From 909606688a3e56c1f079d0e5d32dfd8521314316 Mon Sep 17 00:00:00 2001
From: Bo Anderson <mail@boanderson.me>
Date: Mon, 10 Jun 2024 23:11:33 +0100
Subject: [PATCH] macho/load_commands: support new macOS 15 dylib use command

---
 lib/macho/load_commands.rb | 91 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)

diff --git a/lib/macho/load_commands.rb b/lib/macho/load_commands.rb
index 183f6a6a2..da7c78055 100644
--- a/lib/macho/load_commands.rb
+++ b/lib/macho/load_commands.rb
@@ -195,6 +195,20 @@ module LoadCommands
       :SG_READ_ONLY => 0x10,
     }.freeze
 
+    # association of dylib use flag symbols to values
+    # @api private
+    DYLIB_USE_FLAGS = {
+      :DYLIB_USE_WEAK_LINK => 0x1,
+      :DYLIB_USE_REEXPORT => 0x2,
+      :DYLIB_USE_UPWARD => 0x4,
+      :DYLIB_USE_DELAYED_INIT => 0x8,
+    }.freeze
+
+    # the marker used to denote a newer style dylib use command.
+    # the value is the timestamp 24 January 1984 18:12:16
+    # @api private
+    DYLIB_USE_MARKER = 0x1a741800
+
     # The top-level Mach-O load command structure.
     #
     # This is the most generic load command -- only the type ID and size are
@@ -528,6 +542,41 @@ class DylibCommand < LoadCommand
       # @return [Integer] the library's compatibility version number
       field :compatibility_version, :uint32
 
+      # Instantiates a new DylibCommand or DylibUseCommand.
+      # macOS 15 and later use a new format for dylib commands (DylibUseCommand),
+      # which is determined based on a special timestamp and the name offset.
+      # @param view [MachO::MachOView] the load command's raw view
+      # @return [DylibCommand] the new dylib load command
+      # @api private
+      def self.new_from_bin(view)
+        dylib_command = super(view)
+
+        if dylib_command.instance_of?(DylibCommand) &&
+           dylib_command.timestamp == DYLIB_USE_MARKER &&
+           dylib_command.name.to_i == DylibUseCommand.bytesize
+          DylibUseCommand.new_from_bin(view)
+        else
+          dylib_command
+        end
+      end
+
+      # @example
+      #  puts "this dylib is weakly loaded" if dylib_command.flag?(:DYLIB_USE_WEAK_LINK)
+      # @param flag [Symbol] a dylib use command flag symbol
+      # @return [Boolean] true if `flag` applies to this dylib command
+      def flag?(flag)
+        case cmd
+        when LOAD_COMMAND_CONSTANTS[:LC_LOAD_WEAK_DYLIB]
+          flag == :DYLIB_USE_WEAK_LINK
+        when LOAD_COMMAND_CONSTANTS[:LC_REEXPORT_DYLIB]
+          flag == :DYLIB_USE_REEXPORT
+        when LOAD_COMMAND_CONSTANTS[:LC_LOAD_UPWARD_DYLIB]
+          flag == :DYLIB_USE_UPWARD
+        else
+          false
+        end
+      end
+
       # @param context [SerializationContext]
       #  the context
       # @return [String] the serialized fields of the load command
@@ -553,6 +602,48 @@ def to_h
       end
     end
 
+    # The newer format of load command representing some aspect of shared libraries,
+    # depending on filetype. Corresponds to LC_LOAD_DYLIB or LC_LOAD_WEAK_DYLIB.
+    class DylibUseCommand < DylibCommand
+      # @return [Integer] any flags associated with this dylib use command
+      field :flags, :uint32
+
+      alias marker timestamp
+
+      # @example
+      #  puts "this dylib is weakly loaded" if dylib_command.flag?(:DYLIB_USE_WEAK_LINK)
+      # @param flag [Symbol] a dylib use command flag symbol
+      # @return [Boolean] true if `flag` applies to this dylib command
+      def flag?(flag)
+        flag = DYLIB_USE_FLAGS[flag]
+
+        return false if flag.nil?
+
+        flags & flag == flag
+      end
+
+      # @param context [SerializationContext]
+      #  the context
+      # @return [String] the serialized fields of the load command
+      # @api private
+      def serialize(context)
+        format = Utils.specialize_format(self.class.format, context.endianness)
+        string_payload, string_offsets = Utils.pack_strings(self.class.bytesize,
+                                                            context.alignment,
+                                                            :name => name.to_s)
+        cmdsize = self.class.bytesize + string_payload.bytesize
+        [cmd, cmdsize, string_offsets[:name], marker, current_version,
+         compatibility_version, flags].pack(format) + string_payload
+      end
+
+      # @return [Hash] a hash representation of this {DylibUseCommand}
+      def to_h
+        {
+          "flags" => flags,
+        }.merge super
+      end
+    end
+
     # A load command representing some aspect of the dynamic linker, depending
     # on filetype. Corresponds to LC_ID_DYLINKER, LC_LOAD_DYLINKER, and
     # LC_DYLD_ENVIRONMENT.