Source Code for Module zeroinstall.alias

  1  """ 
  2  Support code for 0alias scripts. 
  3  @since: 0.28 
  4  """ 
  5   
  6  # Copyright (C) 2009, Thomas Leonard 
  7  # See the README file for details, or visit http://0install.net. 
  8   
  9  from zeroinstall import _, SafeException 
 10  from zeroinstall import support 
 11   
 12  _old_template = '''#!/bin/sh 
 13  if [ "$*" = "--versions" ]; then 
 14    exec 0launch -gd '%s' "$@" 
 15  else 
 16    exec 0launch %s '%s' "$@" 
 17  fi 
 18  '''  
 19   
 20  _template = '''#!/bin/sh 
 21  exec 0launch %s'%s' "$@" 
 22  ''' 
 23   
 24 -class NotAnAliasScript(SafeException): 
 25          pass 
 26   
 27 -class ScriptInfo(object): 
 28          """@since: 1.3""" 
 29          uri = None 
 30          main = None 
 31          command = 'run' 
 32   
 33          # For backwards compatibility 
 34 -        def __iter__(self): 
 35                  return iter([self.uri, self.main]) 
 36   
 37 -def parse_script_header(stream): 
 38          """Parse a 0alias script, if possible. 
 39          This does the same as L{parse_script}, except with an existing stream. 
 40          The stream position at exit is undefined. 
 41          @type stream: file 
 42          @rtype: L{ScriptInfo} 
 43          @since: 1.12""" 
 44          try: 
 45                  stream.seek(0) 
 46                  template_header = _template[:_template.index("%s'")] 
 47                  actual_header = stream.read(len(template_header)) 
 48                  stream.seek(0) 
 49                  if template_header == actual_header: 
 50                          # If it's a 0alias script, it should be quite short! 
 51                          rest = stream.read() 
 52                          line = rest.split('\n')[1] 
 53                  else: 
 54                          old_template_header = \ 
 55                              _old_template[:_old_template.index("-gd '")] 
 56                          actual_header = stream.read(len(old_template_header)) 
 57                          if old_template_header != actual_header: 
 58                                  return None 
 59                          rest = stream.read() 
 60                          line = rest.split('\n')[2] 
 61          except UnicodeDecodeError: 
 62                  return None 
 63   
 64          info = ScriptInfo() 
 65          split = line.rfind("' '") 
 66          if split != -1: 
 67                  # We have a --main or --command 
 68                  info.uri = line[split + 3:].split("'")[0] 
 69                  start, value = line[:split].split("'", 1) 
 70                  option = start.split('--', 1)[1].strip() 
 71                  value = value.replace("'\\''", "'") 
 72                  if option == 'main': 
 73                          info.main = value 
 74                  elif option == 'command': 
 75                          info.command = value or None 
 76                  else: 
 77                          return None 
 78          else: 
 79                  info.uri = line.split("'", 2)[1] 
 80   
 81          return info 
 82   
 83 -def parse_script(pathname): 
 84          """Extract the URI and main values from a 0alias script. 
 85          @param pathname: the script to be examined 
 86          @type pathname: str 
 87          @return: information about the alias script 
 88          @rtype: L{ScriptInfo} 
 89          @raise NotAnAliasScript: if we can't parse the script""" 
 90          with open(pathname, 'rt') as stream: 
 91                  info = parse_script_header(stream) 
 92                  if info is None: 
 93                          raise NotAnAliasScript(_("'%s' does not look like a script created by 0alias") % pathname) 
 94                  return info 
 95   
 96 -def write_script(stream, interface_uri, main = None, command = None): 
 97          """Write a shell script to stream that will launch the given program. 
 98          @param stream: the stream to write to 
 99          @type stream: file 
100          @param interface_uri: the program to launch 
101          @type interface_uri: str 
102          @param main: the --main argument to pass to 0launch, if any 
103          @type main: str | None 
104          @param command: the --command argument to pass to 0launch, if any 
105          @type command: str | None""" 
106          assert "'" not in interface_uri 
107          assert "\\" not in interface_uri 
108          assert main is None or command is None, "Can't set --main and --command together" 
109   
110          if main is not None: 
111                  option = "--main '%s' " % main.replace("'", "'\\''") 
112          elif command is not None: 
113                  option = "--command '%s' " % command.replace("'", "'\\''") 
114          else: 
115                  option = "" 
116   
117          stream.write(support.unicode(_template) % (option, interface_uri)) 
118