DEBUG windows socketpair using repeat.bat

1. open sysinternals' dbgview

2. edit repeat.bat var CURL to path of a repo non-debug build curl.exe

3. run repeat.bat.

should repro in less than 5 min, may take 20 min, stops after 30-60 min.

~~~
curl: (6) getaddrinfo() thread failed to start
0.000000
Reproduced in 738 tries.
Ran from 15:58:20.66 to 16:00:18.40.
~~~

Ref: curl#10561 (comment)

Author: jay

lib/asyn-thread.c

@@ -230,13 +230,15 @@ int init_thread_sync_data(struct thread_data *td,
   if(!tsd->mtx)
     goto err_exit;
 
+  OutputDebugStringA("marker1");
   Curl_mutex_init(tsd->mtx);
 
 #ifndef CURL_DISABLE_SOCKETPAIR
   /* create socket pair, avoid AF_LOCAL since it doesn't build on Solaris */
   if(Curl_socketpair(AF_UNIX, SOCK_STREAM, 0, &tsd->sock_pair[0]) < 0) {
     tsd->sock_pair[0] = CURL_SOCKET_BAD;
     tsd->sock_pair[1] = CURL_SOCKET_BAD;
+    OutputDebugStringA("marker2");
     goto err_exit;
   }
 #endif
@@ -245,6 +247,7 @@ int init_thread_sync_data(struct thread_data *td,
   /* Copying hostname string because original can be destroyed by parent
    * thread during gethostbyname execution.
    */
+  OutputDebugStringA("marker3");
   tsd->hostname = strdup(hostname);
   if(!tsd->hostname)
     goto err_exit;
@@ -258,6 +261,7 @@ int init_thread_sync_data(struct thread_data *td,
     tsd->sock_pair[0] = CURL_SOCKET_BAD;
   }
 #endif
+  OutputDebugStringA("marker4");
   destroy_thread_sync_data(tsd);
   return 0;
 }
@@ -440,6 +444,8 @@ static bool init_resolve_thread(struct Curl_easy *data,
   asp->dns = NULL;
   td->thread_hnd = curl_thread_t_null;
 
+  OutputDebugStringA(aprintf("::init_resolve_thread"));
+
   if(!init_thread_sync_data(td, hostname, port, hints)) {
     asp->tdata = NULL;
     free(td);
@@ -456,6 +462,7 @@ static bool init_resolve_thread(struct Curl_easy *data,
 
 #ifdef HAVE_GETADDRINFO
   td->thread_hnd = Curl_thread_create(getaddrinfo_thread, &td->tsd);
+  OutputDebugStringA(aprintf("td->thread_hnd: %p", td->thread_hnd));
 #else
   td->thread_hnd = Curl_thread_create(gethostbyname_thread, &td->tsd);
 #endif

lib/curl_threads.c

@@ -33,6 +33,8 @@
 #elif defined(USE_THREADS_WIN32)
 #  include <process.h>
 #endif
+#include "curl_printf.h"
+
 
 #include "curl_threads.h"
 #include "curl_memory.h"
@@ -117,6 +119,7 @@ curl_thread_t Curl_thread_create(unsigned int (CURL_STDCALL *func) (void *),
   thread_handle = CreateThread(NULL, 0, func, arg, 0, NULL);
 #else
   thread_handle = _beginthreadex(NULL, 0, func, arg, 0, NULL);
+  OutputDebugStringA(aprintf("thread_handle: %p", thread_handle));
 #endif
   t = (curl_thread_t)thread_handle;
   if((t == 0) || (t == LongToHandle(-1L))) {
@@ -126,6 +129,7 @@ curl_thread_t Curl_thread_create(unsigned int (CURL_STDCALL *func) (void *),
               gle == ERROR_NOT_ENOUGH_MEMORY) ?
              EACCES : EINVAL);
 #endif
+    OutputDebugStringA(aprintf("err t: %p", t));
     return curl_thread_t_null;
   }
   return t;

lib/socketpair.c

@@ -85,42 +85,69 @@ int Curl_socketpair(int domain, int type, int protocol,
 
   socks[0] = socks[1] = CURL_SOCKET_BAD;
 
+#define xstr(s) str(s)
+#define str(s) #s
+#define GOTO_ERROR \
+  do { \
+    OutputDebugStringA("error - line " ## xstr(__LINE__)); \
+    goto error; \
+  } while(0)
+
   if(setsockopt(listener, SOL_SOCKET, SO_REUSEADDR,
                 (char *)&reuse, (curl_socklen_t)sizeof(reuse)) == -1)
-    goto error;
+    GOTO_ERROR;
   if(bind(listener, &a.addr, sizeof(a.inaddr)) == -1)
-    goto error;
+    GOTO_ERROR;
   if(getsockname(listener, &a.addr, &addrlen) == -1 ||
      addrlen < (int)sizeof(a.inaddr))
-    goto error;
+    GOTO_ERROR;
   if(listen(listener, 1) == -1)
-    goto error;
+    GOTO_ERROR;
   socks[0] = socket(AF_INET, SOCK_STREAM, 0);
   if(socks[0] == CURL_SOCKET_BAD)
-    goto error;
+    GOTO_ERROR;
   if(connect(socks[0], &a.addr, sizeof(a.inaddr)) == -1)
-    goto error;
+    GOTO_ERROR;
 
   /* use non-blocking accept to make sure we don't block forever */
   if(curlx_nonblock(listener, TRUE) < 0)
-    goto error;
+    GOTO_ERROR;
   pfd[0].fd = listener;
   pfd[0].events = POLLIN;
   pfd[0].revents = 0;
   (void)Curl_poll(pfd, 1, 1000); /* one second */
   socks[1] = accept(listener, NULL, NULL);
   if(socks[1] == CURL_SOCKET_BAD)
-    goto error;
+    GOTO_ERROR;
   else {
     struct curltime check;
     struct curltime now = Curl_now();
+    ssize_t out, in;
 
     /* write data to the socket */
-    swrite(socks[0], &now, sizeof(now));
+    WSASetLastError(0);
+    out = swrite(socks[0], &now, sizeof(now));
+    if(out != sizeof(now)) {
+      if(out == SOCKET_ERROR)
+        OutputDebugStringA(aprintf("send gle: %d", WSAGetLastError()));
+      else
+        OutputDebugStringA(aprintf("out: %zd", out));
+      GOTO_ERROR;
+    }
+
     /* verify that we read the correct data */
-    if((sizeof(now) != sread(socks[1], &check, sizeof(check)) ||
-        memcmp(&now, &check, sizeof(check))))
-      goto error;
+    WSASetLastError(0);
+    in = sread(socks[1], &check, sizeof(check));
+    if(sizeof(now) != in) {
+      if(in == SOCKET_ERROR)
+        OutputDebugStringA(aprintf("recv gle: %d", WSAGetLastError()));
+      else
+        OutputDebugStringA(aprintf("in: %zd", in));
+      GOTO_ERROR;
+    }
+
+    if(memcmp(&now, &check, sizeof(check)))
+      GOTO_ERROR;
   }
 
   sclose(listener);

repeat.bat

@@ -0,0 +1,35 @@
+@echo off
+setlocal ENABLEEXTENSIONS ENABLEDELAYEDEXPANSION
+
+REM set this as the path to your curl
+set "CURL=X:\j\curl\curl\build\Win32\VC10\DLL Release - DLL Windows SSPI - DLL WinIDN\curl.exe"
+
+set START_TIME=%TIME%
+
+REM 20000 is approx 30-60 min of repeated transfers to http://curl.se
+set MAX=20000
+
+echo Use Sysinternals dbgview to collect debug output while this runs.
+timeout 5 /nobreak
+
+REM note the host here is purposely http://curl.se so the command does a real
+REM resolve but then completes faster, since http://curl.se just serves a
+REM redirect that is not followed.
+
+FOR /L %%G IN (1,1,%MAX%) DO (
+  "%CURL%" -sS -f http://curl.se -o NUL --write-out "%%{time_total} "
+  if !ERRORLEVEL! NEQ 0 (
+    echo.
+    if !ERRORLEVEL! EQU 6 (
+      echo Reproduced in %%G tries.
+    ) else (
+      echo Unexpected error code !ERRORLEVEL!, likely not a repro.
+    )
+    goto bye
+  )
+)
+
+echo Failed to reproduce the bug with %MAX% tries.
+
+:bye
+echo Ran from %START_TIME% to !TIME!.