Support non-blocking connect on MS-Windows (Bug#20207)

 Based on ideas from Kim F. Storm <storm@cua.dk>, see
 http://lists.gnu.org/archive/html/emacs-devel/2006-12/msg00873.html.

 src/w32proc.c (reader_thread): If the FILE_CONNECT flag is set, call
 '_sys_wait_connect'.  If it returns STATUS_CONNECT_FAILED, exit
 the thread with code 2.
 (sys_select): Support 'wfds' in addition to 'rfds'.  If a
 descriptor in 'wfds' has its bit set, but the corresponding
 fd_info member doesn't have its FILE_CONNECT flag set, ignore the
 descriptor.  Otherwise, acknowledge a successful non-blocking
 connect by resetting the FILE_CONNECT flag and setting cp->status
 to STATUS_READ_ACKNOWLEDGED.
 src/w32.h (STATUS_CONNECT_FAILED): New enumeration value.
 (struct _child_process): New member 'errcode'.
 (FILE_CONNECT): New flag.
 (_sys_wait_connect): Add prototype.
 src/w32.c (pfn_WSAEnumNetworkEvents): New function pointer.
 (init_winsock): Load WSAEnumNetworkEvents from winsock DLL.
 (set_errno): Map WSAEWOULDBLOCK and WSAENOTCONN.
 (sys_connect): Support non-blocking 'connect' calls by setting the
 FILE_CONNECT flag in the fd_info member and returning EINPROGRESS.
 (_sys_read_ahead): Add debug message if this function is called
 for a descriptor that waits for a non-blocking connect to complete.
 (_sys_wait_connect): New function.
 (sys_read): Support STATUS_CONNECT_FAILED.  Return the error code
 recorded by _sys_wait_connect when the non-blocking connect
 failed.  Don't call WSAGetLastError before a call to set_errno had
 a chance to use its value, since WSAGetLastError clears the last
 error.

 nt/inc/ms-w32.h (BROKEN_NON_BLOCKING_CONNECT): Don't define.

1 files changed, 7 insertions, 2 deletions

diff --git a/src/w32.h b/src/w32.h
index 835557d5ec7..9b3521d077f 100644
--- a/src/w32.h
+++ b/src/w32.h
@@ -61,7 +61,8 @@ enum {
   STATUS_READ_IN_PROGRESS,
   STATUS_READ_FAILED,
   STATUS_READ_SUCCEEDED,
-  STATUS_READ_ACKNOWLEDGED
+  STATUS_READ_ACKNOWLEDGED,
+  STATUS_CONNECT_FAILED
 };
 
 /* This structure is used for both pipes and sockets; for
@@ -96,6 +97,8 @@ typedef struct _child_process
   /* Status of subprocess/connection and of reading its output.  For
      values, see the enumeration above.  */
   volatile int        status;
+  /* Used to store errno value of failed async 'connect' calls.  */
+  volatile int        errcode;
   /* Holds a single character read by _sys_read_ahead, when a
      subprocess has some output ready.  */
   char                chr;
@@ -122,7 +125,8 @@ extern filedesc fd_info [ MAXDESC ];
 /* fd_info flag definitions */
 #define FILE_READ               0x0001
 #define FILE_WRITE              0x0002
-#define FILE_LISTEN		0x0004
+#define FILE_LISTEN             0x0004
+#define FILE_CONNECT            0x0008
 #define FILE_BINARY             0x0010
 #define FILE_LAST_CR            0x0020
 #define FILE_AT_EOF             0x0040
@@ -171,6 +175,7 @@ extern void init_timers (void);
 
 extern int _sys_read_ahead (int fd);
 extern int _sys_wait_accept (int fd);
+extern int _sys_wait_connect (int fd);
 
 extern HMODULE w32_delayed_load (Lisp_Object);