Allow sockets to use longer paths on macOS

Library/Homebrew/build.rb

@@ -13,7 +13,7 @@ require "build_options"
 require "keg"
 require "extend/ENV"
 require "fcntl"
-require "socket"
+require "utils/socket"
 require "cmd/install"
 require "json/add/exception"
 
@@ -221,7 +221,7 @@ begin
   args = Homebrew::Cmd::InstallCmd.new.args
   Context.current = args.context
 
-  error_pipe = UNIXSocket.open(ENV.fetch("HOMEBREW_ERROR_PIPE"), &:recv_io)
+  error_pipe = Utils::UNIXSocketExt.open(ENV.fetch("HOMEBREW_ERROR_PIPE"), &:recv_io)
   error_pipe.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC)
 
   trap("INT", old_trap)

Library/Homebrew/extend/os/mac/utils/socket.rb

@@ -0,0 +1,30 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "socket"
+
+module OS
+  module Mac
+    # Wrapper around UNIXSocket to allow > 104 characters on macOS.
+    module UNIXSocketExt
+      extend T::Helpers
+
+      requires_ancestor { Kernel }
+
+      sig { params(path: String).returns(String) }
+      def sockaddr_un(path)
+        if path.bytesize > 252 # largest size that can fit into a single-byte length
+          raise ArgumentError, "too long unix socket path (#{path.bytesize} bytes given but 252 bytes max)"
+        end
+
+        [
+          path.bytesize + 3, # = length (1 byte) + family (1 byte) + path (variable) + null terminator (1 byte)
+          1, # AF_UNIX
+          path,
+        ].pack("CCZ*")
+      end
+    end
+  end
+end
+
+Utils::UNIXSocketExt.singleton_class.prepend(OS::Mac::UNIXSocketExt)

Library/Homebrew/extend/os/utils/socket.rb

@@ -0,0 +1,4 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "extend/os/mac/utils/socket" if OS.mac?

Library/Homebrew/postinstall.rb

@@ -8,7 +8,7 @@ old_trap = trap("INT") { exit! 130 }
 require_relative "global"
 
 require "fcntl"
-require "socket"
+require "utils/socket"
 require "cli/parser"
 require "cmd/postinstall"
 require "json/add/exception"
@@ -16,7 +16,7 @@ require "json/add/exception"
 begin
   ENV.delete("HOMEBREW_FORBID_PACKAGES_FROM_PATHS")
   args = Homebrew::Cmd::Postinstall.new.args
-  error_pipe = UNIXSocket.open(ENV.fetch("HOMEBREW_ERROR_PIPE"), &:recv_io)
+  error_pipe = Utils::UNIXSocketExt.open(ENV.fetch("HOMEBREW_ERROR_PIPE"), &:recv_io)
   error_pipe.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC)
 
   trap("INT", old_trap)

Library/Homebrew/test.rb

@@ -11,7 +11,7 @@ require "timeout"
 require "formula_assertions"
 require "formula_free_port"
 require "fcntl"
-require "socket"
+require "utils/socket"
 require "cli/parser"
 require "dev-cmd/test"
 require "json/add/exception"
@@ -23,7 +23,7 @@ begin
   args = Homebrew::DevCmd::Test.new.args
   Context.current = args.context
 
-  error_pipe = UNIXSocket.open(ENV.fetch("HOMEBREW_ERROR_PIPE"), &:recv_io)
+  error_pipe = Utils::UNIXSocketExt.open(ENV.fetch("HOMEBREW_ERROR_PIPE"), &:recv_io)
   error_pipe.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC)
 
   trap("INT", old_trap)

Library/Homebrew/utils/fork.rb

@@ -2,7 +2,7 @@
 # frozen_string_literal: true
 
 require "fcntl"
-require "socket"
+require "utils/socket"
 
 module Utils
   def self.rewrite_child_error(child_error)
@@ -37,7 +37,7 @@ module Utils
     require "json/add/exception"
 
     block = proc do |tmpdir|
-      UNIXServer.open("#{tmpdir}/socket") do |server|
+      UNIXServerExt.open("#{tmpdir}/socket") do |server|
         read, write = IO.pipe
 
         pid = fork do

Library/Homebrew/utils/socket.rb

@@ -0,0 +1,57 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "socket"
+
+module Utils
+  # Wrapper around UNIXSocket to allow > 104 characters on macOS.
+  module UNIXSocketExt
+    extend T::Generic
+
+    sig {
+      type_parameters(:U).params(
+        path:   String,
+        _block: T.proc.params(arg0: UNIXSocket).returns(T.type_parameter(:U)),
+      ).returns(T.type_parameter(:U))
+    }
+    def self.open(path, &_block)
+      socket = Socket.new(:UNIX, :STREAM)
+      socket.connect(sockaddr_un(path))
+      unix_socket = UNIXSocket.for_fd(socket.fileno)
+      socket.autoclose = false # Transfer autoclose responsibility to UNIXSocket
+      yield unix_socket
+    end
+
+    sig { params(path: String).returns(String) }
+    def self.sockaddr_un(path)
+      Socket.sockaddr_un(path)
+    end
+  end
+
+  # Wrapper around UNIXServer to allow > 104 characters on macOS.
+  class UNIXServerExt < Socket
+    extend T::Generic
+
+    Elem = type_member(:out) { { fixed: String } }
+
+    sig { returns(String) }
+    attr_reader :path
+
+    sig { params(path: String).void }
+    def initialize(path)
+      super(:UNIX, :STREAM)
+      bind(UNIXSocketExt.sockaddr_un(path))
+      listen(Socket::SOMAXCONN)
+      @path = path
+    end
+
+    sig { returns(UNIXSocket) }
+    def accept_nonblock
+      socket, = super
+      socket.autoclose = false # Transfer autoclose responsibility to UNIXSocket
+      UNIXSocket.for_fd(socket.fileno)
+    end
+  end
+end
+
+require "extend/os/utils/socket"