zeroinstall/injector/run.py

   1 """
   2 Executes a set of implementations as a program.
   3 """
   4
   5 # Copyright (C) 2009, Thomas Leonard
   6 # See the README file for details, or visit http://0install.net.
   7
   8 from zeroinstall import _
   9 import os, sys
  10 from logging import info
  11 from string import Template
  12
  13 from zeroinstall.injector.model import SafeException, EnvironmentBinding, Command
  14 from zeroinstall.injector import namespaces, qdom
  15
  16 def do_env_binding(binding, path):
  17         """Update this process's environment by applying the binding.
  18         @param binding: the binding to apply
  19         @type binding: L{model.EnvironmentBinding}
  20         @param path: the selected implementation
  21         @type path: str"""
  22         os.environ[binding.name] = binding.get_value(path,
  23                                         os.environ.get(binding.name, None))
  24         info("%s=%s", binding.name, os.environ[binding.name])
  25
  26 def execute(policy, prog_args, dry_run = False, main = None, wrapper = None):
  27         """Execute program. On success, doesn't return. On failure, raises an Exception.
  28         Returns normally only for a successful dry run.
  29         @param policy: a policy with the selected versions
  30         @type policy: L{policy.Policy}
  31         @param prog_args: arguments to pass to the program
  32         @type prog_args: [str]
  33         @param dry_run: if True, just print a message about what would have happened
  34         @type dry_run: bool
  35         @param main: the name of the binary to run, or None to use the default
  36         @type main: str
  37         @param wrapper: a command to use to actually run the binary, or None to run the binary directly
  38         @type wrapper: str
  39         @precondition: C{policy.ready and policy.get_uncached_implementations() == []}
  40         """
  41         execute_selections(policy.solver.selections, prog_args, dry_run, main, wrapper)
  42
  43 def test_selections(selections, prog_args, dry_run, main, wrapper = None):
  44         """Run the program in a child process, collecting stdout and stderr.
  45         @return: the output produced by the process
  46         @since: 0.27
  47         """
  48         import tempfile
  49         output = tempfile.TemporaryFile(prefix = '0launch-test')
  50         try:
  51                 child = os.fork()
  52                 if child == 0:
  53                         # We are the child
  54                         try:
  55                                 try:
  56                                         os.dup2(output.fileno(), 1)
  57                                         os.dup2(output.fileno(), 2)
  58                                         execute_selections(selections, prog_args, dry_run, main)
  59                                 except:
  60                                         import traceback
  61                                         traceback.print_exc()
  62                         finally:
  63                                 sys.stdout.flush()
  64                                 sys.stderr.flush()
  65                                 os._exit(1)
  66
  67                 info(_("Waiting for test process to finish..."))
  68
  69                 pid, status = os.waitpid(child, 0)
  70                 assert pid == child
  71
  72                 output.seek(0)
  73                 results = output.read()
  74                 if status != 0:
  75                         results += _("Error from child process: exit code = %d") % status
  76         finally:
  77                 output.close()
  78
  79         return results
  80
  81 def _process_args(args, element):
  82         """Append each <arg> under <element> to args, performing $-expansion."""
  83         for child in element.childNodes:
  84                 if child.uri == namespaces.XMLNS_IFACE and child.name == 'arg':
  85                         args.append(Template(child.content).substitute(os.environ))
  86
  87 class Setup(object):
  88         """@since: 1.1"""
  89         stores = None
  90
  91         def __init__(self, stores):
  92                 """@param stores: where to find cached implementations
  93                 @type stores: L{zerostore.Stores}"""
  94                 self.stores = stores
  95
  96         def build_command_args(self, selections, commands = None):
  97                 """Create a list of strings to be passed to exec to run the <command>s in the selections.
  98                 @param selections: the selections containing the commands
  99                 @type selections: L{selections.Selections}
 100                 @param commands: the commands to be used (taken from selections is None)
 101                 @type commands: [L{model.Command}]
 102                 @return: the argument list
 103                 @rtype: [str]"""
 104
 105                 prog_args = []
 106                 commands = commands or selections.commands
 107                 sels = selections.selections
 108
 109                 # Each command is run by the next, but the last one is run by exec, and we
 110                 # need a path for that.
 111                 if commands[-1].path is None:
 112                         raise SafeException("Missing 'path' attribute on <command>")
 113
 114                 command_iface = selections.interface
 115                 for command in commands:
 116                         command_sel = sels[command_iface]
 117
 118                         command_args = []
 119
 120                         # Add extra arguments for runner
 121                         runner = command.get_runner()
 122                         if runner:
 123                                 command_iface = runner.interface
 124                                 _process_args(command_args, runner.qdom)
 125
 126                         # Add main program path
 127                         command_path = command.path
 128                         if command_path is not None:
 129                                 if command_sel.id.startswith('package:'):
 130                                         prog_path = command_path
 131                                 else:
 132                                         if command_path.startswith('/'):
 133                                                 raise SafeException(_("Command path must be relative, but '%s' starts with '/'!") %
 134                                                                         command_path)
 135                                         prog_path = os.path.join(self._get_implementation_path(command_sel), command_path)
 136
 137                                 assert prog_path is not None
 138
 139                                 if not os.path.exists(prog_path):
 140                                         raise SafeException(_("File '%(program_path)s' does not exist.\n"
 141                                                         "(implementation '%(implementation_id)s' + program '%(main)s')") %
 142                                                         {'program_path': prog_path, 'implementation_id': command_sel.id,
 143                                                         'main': command_path})
 144
 145                                 command_args.append(prog_path)
 146
 147                         # Add extra arguments for program
 148                         _process_args(command_args, command.qdom)
 149
 150                         prog_args = command_args + prog_args
 151
 152                 return prog_args
 153
 154         def _get_implementation_path(self, impl):
 155                 return impl.local_path or self.stores.lookup_any(impl.digests)
 156
 157         def prepare_env(self, selections):
 158                 """Do all the environment bindings in selections (setting os.environ).
 159                 @param selections: the selections to be used
 160                 @type selections: L{selections.Selections}"""
 161
 162                 def _do_bindings(impl, bindings):
 163                         for b in bindings:
 164                                 self.do_binding(impl, b)
 165
 166                 commands = selections.commands
 167                 sels = selections.selections
 168                 for selection in sels.values():
 169                         _do_bindings(selection, selection.bindings)
 170                         for dep in selection.dependencies:
 171                                 dep_impl = sels[dep.interface]
 172                                 if not dep_impl.id.startswith('package:'):
 173                                         _do_bindings(dep_impl, dep.bindings)
 174                 # Process commands' dependencies' bindings too
 175                 # (do this here because we still want the bindings, even with --main)
 176                 for command in commands:
 177                         for dep in command.requires:
 178                                 dep_impl = sels[dep.interface]
 179                                 if not dep_impl.id.startswith('package:'):
 180                                         _do_bindings(dep_impl, dep.bindings)
 181
 182         def do_binding(self, impl, binding):
 183                 """Called by L{prepare_env} for each binding.
 184                 Sub-classes may wish to override this."""
 185                 if isinstance(binding, EnvironmentBinding):
 186                         do_env_binding(binding, self._get_implementation_path(impl))
 187
 188 def execute_selections(selections, prog_args, dry_run = False, main = None, wrapper = None, stores = None):
 189         """Execute program. On success, doesn't return. On failure, raises an Exception.
 190         Returns normally only for a successful dry run.
 191         @param selections: the selected versions
 192         @type selections: L{selections.Selections}
 193         @param prog_args: arguments to pass to the program
 194         @type prog_args: [str]
 195         @param dry_run: if True, just print a message about what would have happened
 196         @type dry_run: bool
 197         @param main: the name of the binary to run, or None to use the default
 198         @type main: str
 199         @param wrapper: a command to use to actually run the binary, or None to run the binary directly
 200         @type wrapper: str
 201         @since: 0.27
 202         @precondition: All implementations are in the cache.
 203         """
 204         #assert stores is not None
 205         if stores is None:
 206                 from zeroinstall import zerostore
 207                 stores = zerostore.Stores()
 208
 209         setup = Setup(stores)
 210
 211         commands = selections.commands
 212         if main is not None:
 213                 # Replace first command with user's input
 214                 if main.startswith('/'):
 215                         main = main[1:]                 # User specified a path relative to the package root
 216                 else:
 217                         old_path = commands[0].path
 218                         assert old_path, "Can't use a relative replacement main when there is no original one!"
 219                         main = os.path.join(os.path.dirname(old_path), main)    # User main is relative to command's name
 220                 # Copy all child nodes (e.g. <runner>) except for the arguments
 221                 user_command_element = qdom.Element(namespaces.XMLNS_IFACE, 'command', {'path': main})
 222                 if commands:
 223                         for child in commands[0].qdom.childNodes:
 224                                 if child.uri == namespaces.XMLNS_IFACE and child.name == 'arg':
 225                                         continue
 226                                 user_command_element.childNodes.append(child)
 227                 user_command = Command(user_command_element, None)
 228                 commands = [user_command] + commands[1:]
 229
 230         setup.prepare_env(selections)
 231         prog_args = setup.build_command_args(selections, commands) + prog_args
 232
 233         if wrapper:
 234                 prog_args = ['/bin/sh', '-c', wrapper + ' "$@"', '-'] + list(prog_args)
 235
 236         if dry_run:
 237                 print _("Would execute: %s") % ' '.join(prog_args)
 238         else:
 239                 info(_("Executing: %s"), prog_args)
 240                 sys.stdout.flush()
 241                 sys.stderr.flush()
 242                 try:
 243                         os.execv(prog_args[0], prog_args)
 244                 except OSError, ex:
 245                         raise SafeException(_("Failed to run '%(program_path)s': %(exception)s") % {'program_path': prog_args[0], 'exception': str(ex)})