meson: enable nativesdk

Currently, we can't build meson into SDKs because we don't autogenerate
the required meson.cross file.

Enable this by using the post-relocate hooks and generating a
meson.cross file based on the SDK environment passed into the
post-relocate hook.

(From OE-Core rev: aabb846b165fec218024a7a57f3c9fdaa2514179)

Signed-off-by: Martin Kelly <mkelly@xevo.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/meson/meson.inc

@@ -0,0 +1,22 @@
+HOMEPAGE = "http://mesonbuild.com"
+SUMMARY = "A high performance build system"
+
+LICENSE = "Apache-2.0"
+LIC_FILES_CHKSUM = "file://COPYING;md5=3b83ef96387f14655fc854ddc3c6bd57"
+
+SRC_URI = "https://github.com/mesonbuild/meson/releases/download/${PV}/meson-${PV}.tar.gz \
+           file://0001-gtkdoc-fix-issues-that-arise-when-cross-compiling.patch \
+           file://0002-gobject-introspection-determine-g-ir-scanner-and-g-i.patch \
+           file://0001-Linker-rules-move-cross_args-in-front-of-output_args.patch \
+           file://0003-native_bindir.patch \
+           file://0004-Prettifying-some-output-with-pathlib.patch \
+           file://0005-Set-the-meson-command-to-use-when-we-know-what-it-is.patch \
+           "
+
+SRC_URI[md5sum] = "1698f6526574839de5dcdc45e3f7d582"
+SRC_URI[sha256sum] = "19497a03e7e5b303d8d11f98789a79aba59b5ad4a81bd00f4d099be0212cee78"
+UPSTREAM_CHECK_URI = "https://github.com/mesonbuild/meson/releases"
+
+inherit setuptools3
+
+RDEPENDS_${PN} = "ninja python3-core python3-modules"

meta/recipes-devtools/meson/meson/meson-setup.py

@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+
+import os
+import sys
+
+def bail(msg):
+    print(msg, file=sys.stderr)
+    sys.exit(1)
+
+_MARKER = '@@'
+def transform_line(line):
+    # Substitute any special markers of this form:
+    # @@ENV@@
+    # with the value of ENV, split into meson array syntax.
+    start = line.find(_MARKER)
+    if start == -1:
+        return line
+
+    end = line.rfind(_MARKER)
+    if end == start:
+        return line
+
+    # Lookup value of the env var.
+    var = line[start+len(_MARKER):end]
+    try:
+        val = os.environ[var]
+    except KeyError:
+        bail('cannot generate meson.cross; env var %s not set' % var)
+
+    # Transform into meson array.
+    val = ["'%s'" % x for x in val.split()]
+    val = ', '.join(val)
+    val = '[%s]' % val
+
+    before = line[:start]
+    after = line[end+len(_MARKER):]
+
+    return '%s%s%s' % (before, val, after)
+
+# Make sure this is really an SDK extraction environment.
+try:
+    sysroot = os.environ['OECORE_NATIVE_SYSROOT']
+except KeyError:
+    bail('OECORE_NATIVE_SYSROOT env var must be set')
+
+cross_file = os.path.join(sysroot, 'usr/share/meson/meson.cross')
+tmp_cross_file = '%s.tmp' % cross_file
+
+# Read through and transform the current meson.cross.
+lines = []
+with open(cross_file, 'r') as f:
+    for line in f:
+        lines.append(transform_line(line))
+
+# Write the transformed result to a tmp file and atomically rename it. In case
+# we crash during the file write, we don't want an invalid meson.cross file.
+with open(tmp_cross_file, 'w') as f:
+    for line in lines:
+        f.write(line)
+    f.flush()
+    os.fdatasync(f.fileno())
+os.rename(tmp_cross_file, cross_file)

meta/recipes-devtools/meson/meson/meson-wrapper

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+if [ -z "$OECORE_NATIVE_SYSROOT" ]; then
+    echo "OECORE_NATIVE_SYSROOT not set; are you in a Yocto SDK environment?" >&2
+fi
+
+# If these are set to a cross-compile path, meson will get confused and try to
+# use them as native tools. Unset them to prevent this, as all the cross-compile
+# config is already in meson.cross.
+unset CC CXX CPP LD AR NM STRIP
+
+exec "$OECORE_NATIVE_SYSROOT/usr/bin/meson.real" \
+     --cross-file "$OECORE_NATIVE_SYSROOT/usr/share/meson/meson.cross" \
+     "$@"

meta/recipes-devtools/meson/meson_0.46.1.bb

@@ -1,23 +1,3 @@
-HOMEPAGE = "http://mesonbuild.com"
-SUMMARY = "A high performance build system"
-
-LICENSE = "Apache-2.0"
-LIC_FILES_CHKSUM = "file://COPYING;md5=3b83ef96387f14655fc854ddc3c6bd57"
-
-SRC_URI = "https://github.com/mesonbuild/meson/releases/download/${PV}/${BP}.tar.gz \
-           file://0001-gtkdoc-fix-issues-that-arise-when-cross-compiling.patch \
-           file://0002-gobject-introspection-determine-g-ir-scanner-and-g-i.patch \
-           file://0001-Linker-rules-move-cross_args-in-front-of-output_args.patch \
-           file://0003-native_bindir.patch \
-           file://0004-Prettifying-some-output-with-pathlib.patch \
-           file://0005-Set-the-meson-command-to-use-when-we-know-what-it-is.patch \
-           "
-SRC_URI[md5sum] = "1698f6526574839de5dcdc45e3f7d582"
-SRC_URI[sha256sum] = "19497a03e7e5b303d8d11f98789a79aba59b5ad4a81bd00f4d099be0212cee78"
-UPSTREAM_CHECK_URI = "https://github.com/mesonbuild/meson/releases"
-
-inherit setuptools3
-
-RDEPENDS_${PN} = "ninja python3-core python3-modules"
+include meson.inc
 
 BBCLASSEXTEND = "native"

meta/recipes-devtools/meson/nativesdk-meson_0.46.1.bb

@@ -0,0 +1,74 @@
+include meson.inc
+
+inherit nativesdk
+
+SRC_URI += "file://meson-setup.py \
+            file://meson-wrapper"
+
+def meson_array(var, d):
+    return "', '".join(d.getVar(var).split()).join(("'", "'"))
+
+# both are required but not used by meson
+MESON_SDK_ENDIAN = "bogus-endian"
+MESON_TARGET_ENDIAN = "bogus-endian"
+
+MESON_TOOLCHAIN_ARGS = "${BUILDSDK_CC_ARCH}${TOOLCHAIN_OPTIONS}"
+MESON_C_ARGS = "${MESON_TOOLCHAIN_ARGS} ${BUILDSDK_CFLAGS}"
+MESON_CPP_ARGS = "${MESON_TOOLCHAIN_ARGS} ${BUILDSDK_CXXFLAGS}"
+MESON_LINK_ARGS = "${MESON_TOOLCHAIN_ARGS} ${BUILDSDK_LDFLAGS}"
+
+# This logic is similar but not identical to that in meson.bbclass, since it's
+# generating for an SDK rather than a cross-compile. Important differences are:
+# - We can't set vars like CC, CXX, etc. yet because they will be filled in with
+#   real paths by meson-setup.sh when the SDK is extracted.
+# - Some overrides aren't needed, since the SDK injects paths that take care of
+#   them.
+addtask write_config before do_install
+do_write_config[vardeps] += "MESON_C_ARGS MESON_CPP_ARGS MESON_LINK_ARGS CC CXX LD AR NM STRIP READELF"
+do_write_config() {
+    # This needs to be Py to split the args into single-element lists
+    cat >${WORKDIR}/meson.cross <<EOF
+[binaries]
+c = @@CC@@
+cpp = @@CXX@@
+ar = @@AR@@
+nm = @@NM@@
+ld = @@LD@@
+strip = @@STRIP@@
+pkgconfig = 'pkg-config'
+
+[properties]
+needs_exe_wrapper = true
+c_args = @@CFLAGS@@
+c_link_args = @@LDFLAGS@@
+cpp_args = @@CPPFLAGS@@
+cpp_link_args = @@LDFLAGS@@
+
+[host_machine]
+system = '${SDK_OS}'
+cpu_family = '${SDK_ARCH}'
+cpu = '${SDK_ARCH}'
+endian = '${MESON_SDK_ENDIAN}'
+EOF
+}
+
+do_install_append() {
+    install -d ${D}${datadir}/meson
+    install -m 0644 ${WORKDIR}/meson.cross ${D}${datadir}/meson/
+
+    install -d ${D}${SDKPATHNATIVE}/post-relocate-setup.d
+    install -m 0755 ${WORKDIR}/meson-setup.py ${D}${SDKPATHNATIVE}/post-relocate-setup.d/
+
+    # We need to wrap the real meson with a thin env setup wrapper.
+    mv ${D}${bindir}/meson ${D}${bindir}/meson.real
+    install -m 0755 ${WORKDIR}/meson-wrapper ${D}${bindir}/meson
+}
+
+RDEPENDS_${PN} += "\
+    nativesdk-ninja \
+    nativesdk-python3-core \
+    nativesdk-python3-misc \
+    nativesdk-python3-modules \
+    "
+
+FILES_${PN} += "${datadir}/meson ${SDKPATHNATIVE}"