build/zbi/zbi_input.gni

# Copyright 2020 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("//build/dist/fini_manifest.gni")

# Define inputs to a dependent zbi() target.
#
# The target generates a manifest that collects any manifest_lines from its
# dependencies' metadata, e.g. contributed by resource() targets.  It
# contributes metadata that will drive zbi() to use this manifest, as well
# as any non-BOOTFS inputs given via $sources and $args.
#
# resource() targets in the dependencies explicitly contribute to the
# manifest.  Many other target types such as executable() and
# shared_library() that have a $install_path parameter (even if defaulted)
# implicitly contribute to the manifest.
#
# It's not necessary to use an explicit zbi_input() target just to collect
# files into the BOOTFS of a zbi().  Use zbi_input() explicitly to get the
# manifest file as an explicit build artifact, to apply a target directory
# prefix to the manfiest file, or to include other types.
#
# Parameters
#
#   data_deps, deps
#     Optional: Dependencies examined for metadata.  Any other zbi_input()
#     or zbi() targets in this dependency graph will flow into any zbi()
#     target that depends on this one.  Any manifest metadata will be collected
#     here into a manifest file; see manifest_file().
#     Type: list(label)
#
#   prefix
#     Optional: Directory prefix prepended to the target path in each
#     manifest entry.  This is normalized when nonempty so it need not end
#     with a `/`.
#     Type: string
#     Default: ""
#
#   type
#     Optional: The input type for any $sources or $args, as in the
#     `--type` switch to the `zbi` tool.  See `zbi --help` for the set of
#     available types.  A value of "" uses `zbi --files`.
#     Type: string
#     Default: ""
#
#   sources
#     Optional: Files to put into the ZBI.  $type determines what kinds of
#     files these can be and how their contents are used.  If $type is ""
#     (the default), then these can be manifest files or directories.
#     Type: list(file)
#
#   args
#     Optional: Additional arguments to the `zbi` tool.  These are switches
#     that will precede the $sources on the `zbi` command line, so they
#     can include e.g. `--prefix=...` to affect contents of manifest file.
#     The most common use is "--entry=..." to provide literal contents right
#     in the GN file (e.g. for `type = "cmdline"`).
#
#   See manifest_file() for additional parameters.  The manifest file
#   produced from those parameters contributes to the BOOTFS (as modified
#   by $prefix).
#
template("zbi_input") {
  manifest_file = "$target_gen_dir/$target_name.fini"

  fini_manifest(target_name) {
    prefix = ""
    forward_variables_from(invoker,
                           "*",
                           [
                             "args",
                             "metadata",
                             "type",
                             "sources",
                           ])

    metadata = {
      migrated_zbi_barrier = []
      migrated_zbi_input_args = []

      if (defined(invoker.metadata)) {
        forward_variables_from(invoker.metadata, "*")
      }

      # When a zbi() target depends on this zbi_input() target, it includes
      # other zbi_input() targets in this target's deps, but not data_deps.
      if (defined(invoker.deps)) {
        migrated_zbi_barrier += invoker.deps
      }

      # An explicit type applies only to $sources and $args.
      if (defined(invoker.type) && invoker.type != "") {
        migrated_zbi_input_args += [ "--type=${invoker.type}" ]
      } else if (defined(invoker.args) || defined(invoker.sources)) {
        migrated_zbi_input_args += [
          # The implicit type is always --files, and needs to be reset in
          # case the previous `zbi_input_args` list collected left a
          # different `--type=...` as the last state.
          "--files",

          # Following $args and $sources entries shouldn't get a
          # previously-set prefix.
          "--prefix=",
        ]
      }

      # Explicit $args come first, for e.g. "-u" or "-g" to affect inputs.
      # $args may also contain "--entry=..." payloads directly.
      if (defined(invoker.args)) {
        migrated_zbi_input_args += invoker.args
      }

      if (defined(invoker.sources)) {
        migrated_zbi_input_args += rebase_path(invoker.sources, root_build_dir)
      }

      # Always include the manifest generated from the deps here.  The
      # presence of the fini_manifest() target will prevent zbi()
      # from collecting entries that are redundant with this manifest.
      migrated_zbi_input_args += [
        "--prefix=$prefix",
        "--files",
        rebase_path(manifest_file, root_build_dir),
      ]
    }
  }
}