core,w32: Avoid recursive use of npth_unprotect.

* src/w32-estream.c (reader): Use standard free.
(writer): Ditto.
--

There are two errors: The minor one is that we allocated with calloc
but released with _gpgrt_free.  The major one is the recursive use of
npth_unprotect due to the syscall_clamp mechanism:

1. Around the call to _gpgrt_w32_poll

2. By gpgrt_lock_lock on behalf of a the custom allocation handler in
   the worker threads at their _gpgrt_free.

This problem was exhibited by GnuPG's dirmngr component.

GnuPG-bug-id: 3937
Signed-off-by: Werner Koch <wk@gnupg.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/src/init.c b/src/init.c
index 7b3eda3..81ebd0f 100644
--- a/src/init.c
+++ b/src/init.c
@@ -300,7 +300,11 @@ _gpg_err_set_errno (int err)
 
 
 /* Internal tracing functions.  Except for TRACE_FP we use flockfile
- * and funlockfile to protect their use. */
+ * and funlockfile to protect their use.
+ *
+ * Warning: Take care with the trace functions - they may not use any
+ * of our services, in particular not the syscall clamp mechanism for
+ * reasons explained in w32-stream.c:create_reader.  */
 static FILE *trace_fp;
 static int trace_save_errno;
 static int trace_with_errno;