//build/toolchain/musl-host-gcc: implement
This is a cc_toolchain which runs on x86 systems with Linux/gcc and
targets Smalltown via static musl builds.
It is currently unused, but can be tested by trying to build any
cc_binary with
--crosstool_top=//build/toolchain/musl-host-gcc:musl_host_cc_suite .
Test Plan: This has been tested manually by running it against a simple cc_binary. Another revision on top of this will attempt to build mkfs.xfs with it.
X-Origin-Diff: phab/D623
GitOrigin-RevId: ebdf51ee76d9d5a7fd94725c66ef53783f787df7
diff --git a/build/toolchain/musl-host-gcc/sysroot/tarball.bzl b/build/toolchain/musl-host-gcc/sysroot/tarball.bzl
new file mode 100644
index 0000000..4f12049
--- /dev/null
+++ b/build/toolchain/musl-host-gcc/sysroot/tarball.bzl
@@ -0,0 +1,76 @@
+# Copyright 2020 The Monogon Project Authors.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+load(
+ "//build/utils:detect_root.bzl",
+ "detect_root",
+)
+
+"""
+Build a sysroot-style tarball containing musl/linux headers and libraries.
+
+This can then be used to build a C toolchain that builds for Smalltown.
+"""
+
+def _musl_gcc_tarball(ctx):
+ tarball_name = ctx.attr.name + ".tar.xz"
+ tarball = ctx.actions.declare_file(tarball_name)
+
+ musl_headers = ctx.file.musl_headers
+ musl_headers_path = musl_headers.path
+ linux_headers = ctx.file.linux_headers
+ linux_headers_path = linux_headers.path
+
+ musl_root = detect_root(ctx.attr.musl)
+ musl_files = ctx.files.musl
+
+ # This builds a tarball containing musl, musl headers and linux headers.
+ # This is done by some carefully crafted tar command line arguments that rewrite
+ # paths to ensure that everything lands in lib/ and include/ in the tarball.
+
+ # TODO(q3k): write nice, small static Go utility for this.
+
+ arguments = [tarball.path]
+ command = "tar -chJf $1"
+
+ arguments += [musl_headers_path]
+ command += " --transform 's|^'$2'|include|' $2"
+
+ arguments += [linux_headers_path]
+ command += " --transform 's|^'$3'|include|' $3"
+
+ arguments += [musl_root]
+ command += " --transform 's|^'$4'|lib|' $4"
+
+ ctx.actions.run_shell(
+ inputs = [musl_headers, linux_headers] + ctx.files.musl,
+ outputs = [tarball],
+ progress_message = "Building toolchain tarball",
+ mnemonic = "BuildToolchainTarball",
+ arguments = arguments,
+ use_default_shell_env = True,
+ command = command,
+ )
+ return [DefaultInfo(files=depset([tarball]))]
+
+musl_gcc_tarball = rule(
+ implementation = _musl_gcc_tarball,
+ attrs = {
+ "musl": attr.label(mandatory = True),
+ "musl_headers": attr.label(mandatory = True, allow_single_file = True),
+ "linux_headers": attr.label(mandatory = True, allow_single_file = True),
+ },
+)