Bazel file to support OpenSSl-style perl -> asm generation

perlasm.bzl

load("@bazel_skylib//lib:paths.bzl", "paths")

def perlasm(src, perlasm_utils, name=None):
  """ Creates a genrule to process the src. Returns rule name."""
  (filename, ext) = paths.split_extension(paths.basename(src))
  if ext != ".pl":
    fail("Provided perlasm file {} must be a Perl file".format(src))
  if name == None:
    name = filename

  native.genrule(
    name = name,
    srcs = [src] + perlasm_utils,
    outs = [name + ".S"],
    cmd = "perl $(rootpath {}) elf $@".format(src),
  )

  return name

def perlasm_cc_library(perlasm_srcs, perlasm_utils, srcs=[], **kwargs):
  """Identical to cc_library, except allows for perlasm_srcs."""
  native.cc_library(
    srcs = srcs + [":" + perlasm(src, perlasm_utils) for src in perlasm_srcs],
    **kwargs
  )