krb5 commit: Fix 64-bit Windows socket write error handling

[Greg Hudson]

https://github.com/krb5/krb5/commit/d98c3238894986765631f1e556f29ca817988816
commit d98c3238894986765631f1e556f29ca817988816
Author: Greg Hudson <ghudson at mit.edu>
Date:   Thu Oct 4 18:10:48 2018 -0400

    Fix 64-bit Windows socket write error handling
    
    Add casts to ensure that the result type of SOCKET_WRITEV() on Windows
    can represent -1.  Otherwise it will be treated as 2^32-1 when cast to
    ssize_t on 64-bit Windows, which can lead to crashes in
    krb5_sendto_kdc().  Reported by Puran Chand.
    
    ticket: 8746 (new)
    tags: pullup
    target_version: 1.13-next

 src/include/port-sockets.h  |    5 +++--
 src/lib/krb5/os/net_write.c |    2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/include/port-sockets.h b/src/include/port-sockets.h
index b3ab9c9..f0fc2b8 100644
--- a/src/include/port-sockets.h
+++ b/src/include/port-sockets.h
@@ -40,8 +40,9 @@ typedef WSABUF sg_buf;
  */
 /* WSASend returns 0 or SOCKET_ERROR.  */
 #define SOCKET_WRITEV_TEMP DWORD
-#define SOCKET_WRITEV(FD, SG, LEN, TMP)                         \
-    (WSASend((FD), (SG), (LEN), &(TMP), 0, 0, 0) ? -1 : (TMP))
+#define SOCKET_WRITEV(FD, SG, LEN, TMP)                 \
+    (WSASend((FD), (SG), (LEN), &(TMP), 0, 0, 0) ?      \
+     (ssize_t)-1 : (ssize_t)(TMP))
 
 #define SHUTDOWN_READ   SD_RECEIVE
 #define SHUTDOWN_WRITE  SD_SEND
diff --git a/src/lib/krb5/os/net_write.c b/src/lib/krb5/os/net_write.c
index 9290726..cc8c309 100644
--- a/src/lib/krb5/os/net_write.c
+++ b/src/lib/krb5/os/net_write.c
@@ -47,7 +47,7 @@ krb5_net_write(krb5_context context, int fd, const char *buf, int len)
 int
 krb5int_net_writev(krb5_context context, int fd, sg_buf *sgp, int nsg)
 {
-    int cc, len = 0;
+    ssize_t cc, len = 0;
     SOCKET_WRITEV_TEMP tmp;
 
     while (nsg > 0) {