#!/usr/local/bin/python
#--
# counter.py:  Web page counter script.  Use this Server-Side
# Include directive:
#   <!--#exec cmd="counter yourfile"-->
# where:
#   counter   is the compiled version of counter.c, with the
#             setuid bit.
#   yourfile  is the name of the file where the hits will be stored.
#--

import sys, string

def Error ( * L ):
    """Displays an error message in HTML.

      [ if (L is a list of strings) ->
          <stdout>  +:=  concatenation of elements of L
          stop execution ]
    """
    print string.join ( L, "")
    sys.exit(1)

# - - -   c o u n t e r . p y   - -   m a i n   - - - - -

#--
# Retrieve the command line argument, which should be the file
# name, and open the file if possible.  If not, assume the
# counter is zero.
#--

argList=sys.argv[1:]

if len(argList) != 1:
  Error ( "Page programming error: the #exec command must provide "
          "a file name argument.")

fileName  =  argList[0]

try:
    f = open ( fileName )
    line = string.rstrip(f.readline())

    try:
        counter = string.atoi(line)
    except ValueError:
        counter = 0

    f.close()
except IOError:
    counter = 0

#--
# Add one, rewrite the file (if possible), and output the new value.
#-- 

counter  =  counter + 1
if  counter == 1: suffix=""
else:             suffix="s"
print "This page has been hit %d time%s." % (counter, suffix)

try:
    f = open ( fileName, "w" )
    f.write ( "%d\n" % counter )
except IOError:
    Error ( "Can't open the counter file `%s' for writing." % fileName )