src/core/packages/xml.sgl

1;;; XML and HTML parsing.

2;;;

3;;; libxml2 is what gives Emacs `libxml-parse-html-region`, and therefore shr

4;;; and eww. Built static and deliberately narrow: no Python bindings, no

5;;; loadable modules, and no HTTP client, because Emacs uses libxml2 purely as

6;;; a parser and its network stack is its own.

7;;;

8;;; It also carries the channel's first patch, and the reason is worth reading

9;;; before touching it -- see the note beside the `patch` phase.

10(define-library (core packages xml)

11 (import (sigil core)

12 (core build-environments)

13 (sigil env package)

14 (sigil build external))

15 (export libxml2 expat)

16 (begin

17 (define libxml2

18 (package

19 name: "libxml2"

20 version: "2.13.5"

21 source: (external-source

22 location: "https://download.gnome.org/sources/libxml2/2.13/libxml2-2.13.5.tar.xz"

23 sha256: "74fc163217a3964257d3be39af943e08861263c4231f9ef5b496b6f6d4c7b2b6")

24 buildenv: core-buildenv

25 phases: (list

26 ;; WHY THIS PATCH EXISTS. The pinned seed's pkgconf 1.9.5

27 ;; ABORTS (SIGABRT, a Zig pointer-overflow panic) on any .pc

28 ;; file carrying an EMPTY dependency-list field, and libxml2

29 ;; installs `Requires:` empty because it is built

30 ;; --without-zlib. Emacs finds libxml2 through

31 ;; PKG_CHECK_MODULES, which runs `pkg-config --exists` and

32 ;; reads ANY non-zero status as "not present" -- so a

33 ;; crashing tool impersonates a calm, plausible absence and

34 ;; configure still exits 0. That is how the port build lost

35 ;; libxml2 with no error and no warning.

36 ;;

37 ;; Measured against the seed's own pkg-config, both

38 ;; directions: with the empty `Requires:` line,

39 ;; `pkg-config --exists libxml-2.0` exits 134 with the panic;

40 ;; with the line deleted it exits 0 and `--cflags --libs`

41 ;; returns exactly what Emacs needs.

42 ;;

43 ;; This patch deletes the line from the TEMPLATE, before

44 ;; configure substitutes it, so no empty field is ever

45 ;; generated. It fixes libxml2 only. The general fix is a

46 ;; seed re-pin onto a pkgconf past the bug

47 ;; (investigations/seed-pkgconf-empty-field-abort), which is

48 ;; still owed -- gnutls' closure will hit the same wall.

49 (external-phase

50 kind: 'patch

51 patches: (list

52 (channel-patch

53 path: "patches/libxml2-pc-drop-empty-requires.patch"

54 sha256: "386f08e511d8f45fd649aacc2a55c7fcd52bdbc9ed11fac8fc613aa63eebf441")))

55 (external-phase

56 kind: 'configure

57 args: (list "--prefix=${out}"

58 "--disable-shared"

59 "--enable-static"

60 "--without-python"

61 "--without-lzma"

62 "--without-zlib"

63 "--without-http"

64 "--without-modules"))

65 (external-phase kind: 'make)

66 (external-phase kind: 'install))))

67

68 ;; expat, the OTHER XML parser in this channel, and it is here rather than

69 ;; folded into libxml2's consumers because two different packages ask for

70 ;; it by name through pkg-config: libwayland (for wayland-scanner, which

71 ;; parses the protocol XML) and fontconfig (for fonts.conf). Neither can

72 ;; use libxml2 instead.

73 ;;

74 ;; MUST SHIP A `.pc` FILE, and this is not incidental. Both consumers find

75 ;; it through PKG_CHECK_MODULES, and a dependency that is found by header

76 ;; probe instead of by pkg-config is how `core/ncurses` poisoned tmux's

77 ;; entire configure -- a probe that tested a header and concluded about a

78 ;; library. expat's autotools build installs `expat.pc` by default; that

79 ;; is asserted below rather than assumed, because "it installs one by

80 ;; default" is exactly the kind of belief that turns out to be false after

81 ;; a build cycle.

82 (define expat

83 (package

84 name: "expat"

85 version: "2.7.1"

86 source: (external-source

87 location: "https://github.com/libexpat/libexpat/releases/download/R_2_7_1/expat-2.7.1.tar.xz"

88 sha256: "354552544b8f99012e5062f7d570ec77f14b412a3ff5c7d8d0dae62c0d217c30")

89 buildenv: core-buildenv

90 phases: (list

91 (external-phase

92 kind: 'configure

93 args: (list "--prefix=${out}"

94 "--disable-shared"

95 "--enable-static"

96 ;; xmlwf is a command-line tool no consumer

97 ;; here uses, and the examples and tests are

98 ;; build-time only.

99 "--without-xmlwf"

100 "--without-examples"

101 "--without-tests"

102 "--without-docbook"))

103 (external-phase kind: 'make)

104 (external-phase kind: 'install)

105 ;; ASSERT THE `.pc` RATHER THAN TRUST IT. If a future expat

106 ;; stops installing one, the failure without this check is

107 ;; not "expat is broken" -- it is fontconfig or wayland

108 ;; quietly configuring itself differently, three packages

109 ;; downstream, with configure still exiting 0.

110 (external-phase

111 kind: 'run

112 args: (list "sh" "-c"

113 (string-append

114 "set -eu\n"

115 "d=\"$(dirname \"$PWD\")/install-root\"\n"

116 "test -f \"$d${out}/lib/pkgconfig/expat.pc\"\n"

117 "echo EXPAT-PC-PRESENT\n"))))))))