#!/bin/sh
#
# Copyright (C) 2019 Free Software Foundation, Inc.
#
# 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; either version 3 of the License, or
# (at your option) any later version.
#
# 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
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.
#

# This script checks whether the files in the GNU gettext package
# have the required copyright headers resp. license notices.
#
# Copyright notices have two purposes:
#
#  1. They tell the people who obtain the package (as a git checkout,
#     source tarball, or binary package) what they are allowed to do
#     with it.
#
#  2. They provide the legal basis for suing people who infringe on
#     the copyright of the package (or part of it).  In particular,
#     they should prove that the infringer knew what they were doing
#     when they took a source file (or part of it) and used it in
#     a way that is not compliant with the license.
#
# For the purpose 1, a file COPYING at the top-level of the package
# and a reference to it in the main README are all that's needed.
#
# For the purpose 2, we put copyright notices in each file that we
# don't want to be abused of. See also the section "Copyright Notices"
# in the 'Information for maintainers of GNU software',
# <https://www.gnu.org/prep/maintain/html_node/Copyright-Notices.html>.
#
# This script helps with purpose 2.  The input of this script is a
# source tarball, not a git checkout.  Rationale:
# - It is convenient to add files to a git repository, without having
#   to attach a copyright notice to it.
# - Files that we don't include in the source tarball are not so valuable
#   that we would like to sue infringers over them.
#
# We classify the files in several categories:
# - Source code that ends up being executed by end users (in source or
#   compiled form).  This is the most valuable one and needs copyright
#   notices.
# - Source of large documentation.  This is valuable too, and needs
#   copyright notices.
# - Source code of build infrastructure.
# - Files that contain convenience information for programmers and
#   packagers.
# The latter categories are not valuable enough to warrant sueing
# infringers.
#
# Not all files qualify for a copyright header.  Namely, since copyright
# applies to the expression of an idea (think roughly of the program as
# an art work), it makes no sense to attach a copyright header to a file
# which different programmers would write in the same way.  This includes
# tiny files, as well as files that contain only machine-generated data.

# Usage: check-copyright-headers UNPACKED-GETTEXT-TARBALL

progname="$0"

if test $# != 1; then
  echo "Usage: check-copyright-headers UNPACKED-GETTEXT-TARBALL" 1>&2
  exit 1
fi

dir="$1"
test -d "$dir" || {
  echo "*** $progname: '$dir' is not a directory." 1>&2
  exit 1
}
if test -d "$dir/.git"; then
  echo "*** $progname: '$dir' is a git checkout, not an unpacked tarball." 1>&2
  exit 1
fi

# func_check_file FILE
# checks FILE, a relative file name.
# Return code: 0 if OK, 1 if missing a copyright header.
func_check_file ()
{
  case "/$1" in

    */tests/* | *-tests/* )
      # A test file.
      # We are not interested in suing infringers of test code.
      # In fact, anyone can apply our test suites to even prorietary software.
      # And this is even welcome (regarding the competing implementations of
      # the libintl functions), because it helps in portability of software
      # that uses the libintl API.
      return 0 ;;

    */modules/* )
      # Gnulib modules are not valuable enough to warrant suing infringers.
      # Also, they often don't have much programmer expression.
      return 0 ;;

    /gettext-tools/doc/ISO_3166 | /gettext-tools/doc/ISO_3166_de | \
    /gettext-tools/doc/ISO_639 | /gettext-tools/doc/ISO_639-2 | \
    /gettext-tools/examples/hello-*/m4/Makefile.am | \
    /gettext-tools/examples/hello-objc-gnustep/po/LocaleAliases )
      # These are a mostly data.  They don't have much programmer expression.
      return 0 ;;

    */ChangeLog* )
      # ChangeLog files are convenience information, not worth sueing for.
      return 0 ;;

    */AUTHORS | */COPYING* | */DEPENDENCIES | */FILES | */HACKING | \
    */INSTALL* | */NEWS | */PACKAGING | */README* | */THANKS )
      # These files contain convenience information, not worth sueing for.
      return 0 ;;

    /os2/* )
      # Old stuff, not worth sueing for.
      return 0 ;;

    */libcroco/* | */libxml/* )
      # We repackage libcroco and libxml as sources and are not interested
      # in attaching our own copyright header to each.
      return 0 ;;

    /gettext-tools/examples/hello-*-gnome/m4/*.m4 | \
    /gettext-tools/projects/GNOME/teams.html )
      # These files come from the GNOME project.
      # We are not interested in attaching our own copyright header to each.
      return 0 ;;

    /gettext-tools/examples/hello-*-kde/admin/* | \
    /gettext-tools/projects/KDE/teams.html )
      # These files come from the KDE project.
      # We are not interested in attaching our own copyright header to each.
      return 0 ;;

    /gettext-tools/examples/hello-*-wxwidgets/m4/wxwidgets.m4 )
      # These files come from the wxwidgets project.
      # We are not interested in attaching our own copyright header to each.
      return 0 ;;

    /gettext-tools/projects/TP/teams.html )
      # These files come from the translationproject.org project.
      # We are not interested in attaching our own copyright header to each.
      return 0 ;;

    /gettext-tools/misc/DISCLAIM )
      # This is a form, used for communication with the FSF.
      return 0 ;;

    /gettext-tools/misc/archive.dir.tar )
      # This is an archive of files that were part of earlier gettext releases.
      # As a binary file, it cannot have a copyright header.
      return 0 ;;

    *.gmo )
      # These are binary files. FOO.gmo is generated from FOO.po, which is
      # also distributed.
      return 0 ;;

    *.class )
      # These are binary files. FOO.class is generated from FOO.java, which is
      # also distributed.
      return 0 ;;

    /gettext-runtime/intl-csharp/doc/* | \
    /gettext-runtime/intl-java/javadoc2/* | \
    /gettext-runtime/doc/matrix.texi | \
    /gettext-tools/doc/iso-639.texi | /gettext-tools/doc/iso-639-2.texi | \
    /gettext-tools/doc/iso-3166.texi | \
    */man/*.[13].html | \
    */*_[0-9].html | */*_[0-9][0-9].html | \
    */*_all.html | */*_toc.html | */*_fot.html | */*_abt.html | \
    *.priv.h | *.vt.h | \
    /libtextstyle/lib/libtextstyle.sym.in )
      # These are generated files.  We ship their sources as well.
      return 0 ;;

    *.diff )
      # These are patches to existing files.  It is understood that the patch
      # preserves the copyright status of the file, that is, that the .diff
      # file delegates its copyright status to the file.
      return 0 ;;

    */quot.sed | */boldquot.sed | */en@quot.header | */en@boldquot.header )
      if test -f "$dir"/`dirname "$1"`/Rules-quot; then
        # These files are covered by the notice in the Rules-quot file in the
        # same directory.
        return 0
      fi
      ;;

    /gettext-tools/libgrep/kwset.c )
      # The file has a copyright header, with the Copyright line spread
      # across two lines.
      return 0 ;;

    */texinfo.tex )
      # The file has a copyright header, with the Copyright line spread
      # across three lines.
      return 0 ;;

    *.texi )
      if head -n 100 "$dir/$1" | LC_ALL=C grep 'Copyright ([Cc]) ' >/dev/null; then
        # The file has a copyright notice, although not exactly at the beginning.
        return 0
      fi
      ;;

    *.rc )
      if LC_ALL=C grep 'This program is free software[:;] you can redistribute it' "$dir/$1" >/dev/null \
         || LC_ALL=C grep 'This library is free software[:;] you can redistribute it' "$dir/$1" >/dev/null; then
        # The file carries a copyright notice in it.
        return 0
      fi
      ;;

  esac

  if head -n 15 "$dir/$1" | LC_ALL=C grep 'Copyright ([Cc]) ' >/dev/null; then
    # The file has a copyright header.
    return 0
  fi

  # <https://www.gnu.org/prep/maintain/html_node/Copyright-Notices.html>
  # says that the (C) "can be omitted entirely; the word ‘Copyright’ suffices.
  if head -n 15 "$dir/$1" | LC_ALL=C grep 'Copyright .* Free Software Foundation' >/dev/null; then
    # The file has a copyright header.
    return 0
  fi

  # <https://www.gnu.org/prep/maintain/html_node/Copyright-Notices.html>
  # says " If a file has been explicitly placed in the public domain, then
  # instead of a copyright notice, it should have a notice saying explicitly
  # that it is in the public domain."
  if head -n 15 "$dir/$1" | LC_ALL=C grep 'This .* is in the public domain\.' >/dev/null \
     || head -n 15 "$dir/$1" | LC_ALL=C fgrep 'In the public domain.' >/dev/null \
     || head -n 15 "$dir/$1" | LC_ALL=C fgrep 'Public domain.' >/dev/null \
     || head -n 15 "$dir/$1" | LC_ALL=C fgrep 'public-domain implementation' >/dev/null; then
    # The file has a public domain notice.
    return 0
  fi

  if head -n 15 "$dir/$1" | LC_ALL=C fgrep 'This file is distributed under the same license as ' >/dev/null; then
    # The file has a notice that delegates to another copyright notice.
    return 0
  fi

  if head -n 1 "$dir/$1" | LC_ALL=C fgrep 'Generated from configure.ac by autoheader.' >/dev/null \
     || head -n 1 "$dir/$1" | LC_ALL=C fgrep 'code produced by gperf version' >/dev/null \
     || head -n 1 "$dir/$1" | LC_ALL=C fgrep 'Creator     : groff version' >/dev/null \
     || head -n 1 "$dir/$1" | LC_ALL=C fgrep 'DO NOT MODIFY THIS FILE!  It was generated by help2man' >/dev/null \
     || head -n 3 "$dir/$1" | LC_ALL=C fgrep 'Generated automatically by gen-uni-tables.c for Unicode' >/dev/null \
     || head -n 6 "$dir/$1" | LC_ALL=C fgrep 'Generated automatically by the gen-uninames utility.' >/dev/null; then
    # These are generated files.  We ship their sources as well.
    return 0
  fi

  if test `LC_ALL=C wc -l < "$dir/$1"` -le 8; then
    # The file has very few lines.
    # It thus doesn't have much programmer expression.
    return 0
  fi

  return 1
}

fail=false
for file in `cd "$dir" && find . -type f -print | sed -e 's,^[.]/,,' | LC_ALL=C sort`; do
  func_check_file "$file" || {
    echo "*** Missing copyright header in file $file" 1>&2
    fail=true
  }
done

if $fail; then
  exit 1
else
  exit 0
fi