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 def parse_script(pathname):
  27         """Extract the URI and main values from a 0alias script.
  28         @param pathname: the script to be examined
  29         @return: a tuple containing the URI and the main (or None if not set)
  30         @rtype: (str, str | None)
  31         @raise NotAnAliasScript: if we can't parse the script
  32         """
  33         stream = file(pathname)
  34         template_header = _template[:_template.index("%s'")]
  35         actual_header = stream.read(len(template_header))
  36         stream.seek(0)
  37         if template_header == actual_header:
  38                 # If it's a 0alias script, it should be quite short!
  39                 rest = stream.read()
  40                 line = rest.split('\n')[1]
  41         else:
  42                 old_template_header = \
  43                     _old_template[:_old_template.index("-gd '")]
  44                 actual_header = stream.read(len(old_template_header))
  45                 if old_template_header != actual_header:
  46                         raise NotAnAliasScript(_("'%s' does not look like a script created by 0alias") % pathname)
  47                 rest = stream.read()
  48                 line = rest.split('\n')[2]
  49
  50         split = line.rfind("' '")
  51         if split != -1:
  52                 # We have a --main
  53                 uri = line[split + 3:].split("'")[0]
  54                 main = line[:split].split("'", 1)[1].replace("'\\''", "'")
  55         else:
  56                 main = None
  57                 uri = line.split("'",2)[1]
  58
  59         return (uri, main)
  60
  61 def write_script(stream, interface_uri, main = None):
  62         """Write a shell script to stream that will launch the given program.
  63         @param stream: the stream to write to
  64         @param interface_uri: the program to launch
  65         @param main: the --main argument to pass to 0launch, if any"""
  66         assert "'" not in interface_uri
  67         assert "\\" not in interface_uri
  68
  69         if main is not None:
  70                 main_arg = "--main '%s' " % main.replace("'", "'\\''")
  71         else:
  72                 main_arg = ""
  73
  74         stream.write(_template % (main_arg, interface_uri))