv(key, default=None): """Portable version of os.getenv""" # For the reason documented in putenv, and for consistency, it is better # to use os.environ instead of os.getenv here. if key in os.environ: return os.environ[key] else: return default class Env (object): """Environment Handling ATTRIBUTES build: default system (autodetected) host: host system target: target system is_cross: true if we are in a cross environment REMARKS build, host and target attributes are instances of Arch class. Do pydoc gnatpython.arch for more information """ # class variable that holds the current environment __instance = {} # class variable that holds the stack of saved environments state __context = [] def __init__(self): """Env constructor PARAMETERS None RETURN VALUE A Env instance REMARKS On first instantiation, build attribute will be computed and host and target set to the build attribute. """ if 'build' not in Env.__instance: self.is_cross = False self.build = Arch() self.host = self.build self.target = self.host self.environ = None self.cwd = None self.main_options = None # Command line switches def __getattr__(self, name): return Env.__instance[name] def __setattr__(self, name, value): Env.__instance[name] = value def set_host(self, host_name=None, host_version=None): """Set host platform PARAMETERS host_name: a string that identify the system to be considered as the host. If None then host is set to the build one (the autodetected platform). host_version: a string containing the system version. If set to None the version is either a default or autodetected when possible RETURN VALUE None REMARKS None """ if host_name is not None: self.host = Arch(platform_name=host_name, is_host=True, version=host_version) else: self.host = self.build if self.target != self.host: self.is_cross = True else: self.is_cross = False def set_target(self, target_name=None, target_version=None, target_machine=None): """Set target platform PARAMETERS host_name: a string that identify the system to be considered as the host. If None then host is set to the host one. host_version: a string containing the system version. If set to None the version is either a default or autodetected when possible RETURN VALUE None REMARKS None """ if target_name is not None: self.target = Arch(platform_name=target_name, version=target_version, machine=target_machine) else: self.target = self.host if self.target != self.host: self.is_cross = True else: self.is_cross = False def get_attr(self, name, default_value=None, forced_value=None): """Return an attribute value PARAMETERS name: name of the attribute to check. Name can contain '.' default_value: returned value if forced_value not set and the attribute does not exist forced_value: if not None, this is the return value RETURN VALUE the attribute value REMARKS This function is useful to get the value of optional functions parameters whose default value might depend on the environment. """ if forced_value is not None: return forced_value attributes = name.split('.') result = self for a in attributes: if not hasattr(result, a): return default_value else: result = getattr(result, a) if result is None or result == "": return default_value return result def store(self, filename=None): """Save environment into memory or file PARAMETERS filename: a string containing the path of the filename in which the environement will be saved. If set to None the environment is saved into memory in a stack like structure. RETURN VALUE None """ # Store environment variables self.environ = os.environ.copy() # Store cwd self.cwd = os.getcwd() if filename is None: Env.__context.append(pickle.dumps(Env.__instance)) else: fd = open(filename, 'w+') pickle.dump(Env.__instance, fd) fd.close() def restore(self, filename=None): """Restore environment from memory or a file PARAMETERS filename: a string containing the path of the filename from which the environement will be restored. If set to None the environment is pop the last saved one RETURN VALUE None """ if filename is None: # We are restoring from memory. In that case, just double-check # that we did store the Env object in memory beforehand (using # the store method). assert (self.environ is not None) if filename is None and Env.__context: Env.__instance = pickle.loads(Env.__context[-1]) Env.__context = Env.__context[:-1] elif filename is not None: fd = open(filename, 'r') Env.__instance = pickle.load(fd) fd.close() else: return # Restore environment variables value os.environ = self.environ.copy() # Restore current directory os.chdir(self.cwd) @classmethod def add_path(cls, path, append=False): """Set a path to PATH environment variable PARAMETERS path: path to add append: if True append, otherwise prepend. Default is prepend RETURN VALUE None REMARKS None """ if append: os.environ['PATH'] += os.path.pathsep + path else: os.environ['PATH'] = path + os.path.pathsep + os.environ['PATH'] @classmethod def add_search_path(cls, env_var, path, append=False): """Add a path to the env_var search paths PARAMETERS env_var: the environment variable name (e.g. PYTHONPATH, LD_LIBRARY_PATH, ...) path: path to add append: if True append, otherwise prepend. Default is prepend RETURN VALUE None REMARKS None """ if not env_var in os.environ: os.environ[env_var] = path else: if append: os.environ[env_var] += os.path.pathsep + path else: os.environ[env_var] = path + os.path.pathsep + \ os.environ[env_var] def add_dll_path(self, path, append=False): """Add a path to the dynamic libraries search paths PARAMETERS path: path to add append: if True append, otherwise prepend. Default is prepend RETURN VALUE None REMARKS None """ # On most platforms LD_LIBRARY_PATH is used. For others use: env_var_name = {'windows': 'PATH', 'hp-ux': 'SHLIB_PATH', 'darwin': 'DYLD_LIBRARY_PATH'} env_var = env_var_name.get( self.host.os.name.lower(), 'LD_LIBRARY_PATH') self.add_search_path(env_var, path, append) @property def discriminants(self): """Compute discriminants""" discs = [self.target.platform, self.target.triplet, self.target.cpu.endian + '-endian', self.target.cpu.name, self.target.os.name, self.target.os.name + '-' + self.target.os.version, self.host.os.name + '-host'] if not self.is_cross: discs.append('native') if self.target.cpu.bits == 64: discs.append('64bits') if self.target.os.name.lower() == 'windows': discs.append('NT') return discs @property def tmp_dir(self): return os.environ.get('TMPDIR', os.environ.get('TMP', '/tmp')) if __name__ == "__main__": print Env().host print "discs: " + ", ".join(Env().discriminants)