check socket creation errors against PGINVALID_SOCKET

Previously, in some places, socket creation errors were checked for
negative values, which is not true for Windows because sockets are
unsigned.  This masked socket creation errors on Windows.

Backpatch through 9.0.  8.4 doesn't have the infrastructure to fix this.

1 files changed, 29 insertions, 5 deletions

diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index d53c41f6a3d..51d4de419b4 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -1632,8 +1632,23 @@ keep_going:						/* We will come back to here until there is
 					conn->raddr.salen = addr_cur->ai_addrlen;
 
 					/* Open a socket */
-					conn->sock = socket(addr_cur->ai_family, SOCK_STREAM, 0);
-					if (conn->sock < 0)
+					{
+						/*
+						 * While we use 'pgsocket' as the socket type in the
+						 * backend, we use 'int' for libpq socket values.
+						 * This requires us to map PGINVALID_SOCKET to -1
+						 * on Windows.
+						 * See http://msdn.microsoft.com/en-us/library/windows/desktop/ms740516%28v=vs.85%29.aspx
+						 */
+						pgsocket sock = socket(addr_cur->ai_family, SOCK_STREAM, 0);
+#ifdef WIN32
+						if (sock == PGINVALID_SOCKET)
+							conn->sock = -1;
+						else
+#endif
+							conn->sock = sock;
+					}
+					if (conn->sock == -1)
 					{
 						/*
 						 * ignore socket() failure if we have more addresses
@@ -3136,7 +3151,7 @@ internal_cancel(SockAddr *raddr, int be_pid, int be_key,
 				char *errbuf, int errbufsize)
 {
 	int			save_errno = SOCK_ERRNO;
-	int			tmpsock = -1;
+	pgsocket	tmpsock = PGINVALID_SOCKET;
 	char		sebuf[256];
 	int			maxlen;
 	struct
@@ -3149,7 +3164,7 @@ internal_cancel(SockAddr *raddr, int be_pid, int be_key,
 	 * We need to open a temporary connection to the postmaster. Do this with
 	 * only kernel calls.
 	 */
-	if ((tmpsock = socket(raddr->addr.ss_family, SOCK_STREAM, 0)) < 0)
+	if ((tmpsock = socket(raddr->addr.ss_family, SOCK_STREAM, 0)) == PGINVALID_SOCKET)
 	{
 		strlcpy(errbuf, "PQcancel() -- socket() failed: ", errbufsize);
 		goto cancel_errReturn;
@@ -3220,7 +3235,7 @@ cancel_errReturn:
 				maxlen);
 		strcat(errbuf, "\n");
 	}
-	if (tmpsock >= 0)
+	if (tmpsock != PGINVALID_SOCKET)
 		closesocket(tmpsock);
 	SOCK_ERRNO_SET(save_errno);
 	return FALSE;
@@ -5300,6 +5315,15 @@ PQerrorMessage(const PGconn *conn)
 	return conn->errorMessage.data;
 }
 
+/*
+ * In Windows, socket values are unsigned, and an invalid socket value
+ * (INVALID_SOCKET) is ~0, which equals -1 in comparisons (with no compiler
+ * warning). Ideally we would return an unsigned value for PQsocket() on
+ * Windows, but that would cause the function's return value to differ from
+ * Unix, so we just return -1 for invalid sockets.
+ * http://msdn.microsoft.com/en-us/library/windows/desktop/cc507522%28v=vs.85%29.aspx
+ * http://stackoverflow.com/questions/10817252/why-is-invalid-socket-defined-as-0-in-winsock2-h-c
+ */
 int
 PQsocket(const PGconn *conn)
 {