diffutils: provide standard file comparison workflows

Formula/diffutils.rb

@@ -0,0 +1,136 @@
+require (Tap.fetch("automattic", "kandelo-homebrew").path/"Kandelo/formula_support/kandelo_formula_support").to_s
+
+class Diffutils < Formula
+  include KandeloFormulaSupport
+
+  GUEST_COREUTILS_PR = "/home/linuxbrew/.linuxbrew/opt/coreutils/bin/pr".freeze
+  GUEST_DIFFUTILS_BIN = "/home/linuxbrew/.linuxbrew/opt/diffutils/bin".freeze
+  GUEST_ED = "/home/linuxbrew/.linuxbrew/opt/ed/bin/ed".freeze
+
+  desc "GNU file comparison utilities for Kandelo"
+  homepage "https://www.gnu.org/software/diffutils/"
+  url "https://ftpmirror.gnu.org/gnu/diffutils/diffutils-3.12.tar.xz"
+  mirror "https://ftp.gnu.org/gnu/diffutils/diffutils-3.12.tar.xz"
+  sha256 "7c8b7f9fc8609141fdea9cece85249d308624391ff61dedaf528fcb337727dfd"
+  license "GPL-3.0-or-later"
+
+  depends_on "binaryen" => :build
+  depends_on "wabt" => :build
+  depends_on "automattic/kandelo-homebrew/coreutils"
+  depends_on "automattic/kandelo-homebrew/ed"
+
+  skip_clean "bin/diff", "bin/cmp", "bin/diff3", "bin/sdiff"
+
+  def install
+    kandelo_require_arch!("wasm32")
+
+    kandelo_wasm_build do
+      ENV["PR_PROGRAM"] = GUEST_COREUTILS_PR
+
+      system kandelo_configure, *kandelo_std_configure_args,
+        "--disable-nls",
+        "--disable-dependency-tracking"
+      system "make", "-j#{ENV.make_jobs}"
+
+      stage = buildpath/"kandelo-stage"
+      system "make", "install", "DESTDIR=#{stage}"
+      staged_prefix = stage/prefix.to_s.delete_prefix("/")
+      odie "Diffutils did not install into its staged prefix" unless staged_prefix.directory?
+
+      %w[diff diff3 sdiff].each do |name|
+        artifact = staged_prefix/"bin"/name
+        kandelo_fork_instrument(artifact)
+        kandelo_validate_wasm_artifact(artifact, fork: :required)
+      end
+      kandelo_validate_wasm_artifact(staged_prefix/"bin/cmp", fork: :forbidden)
+      prefix.install staged_prefix.children
+    end
+  end
+
+  test do
+    assert_path_exists man1/"diff.1"
+    assert_path_exists info/"diffutils.info"
+    left = testpath/"left.txt"
+    right = testpath/"right.txt"
+    base = testpath/"base.txt"
+    left.write "alpha\nbeta\ngamma\n"
+    right.write "alpha\nBETA\ngamma\n"
+    base.write "alpha\nbase\ngamma\n"
+
+    mount = { "/work" => testpath }
+    cwd_env = { "KERNEL_CWD" => "/work", "KERNEL_PATH" => GUEST_DIFFUTILS_BIN }
+    diff_program = { "#{GUEST_DIFFUTILS_BIN}/diff" => bin/"diff" }
+    assert_empty kandelo_run_wasm(
+      bin/"diff", ["left.txt", "left.txt"], env: cwd_env, writable_host_directories: mount
+    )
+
+    brief = kandelo_run_wasm(
+      bin/"diff", ["--brief", "left.txt", "right.txt"],
+      env:                       cwd_env,
+      writable_host_directories: mount,
+      expected_status:           1
+    )
+    assert_equal "Files left.txt and right.txt differ\n", brief
+
+    assert_empty kandelo_run_wasm(
+      bin/"cmp", ["--silent", "left.txt", "right.txt"],
+      env:                       cwd_env,
+      writable_host_directories: mount,
+      expected_status:           1
+    )
+
+    coreutils_pr = formula_opt_bin("automattic/kandelo-homebrew/coreutils")/"pr"
+    paginated = kandelo_run_wasm(
+      bin/"diff", ["--paginate", "left.txt", "right.txt"],
+      env:                       cwd_env,
+      exec_programs:             { GUEST_COREUTILS_PR => coreutils_pr },
+      writable_host_directories: mount,
+      expected_status:           1
+    )
+    assert_match(/diff --paginate left\.txt right\.txt\s+Page 1/, paginated)
+    assert_match(/^2c2$/, paginated)
+
+    merged = kandelo_run_wasm(
+      bin/"diff3", ["--merge", "left.txt", "base.txt", "right.txt"],
+      env:                       cwd_env,
+      exec_programs:             diff_program,
+      writable_host_directories: mount,
+      expected_status:           1
+    )
+    assert_match "<<<<<<< left.txt", merged
+    assert_match "=======", merged
+    assert_match ">>>>>>> right.txt", merged
+
+    side_by_side = kandelo_run_wasm(
+      bin/"sdiff", ["--width=50", "left.txt", "right.txt"],
+      env:                       cwd_env,
+      exec_programs:             diff_program,
+      writable_host_directories: mount,
+      expected_status:           1
+    )
+    assert_match(/beta\s+\|\s+BETA/, side_by_side)
+
+    ed = formula_opt_bin("automattic/kandelo-homebrew/ed")/"ed"
+    editor_env = cwd_env.merge("KERNEL_PATH" => "#{GUEST_DIFFUTILS_BIN}:#{File.dirname(GUEST_ED)}")
+    kandelo_run_wasm(
+      bin/"sdiff", ["--output=merged.txt", "left.txt", "right.txt"],
+      env:                       cwd_env,
+      exec_programs:             diff_program,
+      stdin:                     "l\n",
+      writable_host_directories: mount,
+      expected_status:           1
+    )
+    assert_equal left.read, (testpath/"merged.txt").read
+
+    kandelo_run_pty_wasm(
+      bin/"sdiff", ["--output=edited.txt", "left.txt", "right.txt"],
+      argv0:                     "#{GUEST_DIFFUTILS_BIN}/sdiff",
+      env:                       editor_env,
+      exec_programs:             diff_program.merge(GUEST_ED => ed),
+      inputs:                    ["e l\n", "1c\n", "edited\n", ".\n", "w\n", "q\n"],
+      writable_host_directories: mount,
+      expected_status:           1
+    )
+    assert_equal "alpha\nedited\ngamma\n", (testpath/"edited.txt").read
+  end
+end

README.md

@@ -68,6 +68,7 @@ Current migration controls and pilots include:
 - `tar`, the GNU archive creation and extraction CLI.
 - `wget`, GNU HTTP and HTTPS retrieval linked against the tap TLS and compression roots.
 - `coreutils`, the GNU filesystem, text, checksum, and shell utility suite.
+- `diffutils`, GNU `diff`, `cmp`, `diff3`, and `sdiff` file-comparison tools.
 
 The SDK is not yet a Homebrew dependency. Trusted builds supply an
 `HOMEBREW_KANDELO_ROOT` checkout containing the SDK, sysroot, kernel, and Node