1 files changed, 87 insertions, 0 deletions
diff --git a/lib/irb/history.rb b/lib/irb/history.rb
new file mode 100644
index 0000000000..685354b2d8
--- /dev/null
+++ b/lib/irb/history.rb
@@ -0,0 +1,87 @@
+require "pathname"
+
+module IRB
+  module HistorySavingAbility # :nodoc:
+    def support_history_saving?
+      true
+    end
+
+    def reset_history_counter
+      @loaded_history_lines = self.class::HISTORY.size
+    end
+
+    def load_history
+      history = self.class::HISTORY
+
+      if history_file = IRB.conf[:HISTORY_FILE]
+        history_file = File.expand_path(history_file)
+      end
+      history_file = IRB.rc_file("_history") unless history_file
+      if history_file && File.exist?(history_file)
+        File.open(history_file, "r:#{IRB.conf[:LC_MESSAGES].encoding}") do |f|
+          f.each { |l|
+            l = l.chomp
+            if self.class == RelineInputMethod and history.last&.end_with?("\\")
+              history.last.delete_suffix!("\\")
+              history.last << "\n" << l
+            else
+              history << l
+            end
+          }
+        end
+        @loaded_history_lines = history.size
+        @loaded_history_mtime = File.mtime(history_file)
+      end
+    end
+
+    def save_history
+      history = self.class::HISTORY.to_a
+
+      if num = IRB.conf[:SAVE_HISTORY] and (num = num.to_i) != 0
+        if history_file = IRB.conf[:HISTORY_FILE]
+          history_file = File.expand_path(history_file)
+        end
+        history_file = IRB.rc_file("_history") unless history_file
+
+        # When HOME and XDG_CONFIG_HOME are not available, history_file might be nil
+        return unless history_file
+
+        # Change the permission of a file that already exists[BUG #7694]
+        begin
+          if File.stat(history_file).mode & 066 != 0
+            File.chmod(0600, history_file)
+          end
+        rescue Errno::ENOENT
+        rescue Errno::EPERM
+          return
+        rescue
+          raise
+        end
+
+        if File.exist?(history_file) &&
+           File.mtime(history_file) != @loaded_history_mtime
+          history = history[@loaded_history_lines..-1] if @loaded_history_lines
+          append_history = true
+        end
+
+        pathname = Pathname.new(history_file)
+        unless Dir.exist?(pathname.dirname)
+          warn "Warning: The directory to save IRB's history file does not exist. Please double check `IRB.conf[:HISTORY_FILE]`'s value."
+          return
+        end
+
+        File.open(history_file, (append_history ? 'a' : 'w'), 0o600, encoding: IRB.conf[:LC_MESSAGES]&.encoding) do |f|
+          hist = history.map{ |l| l.scrub.split("\n").join("\\\n") }
+          unless append_history
+            begin
+              hist = hist.last(num) if hist.size > num and num > 0
+            rescue RangeError # bignum too big to convert into `long'
+              # Do nothing because the bignum should be treated as infinity
+            end
+          end
+          f.puts(hist)
+        end
+      end
+    end
+  end
+end