some more playlist stuff

mochis_tale/interlude/picker_3/picker-III.py

@@ -0,0 +1,198 @@
+
+import re
+
+
+
+USER_ALIVE = True
+FUNC_TABLE_SIZE = 4
+FUNC_TABLE_ENTRY_SIZE = 32
+CORRUPT_MESSAGE = 'Table corrupted. Try entering \'reset\' to fix it'
+
+func_table = ''
+
+def reset_table():
+  global func_table
+
+  # This table is formatted for easier viewing, but it is really one line
+  func_table = \
+'''\
+print_table                     \
+read_variable                   \
+write_variable                  \
+getRandomNumber                 \
+'''
+
+def check_table():
+  global func_table
+
+  if( len(func_table) != FUNC_TABLE_ENTRY_SIZE * FUNC_TABLE_SIZE):
+    return False
+
+  return True
+
+
+def get_func(n):
+  global func_table
+
+  # Check table for viability
+  if( not check_table() ):
+    print(CORRUPT_MESSAGE)
+    return
+
+  # Get function name from table
+  func_name = ''
+  func_name_offset = n * FUNC_TABLE_ENTRY_SIZE
+  for i in range(func_name_offset, func_name_offset+FUNC_TABLE_ENTRY_SIZE):
+    if( func_table[i] == ' '):
+      func_name = func_table[func_name_offset:i]
+      break
+
+  if( func_name == '' ):
+    func_name = func_table[func_name_offset:func_name_offset+FUNC_TABLE_ENTRY_SIZE]
+  
+  return func_name
+
+
+def print_table():
+  # Check table for viability
+  if( not check_table() ):
+    print(CORRUPT_MESSAGE)
+    return
+
+  for i in range(0, FUNC_TABLE_SIZE):
+    j = i + 1
+    print(str(j)+': ' + get_func(i))
+
+
+def filter_var_name(var_name):
+  r = re.search('^[a-zA-Z_][a-zA-Z_0-9]*$', var_name)
+  if r:
+    return True
+  else:
+    return False
+
+
+def read_variable():
+  var_name = input('Please enter variable name to read: ')
+  if( filter_var_name(var_name) ):
+    eval('print('+var_name+')')
+  else:
+    print('Illegal variable name')
+
+
+def filter_value(value):
+  if ';' in value or '(' in value or ')' in value:
+    return False
+  else:
+    return True
+
+
+def write_variable():
+  var_name = input('Please enter variable name to write: ')
+  if( filter_var_name(var_name) ):
+    value = input('Please enter new value of variable: ')
+    if( filter_value(value) ):
+      exec('global '+var_name+'; '+var_name+' = '+value)
+    else:
+      print('Illegal value')
+  else:
+    print('Illegal variable name')
+
+
+def call_func(n):
+  """
+  Calls the nth function in the function table.
+  Arguments:
+    n: The function to call. The first function is 0.
+  """
+
+  # Check table for viability
+  if( not check_table() ):
+    print(CORRUPT_MESSAGE)
+    return
+
+  # Check n
+  if( n < 0 ):
+    print('n cannot be less than 0. Aborting...')
+    return
+  elif( n >= FUNC_TABLE_SIZE ):
+    print('n cannot be greater than or equal to the function table size of '+FUNC_TABLE_SIZE)
+    return
+
+  # Get function name from table
+  func_name = get_func(n)
+
+  # Run the function
+  eval(func_name+'()')
+
+
+def dummy_func1():
+  print('in dummy_func1')
+
+def dummy_func2():
+  print('in dummy_func2')
+
+def dummy_func3():
+  print('in dummy_func3')
+
+def dummy_func4():
+  print('in dummy_func4')
+
+def getRandomNumber():
+  print(4)  # Chosen by fair die roll.
+            # Guaranteed to be random.
+            # (See XKCD)
+
+def win():
+  # This line will not work locally unless you create your own 'flag.txt' in
+  #   the same directory as this script
+  flag = open('flag.txt', 'r').read()
+  #flag = flag[:-1]
+  flag = flag.strip()
+  str_flag = ''
+  for c in flag:
+    str_flag += str(hex(ord(c))) + ' '
+  print(str_flag)
+
+def help_text():
+  print(
+  '''
+This program fixes vulnerabilities in its predecessor by limiting what
+functions can be called to a table of predefined functions. This still puts
+the user in charge, but prevents them from calling undesirable subroutines.
+
+* Enter 'quit' to quit the program.
+* Enter 'help' for this text.
+* Enter 'reset' to reset the table.
+* Enter '1' to execute the first function in the table.
+* Enter '2' to execute the second function in the table.
+* Enter '3' to execute the third function in the table.
+* Enter '4' to execute the fourth function in the table.
+
+Here's the current table:
+  '''
+  )
+  print_table()
+
+
+
+reset_table()
+
+while(USER_ALIVE):
+  choice = input('==> ')
+  if( choice == 'quit' or choice == 'exit' or choice == 'q' ):
+    USER_ALIVE = False
+  elif( choice == 'help' or choice == '?' ):
+    help_text()
+  elif( choice == 'reset' ):
+    reset_table()
+  elif( choice == '1' ):
+    call_func(0)
+  elif( choice == '2' ):
+    call_func(1)
+  elif( choice == '3' ):
+    call_func(2)
+  elif( choice == '4' ):
+    call_func(3)
+  else:
+    print('Did not understand "'+choice+'" Have you tried "help"?')