Avoid expanding mtree spec during analysis phase (#576)

* Avoid expanding mtree spec during analysis phase

* Update tar.bzl

remove comment and unused code

---------

Co-authored-by: Alex Eagle <alex@aspect.dev>

.gitignore

@@ -1,3 +1,4 @@
 bazel-*
 **/.terraform/*
 test-out/
+.DS_Store

lib/private/tar.bzl

@@ -73,7 +73,7 @@ def _tar_impl(ctx):
  args = ctx.actions.args()
 
  # Set mode
- args.add("--" + ctx.attr.mode)
+ args.add(ctx.attr.mode, format = "--%s")
 
  # User-provided args first
  args.add_all(ctx.attr.args)
@@ -82,9 +82,9 @@ def _tar_impl(ctx):
  _add_compress_options(ctx.attr.compress, args)
 
  out = ctx.outputs.out or ctx.actions.declare_file(ctx.attr.name + ".tar")
- args.add_all(["--file", out.path])
+ args.add("--file", out)
 
- args.add("@" + ctx.file.mtree.path)
+ args.add(ctx.file.mtree, format = "@%s")
  inputs.append(ctx.file.mtree)
 
  ctx.actions.run(
@@ -97,6 +97,10 @@ def _tar_impl(ctx):
 
  return DefaultInfo(files = depset([out]), runfiles = ctx.runfiles([out]))
 
+def _default_mtree_line(file):
+ # Functions passed to map_each cannot take optional arguments.
+ return _mtree_line(file)
+
 def _mtree_line(file, uid = "0", gid = "0", time = "1672560000", mode = "0755"):
  return " ".join([
  file.short_path,
@@ -109,11 +113,13 @@ def _mtree_line(file, uid = "0", gid = "0", time = "1672560000", mode = "0755"):
  ])
 
 def _mtree_impl(ctx):
- specification = []
  out = ctx.outputs.out or ctx.actions.declare_file(ctx.attr.name + ".spec")
- for s in ctx.files.srcs:
- specification.append(_mtree_line(s))
- ctx.actions.write(out, "\n".join(specification + [""]))
+
+ content = ctx.actions.args()
+ content.set_param_file_format("multiline")
+ content.add_all(ctx.files.srcs, map_each = _default_mtree_line)
+ ctx.actions.write(out, content = content)
+
  return DefaultInfo(files = depset([out]), runfiles = ctx.runfiles([out]))
 
 tar_lib = struct(