use close_others Ruby mechanism to prevent file descriptor leaking to Python (#219)

Author: slonopotamus

CHANGELOG.adoc

@@ -8,6 +8,7 @@ For a detailed view of what has changed, refer to the {uri-repo}/commits/master[
 == Unreleased
 
 * stop sending/receiving `ids` between Ruby and Python
+* use `close_others` Ruby mechanism to prevent file descriptor leaking to Python
 
 == 2.0.0.rc3 (2021-01-08) - @slonopotamus
 

lib/pygments/mentos.py

@@ -213,7 +213,7 @@ def start(self):
         pygmentized, this header will be followed by the text to be pygmentized.
 
         The header is of form:
-        { "method": "highlight", "args": [], "kwargs": {"arg1": "v"}, "bytes": 128, "fd": "8"}
+        { "method": "highlight", "args": [], "kwargs": {"arg1": "v"}, "bytes": 128}
         """
 
         while True:
@@ -258,20 +258,6 @@ def main():
         signal.signal(signal.SIGHUP, _signal_handler)
 
     mentos = Mentos()
-
-    if sys.platform != "win32":
-        # close fd's inherited from the ruby parent
-        import resource
-        maxfd = resource.getrlimit(resource.RLIMIT_NOFILE)[1]
-        if maxfd == resource.RLIM_INFINITY:
-            maxfd = 65536
-
-        for fd in range(3, maxfd):
-            try:
-                os.close(fd)
-            except:
-                pass
-
     mentos.start()
 
 if __name__ == "__main__":

lib/pygments/popen.rb

@@ -14,7 +14,7 @@ class MentosError < IOError
 module Pygments
   class Popen
     def popen4(argv)
-      stdin, stdout, stderr, wait_thr = Open3.popen3(*argv)
+      stdin, stdout, stderr, wait_thr = Open3.popen3(*argv, { close_others: true })
       while (pid = wait_thr.pid).nil? && wait_thr.alive?
         # For unknown reasons, wait_thr.pid is not immediately available on JRuby
       end
@@ -42,7 +42,7 @@ def start(pygments_path = File.expand_path('../../vendor/pygments-main', __dir__
       @pid, @in, @out, @err = popen4(argv)
       @in.binmode
       @out.binmode
-      @log.info "Starting pid #{@pid} with fd #{@out.to_i} and python #{python_binary}."
+      @log.info "Starting pid #{@pid} with python #{python_binary}."
     end
 
     def python_binary
@@ -280,7 +280,7 @@ def mentos(method, args = [], kwargs = {}, code = nil)
                  end
 
       kwargs.freeze
-      kwargs = kwargs.merge('fd' => @out.to_i, 'bytes' => bytesize)
+      kwargs = kwargs.merge('bytes' => bytesize)
       out_header = JSON.generate(method: method, args: args, kwargs: kwargs)
 
       begin