FTP: prevent the multi interface from blocking

As pointed out in Bug report #3579064, curl_multi_perform() would
wrongly use a blocking mechanism internally for some commands which
could lead to for example a very long block if the LIST response never
showed.

The solution was to make sure to properly continue to use the multi
interface non-blocking state machine.

The new test 1501 verifies the fix.

Bug: http://curl.haxx.se/bug/view.cgi?id=3579064
Reported by: Guido Berhoerster

3 files changed, 130 insertions, 2 deletions

diff --git a/tests/libtest/.gitignore b/tests/libtest/.gitignore
index 80be891d6..28e83c08d 100644
--- a/tests/libtest/.gitignore
+++ b/tests/libtest/.gitignore
@@ -1,5 +1,5 @@
 chkhostname
 lib5[0-9][0-9]
-lib1500
+lib150[0-9]
 libauthretry
 libntlmconnect
diff --git a/tests/libtest/Makefile.inc b/tests/libtest/Makefile.inc
index fa0c69cb5..e0ebcb4c7 100644
--- a/tests/libtest/Makefile.inc
+++ b/tests/libtest/Makefile.inc
@@ -20,7 +20,7 @@ noinst_PROGRAMS = chkhostname \
   lib556 lib539 lib557 lib560 lib562 lib564 lib565 lib566 lib567 lib568	\
   lib569 lib570 lib571 lib572 lib573 lib582 lib583 lib585 lib586 lib587 \
   lib590 lib591 lib597 lib598 lib599 libauthretry libntlmconnect \
-  lib1500
+  lib1500 lib1501
 
 chkhostname_SOURCES = chkhostname.c $(top_srcdir)/lib/curl_gethostname.c
 chkhostname_LDADD = @CURL_NETWORK_LIBS@
@@ -189,6 +189,8 @@ lib599_SOURCES = lib599.c $(SUPPORTFILES)
 
 lib1500_SOURCES = lib1500.c $(SUPPORTFILES) $(TESTUTIL)
 
+lib1501_SOURCES = lib1501.c $(SUPPORTFILES) $(TESTUTIL)
+
 libauthretry_SOURCES = libauthretry.c $(SUPPORTFILES)
 
 libntlmconnect_SOURCES = libntlmconnect.c $(SUPPORTFILES) $(TESTUTIL)
diff --git a/tests/libtest/lib1501.c b/tests/libtest/lib1501.c
new file mode 100644
index 000000000..8d1a40571
--- /dev/null
+++ b/tests/libtest/lib1501.c
@@ -0,0 +1,126 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2012, 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 http://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 <fcntl.h>
+
+#include "testutil.h"
+#include "warnless.h"
+#include "memdebug.h"
+
+#define TEST_HANG_TIMEOUT 30 * 1000
+
+/* 500 milliseconds allowed. An extreme number but lets be really conservative
+   to allow old and slow machines to run this test too */
+#define MAX_BLOCKED_TIME_US 500000
+
+/* return the number of microseconds between two time stamps */
+static int elapsed(struct timeval *before,
+                   struct timeval *after)
+{
+  ssize_t result;
+
+  result = (after->tv_sec - before->tv_sec) * 1000000 +
+    after->tv_usec - before->tv_usec;
+  if (result < 0)
+    result = 0;
+
+  return curlx_sztosi(result);
+}
+
+
+int test(char *URL)
+{
+  CURL *handle = NULL;
+  CURLM *mhandle = NULL;
+  int res = 0;
+  int still_running = 0;
+
+  start_test_timing();
+
+  global_init(CURL_GLOBAL_ALL);
+
+  easy_init(handle);
+
+  easy_setopt(handle, CURLOPT_URL, URL);
+  easy_setopt(handle, CURLOPT_VERBOSE, 1L);
+
+  multi_init(mhandle);
+
+  multi_add_handle(mhandle, handle);
+
+  multi_perform(mhandle, &still_running);
+
+  abort_on_test_timeout();
+
+  while(still_running) {
+    struct timeval timeout;
+    fd_set fdread;
+    fd_set fdwrite;
+    fd_set fdexcep;
+    int maxfd = -99;
+    struct timeval before;
+    struct timeval after;
+    int e;
+
+    timeout.tv_sec = 0;
+    timeout.tv_usec = 100000L; /* 100 ms */
+
+    FD_ZERO(&fdread);
+    FD_ZERO(&fdwrite);
+    FD_ZERO(&fdexcep);
+
+    multi_fdset(mhandle, &fdread, &fdwrite, &fdexcep, &maxfd);
+
+    /* At this point, maxfd is guaranteed to be greater or equal than -1. */
+
+    select_test(maxfd+1, &fdread, &fdwrite, &fdexcep, &timeout);
+
+    abort_on_test_timeout();
+
+    fprintf(stderr, "ping\n");
+    gettimeofday(&before, 0);
+
+    multi_perform(mhandle, &still_running);
+
+    abort_on_test_timeout();
+
+    gettimeofday(&after, 0);
+    e = elapsed(&before, &after);
+    fprintf(stderr, "pong = %d\n", e);
+
+    if(e > MAX_BLOCKED_TIME_US) {
+      res = 100;
+      break;
+    }
+  }
+
+test_cleanup:
+
+  /* undocumented cleanup sequence - type UA */
+
+  curl_multi_cleanup(mhandle);
+  curl_easy_cleanup(handle);
+  curl_global_cleanup();
+
+  return res;
+}