4 files changed, 78 insertions, 3 deletions
diff --git a/ext/io/console/depend b/ext/io/console/depend
index c961843bcc..1e485fd194 100644
--- a/ext/io/console/depend
+++ b/ext/io/console/depend
@@ -1,3 +1,5 @@
+WIN32_VK_HEADER = {$(srcdir)}win32_vk.chksum
+
 $(OBJS): $(HDRS) $(ruby_headers) \
   $(VK_HEADER) \
   $(hdrdir)/ruby/io.h \
@@ -6,5 +8,12 @@ $(OBJS): $(HDRS) $(ruby_headers) \
 
 win32_vk.h: win32_vk.list
 
-.list.h:
-	gperf --ignore-case -E -C -P -p -j1 -i 1 -g -o -t -K ofs -N console_win32_vk -k* --output-file=$@ $<
+{$(srcdir)}.list.h:
+	gperf --ignore-case -E -C -P -p -j1 -i 1 -g -o -t -K ofs -N console_win32_vk -k* --output-file=$(@F) $<
+
+.SUFFIXES: .chksum .list
+
+{$(srcdir)}.list.chksum:
+	@$(RUBY) -I$(top_srcdir)/tool -rchecksum \
+	    -e "Checksum.update(ARGV) {|k,f|k.copy(f) rescue k.make(f)}" \
+	    -- --make=$(MAKE) -I$(srcdir) $(<F) $(@F:.chksum=.h)
diff --git a/ext/io/console/extconf.rb b/ext/io/console/extconf.rb
index 1658dc01eb..15fa798a4d 100644
--- a/ext/io/console/extconf.rb
+++ b/ext/io/console/extconf.rb
@@ -5,7 +5,7 @@ hdr = nil
 case
 when macro_defined?("_WIN32", "")
   # rb_w32_map_errno: 1.8.7
-  vk_header = "win32_vk.h"
+  vk_header = "$(WIN32_VK_HEADER)"
 when hdr = %w"termios.h termio.h".find {|h| have_header(h)}
   have_func("cfmakeraw", hdr)
 when have_header(hdr = "sgtty.h")
diff --git a/ext/io/console/win32_vk.chksum b/ext/io/console/win32_vk.chksum
new file mode 100644
index 0000000000..bc9fff7560
--- /dev/null
+++ b/ext/io/console/win32_vk.chksum
@@ -0,0 +1 @@
+src="win32_vk.list", len=3269, checksum=34076
diff --git a/tool/checksum.rb b/tool/checksum.rb
new file mode 100755
index 0000000000..40f444efd2
--- /dev/null
+++ b/tool/checksum.rb
@@ -0,0 +1,65 @@
+#!ruby
+
+require_relative 'vpath'
+
+class Checksum
+  def initialize(vpath)
+    @vpath = vpath
+  end
+
+  def source=(source)
+    @source = source
+    @checksum = File.basename(source, ".*") + ".chksum"
+  end
+
+  def update?
+    src = @vpath.read(@source)
+    @len = src.length
+    @sum = src.sum
+    begin
+      data = @vpath.read(@checksum)
+    rescue
+      return false
+    else
+      return false unless data[/src="([0-9a-z_.-]+)",/, 1] == @source
+      return false unless @len == data[/\blen=(\d+)/, 1].to_i
+      return false unless @sum == data[/\bchecksum=(\d+)/, 1].to_i
+      return true
+    end
+  end
+
+  def update!
+    open(@checksum, "wb") {|f|
+      f.puts("src=\"#{@source}\", len=#{@len}, checksum=#{@sum}")
+    }
+  end
+
+  def update
+    return true if update?
+    update! if ret = yield(self)
+    ret
+  end
+
+  def copy(name)
+    @vpath.open(name, "rb") {|f|
+      IO.copy_stream(f, name)
+    }
+    true
+  end
+
+  def make(arg)
+    system([@make, arg].compact.join(' '))
+  end
+
+  def def_options(opt = (require 'optparse'; OptionParser.new))
+    @vpath.def_options(opt)
+    opt.on("--make=PATH") {|v| @make = v}
+    opt
+  end
+
+  def self.update(argv)
+    k = new(VPath.new)
+    k.source, *argv = k.def_options.parse(*argv)
+    k.update {|k| yield(k, *argv)}
+  end
+end