scripts/check-variable-fonts.sh

   1 #!/bin/sh
   2 # SPDX-License-Identifier: GPL-2.0-only
   3 # Copyright (C) Akira Yokosawa, 2024
   4 #
   5 # For "make pdfdocs", reports of build errors of translations.pdf started
   6 # arriving early 2024 [1, 2].  It turned out that Fedora and openSUSE
   7 # tumbleweed have started deploying variable-font [3] format of "Noto CJK"
   8 # fonts [4, 5].  For PDF, a LaTeX package named xeCJK is used for CJK
   9 # (Chinese, Japanese, Korean) pages.  xeCJK requires XeLaTeX/XeTeX, which
  10 # does not (and likely never will) understand variable fonts for historical
  11 # reasons.
  12 #
  13 # The build error happens even when both of variable- and non-variable-format
  14 # fonts are found on the build system.  To make matters worse, Fedora enlists
  15 # variable "Noto CJK" fonts in the requirements of langpacks-ja, -ko, -zh_CN,
  16 # -zh_TW, etc.  Hence developers who have interest in CJK pages are more
  17 # likely to encounter the build errors.
  18 #
  19 # This script is invoked from the error path of "make pdfdocs" and emits
  20 # suggestions if variable-font files of "Noto CJK" fonts are in the list of
  21 # fonts accessible from XeTeX.
  22 #
  23 # References:
  24 # [1]: https://lore.kernel.org/r/8734tqsrt7.fsf@meer.lwn.net/
  25 # [2]: https://lore.kernel.org/r/1708585803.600323099@f111.i.mail.ru/
  26 # [3]: https://en.wikipedia.org/wiki/Variable_font
  27 # [4]: https://fedoraproject.org/wiki/Changes/Noto_CJK_Variable_Fonts
  28 # [5]: https://build.opensuse.org/request/show/1157217
  29 #
  30 #===========================================================================
  31 # Workarounds for building translations.pdf
  32 #===========================================================================
  33 #
  34 # * Denylist "variable font" Noto CJK fonts.
  35 #   - Create $HOME/deny-vf/fontconfig/fonts.conf from template below, with
  36 #     tweaks if necessary.  Remove leading "# ".
  37 #   - Path of fontconfig/fonts.conf can be overridden by setting an env
  38 #     variable FONTS_CONF_DENY_VF.
  39 #
  40 #     * Template:
  41 # -----------------------------------------------------------------
  42 # <?xml version="1.0"?>
  43 # <!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
  44 # <fontconfig>
  45 # <!--
  46 #   Ignore variable-font glob (not to break xetex)
  47 # -->
  48 #     <selectfont>
  49 #         <rejectfont>
  50 #             <!--
  51 #                 for Fedora
  52 #             -->
  53 #             <glob>/usr/share/fonts/google-noto-*-cjk-vf-fonts</glob>
  54 #             <!--
  55 #                 for openSUSE tumbleweed
  56 #             -->
  57 #             <glob>/usr/share/fonts/truetype/Noto*CJK*-VF.otf</glob>
  58 #         </rejectfont>
  59 #     </selectfont>
  60 # </fontconfig>
  61 # -----------------------------------------------------------------
  62 #
  63 #     The denylisting is activated for "make pdfdocs".
  64 #
  65 # * For skipping CJK pages in PDF
  66 #   - Uninstall texlive-xecjk.
  67 #     Denylisting is not needed in this case.
  68 #
  69 # * For printing CJK pages in PDF
  70 #   - Need non-variable "Noto CJK" fonts.
  71 #     * Fedora
  72 #       - google-noto-sans-cjk-fonts
  73 #       - google-noto-serif-cjk-fonts
  74 #     * openSUSE tumbleweed
  75 #       - Non-variable "Noto CJK" fonts are not available as distro packages
  76 #         as of April, 2024.  Fetch a set of font files from upstream Noto
  77 #         CJK Font released at:
  78 #           https://github.com/notofonts/noto-cjk/tree/main/Sans#super-otc
  79 #         and at:
  80 #           https://github.com/notofonts/noto-cjk/tree/main/Serif#super-otc
  81 #         , then uncompress and deploy them.
  82 #       - Remember to update fontconfig cache by running fc-cache.
  83 #
  84 # !!! Caution !!!
  85 #     Uninstalling "variable font" packages can be dangerous.
  86 #     They might be depended upon by other packages important for your work.
  87 #     Denylisting should be less invasive, as it is effective only while
  88 #     XeLaTeX runs in "make pdfdocs".
  89
  90 # Default per-user fontconfig path (overridden by env variable)
  91 : ${FONTS_CONF_DENY_VF:=$HOME/deny-vf}
  92
  93 export XDG_CONFIG_HOME=${FONTS_CONF_DENY_VF}
  94
  95 notocjkvffonts=`fc-list : file family variable | \
  96                 grep 'variable=True' | \
  97                 grep -E -e 'Noto (Sans|Sans Mono|Serif) CJK' | \
  98                 sed -e 's/^/    /' -e 's/: Noto S.*$//' | sort | uniq`
  99
 100 if [ "x$notocjkvffonts" != "x" ] ; then
 101         echo '============================================================================='
 102         echo 'XeTeX is confused by "variable font" files listed below:'
 103         echo "$notocjkvffonts"
 104         echo
 105         echo 'For CJK pages in PDF, they need to be hidden from XeTeX by denylisting.'
 106         echo 'Or, CJK pages can be skipped by uninstalling texlive-xecjk.'
 107         echo
 108         echo 'For more info on denylisting, other options, and variable font, see header'
 109         echo 'comments of scripts/check-variable-fonts.sh.'
 110         echo '============================================================================='
 111 fi
 112
 113 # As this script is invoked from Makefile's error path, always error exit
 114 # regardless of whether any variable font is discovered or not.
 115 exit 1