cookies: only save the cookie file if the engine is enabled

Follow-up to 8eddb8f4259.

If the cookieinfo pointer is NULL there really is nothing to save.

Without this fix, we got a problem when a handle was using shared object
with cookies and is told to "FLUSH" it to file (which worked) and then
the share object was removed and when the easy handle was closed just
afterwards it has no cookieinfo and no cookies so it decided to save an
empty jar (overwriting the file just flushed).

Test 1905 now verifies that this works.

Assisted-by: Michael Wallner
Assisted-by: Marcel Raad

Closes #3621

2 files changed, 98 insertions, 1 deletions

diff --git a/tests/libtest/Makefile.inc b/tests/libtest/Makefile.inc
index 2e5236fad..91fd85a87 100644
--- a/tests/libtest/Makefile.inc
+++ b/tests/libtest/Makefile.inc
@@ -33,7 +33,7 @@ noinst_PROGRAMS = chkhostname libauthretry libntlmconnect                \
  lib1558 \
  lib1560 \
  lib1591 lib1592 \
- lib1900 \
+ lib1900 lib1905 \
  lib2033
 
 chkdecimalpoint_SOURCES = chkdecimalpoint.c ../../lib/mprintf.c \
@@ -535,6 +535,10 @@ lib1900_SOURCES = lib1900.c $(SUPPORTFILES) $(TESTUTIL) $(WARNLESS)
 lib1900_LDADD = $(TESTUTIL_LIBS)
 lib1900_CPPFLAGS = $(AM_CPPFLAGS)
 
+lib1905_SOURCES = lib1905.c $(SUPPORTFILES) $(TESTUTIL) $(WARNLESS)
+lib1905_LDADD = $(TESTUTIL_LIBS)
+lib1905_CPPFLAGS = $(AM_CPPFLAGS)
+
 lib2033_SOURCES = libntlmconnect.c $(SUPPORTFILES) $(TESTUTIL) $(WARNLESS)
 lib2033_LDADD = $(TESTUTIL_LIBS)
 lib2033_CPPFLAGS = $(AM_CPPFLAGS) -DUSE_PIPELINING
diff --git a/tests/libtest/lib1905.c b/tests/libtest/lib1905.c
new file mode 100644
index 000000000..1d1de27e7
--- /dev/null
+++ b/tests/libtest/lib1905.c
@@ -0,0 +1,93 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+#include "test.h"
+
+#include "testutil.h"
+#include "warnless.h"
+#include "memdebug.h"
+
+int test(char *URL)
+{
+  CURLM *cm = NULL;
+  CURLSH *sh = NULL;
+  CURL *ch = NULL;
+  int unfinished;
+
+  cm = curl_multi_init();
+  if(!cm)
+    return 1;
+  sh = curl_share_init();
+  if(!sh)
+    goto cleanup;
+
+  curl_share_setopt(sh, CURLSHOPT_SHARE, CURL_LOCK_DATA_COOKIE);
+  curl_share_setopt(sh, CURLSHOPT_SHARE, CURL_LOCK_DATA_COOKIE);
+
+  ch = curl_easy_init();
+  if(!ch)
+    goto cleanup;
+
+  curl_easy_setopt(ch, CURLOPT_SHARE, sh);
+  curl_easy_setopt(ch, CURLOPT_URL, URL);
+  curl_easy_setopt(ch, CURLOPT_COOKIEFILE, "log/cookies1905");
+  curl_easy_setopt(ch, CURLOPT_COOKIEJAR, "log/cookies1905");
+
+  curl_multi_add_handle(cm, ch);
+
+  unfinished = 1;
+  while(unfinished) {
+    int MAX;
+    long max_tout;
+    fd_set R, W, E;
+    struct timeval timeout;
+
+    FD_ZERO(&R);
+    FD_ZERO(&W);
+    FD_ZERO(&E);
+    curl_multi_perform(cm, &unfinished);
+
+    curl_multi_fdset(cm, &R, &W, &E, &MAX);
+    curl_multi_timeout(cm, &max_tout);
+
+    if(max_tout > 0) {
+      timeout.tv_sec = max_tout / 1000;
+      timeout.tv_usec = (max_tout % 1000) * 1000;
+    }
+    else {
+      timeout.tv_sec = 0;
+      timeout.tv_usec = 1000;
+    }
+
+    select(MAX + 1, &R, &W, &E, &timeout);
+  }
+
+  curl_easy_setopt(ch, CURLOPT_COOKIELIST, "FLUSH");
+  curl_easy_setopt(ch, CURLOPT_SHARE, NULL);
+
+  curl_multi_remove_handle(cm, ch);
+  cleanup:
+  curl_easy_cleanup(ch);
+  curl_share_cleanup(sh);
+  curl_multi_cleanup(cm);
+
+  return 0;
+}