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 _template = '''#!/bin/sh
  12 if [ "$*" = "--versions" ]; then
  13   exec 0launch -gd '%s' "$@"
  14 else
  15   exec 0launch %s '%s' "$@"
  16 fi
  17 '''
  18
  19 class NotAnAliasScript(Exception):
  20         pass
  21
  22 def parse_script(pathname):
  23         """Extract the URI and main values from a 0alias script.
  24         @param pathname: the script to be examined
  25         @return: a tuple containing the URI and the main (or None if not set)
  26         @rtype: (str, str | None)
  27         @raise NotAnAliasScript: if we can't parse the script
  28         """
  29         stream = file(pathname)
  30         template_header = _template[:_template.index("-gd '")]
  31         actual_header = stream.read(len(template_header))
  32         if template_header != actual_header:
  33                 raise NotAnAliasScript(_("'%s' does not look like a script created by 0alias") % pathname)
  34         rest = stream.read()    # If it's a 0alias script, it should be quite short!
  35         line = rest.split('\n')[2]
  36         split = line.rfind("' '")
  37         if split != -1:
  38                 # We have a --main
  39                 uri = line[split + 3:].split("'")[0]
  40                 main = line[:split].split("'", 1)[1].replace("'\\''", "'")
  41         else:
  42                 main = None
  43                 uri = line.split("'",2)[1]
  44
  45         return (uri, main)
  46
  47 def write_script(stream, interface_uri, main = None):
  48         """Write a shell script to stream that will launch the given program.
  49         @param stream: the stream to write to
  50         @param interface_uri: the program to launch
  51         @param main: the --main argument to pass to 0launch, if any"""
  52         assert "'" not in interface_uri
  53         assert "\\" not in interface_uri
  54
  55         if main is not None:
  56                 main_arg = "--main '%s'" % main.replace("'", "'\\''")
  57         else:
  58                 main_arg = ""
  59
  60         stream.write(_template % (interface_uri, main_arg, interface_uri))