From a64865dca58b0a904af9ad78b1f5f3135ad35601 Mon Sep 17 00:00:00 2001
From: "MATSUMOTO, Katsuyoshi" <github@katsyoshi.org>
Date: Fri, 21 Aug 2026 00:42:31 +0900
Subject: [PATCH 1/4] add archive reader

---
 lib/caotral/binary/archive.rb        | 14 ++++++++++++
 lib/caotral/binary/archive/header.rb | 13 +++++++++++
 lib/caotral/binary/archive/member.rb | 20 ++++++++++++++++
 lib/caotral/binary/archive/reader.rb | 32 ++++++++++++++++++++++++++
 lib/caotral/binary/elf.rb            |  3 +++
 test/caotral/binary/archive_test.rb  | 34 ++++++++++++++++++++++++++++
 test/test_suite.rb                   | 15 ++++++++++--
 7 files changed, 129 insertions(+), 2 deletions(-)
 create mode 100644 lib/caotral/binary/archive.rb
 create mode 100644 lib/caotral/binary/archive/header.rb
 create mode 100644 lib/caotral/binary/archive/member.rb
 create mode 100644 lib/caotral/binary/archive/reader.rb
 create mode 100644 test/caotral/binary/archive_test.rb

diff --git a/lib/caotral/binary/archive.rb b/lib/caotral/binary/archive.rb
new file mode 100644
index 00000000..138f651a
--- /dev/null
+++ b/lib/caotral/binary/archive.rb
@@ -0,0 +1,14 @@
+require_relative "archive/header"
+require_relative "archive/member"
+
+module Caotral
+  module Binary
+    class Archive
+      attr_reader :members
+
+      def initialize
+        @members = []
+      end
+    end
+  end
+end
diff --git a/lib/caotral/binary/archive/header.rb b/lib/caotral/binary/archive/header.rb
new file mode 100644
index 00000000..63c94e29
--- /dev/null
+++ b/lib/caotral/binary/archive/header.rb
@@ -0,0 +1,13 @@
+module Caotral
+  module Binary
+    class Archive
+      class Header
+        attr_reader :name, :size, :fmsg
+        def initialize(str)
+          @name, size, @fmsg = str.unpack("A16x12x6x6x8A10a2")
+          @size = Integer(size, 10)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/caotral/binary/archive/member.rb b/lib/caotral/binary/archive/member.rb
new file mode 100644
index 00000000..d479f2bc
--- /dev/null
+++ b/lib/caotral/binary/archive/member.rb
@@ -0,0 +1,20 @@
+require_relative "header"
+
+module Caotral
+  module Binary
+    class Archive
+      class Member
+        attr_reader :body, :header
+
+        def initialize(bin)
+          @header = Caotral::Binary::Archive::Header.new(bin.read(60))
+          size = @header.size
+          @body_bin = bin.read(@header.size)
+          bin.read(1) if size.odd?
+        end
+
+        def read! = @body = ""
+      end
+    end
+  end
+end
diff --git a/lib/caotral/binary/archive/reader.rb b/lib/caotral/binary/archive/reader.rb
new file mode 100644
index 00000000..44118602
--- /dev/null
+++ b/lib/caotral/binary/archive/reader.rb
@@ -0,0 +1,32 @@
+require_relative "../archive"
+
+module Caotral
+  module Binary
+    class Archive
+      class Reader
+        attr_reader :archive
+
+        def initialize(path)
+          input = decision(path)
+          @bin = StringIO.new(input.read)
+          @archive = Caotral::Binary::Archive.new
+        end
+
+        def read!
+          _magic = @bin.read(8)
+          archive.members << Caotral::Binary::Archive::Member.new(@bin) until @bin.eof?
+        end
+
+        private
+        def decision(path)
+          case path
+          when String, Pathname
+            File.open(File.expand_path(path.to_s), "rb")
+          else
+            raise ArgumentError, "wrong input type"
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/caotral/binary/elf.rb b/lib/caotral/binary/elf.rb
index 47fae990..aacf43da 100644
--- a/lib/caotral/binary/elf.rb
+++ b/lib/caotral/binary/elf.rb
@@ -11,6 +11,9 @@
 require_relative "elf/section_header"
 require_relative "elf/symtab_methods"
 
+require_relative "archive"
+
+require_relative "archive/reader"
 require_relative "elf/reader"
 
 module Caotral
diff --git a/test/caotral/binary/archive_test.rb b/test/caotral/binary/archive_test.rb
new file mode 100644
index 00000000..76538fd5
--- /dev/null
+++ b/test/caotral/binary/archive_test.rb
@@ -0,0 +1,34 @@
+require_relative "../../test_suite"
+
+class Caotral::Binary::ArchiveTest < Test::Unit::TestCase
+  include BuildFixtureHelper
+
+  attr_reader :output, :inputs
+
+  def teardown
+    @inputs.each { |name| File.delete(name) }
+    File.delete(output)
+  end
+
+  def test_archive
+    @output = "archive.a"
+    @inputs = []
+    [
+      "sample/C/multi-file-link-a.c",
+      "sample/C/add.c"
+    ].each do |input|
+      output = File.basename(input, ".c") + ".s"
+      compile_fixture(output:, input:, options: ["-fno-pie"])
+      input = output
+      asm = output
+      output = File.basename(input, ".s") + ".o"
+      assemble_fixture(output:, input:)
+      File.delete(asm)
+      @inputs << output
+    end
+
+    create_archive(output:, inputs:)
+    archive = Caotral::Binary::Archive::Reader.new(output)
+    archive.read!
+  end 
+end
diff --git a/test/test_suite.rb b/test/test_suite.rb
index 0a526c66..35d47fa7 100644
--- a/test/test_suite.rb
+++ b/test/test_suite.rb
@@ -1,10 +1,21 @@
 require "caotral"
 require "test/unit"
-require "pathname"
 require "open3"
 
+module BuildFixtureHelper
+  def fixture_command(*command)
+    o, e, s = Open3.capture3(*command)
+    return o if s.success?
+
+    raise "command failed: #{command.join(" ")}\n#{e}"
+  end
+
+  def compile_fixture(output:, input:, options: []) = fixture_command("gcc", *options, "-S", "-o", output, input)
+  def assemble_fixture(output:, input:) = fixture_command("as", "-o", output, input)
+  def create_archive(output:, inputs:) = fixture_command("ar", "rcsD", output, *inputs)
+end
+
 module TestProcessHelper
-  private
   def check_process(status)
     exit_code = status >> 8
     handle_code = status & 0x7f

From 0d9ae2d5400c791eb3c783746761c837256c3e35 Mon Sep 17 00:00:00 2001
From: "MATSUMOTO, Katsuyoshi" <github@katsyoshi.org>
Date: Sat, 22 Aug 2026 01:19:05 +0900
Subject: [PATCH 2/4] add archive reader support

---
 lib/caotral/binary/archive.rb              |  9 +++++-
 lib/caotral/binary/archive/error.rb        |  9 ++++++
 lib/caotral/binary/archive/header.rb       |  3 ++
 lib/caotral/binary/archive/member.rb       | 20 +++++++------
 lib/caotral/binary/archive/name_table.rb   | 33 ++++++++++++++++++++++
 lib/caotral/binary/archive/reader.rb       | 24 +++++++++++++++-
 lib/caotral/binary/archive/symbol_table.rb | 31 ++++++++++++++++++++
 lib/caotral/binary/elf/reader.rb           |  2 ++
 test/caotral/binary/archive_test.rb        | 31 ++++++++++++++------
 9 files changed, 142 insertions(+), 20 deletions(-)
 create mode 100644 lib/caotral/binary/archive/error.rb
 create mode 100644 lib/caotral/binary/archive/name_table.rb
 create mode 100644 lib/caotral/binary/archive/symbol_table.rb

diff --git a/lib/caotral/binary/archive.rb b/lib/caotral/binary/archive.rb
index 138f651a..ebea80fb 100644
--- a/lib/caotral/binary/archive.rb
+++ b/lib/caotral/binary/archive.rb
@@ -1,13 +1,20 @@
+require_relative "archive/error"
+
 require_relative "archive/header"
 require_relative "archive/member"
+require_relative "archive/name_table"
+require_relative "archive/symbol_table"
 
 module Caotral
   module Binary
     class Archive
-      attr_reader :members
+      attr_accessor :name_table
+      attr_reader :members, :symbol_tables
 
       def initialize
         @members = []
+        @symbol_tables = []
+        @name_table = nil
       end
     end
   end
diff --git a/lib/caotral/binary/archive/error.rb b/lib/caotral/binary/archive/error.rb
new file mode 100644
index 00000000..031c74cc
--- /dev/null
+++ b/lib/caotral/binary/archive/error.rb
@@ -0,0 +1,9 @@
+module Caotral
+  module Binary
+    class Archive
+      class Error < StandardError
+      end
+    end
+  end
+end
+
diff --git a/lib/caotral/binary/archive/header.rb b/lib/caotral/binary/archive/header.rb
index 63c94e29..dbc26403 100644
--- a/lib/caotral/binary/archive/header.rb
+++ b/lib/caotral/binary/archive/header.rb
@@ -7,6 +7,9 @@ def initialize(str)
           @name, size, @fmsg = str.unpack("A16x12x6x6x8A10a2")
           @size = Integer(size, 10)
         end
+
+        def symbol_table? = @name == "/"
+        def name_table? = @name == "//"
       end
     end
   end
diff --git a/lib/caotral/binary/archive/member.rb b/lib/caotral/binary/archive/member.rb
index d479f2bc..4f7c0b30 100644
--- a/lib/caotral/binary/archive/member.rb
+++ b/lib/caotral/binary/archive/member.rb
@@ -1,19 +1,21 @@
-require_relative "header"
-
 module Caotral
   module Binary
     class Archive
       class Member
-        attr_reader :body, :header
+        attr_reader :elf, :offset, :name
 
-        def initialize(bin)
-          @header = Caotral::Binary::Archive::Header.new(bin.read(60))
-          size = @header.size
-          @body_bin = bin.read(@header.size)
-          bin.read(1) if size.odd?
+        def initialize(name:, body:, offset:)
+          @name = name
+          @body = StringIO.new(body)
+          @offset = offset
         end
 
-        def read! = @body = ""
+        def read!
+          reader = Caotral::Binary::ELF::Reader.new(input: @body)
+          reader.read
+          @elf = reader.context
+          self
+        end
       end
     end
   end
diff --git a/lib/caotral/binary/archive/name_table.rb b/lib/caotral/binary/archive/name_table.rb
new file mode 100644
index 00000000..c48952b7
--- /dev/null
+++ b/lib/caotral/binary/archive/name_table.rb
@@ -0,0 +1,33 @@
+module Caotral
+  module Binary
+    class Archive
+      class NameTable
+        attr_reader :names
+
+        def initialize(body:)
+          @body = StringIO.new(body)
+          @names = []
+          @name_offsets = {}
+        end
+
+        def parse!
+          until @body.eof?
+            offset = @body.pos
+            entry = @body.gets("/\n")
+            break if entry == "\n"
+            name = entry.delete_suffix("/\n")
+            @names << name
+            @name_offsets[offset] = name
+          end
+          self
+        end
+
+        def resolve(offset)
+          @name_offsets.fetch(offset) do
+            raise Caotral::Binary::Archive::Error, "invalid name offset: #{offset}"
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/caotral/binary/archive/reader.rb b/lib/caotral/binary/archive/reader.rb
index 44118602..58b658e0 100644
--- a/lib/caotral/binary/archive/reader.rb
+++ b/lib/caotral/binary/archive/reader.rb
@@ -14,7 +14,29 @@ def initialize(path)
 
         def read!
           _magic = @bin.read(8)
-          archive.members << Caotral::Binary::Archive::Member.new(@bin) until @bin.eof?
+          nt = nil
+          until @bin.eof?
+            offset = @bin.pos
+            header = Caotral::Binary::Archive::Header.new(@bin.read(60))
+            size = header.size
+            body = @bin.read(size)
+            raw_name = header.name
+            case header.name
+            when "/"
+              archive.symbol_tables << Caotral::Binary::Archive::SymbolTable.new(body:).parse!
+            when "//"
+              nt = archive.name_table = Caotral::Binary::Archive::NameTable.new(body:).parse!
+            else
+              name = if /\A\/(?<idx>\d+)\z/ =~ raw_name
+                       nt.resolve(Integer(idx, 10))
+                     else
+                       raw_name.delete_suffix("/")
+                     end
+
+              archive.members << Caotral::Binary::Archive::Member.new(name:, body:, offset:).read!
+            end
+            @bin.read(1) if size.odd?
+          end
         end
 
         private
diff --git a/lib/caotral/binary/archive/symbol_table.rb b/lib/caotral/binary/archive/symbol_table.rb
new file mode 100644
index 00000000..e19a5721
--- /dev/null
+++ b/lib/caotral/binary/archive/symbol_table.rb
@@ -0,0 +1,31 @@
+module Caotral
+  module Binary
+    class Archive
+      class SymbolTable
+        attr_reader :symbols
+
+        Symbol = Data.define(:name, :offset)
+        def initialize(body:)
+          @body = StringIO.new(body)
+          @symbols = []
+        end
+
+        def parse!
+          count = @body.read(4).unpack1("N")
+
+          offsets = count.times.map { @body.read(4).unpack1("N") }
+          names = count.times.map do
+            entry = @body.gets("\0")
+            unless entry&.end_with?("\0")
+              raise Caotral::Binary::Archive::Error, "invalid symbol table"
+            end
+
+            entry.delete_suffix("\0")
+          end
+          @symbols = names.zip(offsets).map { |name, offset| Symbol.new(name:, offset:) }
+          self
+        end
+      end
+    end
+  end
+end
diff --git a/lib/caotral/binary/elf/reader.rb b/lib/caotral/binary/elf/reader.rb
index f78337bc..35c44bef 100644
--- a/lib/caotral/binary/elf/reader.rb
+++ b/lib/caotral/binary/elf/reader.rb
@@ -209,6 +209,8 @@ def decision(input)
           case input
           when String, Pathname
             File.open(File.expand_path(input.to_s), "rb")
+          when StringIO
+            input
           else
             raise ArgumentError, "wrong input type"
           end
diff --git a/test/caotral/binary/archive_test.rb b/test/caotral/binary/archive_test.rb
index 76538fd5..5d05c3a2 100644
--- a/test/caotral/binary/archive_test.rb
+++ b/test/caotral/binary/archive_test.rb
@@ -5,30 +5,43 @@ class Caotral::Binary::ArchiveTest < Test::Unit::TestCase
 
   attr_reader :output, :inputs
 
-  def teardown
-    @inputs.each { |name| File.delete(name) }
-    File.delete(output)
-  end
+  def teardown = @garbage_box.each { |name| File.delete(name) if File.exist?(name) }
 
   def test_archive
     @output = "archive.a"
+    @garbage_box = [@output]
     @inputs = []
     [
       "sample/C/multi-file-link-a.c",
       "sample/C/add.c"
     ].each do |input|
       output = File.basename(input, ".c") + ".s"
+      @garbage_box << output
       compile_fixture(output:, input:, options: ["-fno-pie"])
       input = output
-      asm = output
       output = File.basename(input, ".s") + ".o"
+      @garbage_box << output
       assemble_fixture(output:, input:)
-      File.delete(asm)
       @inputs << output
     end
 
     create_archive(output:, inputs:)
-    archive = Caotral::Binary::Archive::Reader.new(output)
-    archive.read!
-  end 
+    reader = Caotral::Binary::Archive::Reader.new(output)
+    reader.read!
+    archive = reader.archive
+    mul = archive.members.first
+    add = archive.members.last
+    symbol_tables = archive.symbol_tables
+    name_table = archive.name_table
+    assert_equal(2, archive.members.size)
+    assert_equal("multi-file-link-a.o", mul.name)
+    assert_equal("add.o", add.name)
+
+    assert_equal(1, symbol_tables.size)
+    assert_equal("foo", symbol_tables.first.symbols.first.name)
+    assert_equal(170, symbol_tables.first.symbols.first.offset)
+    assert_not_nil(name_table)
+    assert_equal(["multi-file-link-a.o"], name_table.names)
+    assert_equal("multi-file-link-a.o", name_table.resolve(0))
+  end
 end

From d9e7a1696f2ea157283677a0a64438c6be3d8d7c Mon Sep 17 00:00:00 2001
From: "MATSUMOTO, Katsuyoshi" <github@katsyoshi.org>
Date: Sun, 23 Aug 2026 23:59:45 +0900
Subject: [PATCH 3/4] support archive inputs in self linker

---
 lib/caotral/binary/archive.rb                 |  3 +
 lib/caotral/binary/archive/member.rb          |  4 +-
 lib/caotral/binary/archive/reader.rb          |  9 ++-
 lib/caotral/binary/archive/symbol_table.rb    |  3 +
 lib/caotral/linker.rb                         | 15 +++--
 lib/caotral/linker/builder.rb                 | 64 ++++++++++++-------
 sample/C/archive-recursive.c                  |  5 ++
 test/caotral/binary/archive_test.rb           | 23 ++-----
 .../linker/integration/archive_test.rb        | 48 ++++++++++++++
 test/caotral/linker/writer_test.rb            |  4 +-
 test/test_suite.rb                            | 43 ++++++++++++-
 11 files changed, 167 insertions(+), 54 deletions(-)
 create mode 100644 sample/C/archive-recursive.c
 create mode 100644 test/caotral/linker/integration/archive_test.rb

diff --git a/lib/caotral/binary/archive.rb b/lib/caotral/binary/archive.rb
index ebea80fb..548c9305 100644
--- a/lib/caotral/binary/archive.rb
+++ b/lib/caotral/binary/archive.rb
@@ -16,6 +16,9 @@ def initialize
         @symbol_tables = []
         @name_table = nil
       end
+
+      def symbol_offset(name) = @symbol_tables.map { |symbol_table| symbol_table.offset_of(name) }&.compact&.first
+      def find_member_by_offset(offset) = @members.find { |member| member.offset == offset }
     end
   end
 end
diff --git a/lib/caotral/binary/archive/member.rb b/lib/caotral/binary/archive/member.rb
index 4f7c0b30..49890375 100644
--- a/lib/caotral/binary/archive/member.rb
+++ b/lib/caotral/binary/archive/member.rb
@@ -10,10 +10,12 @@ def initialize(name:, body:, offset:)
           @offset = offset
         end
 
-        def read!
+        def read
+          return self if @elf
           reader = Caotral::Binary::ELF::Reader.new(input: @body)
           reader.read
           @elf = reader.context
+          @body = nil
           self
         end
       end
diff --git a/lib/caotral/binary/archive/reader.rb b/lib/caotral/binary/archive/reader.rb
index 58b658e0..bc583ff0 100644
--- a/lib/caotral/binary/archive/reader.rb
+++ b/lib/caotral/binary/archive/reader.rb
@@ -10,6 +10,8 @@ def initialize(path)
           input = decision(path)
           @bin = StringIO.new(input.read)
           @archive = Caotral::Binary::Archive.new
+        ensure
+          input.close
         end
 
         def read!
@@ -33,10 +35,13 @@ def read!
                        raw_name.delete_suffix("/")
                      end
 
-              archive.members << Caotral::Binary::Archive::Member.new(name:, body:, offset:).read!
+              archive.members << Caotral::Binary::Archive::Member.new(name:, body:, offset:)
             end
             @bin.read(1) if size.odd?
           end
+          @archive
+        ensure
+          @bin.close
         end
 
         private
@@ -44,6 +49,8 @@ def decision(path)
           case path
           when String, Pathname
             File.open(File.expand_path(path.to_s), "rb")
+          when StringIO
+            path
           else
             raise ArgumentError, "wrong input type"
           end
diff --git a/lib/caotral/binary/archive/symbol_table.rb b/lib/caotral/binary/archive/symbol_table.rb
index e19a5721..15305cb2 100644
--- a/lib/caotral/binary/archive/symbol_table.rb
+++ b/lib/caotral/binary/archive/symbol_table.rb
@@ -25,6 +25,9 @@ def parse!
           @symbols = names.zip(offsets).map { |name, offset| Symbol.new(name:, offset:) }
           self
         end
+
+        def names = @symbols.map(&:name)
+        def offset_of(name) = @symbols.find { |symbol| symbol.name == name }&.offset
       end
     end
   end
diff --git a/lib/caotral/linker.rb b/lib/caotral/linker.rb
index 33687110..48f0acf6 100644
--- a/lib/caotral/linker.rb
+++ b/lib/caotral/linker.rb
@@ -8,14 +8,14 @@
 
 module Caotral
   class Linker
-    def self.link!(inputs:, output: "a.out", linker: "mold", debug: false, shared: false, executable: true, pie: false, needed: [])
-      new(inputs:, output:, linker:, debug:, shared:, executable:, pie:, needed:).link
+    def self.link!(inputs:, output: "a.out", linker: "mold", debug: false, shared: false, executable: true, pie: false, needed: [], archives: [])
+      new(inputs:, output:, linker:, debug:, shared:, executable:, pie:, needed:, archives:).link
     end
 
-    def initialize(inputs:, output: "a.out", linker: "mold", linker_options: [], executable: true, shared: false, pie: false, debug: false, needed: [])
+    def initialize(inputs:, output: "a.out", linker: "mold", linker_options: [], executable: true, shared: false, pie: false, debug: false, needed: [], archives: [])
       @inputs, @output, @linker = inputs, output, linker
       @options = linker_options
-      @needed = needed
+      @needed, @archives = needed, archives
       @executable = shared ? false : executable
       @debug, @shared, @pie = debug, shared, pie
     end
@@ -54,12 +54,13 @@ def link_command(inputs: @inputs, output: @output)
     def libpath = @libpath ||= File.dirname(Dir.glob("/usr/lib*/**/crti.o").last)
     def gcc_libpath = @gcc_libpath ||= File.dirname(Dir.glob("/usr/lib/gcc/x86_64-*/*/crtbegin.o").last)
 
-    def to_elf(inputs: @inputs, output: @output, debug: @debug, shared: @shared, executable: @executable, pie: @pie, needed: @needed)
+    def to_elf(inputs: @inputs, output: @output, debug: @debug, shared: @shared, executable: @executable, pie: @pie, needed: @needed, archives: @archives)
       raise Caotral::Binary::ELF::Error, "disallow both mode: shared and PIE" if shared && pie
 
       elf_objs = inputs.map { |input| Caotral::Binary::ELF::Reader.new(input:, debug:).read }
-      builder = Caotral::Linker::Builder.new(elf_objs:, debug:, shared:, executable:, pie:, needed:)
-      builder.resolve_symbols
+      builder = Caotral::Linker::Builder.new(elf_objs:, debug:, shared:, executable:, pie:, needed:, archives:)
+      builder.resolve_symbols!
+      builder.extract_archive_members! unless archives.empty?
       elf = builder.build
       metadata = builder.linker_metadata
       Caotral::Linker::Layout.new(elf:, shared:, executable:, pie:).apply!
diff --git a/lib/caotral/linker/builder.rb b/lib/caotral/linker/builder.rb
index 259294f0..3c7ef8b1 100644
--- a/lib/caotral/linker/builder.rb
+++ b/lib/caotral/linker/builder.rb
@@ -31,8 +31,9 @@ class Builder
 
       attr_reader :symbols, :linker_metadata
 
-      def initialize(elf_objs:, executable: true, debug: false, shared: false, pie: false, needed: [])
+      def initialize(elf_objs:, executable: true, debug: false, shared: false, pie: false, needed: [], archives: [])
         @elf_objs = elf_objs
+        @archives = archives.map { |archive| Caotral::Binary::Archive::Reader.new(archive).read! }
         @executable, @debug, @shared, @pie, @needed = executable, debug, shared, pie, needed
         @symbols = {
           locals: Set.new,
@@ -486,33 +487,52 @@ def build
         elf
       end
 
-      def resolve_symbols
-        @elf_objs.each do |elf_obj|
-          elf_obj.find_by_name(".symtab").body.each do |symtab|
-            name = symtab.name_string
-            next if name.empty?
-            info = symtab.info
-            bind = BIND_BY_VALUE.fetch(info >> 4)
-            if bind == :globals
-              if symtab.shndx == 0
-                @symbols[bind][:undefined] << name unless @symbols[bind][:defined].include?(name)
-              else
-                if @symbols[bind][:defined].keys.include?(name)
-                  raise Caotral::Binary::ELF::Error,"cannot add into globals: #{name}"
-                end
-                @symbols[bind][:undefined].delete(name)
-                @symbols[bind][:defined][name] = symtab.shndx
-              end
-            else
-              @symbols[bind] << name
-            end
+      def resolve_symbols! = @elf_objs.each { |elf_obj| resolve_symbol_for(elf_obj) }
+      def extract_archive_members!
+        resolved = Set[]
+        loop do
+          elfs = []
+          @symbols[:globals][:undefined].each do |symbol|
+            archive = implement_symbol_archive(symbol)
+            next if archive.nil?
+            offset = archive.symbol_offset(symbol)
+            member = archive.find_member_by_offset(offset)
+            next if member.nil?
+            next unless resolved.add?(member)
+            elfs << member.read.elf
           end
+          break if elfs.empty?
+          elfs.each { |elf| resolve_symbol_for(elf) }
+          @elf_objs += elfs
         end
-        @symbols
       end
 
       private
 
+      def implement_symbol_archive(symbol) = @archives.find { |archive| archive.symbol_tables.any? { |symbol_table| symbol_table.names.include?(symbol) } }
+
+      def resolve_symbol_for(elf_obj)
+        elf_obj.find_by_name(".symtab").body.each do |symtab|
+          name = symtab.name_string
+          next if name.empty?
+          info = symtab.info
+          bind = BIND_BY_VALUE.fetch(info >> 4)
+          if bind == :globals
+            if symtab.shndx == 0
+              @symbols[bind][:undefined] << name unless @symbols[bind][:defined].include?(name)
+            else
+              if @symbols[bind][:defined].keys.include?(name)
+                raise Caotral::Binary::ELF::Error,"cannot add into globals: #{name}"
+              end
+              @symbols[bind][:undefined].delete(name)
+              @symbols[bind][:defined][name] = symtab.shndx
+            end
+          else
+            @symbols[bind] << name
+          end
+        end
+      end
+
       def build_shared_dynamic_sections
         dynstr_section = Caotral::Binary::ELF::Section.new(
           body: Caotral::Binary::ELF::Section::Strtab.new("\0".b),
diff --git a/sample/C/archive-recursive.c b/sample/C/archive-recursive.c
new file mode 100644
index 00000000..e704b6c0
--- /dev/null
+++ b/sample/C/archive-recursive.c
@@ -0,0 +1,5 @@
+int add(int x, int y);
+
+int foo(void) {
+  return add(40, 2);
+}
diff --git a/test/caotral/binary/archive_test.rb b/test/caotral/binary/archive_test.rb
index 5d05c3a2..f97cd360 100644
--- a/test/caotral/binary/archive_test.rb
+++ b/test/caotral/binary/archive_test.rb
@@ -1,31 +1,18 @@
 require_relative "../../test_suite"
 
 class Caotral::Binary::ArchiveTest < Test::Unit::TestCase
+  include CommonSetupHelper
   include BuildFixtureHelper
 
-  attr_reader :output, :inputs
-
-  def teardown = @garbage_box.each { |name| File.delete(name) if File.exist?(name) }
-
   def test_archive
     @output = "archive.a"
-    @garbage_box = [@output]
+    @generated = [@output]
     @inputs = []
-    [
+    inputs = [
       "sample/C/multi-file-link-a.c",
       "sample/C/add.c"
-    ].each do |input|
-      output = File.basename(input, ".c") + ".s"
-      @garbage_box << output
-      compile_fixture(output:, input:, options: ["-fno-pie"])
-      input = output
-      output = File.basename(input, ".s") + ".o"
-      @garbage_box << output
-      assemble_fixture(output:, input:)
-      @inputs << output
-    end
-
-    create_archive(output:, inputs:)
+    ]
+    create_archive(output: @output, inputs:)
     reader = Caotral::Binary::Archive::Reader.new(output)
     reader.read!
     archive = reader.archive
diff --git a/test/caotral/linker/integration/archive_test.rb b/test/caotral/linker/integration/archive_test.rb
new file mode 100644
index 00000000..c12725e9
--- /dev/null
+++ b/test/caotral/linker/integration/archive_test.rb
@@ -0,0 +1,48 @@
+require_relative "../../../test_suite"
+
+class Caotral::Linker::ArchiveTest < Test::Unit::TestCase
+  include CommonSetupHelper
+  include BuildFixtureHelper
+  include TestProcessHelper
+
+  def test_integrate_archive_file
+    @output = "archive"
+    output = "archive.a"
+    @generated << @output
+    @generated << output
+    inputs = [
+      "sample/C/multi-file-link-a.c",
+      "sample/C/add.c"
+    ]
+    create_archive(output:, inputs:, options: ["-fno-pie"])
+    create_object(output: "multi-file-link-b.o", input: "sample/C/multi-file-link-b.c")
+    @inputs << "multi-file-link-b.o"
+    archives = [output]
+    Caotral::Linker.link!(output: @output, inputs: @inputs, archives:, linker: "self")
+    elf = Caotral::Binary::ELF::Reader.read!(input: @output)
+    IO.popen("./#{@output}").close
+    exit_code, handle_code = check_process($?.to_i)
+    assert_equal(42, exit_code)
+    assert_equal(0, handle_code)
+  end
+
+  def test_extract_dependent_archive_member
+    @output = "recursive-archive"
+    output = "recursive-archive.a"
+    @generated << @output
+    @generated << output
+    inputs = [
+      "sample/C/archive-recursive.c",
+      "sample/C/add.c"
+    ]
+    create_archive(output:, inputs:, options: ["-fno-pie"])
+    create_object(output: "multi-file-link-b.o", input: "sample/C/multi-file-link-b.c")
+    @inputs << "multi-file-link-b.o"
+    archives = [output]
+    Caotral::Linker.link!(output: @output, inputs: @inputs, archives:, linker: "self")
+    IO.popen("./#{@output}").close
+    exit_code, handle_code = check_process($?.to_i)
+    assert_equal(42, exit_code)
+    assert_equal(0, handle_code)
+  end
+end
diff --git a/test/caotral/linker/writer_test.rb b/test/caotral/linker/writer_test.rb
index 4a132405..d0b67d85 100644
--- a/test/caotral/linker/writer_test.rb
+++ b/test/caotral/linker/writer_test.rb
@@ -5,7 +5,7 @@ def setup
     Caotral.assemble(input: "sample/assembler/plus.s", assembler: "self", output: "plus.o")
     elf_obj = Caotral::Binary::ELF::Reader.read!(input: "plus.o", debug: false)
     builder = Caotral::Linker::Builder.new(elf_objs: [elf_obj], debug: false)
-    builder.resolve_symbols
+    builder.resolve_symbols!
     @elf_obj = builder.build
     metadata = builder.linker_metadata
     Caotral::Linker::Layout.new(elf: @elf_obj, shared: false, pie: false, executable: true).apply!
@@ -40,7 +40,7 @@ def test_relocation_write_and_execute
     IO.popen("gcc -c -fno-pic -fno-pie -o relocatable.o sample/C/rel_text.c").close
     input_elf = Caotral::Binary::ELF::Reader.read!(input: "relocatable.o", debug: false)
     builder = Caotral::Linker::Builder.new(elf_objs: [input_elf], debug: false)
-    builder.resolve_symbols
+    builder.resolve_symbols!
     elf = builder.build
     metadata = builder.linker_metadata
     Caotral::Linker::Layout.new(elf:, shared: false, pie: false, executable: true).apply!
diff --git a/test/test_suite.rb b/test/test_suite.rb
index 35d47fa7..862a2c2d 100644
--- a/test/test_suite.rb
+++ b/test/test_suite.rb
@@ -2,6 +2,13 @@
 require "test/unit"
 require "open3"
 
+module CommonSetupHelper
+  attr_reader :generated, :inputs, :output
+
+  def setup = (@generated, @inputs, @output = [], [], nil)
+  def teardown = @generated.each { |f| File.delete(f) if File.exist?(f) }
+end
+
 module BuildFixtureHelper
   def fixture_command(*command)
     o, e, s = Open3.capture3(*command)
@@ -10,9 +17,39 @@ def fixture_command(*command)
     raise "command failed: #{command.join(" ")}\n#{e}"
   end
 
-  def compile_fixture(output:, input:, options: []) = fixture_command("gcc", *options, "-S", "-o", output, input)
-  def assemble_fixture(output:, input:) = fixture_command("as", "-o", output, input)
-  def create_archive(output:, inputs:) = fixture_command("ar", "rcsD", output, *inputs)
+  def compile_fixture(output:, input:, options: [])
+    fixture_command("gcc", *options, "-S", "-o", output, input)
+    output
+  end
+
+  def assemble_fixture(output:, input:)
+    fixture_command("as", "-o", output, input)
+    output
+  end
+
+  def build_archive(output:, inputs:)
+    fixture_command("ar", "rcsD", output, *inputs)
+    output
+  end
+
+  def create_archive(output:, inputs:, options: [])
+    inputs = inputs.map { |input| create_object(output: File.basename(input, ".c") + ".o", input:, options:) }
+    build_archive(output:, inputs:)
+  end
+
+  def create_object(output:, input:, options: [])
+    compiler_output = compile_fixture(output: File.basename(input, ".c") + ".s", input:, options:)
+    @generated << compiler_output
+    input = compiler_output
+    assembler_output = assemble_fixture(output:, input:)
+    @generated << assembler_output
+    assembler_output
+  end
+
+  def create_objects(output:, inputs:, options: [], execution_options: [])
+    inputs = inputs.map { |input| create_object(output:, input:, options:) }
+    fixture_command("gcc", *execution_options, "-o", output, *inputs)
+  end
 end
 
 module TestProcessHelper

From 185a9317ec1d596d8572c863b1c7650ae3a1f2b7 Mon Sep 17 00:00:00 2001
From: "MATSUMOTO, Katsuyoshi" <github@katsyoshi.org>
Date: Mon, 24 Aug 2026 17:48:42 +0900
Subject: [PATCH 4/4] validate archive inputs

---
 lib/caotral/binary/archive/reader.rb | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/lib/caotral/binary/archive/reader.rb b/lib/caotral/binary/archive/reader.rb
index bc583ff0..eb703d6a 100644
--- a/lib/caotral/binary/archive/reader.rb
+++ b/lib/caotral/binary/archive/reader.rb
@@ -8,14 +8,17 @@ class Reader
 
         def initialize(path)
           input = decision(path)
-          @bin = StringIO.new(input.read)
-          @archive = Caotral::Binary::Archive.new
-        ensure
-          input.close
+          begin
+            @bin = StringIO.new(input.read)
+            @archive = Caotral::Binary::Archive.new
+          ensure
+            input.close
+          end
         end
 
         def read!
-          _magic = @bin.read(8)
+          magic = @bin.read(8)
+          raise Caotral::Binary::Archive::Error, "unsupported archive type" unless magic == "!<arch>\n"
           nt = nil
           until @bin.eof?
             offset = @bin.pos