estream: Add gpgrt_fcancel

* src/estream.c (do_close): Add arg 'cancel_mode' and chnage all
callers.
(_gpgrt_fcancel): New.
* src/gpg-error.def.in, src/gpg-error.vers: Add function.
* src/visibility.c (gpgrt_fcancel): New.
* src/gpg-error.h.in (gpgrt_fcancel): New.
--

Signed-off-by: Werner Koch <[email protected]>

8 files changed, 49 insertions, 9 deletions

diff --git a/NEWS b/NEWS
index 4ec9b56..20026db 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,11 @@ Noteworthy changes in version 1.39 (unreleased) [C29/A29/R1]
 -----------------------------------------------
 
 
+ * Interface changes relative to the 1.38 release:
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ gpgrt_fcancel                    NEW.
+
+
 Noteworthy changes in version 1.38 (2020-05-29) [C29/A29/R0]
 -----------------------------------------------
 
diff --git a/src/estream.c b/src/estream.c
index 6b531fb..06ebdaa 100644
--- a/src/estream.c
+++ b/src/estream.c
@@ -2167,10 +2167,11 @@ create_stream (estream_t *r_stream, void *cookie, es_syshd_t *syshd,
 
 
 /*
- * Deinitialize a stream object and destroy it.
+ * Deinitialize a stream object and destroy it.  With CANCEL_MODE set
+ * try to cancel as much as possible (see _gpgrt_fcancel).
  */
 static int
-do_close (estream_t stream, int with_locked_list)
+do_close (estream_t stream, int cancel_mode, int with_locked_list)
 {
   int err;
 
@@ -2179,6 +2180,11 @@ do_close (estream_t stream, int with_locked_list)
   if (stream)
     {
       do_list_remove (stream, with_locked_list);
+      if (cancel_mode)
+        {
+          stream->flags.writing = 0;
+          es_empty (stream);
+        }
       while (stream->intern->onclose)
         {
           notify_list_t tmp = stream->intern->onclose->next;
@@ -2943,7 +2949,7 @@ doreadline (estream_t _GPGRT__RESTRICT stream, size_t max_length,
  out:
 
   if (line_stream)
-    do_close (line_stream, 0);
+    do_close (line_stream, 0, 0);
   else if (line_stream_cookie)
     func_mem_destroy (line_stream_cookie);
 
@@ -3617,7 +3623,7 @@ _gpgrt_freopen (const char *_GPGRT__RESTRICT path,
 	  if (create_called)
 	    func_fd_destroy (cookie);
 
-	  do_close (stream, 0);
+	  do_close (stream, 0, 0);
 	  stream = NULL;
 	}
       else
@@ -3632,7 +3638,7 @@ _gpgrt_freopen (const char *_GPGRT__RESTRICT path,
       /* FIXME?  We don't support re-opening at the moment.  */
       _set_errno (EINVAL);
       deinit_stream_obj (stream);
-      do_close (stream, 0);
+      do_close (stream, 0, 0);
       stream = NULL;
     }
 
@@ -3645,7 +3651,22 @@ _gpgrt_fclose (estream_t stream)
 {
   int err;
 
-  err = do_close (stream, 0);
+  err = do_close (stream, 0, 0);
+
+  return err;
+}
+
+
+/* gpgrt_fcancel does the same as gpgrt_fclose but tries to avoid
+ * flushing out any data still held in internal buffers.  It may or
+ * may not remove a new file created for that stream by the open
+ * function.  */
+int
+_gpgrt_fcancel (estream_t stream)
+{
+  int err;
+
+  err = do_close (stream, 1, 0);
 
   return err;
 }
@@ -3698,7 +3719,7 @@ _gpgrt_fclose_snatch (estream_t stream, void **r_buffer, size_t *r_buflen)
         *r_buflen = buflen;
     }
 
-  err = do_close (stream, 0);
+  err = do_close (stream, 0, 0);
 
  leave:
   if (err && r_buffer)
@@ -3726,8 +3747,10 @@ _gpgrt_fclose_snatch (estream_t stream, void **r_buffer, size_t *r_buflen)
 
    FIXME: Unregister is not thread safe.
 
-   The notification will be called right before the stream is closed.
-   It may not call any estream function for STREAM, neither direct nor
+   The notification will be called right before the stream is
+   closed. If gpgrt_fcancel is used, the cancellation of internal
+   buffers is done before the notifications.  The notification handler
+   may not call any estream function for STREAM, neither direct nor
    indirectly. */
 int
 _gpgrt_onclose (estream_t stream, int mode,
diff --git a/src/gpg-error.def.in b/src/gpg-error.def.in
index bf8773b..de408db 100644
--- a/src/gpg-error.def.in
+++ b/src/gpg-error.def.in
@@ -236,5 +236,6 @@ EXPORTS
  gpgrt_absfnameconcat         @179
 
  gpgrt_reallocarray           @180
+ gpgrt_fclose                 @181
 
 ;; end of file with public symbols for Windows.
diff --git a/src/gpg-error.h.in b/src/gpg-error.h.in
index e915797..925ef51 100644
--- a/src/gpg-error.h.in
+++ b/src/gpg-error.h.in
@@ -689,6 +689,7 @@ gpgrt_stream_t gpgrt_fopencookie (void *_GPGRT__RESTRICT cookie,
                                   const char *_GPGRT__RESTRICT mode,
                                   gpgrt_cookie_io_functions_t functions);
 int gpgrt_fclose (gpgrt_stream_t stream);
+int gpgrt_fcancel (gpgrt_stream_t stream);
 int gpgrt_fclose_snatch (gpgrt_stream_t stream,
                          void **r_buffer, size_t *r_buflen);
 int gpgrt_onclose (gpgrt_stream_t stream, int mode,
diff --git a/src/gpg-error.vers b/src/gpg-error.vers
index ab3bbb0..e67a16f 100644
--- a/src/gpg-error.vers
+++ b/src/gpg-error.vers
@@ -55,6 +55,7 @@ GPG_ERROR_1.0 {
     gpgrt_freopen;
     gpgrt_fopencookie;
     gpgrt_fclose;
+    gpgrt_fcancel;
     gpgrt_fclose_snatch;
     gpgrt_onclose;
     gpgrt_fileno;
diff --git a/src/gpgrt-int.h b/src/gpgrt-int.h
index 629f527..913b9ba 100644
--- a/src/gpgrt-int.h
+++ b/src/gpgrt-int.h
@@ -339,6 +339,7 @@ gpgrt_stream_t _gpgrt_fopencookie (void *_GPGRT__RESTRICT cookie,
                                    const char *_GPGRT__RESTRICT mode,
                                    gpgrt_cookie_io_functions_t functions);
 int _gpgrt_fclose (gpgrt_stream_t stream);
+int _gpgrt_fcancel (gpgrt_stream_t stream);
 int _gpgrt_fclose_snatch (gpgrt_stream_t stream,
                           void **r_buffer, size_t *r_buflen);
 int _gpgrt_onclose (gpgrt_stream_t stream, int mode,
diff --git a/src/visibility.c b/src/visibility.c
index 2e6aed7..85caef3 100644
--- a/src/visibility.c
+++ b/src/visibility.c
@@ -251,6 +251,12 @@ gpgrt_fclose (estream_t stream)
 }
 
 int
+gpgrt_fcancel (estream_t stream)
+{
+  return _gpgrt_fcancel (stream);
+}
+
+int
 gpgrt_fclose_snatch (estream_t stream, void **r_buffer, size_t *r_buflen)
 {
   return _gpgrt_fclose_snatch (stream, r_buffer, r_buflen);
diff --git a/src/visibility.h b/src/visibility.h
index f7d16be..3b12acf 100644
--- a/src/visibility.h
+++ b/src/visibility.h
@@ -79,6 +79,7 @@ MARK_VISIBLE (gpgrt_fpopen_nc)
 MARK_VISIBLE (gpgrt_freopen)
 MARK_VISIBLE (gpgrt_fopencookie)
 MARK_VISIBLE (gpgrt_fclose)
+MARK_VISIBLE (gpgrt_fcancel)
 MARK_VISIBLE (gpgrt_fclose_snatch)
 MARK_VISIBLE (gpgrt_onclose)
 MARK_VISIBLE (gpgrt_fileno)
@@ -265,6 +266,7 @@ MARK_VISIBLE (gpgrt_absfnameconcat);
 #define gpgrt_freopen               _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_fopencookie           _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_fclose                _gpgrt_USE_UNDERSCORED_FUNCTION
+#define gpgrt_fcancel               _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_fclose_snatch         _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_onclose               _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_fileno                _gpgrt_USE_UNDERSCORED_FUNCTION