file: add the compression-aware identification CLI

Aliases/file

@@ -0,0 +1 @@
+../Formula/file-formula.rb

Formula/file-formula.rb

@@ -0,0 +1,139 @@
+require (Tap.fetch("automattic", "kandelo-homebrew").path/"Kandelo/formula_support/kandelo_formula_support").to_s
+
+# File is a reserved Ruby class name.
+class FileFormula < Formula
+  include KandeloFormulaSupport
+
+  desc "Command-line file type identification tool for Kandelo"
+  homepage "https://www.darwinsys.com/file/"
+  url "https://astron.com/pub/file/file-5.45.tar.gz"
+  sha256 "fc97f51029bb0e2c9f4e3bffefdaf678f0e039ee872b9de5c002a6d09c784d82"
+  license "BSD-2-Clause-Darwin"
+
+  depends_on "pkgconf" => :build
+  depends_on "automattic/kandelo-homebrew/bzip2"
+  depends_on "automattic/kandelo-homebrew/libmagic"
+  depends_on "automattic/kandelo-homebrew/xz"
+  depends_on "automattic/kandelo-homebrew/zlib"
+
+  skip_clean "bin/file"
+
+  def install
+    kandelo_require_arch!("wasm32")
+    bzip2 = formula_opt_prefix("automattic/kandelo-homebrew/bzip2")
+    libmagic = formula_opt_prefix("automattic/kandelo-homebrew/libmagic")
+    xz = formula_opt_prefix("automattic/kandelo-homebrew/xz")
+    zlib = formula_opt_prefix("automattic/kandelo-homebrew/zlib")
+    instrumented = buildpath/"src/file.instrumented"
+
+    kandelo_wasm_build do |root|
+      ENV["PKG_CONFIG_LIBDIR"] = [
+        libmagic/"lib/pkgconfig",
+        xz/"lib/pkgconfig",
+        zlib/"lib/pkgconfig",
+      ].join(":")
+      ENV.delete("PKG_CONFIG_PATH")
+      ENV.delete("PKG_CONFIG_SYSROOT_DIR")
+
+      pkgconf = formula_opt_bin("pkgconf")/"pkg-config"
+      libmagic_version = Utils.safe_popen_read(pkgconf, "--modversion", "libmagic").strip
+      odie "file #{version} requires libmagic #{version}, found #{libmagic_version}" if libmagic_version != version.to_s
+      compile_flags = Utils.safe_popen_read(pkgconf, "--cflags", "libmagic").split
+      link_flags = Utils.safe_popen_read(pkgconf, "--static", "--libs", "libmagic").split
+      %W[-lmagic -llzma -L#{bzip2}/lib -lbz2 -lz -lm].each do |flag|
+        odie "libmagic static interface omits #{flag}" unless link_flags.include?(flag)
+      end
+
+      ENV["CPPFLAGS"] = compile_flags.join(" ")
+      system kandelo_configure, *kandelo_std_configure_args,
+        "--disable-shared",
+        "--enable-static",
+        "--enable-fsect-man5",
+        "--disable-zlib",
+        "--disable-bzlib",
+        "--disable-xzlib",
+        "--disable-zstdlib",
+        "--disable-lzlib",
+        "--disable-libseccomp",
+        "--disable-silent-rules"
+
+      system "make", "-C", "src", "magic.h"
+
+      # Upstream's file target hardcodes the sibling libmagic.la. Build only
+      # the CLI and link it against the installed tap library contract.
+      system "make", "-C", "src", "file",
+        "MAGIC=#{libmagic}/share/misc/magic",
+        "file_DEPENDENCIES=",
+        "file_LDADD=#{link_flags.join(" ")}"
+      system "#{root}/scripts/run-wasm-fork-instrument.sh",
+        buildpath/"src/file", "-o", instrumented
+
+      # The CLI owns file(1), with the installed libmagic opt path documented
+      # as its default database. libmagic owns the library manuals.
+      system "make", "-C", "doc", "file.1",
+        "MAGIC=#{libmagic}/share/misc/magic"
+    end
+
+    kandelo_install_bin(buildpath/"src", "file.instrumented", "file")
+    man1.install buildpath/"doc/file.1"
+  end
+
+  test do
+    assert_path_exists man1/"file.1"
+
+    workspace = testpath/"workspace"
+    workspace.mkpath
+    (workspace/"module.wasm").binwrite("\0asm\x01\0\0\0")
+    (workspace/"document.pdf").write("%PDF-1.7\n")
+    (workspace/"plain.txt").write("Kandelo file utility test payload.\n")
+    (workspace/"plain-link").make_symlink("plain.txt")
+
+    # These are the same ASCII payload encoded as zlib, bzip2, xz, and gzip streams.
+    (workspace/"payload.z").binwrite([
+      "789cf34ecc4b49cdc95748cbcc4955282dc9ccc92ca95448cecf2d284a2d2e" \
+      "4e4d512848acccc94f4cd1e3020047220f4a",
+    ].pack("H*"))
+    (workspace/"payload.bz2").binwrite([
+      "425a6839314159265359ee7e1d9a00000355800010400100082f27de20200022" \
+      "80d190da9885309a680d312b0ba3a62d91a230ac8d90e4d240bcc498dc29c6" \
+      "cb89f177245385090ee7e1d9a0",
+    ].pack("H*"))
+    (workspace/"payload.xz").binwrite([
+      "fd377a585a000004e6d6b44604c02d29210116000000000000000000727c299" \
+      "a0100284b616e64656c6f2066696c65207574696c69747920636f6d70726573" \
+      "736564207061796c6f61642e0a00000000a6f1317d726e0bb9000149290bd9" \
+      "8f431fb6f37d010000000004595a",
+    ].pack("H*"))
+    (workspace/"payload.gz").binwrite([
+      "1f8b0800000000000003f34ecc4b49cdc95748cbcc4955282dc9ccc92ca9544" \
+      "8cecf2d284a2d2e4e4d512848acccc94f4cd1e3020006c327d729000000",
+    ].pack("H*"))
+
+    env = { "KERNEL_CWD" => workspace }
+    version_output = kandelo_run_wasm(bin/"file", ["--version"])
+    assert_match(/^file(?:\.wasm)?-5\.45$/, version_output)
+    assert_match(%r{magic file from .*/opt/libmagic/share/misc/magic$}, version_output)
+
+    assert_match(/^WebAssembly \(wasm\) binary module/,
+      kandelo_run_wasm(bin/"file", ["-b", "module.wasm"], env: env))
+    assert_equal "application/pdf\n",
+      kandelo_run_wasm(bin/"file", ["-b", "--mime-type", "document.pdf"], env: env)
+    assert_match(/^PDF document/,
+      kandelo_run_wasm(bin/"file", ["-b", "-"], stdin: "%PDF-1.7\n"))
+
+    assert_equal "symbolic link to plain.txt\n",
+      kandelo_run_wasm(bin/"file", ["-b", "plain-link"], env: env)
+    assert_match(/^ASCII text/,
+      kandelo_run_wasm(bin/"file", ["-L", "-b", "plain-link"], env: env))
+
+    {
+      "payload.z"   => "zlib compressed data",
+      "payload.bz2" => "bzip2 compressed data",
+      "payload.xz"  => "XZ compressed data",
+      "payload.gz"  => "gzip compressed data",
+    }.each do |path, compression|
+      output = kandelo_run_wasm(bin/"file", ["-z", "-b", path], env: env)
+      assert_match(/^ASCII text \(#{Regexp.escape(compression)}/, output)
+    end
+  end
+end

README.md

@@ -38,7 +38,9 @@ Current migration controls and pilots include:
 - `make`, GNU dependency-driven build automation using the tap's POSIX shell;
 - `ed`, the conforming line editor and restricted editor required by patch workflows;
 - `m4`, the GNU macro processor with process-executing builtins backed by the tap's Dash shell;
-- `gawk`, GNU's pattern scanning and text-processing language.
+- `gawk`, GNU's pattern scanning and text-processing language;
+- `file`, compression-aware file type identification backed by the complete
+  `libmagic` database.
 
 The SDK is not yet a Homebrew dependency. Trusted builds supply an
 `HOMEBREW_KANDELO_ROOT` checkout containing the SDK, sysroot, kernel, and Node