src/core/packages/viewer.sgl

1;;; Image viewing.

2;;;

3;;; PROVENANCE: THE SAME SCOPED EXCEPTION AS `core/luajit`, AND FOR THE SAME

4;;; REASON. swayimg publishes NO release assets -- only GitHub's

5;;; auto-generated source archive, which is what every distribution pins. A

6;;; synthetic archive whose bytes can be regenerated does not belong on the

7;;; critical path of a chain intended to SHIP.

8;;;

9;;; This is not that. `core/swayimg` and `core/luajit` exist as a DISCOVERY

10;;; EXERCISE whose product is knowledge about what this packaging model can

11;;; host -- where the blind spots are -- rather than a published dependency.

12;;; Two auto-generated archives are acceptable for that purpose and would not

13;;; be acceptable for a shipped chain. NEITHER PACKAGE SHOULD BE PUBLISHED OR

14;;; SIGNED ON THIS PROVENANCE WITHOUT REVISITING THE QUESTION.

15;;;

16;;; AND A CONCRETE DEMONSTRATION OF WHY, MET WHILE WRITING THIS PACKAGE.

17;;; The first build refused:

18;;;

19;;; REFUSING source sha256 mismatch; expected 64ae8713... actual f84fec72...

20;;;

21;;; That was my error -- I hashed one URL and pinned another -- but the reason

22;;; the two hashes differ is the point. GitHub serves the SAME TAG from two

23;;; endpoints and they are not the same artifact:

24;;;

25;;; api.github.com/repos/OWNER/REPO/tarball/TAG -> artemsen-swayimg-682fecf/

26;;; codeload.github.com/OWNER/REPO/tar.gz/TAG -> swayimg-5.5/

27;;;

28;;; Identical CONTENT once the prefix is stripped -- verified by extracting

29;;; both and diffing -- but a different embedded top-level directory name, so

30;;; different bytes and different hashes. Each endpoint is individually

31;;; stable (the api one was fetched twice and matched), so this is not

32;;; regeneration. It is that THERE IS NO SINGLE CANONICAL BYTE STREAM for a

33;;; tag that ships no release artifact.

34;;;

35;;; A real dist tarball has one answer to "what are the bytes". This has two,

36;;; and nothing upstream declares which is meant. That is the argument

37;;; against synthetic archives stated more precisely than "they can change".

38;;;

39;;; WHAT IT COST, which is the interesting number: ONE new library, and that

40;;; one is LuaJIT. Every other dependency swayimg has -- libxkbcommon,

41;;; fontconfig, freetype, wayland, wayland-protocols, libpng -- already existed

42;;; because foot needed them. The Wayland half of this channel turns out to be

43;;; reusable rather than foot-shaped, which is the same thing `core/grim`

44;;; demonstrated and is worth more than either program.

45(define-library (core packages viewer)

46 (import (sigil core)

47 (core build-environments)

48 (core packages compression)

49 (core packages xml)

50 (core packages ffi)

51 (core packages graphics)

52 (core packages fonts)

53 (core packages wayland)

54 (core packages input)

55 (core packages luajit)

56 (core packages build-tools)

57 (core packages python)

58 (sigil env package)

59 (sigil build external))

60 (export swayimg)

61 (begin

62 ;; LUAJIT IS NOT OPTIONAL, and it is LuaJIT rather than Lua.

63 ;; meson.build:38 is `dependency('luajit')` under a comment reading

64 ;; `# mandatory dependencies`, with no `required:` kwarg and no

65 ;; corresponding entry in meson.options. An earlier estimate of this

66 ;; package's cost read `dependency(get_option('liblua'))` from upstream

67 ;; MASTER and concluded plain Lua would do; the RELEASE hardcodes luajit.

68 ;; Read the version you are packaging, not the branch.

69 ;;

70 ;; expat, zlib, libffi and freetype are declared although swayimg names

71 ;; none of them: they are reached through the `Requires:` and

72 ;; `Requires.private:` chains of fontconfig.pc, freetype2.pc, libpng.pc and

73 ;; wayland-client.pc, and this channel composes PKG_CONFIG_PATH from DIRECT

74 ;; dependencies only. The union was printed from the store before writing

75 ;; this line rather than discovered one build failure at a time.

76 ;; [[topics/core-channel-pkgconfig-is-not-transitive]]

77 (define swayimg

78 (package

79 name: "swayimg"

80 version: "5.5"

81 source: (external-source

82 location: "https://codeload.github.com/artemsen/swayimg/tar.gz/v5.5"

83 sha256: "f84fec722cd0b4cfd86d0a8a820b15a95bbdb1d2cfcded7f67446a7a0c1d1c09")

84 buildenv: core-buildenv

85 dependencies: (list libxkbcommon fontconfig freetype wayland

86 wayland-protocols libpng luajit

87 expat zlib libffi)

88 ;; SWAYIMG IS A C++ PROJECT, AND I MISSED THAT WHEN SCOPING IT.

89 ;;

90 ;; `meson.build:3` is `project('swayimg', 'c', 'cpp', ...)` with

91 ;; `cpp_std=c++20` and roughly thirty `.cpp` sources. My scoping pass

92 ;; enumerated every `dependency()` call carefully and never read the

93 ;; `project()` line, so the estimate said "one new package, LuaJIT" when

94 ;; the truth is one new package AND a C++ toolchain requirement. The

95 ;; libraries were right; the LANGUAGE was not looked at.

96 ;;

97 ;; The failure is loud and names itself, at least:

98 ;;

99 ;; meson.build:3:0: ERROR: Unknown compiler(s):

100 ;; [['c++'], ['g++'], ['clang++'], ['nvc++'], ['pgc++'], ...]

101 ;;

102 ;; meson probes for a C++ compiler BY NAME and the toolchain ships

103 ;; none, so it falls through every candidate. `CXX` is not

104 ;; builder-owned -- the refusal list is derived from what the builder

105 ;; emits and it emits no C++ assignment -- so a package may declare

106 ;; one, and meson honours `CXX` for the cpp language. This is the same

107 ;; mechanism `core/gperf` uses and the second package in the channel to

108 ;; need it. The explicit `-target` is required by the zig guard.

109 env: (list (cons "CXX" "zig c++ -target x86_64-linux-musl"))

110 build-inputs: (list meson samurai python)

111 phases: (list

112 (external-phase

113 kind: 'run

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

115 (string-append

116 "set -eu\n"

117 "meson setup build"

118 " --prefix=${out}"

119 " --buildtype=plain"

120 " --default-library=static"

121 ;; fontconfig.pc carries `Requires.private: expat`,

122 ;; and swayimg links an executable, so the static

123 ;; pkg-config query is required or the link fails

124 ;; on XML_* symbols. Same lesson as foot.

125 " -Dprefer_static=true"

126 ;; PNG only. Every other decoder is a feature

127 ;; option defaulting to `auto`, which would make

128 ;; the output depend on what happened to be

129 ;; visible -- the thing this channel exists to

130 ;; prevent. Turning them off explicitly is what

131 ;; makes the result a function of the declared

132 ;; inputs.

133 " -Dpng=enabled"

134 " -Dexr=disabled -Dgif=disabled -Dheif=disabled"

135 " -Davif=disabled -Djpeg=disabled -Djp2=disabled"

136 " -Djxl=disabled -Dsvg=disabled -Dtiff=disabled"

137 " -Dsixel=disabled -Draw=disabled -Dwebp=disabled"

138 " -Dexif=disabled"

139 ;; Wayland yes, DRM no: the DRM backend wants

140 ;; libdrm and a console, and the acceptance case

141 ;; is a Wayland compositor.

142 " -Dwayland=enabled -Ddrm=disabled"

143 ;; Completions want bash-completion and zsh; the

144 ;; man page wants scdoc. None is packaged and

145 ;; none is read by anything here.

146 " -Dbash=disabled -Dzsh=disabled"

147 " -Dman=false -Ddoc=false -Ddesktop=false"

148 " -Dluameta=false"

149 ;; The version option exists because swayimg

150 ;; otherwise derives it from `git`, which is not

151 ;; in the seed and would leave it at 0.0.0.

152 " -Dversion=5.5\n"

153 "echo SWAYIMG-CONFIGURED\n")))

154 (external-phase

155 kind: 'run

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

157 (string-append

158 "set -eu\n"

159 "meson compile -C build\n"

160 "echo SWAYIMG-COMPILED\n")))

161 (external-phase

162 kind: 'run

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

164 (string-append

165 "set -eu\n"

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

167 "DESTDIR=\"$d\" meson install -C build --no-rebuild\n"

168 "test -x \"$d${out}/bin/swayimg\"\n"

169 ;; ASSERT PNG SUPPORT IS ACTUALLY IN, not merely

170 ;; requested. `-Dpng=enabled` makes meson FAIL if

171 ;; libpng is missing, so this is belt-and-braces

172 ;; rather than the only guard -- but a viewer that

173 ;; installs and cannot decode the one format it

174 ;; was built for is exactly the silent

175 ;; feature-loss this channel keeps finding, and

176 ;; the binary is the only thing that can answer it.

177 "\"$d${out}/bin/swayimg\" --version\n"

178 "echo SWAYIMG-INSTALLED\n"))))))))