zeroinstall/alias.py

   1 """
   2 Support code for 0alias scripts.
   3 @since: 0.28
   4 """
   5
   6 # Copyright (C) 2007, Thomas Leonard
   7 # See the README file for details, or visit http://0install.net.
   8
   9 _template = '''#!/bin/sh
  10 if [ "$*" = "--versions" ]; then
  11   exec 0launch -gd '%s' "$@"
  12 else
  13   exec 0launch %s '%s' "$@"
  14 fi
  15 '''
  16
  17 class NotAnAliasScript(Exception):
  18         pass
  19
  20 def parse_script(pathname):
  21         """Extract the URI and main values from a 0alias script.
  22         @param pathname: the script to be examined
  23         @return: a tuple containing the URI and the main (or None if not set)
  24         @rtype: (str, str | None)
  25         @raise NotAnAliasScript: if we can't parse the script
  26         """
  27         stream = file(pathname)
  28         template_header = _template[:_template.index("-gd '")]
  29         actual_header = stream.read(len(template_header))
  30         if template_header != actual_header:
  31                 raise NotAnAliasScript("'%s' does not look like a script created by 0alias" % pathname)
  32         rest = stream.read()    # If it's a 0alias script, it should be quite short!
  33         line = rest.split('\n')[2]
  34         split = line.rfind("' '")
  35         if split != -1:
  36                 # We have a --main
  37                 uri = line[split + 3:].split("'")[0]
  38                 main = line[:split].split("'", 1)[1].replace("'\\''", "'")
  39         else:
  40                 main = None
  41                 uri = line.split("'",2)[1]
  42
  43         return (uri, main)
  44
  45 def write_script(stream, interface_uri, main = None):
  46         """Write a shell script to stream that will launch the given program.
  47         @param stream: the stream to write to
  48         @param interface_uri: the program to launch
  49         @param main: the --main argument to pass to 0launch, if any"""
  50         assert "'" not in interface_uri
  51         assert "\\" not in interface_uri
  52
  53         if main is not None:
  54                 main_arg = "--main '%s'" % main.replace("'", "'\\''")
  55         else:
  56                 main_arg = ""
  57
  58         stream.write(_template % (interface_uri, main_arg, interface_uri))