# $Id: DependenceVerify,v 1.2 2003/03/04 06:16:27 wychen Exp $
###########################################################################
#         Copyright (c) 1990, 1991, 1992, 1993, 1994 Rice University
#                            All Rights Reserved
###########################################################################

###########################################################################
#                                                                         #
#  File:    DependenceVerify                                              #
#  Author:  Kevin Cureton                                                 #
#           Taken from verifydepends.C by John Mellor-Crummey             #
#                                                                         #
###########################################################################
#                                                                         #
#   Process a list of files containing compilation dependences.           #
#                                                                         #
#   Each file contains a list of dependences and a list of files          #
#   that would shadow the dependents.                                     #
#                                                                         #
#   for each DEP file                                                     #
#   {                                                                     #
#     if a dependent does not exist or is newer than a DEP file           #
#     citing it, remove the DEP file                                      #
#                                                                         #
#     if a nearer file exists, remove the DEP file citing it              #
#   }                                                                     #
#                                                                         #
###########################################################################

###########################################################################
#
# Set the needed environment variables
#
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     # get the command line arguments
  @depend_files = split(/\s/, $ARGV[0]);


     # check each of the dependence files for dpendency changes
  DO_FILES: for $depend_file (@depend_files)
  {
     next DO_FILES if (! -e $depend_file);

     @stat_buffer = stat($depend_file);

     $last_mod_time = $stat_buffer[9];

     $has_a_dependence = "false";

     open(DEPEND_FILE, $depend_file);
        
        # check to see if the file is empty and if it is delete it
     if (eof(DEPEND_FILE) == 1)
     {
        close(DEPEND_FILE);
        unlink($depend_file);
        next DO_FILES;
     }

        # begin reading the dependencies from the file and check them
     READ_FILE: while (<DEPEND_FILE>)
     {
        next READ_FILE if /^\n$/;

        #---------------------------------------------------
        # check the dependences for the file
        # if they don't exist or if they are newer than the 
        # dependence file, remove the dependence file
        #---------------------------------------------------
        if (/^# dependences.*\n/)
        {
           READ_DEPENDS: while (<DEPEND_FILE>)
           {
              next READ_DEPENDS if /^\n$/;
              last READ_DEPENDS if /^# files.*\n/;

              $has_a_dependence = "true";

              $current_file = $_; 
              $current_file =~ s/\n$//;

              if (! -e $current_file)
              {
                 close(DEPEND_FILE);
                 unlink($depend_file);
                 next DO_FILES;
              }

              @file_stat = stat($current_file);

              $file_last_mod_time = $file_stat[9];

              if ($file_last_mod_time > $last_mod_time)
              {
                 close(DEPEND_FILE);
                 unlink($depend_file);
                 next DO_FILES;
              }
           }
        }

        #---------------------------------------------------
        # if there are no dependences in the file, it is a bogus file
        # so delete it.
        #---------------------------------------------------
        if ($has_a_dependence eq "false")
        {
           close(DEPEND_FILE);
           unlink($depend_file); 
           last READ_FILE;
        }

     }

     close(DEPEND_FILE);
  }