zeroinstall/alias.py

   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 _
  10
  11 _old_template = '''#!/bin/sh
  12 if [ "$*" = "--versions" ]; then
  13   exec 0launch -gd '%s' "$@"
  14 else
  15   exec 0launch %s '%s' "$@"
  16 fi
  17 '''
  18
  19 _template = '''#!/bin/sh
  20 exec 0launch %s'%s' "$@"
  21 '''
  22
  23 class NotAnAliasScript(Exception):
  24         pass
  25
  26 class ScriptInfo:
  27         """@since: 1.3"""
  28         uri = None
  29         main = None
  30         command = None
  31
  32         # For backwards compatibility
  33         def __iter__(self):
  34                 return iter([self.uri, self.main])
  35
  36 def parse_script(pathname):
  37         """Extract the URI and main values from a 0alias script.
  38         @param pathname: the script to be examined
  39         @return: information about the alias script
  40         @rtype: L{ScriptInfo}
  41         @raise NotAnAliasScript: if we can't parse the script
  42         """
  43         stream = file(pathname)
  44         template_header = _template[:_template.index("%s'")]
  45         actual_header = stream.read(len(template_header))
  46         stream.seek(0)
  47         if template_header == actual_header:
  48                 # If it's a 0alias script, it should be quite short!
  49                 rest = stream.read()
  50                 line = rest.split('\n')[1]
  51         else:
  52                 old_template_header = \
  53                     _old_template[:_old_template.index("-gd '")]
  54                 actual_header = stream.read(len(old_template_header))
  55                 if old_template_header != actual_header:
  56                         raise NotAnAliasScript(_("'%s' does not look like a script created by 0alias") % pathname)
  57                 rest = stream.read()
  58                 line = rest.split('\n')[2]
  59
  60         info = ScriptInfo()
  61         split = line.rfind("' '")
  62         if split != -1:
  63                 # We have a --main or --command
  64                 info.uri = line[split + 3:].split("'")[0]
  65                 start, value = line[:split].split("'", 1)
  66                 option = start.split('--', 1)[1].strip()
  67                 value = value.replace("'\\''", "'")
  68                 if option == 'main':
  69                         info.main = value
  70                 elif option == 'command':
  71                         info.command = value
  72                 else:
  73                         raise NotAnAliasScript("Unknown option '{option}' in alias script".format(option = option))
  74         else:
  75                 info.uri = line.split("'",2)[1]
  76
  77         return info
  78
  79 def write_script(stream, interface_uri, main = None, command = None):
  80         """Write a shell script to stream that will launch the given program.
  81         @param stream: the stream to write to
  82         @param interface_uri: the program to launch
  83         @param main: the --main argument to pass to 0launch, if any
  84         @param command: the --command argument to pass to 0launch, if any"""
  85         assert "'" not in interface_uri
  86         assert "\\" not in interface_uri
  87         assert main is None or command is None, "Can't set --main and --command together"
  88
  89         if main is not None:
  90                 option = "--main '%s' " % main.replace("'", "'\\''")
  91         elif command is not None:
  92                 option = "--command '%s' " % command.replace("'", "'\\''")
  93         else:
  94                 option = ""
  95
  96         stream.write(_template % (option, interface_uri))