Support linux jail on FreeBSD

Author: ntkme

.github/workflows/build.yml

@@ -80,7 +80,26 @@ jobs:
           - os: ubuntu-latest
             vm:
               os: freebsd
-              run: pkg install -y node npm protobuf ruby rubygem-bundler rubygem-rake
+              run: |
+                pkg install -y node npm protobuf ruby rubygem-bundler rubygem-rake
+          - os: ubuntu-latest
+            vm:
+              os: freebsd
+              run: |
+                pkg install -y node npm protobuf ruby rubygem-bundler rubygem-rake
+                sysrc linux_enable="YES"
+                service linux start
+          - os: ubuntu-latest
+            vm:
+              os: freebsd
+              run: |
+                pkg install -y debootstrap ruby rubygem-bundler rubygem-rake
+                sysrc linux_enable="YES"
+                service linux start
+                debootstrap jammy /compat/ubuntu
+                ln -sf ../lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 /compat/ubuntu/lib64/ld-linux-x86-64.so.2
+                mount -t linprocfs linproc /compat/ubuntu/proc
+                sysctl compat.linux.emul_path=/compat/ubuntu
           - os: ubuntu-latest
             vm:
               os: openbsd
@@ -90,11 +109,13 @@ jobs:
           - os: ubuntu-latest
             vm:
               os: netbsd
-              run: /usr/sbin/pkg_add nodejs protobuf ruby
+              run: |
+                /usr/sbin/pkg_add nodejs protobuf ruby
           - os: ubuntu-latest
             vm:
               os: dragonflybsd
-              run: pkg install -y libnghttp2 libuv node npm protobuf ruby rubygem-bundler rubygem-rake
+              run: |
+                pkg install -y libnghttp2 libuv node npm protobuf ruby rubygem-bundler rubygem-rake
           - os: ubuntu-latest
             vm:
               os: omnios
@@ -139,7 +160,7 @@ jobs:
         run: bundle exec rake compile
 
       - name: Spec
-        if: "!matrix.vm" # TODO: remove after https://github.com/sass/dart-sass/pull/2413
+        if: "!matrix.vm || contains(matrix.vm.run, 'sysctl compat.linux.emul_path')" # TODO: remove after https://github.com/sass/dart-sass/pull/2413
         run: bundle exec rake spec
 
       - name: Install

ext/sass/.gitignore

@@ -5,6 +5,7 @@
 /dart-sass/
 /embedded_sass.proto
 /embedded_sass_pb.rb
+/exit-*
 /node_modules/
 /package-lock.json
 /pnpm-lock.yaml

ext/sass/Rakefile

@@ -9,6 +9,11 @@ task install: %w[cli.rb] do
 end
 
 CLEAN.include %w[
+  exit-aarch64
+  exit-arm
+  exit-i386
+  exit-riscv64
+  exit-x86_64
   protoc.exe
   ruby
   *.proto
@@ -65,6 +70,15 @@ end
 
 task 'dart-sass' do
   Rake::Task['dart-sass/sass'].invoke
+
+  if SassConfig.linuxulator?
+    begin
+      sh 'dart-sass/sass', '--version'
+    rescue StandardError
+      rm_rf 'dart-sass'
+      raise NotImplementedError
+    end
+  end
 rescue NotImplementedError
   Rake::Task['node_modules/sass'].invoke
 end
@@ -158,6 +172,123 @@ rule '_pb.rb' => %w[.proto protoc.exe] do |t|
   sh './protoc.exe', '--proto_path=.', '--ruby_out=.', t.source
 end
 
+rule(/^exit-\w+$/) do |t|
+  require_relative '../../lib/sass/elf'
+
+  elf = Sass.const_get(:ELF)
+
+  case t.name.delete_prefix('exit-')
+  when 'aarch64'
+    ei_class  = elf::ELFCLASS64
+    ei_data   = elf::ELFDATA2LSB
+    e_machine = 0xb7
+    e_flags   = 0
+
+    # 0x0000000000000078:  A8 0B 80 D2    mov x8, #0x5d
+    # 0x000000000000007c:  00 00 80 D2    mov x0, #0
+    # 0x0000000000000080:  01 00 00 D4    svc #0
+    entry = ['a80b80d2000080d2010000d4'].pack('H*')
+  when 'arm'
+    ei_class  = elf::ELFCLASS32
+    ei_data   = elf::ELFDATA2LSB
+    e_machine = 0x28
+    e_flags   = 0x5000400
+
+    # 0x0000000000000054:  00 00 A0 E3    mov r0, #0
+    # 0x0000000000000058:  01 70 A0 E3    mov r7, #1
+    # 0x000000000000005c:  00 00 00 EF    svc #0
+    entry = ['0000a0e30170a0e3000000ef'].pack('H*')
+  when 'riscv64'
+    ei_class  = elf::ELFCLASS64
+    ei_data   = elf::ELFDATA2LSB
+    e_machine = 0xf3
+    e_flags   = 0x5
+
+    # 0x0000000000000078:  93 08 D0 05    addi  a7, x0, 93
+    # 0x000000000000007c:  01 45          c.li  a0, 0
+    # 0x000000000000007e:  73 00 00 00    ecall
+    entry = ['9308d005014573000000'].pack('H*')
+  when 'x86_64'
+    ei_class  = elf::ELFCLASS64
+    ei_data   = elf::ELFDATA2LSB
+    e_machine = 0x3e
+    e_flags   = 0
+
+    # 0x0000000000000078:  31 FF             xor     edi, edi
+    # 0x000000000000007a:  B8 3C 00 00 00    mov     eax, 0x3c
+    # 0x000000000000007f:  0F 05             syscall
+    entry = ['31ffb83c0000000f05'].pack('H*')
+  when 'i386'
+    ei_class  = elf::ELFCLASS32
+    ei_data   = elf::ELFDATA2LSB
+    e_machine = 0x03
+    e_flags   = 0
+
+    # 0x0000000000000054:  31 DB             xor ebx, ebx
+    # 0x0000000000000056:  B8 01 00 00 00    mov eax, 1
+    # 0x000000000000005b:  CD 80             int 0x80
+    entry = ['31dbb801000000cd80'].pack('H*')
+  else
+    raise NotImplementedError
+  end
+
+  File.open(t.name, 'wb', 0o755) do |file|
+    elf.allocate.instance_eval do
+      case ei_class
+      when elf::ELFCLASS32
+        e_ehsize    = elf::Elf32_Ehdr.sizeof
+        e_phentsize = elf::Elf32_Phdr.sizeof
+        e_shentsize = elf::Elf32_Shdr.sizeof
+      when elf::ELFCLASS64
+        e_ehsize    = elf::Elf64_Ehdr.sizeof
+        e_phentsize = elf::Elf64_Phdr.sizeof
+        e_shentsize = elf::Elf64_Shdr.sizeof
+      else
+        raise EncodingError
+      end
+      e_phoff  = e_ehsize
+      p_offset = e_phoff + e_phentsize
+      e_entry  = (2**22) + p_offset
+      p_vaddr  = e_entry
+      p_filesz = entry.length
+      p_memsz  = p_filesz
+
+      @ehdr = {
+        e_ident: [127, 69, 76, 70, ei_class, ei_data, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+        e_type: 2,
+        e_machine:,
+        e_version: 1,
+        e_entry:,
+        e_phoff:,
+        e_shoff: 0,
+        e_flags:,
+        e_ehsize:,
+        e_phentsize:,
+        e_phnum: 1,
+        e_shentsize:,
+        e_shnum: 0,
+        e_shstrndx: 0
+      }
+      @phdrs = [
+        {
+          p_type: 1,
+          p_flags: 5,
+          p_offset:,
+          p_vaddr:,
+          p_paddr: 0,
+          p_filesz:,
+          p_memsz:,
+          p_align: 4096
+        }
+      ]
+      @shdrs = []
+
+      dump(file)
+      file.write(entry)
+    end
+  end
+end
+
 # This is a FileUtils extension that defines several additional commands to be
 # added to the FileUtils utility functions.
 module FileUtils
@@ -305,6 +436,33 @@ end
 # The {SassConfig} module.
 module SassConfig
   module Platform
+    CPU = case RbConfig::CONFIG['host_cpu'].downcase
+          when /amd64|x86_64|x64/
+            'x86_64'
+          when /i\d86|x86|i86pc/
+            'x86'
+          when /arm64|aarch64/
+            'aarch64'
+          when /arm/
+            'arm'
+          when /ppc64le|powerpc64le/
+            'powerpc64le'
+          else
+            RbConfig::CONFIG['host_cpu']
+          end
+
+    LINUXULATOR = if RbConfig::CONFIG['host_os'].include?('freebsd')
+                    begin
+                      Rake::Task["exit-#{CPU}"].invoke
+                      RbConfig::CONFIG['host_os'] = 'linux-gnu' if system("./exit-#{CPU}")
+                      true
+                    rescue NotImplementedError
+                      false
+                    end
+                  else
+                    false
+                  end
+
     OS = case RbConfig::CONFIG['host_os'].downcase
          when /darwin/
            'darwin'
@@ -322,21 +480,6 @@ module SassConfig
            RbConfig::CONFIG['host_os'].downcase
          end
 
-    CPU = case RbConfig::CONFIG['host_cpu'].downcase
-          when /amd64|x86_64|x64/
-            'x86_64'
-          when /i\d86|x86|i86pc/
-            'x86'
-          when /arm64|aarch64/
-            'aarch64'
-          when /arm/
-            'arm'
-          when /ppc64le|powerpc64le/
-            'powerpc64le'
-          else
-            RbConfig::CONFIG['host_cpu']
-          end
-
     ARCH = "#{CPU}-#{OS}".freeze
   end
 
@@ -518,4 +661,8 @@ module SassConfig
       platform
     end
   end
+
+  def linuxulator?
+    Platform::LINUXULATOR
+  end
 end

spec/sass/elf_spec.rb

@@ -7,32 +7,35 @@
     Sass.const_get(:ELF)
   end
 
-  describe 'ruby program interpreter' do
-    it 'starts with ld-' do
+  describe 'ruby', skip: (File.exist?('/proc/self/exe') ? false : 'procfs is not available') do
+    it 'extracts program interpreter' do
       expect(File.basename(described_class::INTERPRETER)).to start_with('ld-')
     end
+
+    it 'dumps elf headers' do
+      input = StringIO.new(File.binread('/proc/self/exe'))
+      output = StringIO.new.binmode
+
+      described_class.new(input).dump(output)
+      expect(output.string).to eq(input.string.slice(0, output.length))
+    end
   end
 
-  describe 'dart program interpreter' do
+  describe 'dart' do
     subject(:interpreter) do
       Sass.const_get(:CLI)::INTERPRETER
     end
 
-    it 'starts with ld-' do
+    it 'extracts program interpreter' do
       expect(File.basename(interpreter)).to start_with('ld-')
     end
 
-    it 'is the same as ruby' do
-      expect(File.basename(interpreter))
-        .to eq(File.basename(described_class::INTERPRETER))
-    end
-  end
-
-  it 'dumps elf headers' do
-    input = StringIO.new(File.binread('/proc/self/exe'))
-    output = StringIO.new.binmode
+    it 'dumps elf headers' do
+      input = StringIO.new(File.binread(Sass.const_get(:CLI)::COMMAND[0]))
+      output = StringIO.new.binmode
 
-    described_class.new(input).dump(output)
-    expect(output.string).to eq(input.string.slice(0, output.length))
+      described_class.new(input).dump(output)
+      expect(output.string).to eq(input.string.slice(0, output.length))
+    end
   end
 end