Add a support to compile libzim for wasm.

`icu4c_wasm.patch` is build by :
 - Copying config.sub from liblzma source as new version of config.sub there
   knows about wasm architecture.
 - Copying `mh-linux` on `mh-unknown` as specified in (origin) `mh-unknown`.
   This is because icu4c configure doesn't detect `emscripten` platform and
   "fallback" to `mh-unknown`.

.github/scripts/common.py

@@ -280,6 +280,7 @@ def make_deps_archive(target=None, name=None, full=False):
         if (base_dir / "meson_cross_file.txt").exists():
             files_to_archive.append(base_dir / "meson_cross_file.txt")
     files_to_archive += HOME.glob("BUILD_*/android-ndk*")
+    files_to_archive += HOME.glob("BUILD_*/emsdk*")
     if (BASE_DIR / "meson_cross_file.txt").exists():
         files_to_archive.append(BASE_DIR / "meson_cross_file.txt")
 

kiwixbuild/dependencies/__init__.py

@@ -6,6 +6,7 @@ from . import (
     aria2,
     armhf,
     docoptcpp,
+    emsdk,
     flatpak,
     gumbo,
     icu4c,

kiwixbuild/dependencies/base.py

@@ -340,7 +340,7 @@ class MakeBuilder(Builder):
 
     @property
     def make_install_target(self):
-        if self.buildEnv.platformInfo.build == 'iOS':
+        if self.buildEnv.platformInfo.build in ('iOS', "wasm"):
             return 'install'
         return 'install-strip'
 

kiwixbuild/dependencies/emsdk.py

@@ -0,0 +1,47 @@
+import os
+
+from .base import Dependency, ReleaseDownload, Builder
+from kiwixbuild.utils import Remotefile, run_command, copy_tree
+
+pj = os.path.join
+
+class emsdk(Dependency):
+    dont_skip = True
+    neutral = False
+    name = 'emsdk'
+
+    class Source(ReleaseDownload):
+        archive = Remotefile('emsdk-3.1.24.tar.gz',
+                             '1aa5365ccb2147701cc9d1e59a5a49577c1d6aea55da7c450df2d5ffa48b8a58',
+                             'https://codeload.github.com/emscripten-core/emsdk/tar.gz/refs/tags/3.1.24')
+
+        @property
+        def source_dir(self):
+            return self.target.full_name()
+
+
+    class Builder(Builder):
+        @property
+        def install_path(self):
+            return self.build_path
+
+        def _copy_source(self, context):
+            context.try_skip(self.build_path)
+            copy_tree(self.source_path, self.build_path)
+
+        def _install(self, context):
+            context.try_skip(self.build_path)
+            command = "./emsdk install 3.1.24"
+            run_command(command, self.build_path, context)
+
+        def _activate(self, context):
+            context.try_skip(self.build_path)
+            command = "./emsdk activate 3.1.24"
+            run_command(command, self.build_path, context)
+
+
+        def build(self):
+            self.command('copy_source', self._copy_source)
+            self.command('install', self._install)
+            self.command('activate', self._activate)
+

kiwixbuild/dependencies/icu4c.py

@@ -18,7 +18,9 @@ class Icu(Dependency):
                    "icu4c_custom_data.patch",
                    "icu4c_noxlocale.patch",
                    "icu4c_rpath.patch",
-                   "icu4c_build_config.patch"]
+                   "icu4c_build_config.patch",
+                   "icu4c_wasm.patch"
+                  ]
 
 
     class Builder(MakeBuilder):
@@ -42,6 +44,6 @@ class Icu(Dependency):
                     'native_static' if platformInfo.static else 'native_dyn')
                 options += " --with-cross-build={} --disable-tools".format(
                     icu_native_builder.build_path)
-            if platformInfo.build == 'android':
+            if platformInfo.build in ('android', 'wasm'):
                 options += " --with-data-packaging=archive"
             return options

kiwixbuild/dependencies/libzim.py

@@ -19,7 +19,7 @@ class Libzim(Dependency):
         @classmethod
         def get_dependencies(cls, platformInfo, allDeps):
             deps = ['lzma', 'zstd', 'xapian-core', 'icu4c']
-            if platformInfo.build != 'flatpak':
+            if platformInfo.name not in ('flatpak', 'wasm'):
                 deps.append('zim-testing-suite')
             return deps
 
@@ -37,7 +37,9 @@ class Libzim(Dependency):
             if platformInfo.name == "flatpak":
                 config_options.append("--wrap-mode=nodownload")
                 config_options.append("-Dtest_data_dir=none")
-            else:
+            if platformInfo.name == "wasm":
+                config_options.append("-Dexamples=false")
+            if platformInfo.name not in ("flatpak", "wasm"):
                 zim_testing_suite = get_target_step('zim-testing-suite', 'source')
                 config_options.append('-Dtest_data_dir={}'.format(zim_testing_suite.source_path))
             return " ".join(config_options)

kiwixbuild/dependencies/xapian.py

@@ -24,7 +24,7 @@ class Xapian(Dependency):
         @classmethod
         def get_dependencies(cls, platformInfo, allDeps):
             deps = ['zlib', 'lzma']
-            if (platformInfo.build == 'win32'
+            if (platformInfo.build in ('win32', 'wasm')
              or neutralEnv('distname') == 'Darwin'):
                 return deps
             return deps + ['uuid']

kiwixbuild/platforms/__init__.py

@@ -9,5 +9,6 @@ from . import (
     ios,
     native,
     neutral,
-    win32
+    win32,
+    wasm
 )

kiwixbuild/platforms/wasm.py

@@ -0,0 +1,100 @@
+from .base import PlatformInfo
+
+from kiwixbuild.utils import pj
+from kiwixbuild._global import get_target_step
+
+
+class WasmPlatformInfo(PlatformInfo):
+    name = 'wasm'
+    static = True
+    build = 'wasm'
+    arch_full = 'wasm64-emscripten'
+    #arch_full = 'wasm64-linux'
+    toolchain_names = ['emsdk']
+    compatible_hosts = ['fedora', 'debian']
+    exe_wrapper_def = ""
+
+    def get_cross_config(self):
+        return {
+            'binaries': self.binaries,
+            'exe_wrapper_def': '',
+            'root_path': self.root_path,
+            'extra_libs': [],
+            'extra_cflags': [],
+            'host_machine': {
+                'system': 'emscripten',
+                'lsystem': 'emscripten',
+                'cpu_family': 'wasm64',
+                'cpu': 'wasm64',
+                'endian': 'little',
+                'abi': ''
+            }
+        }
+
+    @property
+    def wasm_sdk(self):
+        return get_target_step('emsdk', self.name)
+
+    @property
+    def install_path(self):
+        return self.wasm_sdk.install_path
+
+    @property
+    def root_path(self):
+        return self.install_path
+
+    @property
+    def binaries(self):
+        binaries = (('CC', 'emcc'),
+                    ('CXX', 'em++'),
+                    ('AR', 'emar'),
+                    ('STRIP', 'emstrip'),
+                    ('WINDRES', 'windres'),
+                    ('RANLIB', 'emranlib'),
+                    ('LD', 'wasm-ld'))
+        binaries = {k:pj(self.install_path, 'upstream', 'emscripten', v)
+                    for k,v in binaries}
+        binaries['PKGCONFIG'] = 'pkg-config'
+        return binaries
+
+    @property
+    def configure_option(self):
+        #return ""
+        return '--host={}'.format(self.arch_full)
+
+    @property
+    def configure_wrapper(self):
+        return "emconfigure"
+
+    @property
+    def make_wrapper(self):
+        return "emmake"
+
+    def get_bin_dir(self):
+        return [pj(self.install_path, 'bin')]
+
+    def get_env(self):
+        env = super().get_env()
+        env['PATH'] = ':'.join([
+            env['PATH'],
+            self.install_path,
+            pj(self.install_path, 'upstream', 'emscripten'),
+            pj(self.install_path, 'node', '14.18.2_64bit', 'bin')
+        ])
+        env['EMSDK'] = self.install_path
+        env['EMSDK_NODE'] = pj(self.install_path, 'node', '14.18.2_64bit', 'bin', 'node')
+        return env
+
+    def set_comp_flags(self, env):
+        super().set_comp_flags(env)
+        env['CFLAGS'] = " -Wp,-D_FORTIFY_SOURCE=2 -fexceptions --param=ssp-buffer-size=4 "+env['CFLAGS']
+        env['CXXFLAGS'] = " -Wp,-D_FORTIFY_SOURCE=2 -fexceptions --param=ssp-buffer-size=4 "+env['CXXFLAGS']
+
+    def set_compiler(self, env):
+        for k, v in self.binaries.items():
+            env[k] = v
+
+    def finalize_setup(self):
+        super().finalize_setup()
+        self.buildEnv.cmake_crossfile = self._gen_crossfile('cmake_cross_file.txt')
+        self.buildEnv.meson_crossfile = self._gen_crossfile('meson_cross_file.txt')