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