template

multitool/cwd.bzl

@@ -1,24 +1,5 @@
-"cwd: a rule for executing an executable in the BUILD_WORKING_DIRECTORY"
+"multitool cwd execution rule"
 
-def _cwd_impl(ctx):
-    output = ctx.actions.declare_file(ctx.label.name)
-    ctx.actions.write(
-        content = "\n".join([
-            "#!/usr/bin/env bash",
-            "execdir=\"$PWD\"",
-            "pushd $BUILD_WORKING_DIRECTORY > /dev/null",
-            "\"$execdir/{tool}\" \"$@\"".format(tool = ctx.file.tool.short_path),
-            "popd > /dev/null",
-            "",
-        ]),
-        output = output,
-    )
-    return [DefaultInfo(executable = output, runfiles = ctx.runfiles(files = [ctx.file.tool]))]
+load("@rules_multitool//multitool/private:cwd.bzl", _cwd = "cwd")
 
-cwd = rule(
-    implementation = _cwd_impl,
-    attrs = {
-        "tool": attr.label(mandatory = True, allow_single_file = True, executable = True, cfg = "exec"),
-    },
-    executable = True,
-)
+cwd = _cwd

multitool/private/BUILD.bazel

@@ -1,5 +1,9 @@
 load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
 
+exports_files([
+    "cwd.template.sh",
+])
+
 bzl_library(
     name = "multitool",
     srcs = ["multitool.bzl"],

multitool/private/cwd.bzl

@@ -0,0 +1,21 @@
+"cwd: a rule for executing an executable in the BUILD_WORKING_DIRECTORY"
+
+def _cwd_impl(ctx):
+    output = ctx.actions.declare_file(ctx.label.name)
+    ctx.actions.expand_template(
+        template = ctx.file._template,
+        output = output,
+        substitutions = {
+            "{{tool}}": ctx.file.tool.short_path,
+        },
+    )
+    return [DefaultInfo(executable = output, runfiles = ctx.runfiles(files = [ctx.file.tool]))]
+
+cwd = rule(
+    implementation = _cwd_impl,
+    attrs = {
+        "tool": attr.label(mandatory = True, allow_single_file = True, executable = True, cfg = "exec"),
+        "_template": attr.label(default = "//multitool/private:cwd.template.sh", allow_single_file = True),
+    },
+    executable = True,
+)

multitool/private/cwd.template.sh

@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+
+tool="{{tool}}"
+execdir="$PWD"
+
+pushd $BUILD_WORKING_DIRECTORY > /dev/null
+"$execdir/$tool" "$@"
+popd > /dev/null