# Copyright 2019 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import("$zx/public/gn/toolchain/c_utils.gni")

# Generate a header file with address constants from an RODSO layout object.
#
# The userboot loadable_module() and the vdso (libzircon) shared_library()
# both use the special RODSO layout (by default in lld or via rodso.ld in
# gold).  The kernel needs to use address constants extracted from these
# ELF files' headers and symbols.
#
# This generates two targets: $target_name creates the $outputs file;
# and $target_name.rsp generates "$target_gen_dir/$target_name.rsp"
# via link_output_rspfile().
#
# Parameters
#
#   outputs
#     Required: See action().
#
#   deps
#     Required; Should reach the loadable_module() or library() target
#     and no other linking targets; see link_output_rspfile().
#     Type: list(label)
#
template("rodso_code_header") {
  main_target_name = target_name
  rspfile_target_name = "$main_target_name.rsp"
  rspfile = "$target_gen_dir/$target_name.rsp"

  link_output_rspfile(rspfile_target_name) {
    forward_variables_from(invoker,
                           [
                             "deps",
                             "testonly",
                             "visibility",
                           ])
    if (defined(visibility)) {
      visibility += [ ":$main_target_name" ]
    }
    outputs = [
      rspfile,
    ]
  }

  toolchain_utils_action(main_target_name) {
    forward_variables_from(invoker,
                           [
                             "testonly",
                             "visibility",
                           ])

    deps = [
      ":$rspfile_target_name",
    ]
    outputs = invoker.outputs
    assert(outputs == [ outputs[0] ],
           "rodso_code_header() outputs must have exactly one element")
    depfile = "${outputs[0]}.d"

    script = "$zx/kernel/lib/vdso/gen-rodso-code.sh"
    utils = [
      "nm",
      "readelf",
    ]
    sources = [
      rspfile,
    ]
    args = [
      "--depfile",
      rebase_path(depfile, root_build_dir),
      rebase_path(outputs[0], root_build_dir),
      invoker.name,
      "@" + rebase_path(rspfile, root_build_dir),
    ]

    metadata = {
      generated_sources = rebase_path(outputs, root_build_dir)
    }
  }
}