#!/usr/bin/perl -w
# Read a module description file and derive the set of files
# included directly by any .c or .h file listed in the `Files:' section.
# Take the union of all such sets for any dependent modules.
# Then, compare that set with the set derived from the names
# listed in the various Files: sections.

# This script makes no attempt to diagnose invalid or empty
# module-description files.

# Written by Jim Meyering

use strict;
use Getopt::Long;
#use Coda;

(my $VERSION = '$Revision: 1.1 $ ') =~ tr/[0-9].//cd;
(my $ME = $0) =~ s|.*/||;

use constant ST_INIT => 1;
use constant ST_FILES => 2;
use constant ST_DEPENDENTS => 3;

# Parse a module file (returning list of Files: names and
# list of dependent-modules.
# my ($file, $dep) = parse_module_file $module_file;
sub parse_module_file ($)
{
  my ($module_file) = @_;

  open FH, '<', $module_file
    or die "$ME: can't open `$module_file' for reading: $!\n";

  my %file_set;
  my %dep_set;

  my $state = ST_INIT;
  while (defined (my $line = <FH>))
    {
      if ($state eq ST_INIT)
	{
	  if ($line =~ /^Files:$/)
	    {
	      $state = ST_FILES;
	    }
	  elsif ($line =~ /^Depends-on:$/)
	    {
	      $state = ST_DEPENDENTS;
	    }
	}
      else
	{
	  chomp $line;
	  $line =~ s/^\s+//;
	  $line =~ s/\s+$//;
	  if ( ! $line)
	    {
	      $state = ST_INIT;
	      next;
	    }

	  if ($state eq ST_FILES)
	    {
	      $file_set{$line} = 1;
	    }
	  elsif ($state eq ST_DEPENDENTS)
	    {
	      $dep_set{$line} = 1;
	    }
	}
    }
  close FH;

  # my @t = sort keys %file_set;
  # print "files: @t\n";
  # my @u = sort keys %dep_set;
  # print "dependents: @u\n";

  return (\%file_set, \%dep_set);
}

# Extract the set of files required for this module, including
# those required via dependent modules.

# Files:
# lib/stat.c
# m4/stat.m4
# lib/foo.h
#
# Depends-on:
# some-other-module

sub usage ($)
{
  my ($exit_code) = @_;
  my $STREAM = ($exit_code == 0 ? *STDOUT : *STDERR);
  if ($exit_code != 0)
    {
      print $STREAM "Try `$ME --help' for more information.\n";
    }
  else
    {
      print $STREAM <<EOF;
Usage: $ME [OPTIONS] FILE...

Read a module description file and derive the set of files
included directly by any .c or .h file listed in the `Files:' section.
Take the union of all such sets for any dependent modules.
Then, compare that set with the set derived from the names
listed in the various Files: sections.

OPTIONS:

   --help             display this help and exit
   --version          output version information and exit

EOF
    }
  exit $exit_code;
}

sub find_included_lib_files ($)
{
  my ($file) = @_;

  # Special cases...
  my %special_non_dup = ( 'fnmatch_loop.c' => 1, 'regex.c' => 1 );

  my %inc;
  open FH, '<', $file
    or die "$ME: can't open `$file' for reading: $!\n";

  while (defined (my $line = <FH>))
    {
      # Ignore test-driver code at end of file.
      $line =~ m!^\#if(def)? TEST_!
	and last;

      $line =~ m!^\s*\#\s*include\s+"!
	or next;
      $line =~ s///;
      chomp $line;
      $line =~ s/".*//;
      exists $inc{$line} && ! exists $special_non_dup{$line}
	and warn "$ME: $file: duplicate inclusion of $line\n";

      # Some known exceptions.
      $file =~ /\bfull-write\.c$/ && $line eq 'full-read.h'
	and next;
      $file =~ /\bsafe-read.c$/ && $line eq 'safe-write.h'
	and next;
      $file =~ /\bhash\.c$/ && $line eq 'obstack.h'
	and next;

      $inc{$line} = 1;
    }
  close FH;

  return \%inc;
}

{
  GetOptions
    (
     help => sub { usage 0 },
     version => sub { print "$ME version $VERSION\n"; exit },
    ) or usage 1;

  @ARGV < 1
    and (warn "$ME: missing FILE argument\n"), usage 1;

  my %file;
  my %module_all_files;
  my %dep;
  my %seen_module;

  my @m = $ARGV[0];

  while (@m)
    {
      my $m = pop @m;
      # warn "M: $m\n";
      exists $seen_module{$m}
	and next;
      $seen_module{$m} = 1;
      my ($file, $dep) = parse_module_file $m;
      push @m, keys %$dep;
      foreach my $f (keys %$file)
	{
	  $module_all_files{$f} = 1;
	}
    }

  my %exempt_header =
    (
     # Exempt headers like unlocked-io.h that are `#include'd
     # but not necessarily used.
     'unlocked-io.h' => 1,

     # Give gettext.h a free pass only when included from lib/error.c,
     # since that we've made that exception solely to make the error
     # module easier to use -- at RMS's request.
     'lib/error.c:gettext.h' => 1,
    );

  my @t = sort keys %module_all_files;
  # warn "ALL files: @t\n";

  # Derive from %module_all_files (by parsing the .c and .h files therein),
  # the list of all #include'd files that reside in lib/.
  foreach my $f (keys %module_all_files)
    {
      $f =~ /\.[ch]$/
	or next;
      # FIXME: this is too naive
      my $inc = find_included_lib_files "../$f";
      foreach my $i (sort keys %$inc)
	{
	  my $lib_file = "lib/$i";
	  exists $exempt_header{"$f:$i"}
	    || exists $exempt_header{$i}
	      and next;
	  !exists $module_all_files{$lib_file} && -f "../lib/$i"
	    and warn "$f: $i is `#include'd, but not "
	      . "listed in module's Files: section\n";
	}
      #my @t = sort keys %$inc;
      #print "** $f: @t\n";
    }

  exit 0;
}