old_contents: ##############################################################################
  # Copyright (c) 2013-2015, Lawrence Livermore National Security, LLC.
  # Produced at the Lawrence Livermore National Laboratory.
  #
  # This file is part of Spack.
  # Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
  # LLNL-CODE-647188
  #
  # For details, see https://github.com/llnl/spack
  # Please also see the LICENSE file for our notice and the LGPL.
  #
  # This program is free software; you can redistribute it and/or modify
  # it under the terms of the GNU General Public License (as published by
  # the Free Software Foundation) version 2.1 dated February 1999.
  #
  # This program is distributed in the hope that it will be useful, but
  # WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
  # conditions of the GNU General Public License for more details.
  #
  # You should have received a copy of the GNU Lesser General Public License
  # along with this program; if not, write to the Free Software Foundation,
  # Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  ##############################################################################
  import os
  
  from llnl.util.filesystem import *
  import llnl.util.tty as tty
  
  import spack
  import spack.modules
  
  # Character limit for shebang line.  Using Linux's 127 characters
  # here, as it is the shortest I could find on a modern OS.
  shebang_limit = 127
  
  def shebang_too_long(path):
      """Detects whether an file has a shebang line that is too long."""
      with open(path, 'r') as script:
          bytes = script.read(2)
          if bytes != '#!':
              return False
  
          line = bytes + script.readline()
          return len(line) > shebang_limit
  
  
  def filter_shebang(path):
      """Adds a second shebang line, using sbang, at the beginning of a file."""
      backup = path + ".shebang.bak"
      os.rename(path, backup)
  
      with open(backup, 'r') as bak_file:
          original = bak_file.read()
  
      with open(path, 'w') as new_file:
          new_file.write('#!/bin/bash %s/bin/sbang\n' % spack.spack_root)
          new_file.write(original)
  
      copy_mode(backup, path)
      unset_executable_mode(backup)
  
      tty.warn("Patched overly long shebang in %s" % path)
  
  
  def post_install(pkg):
      """This hook edits scripts so that they call /bin/bash
         $spack_prefix/bin/sbang instead of something longer than the
         shebang limit."""
      for file in os.listdir(pkg.prefix.bin):
          path = os.path.join(pkg.prefix.bin, file)
          if shebang_too_long(path):
              filter_shebang(path)
  
  
new_contents: ##############################################################################
  # Copyright (c) 2013-2015, Lawrence Livermore National Security, LLC.
  # Produced at the Lawrence Livermore National Laboratory.
  #
  # This file is part of Spack.
  # Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
  # LLNL-CODE-647188
  #
  # For details, see https://github.com/llnl/spack
  # Please also see the LICENSE file for our notice and the LGPL.
  #
  # This program is free software; you can redistribute it and/or modify
  # it under the terms of the GNU General Public License (as published by
  # the Free Software Foundation) version 2.1 dated February 1999.
  #
  # This program is distributed in the hope that it will be useful, but
  # WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
  # conditions of the GNU General Public License for more details.
  #
  # You should have received a copy of the GNU Lesser General Public License
  # along with this program; if not, write to the Free Software Foundation,
  # Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  ##############################################################################
  import os
  
  from llnl.util.filesystem import *
  import llnl.util.tty as tty
  
  import spack
  import spack.modules
  
  # Character limit for shebang line.  Using Linux's 127 characters
  # here, as it is the shortest I could find on a modern OS.
  shebang_limit = 127
  
  def shebang_too_long(path):
      """Detects whether an file has a shebang line that is too long."""
      with open(path, 'r') as script:
          bytes = script.read(2)
          if bytes != '#!':
              return False
  
          line = bytes + script.readline()
          return len(line) > shebang_limit
  
  
  def filter_shebang(path):
      """Adds a second shebang line, using sbang, at the beginning of a file."""
      backup = path + ".shebang.bak"
      os.rename(path, backup)
  
      with open(backup, 'r') as bak_file:
          original = bak_file.read()
  
      with open(path, 'w') as new_file:
          new_file.write('#!/bin/bash %s/bin/sbang\n' % spack.spack_root)
          new_file.write(original)
  
      copy_mode(backup, path)
      unset_executable_mode(backup)
  
      tty.warn("Patched overly long shebang in %s" % path)
  
  
  def post_install(pkg):
      """This hook edits scripts so that they call /bin/bash
         $spack_prefix/bin/sbang instead of something longer than the
         shebang limit."""
      if not os.path.isdir(pkg.prefix.bin):
          return
  
      for file in os.listdir(pkg.prefix.bin):
          path = os.path.join(pkg.prefix.bin, file)
          if shebang_too_long(path):
              filter_shebang(path)
  
  
subject: Fix bug in hook: ensure bin directory exists before listing.