[PATCH V4] xdrstdio_create buffers do not output encoded values on ppc

[Steve Dickson <steved@redhat.com>]

The cause is that the xdr_putlong uses a long to store the
converted value, then passes it to fwrite as a byte buffer.
Only the first 4 bytes are written, which is okay for a LE
system after byteswapping, but writes all zeroes on BE systems.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1261738

Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>
---
v4: Use UINT32_MAX instead of INT32_MAX in boundary check.

v3: Reworked the bounds checking

v2: Added bounds checking
    Changed from unsigned to signed

 src/xdr_stdio.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/src/xdr_stdio.c b/src/xdr_stdio.c
index 4410262..846c7bf 100644
--- a/src/xdr_stdio.c
+++ b/src/xdr_stdio.c
@@ -38,6 +38,7 @@
  */
 
 #include <stdio.h>
+#include <stdint.h>
 
 #include <arpa/inet.h>
 #include <rpc/types.h>
@@ -103,10 +104,12 @@ xdrstdio_getlong(xdrs, lp)
 	XDR *xdrs;
 	long *lp;
 {
+	int32_t mycopy;
 
-	if (fread(lp, sizeof(int32_t), 1, (FILE *)xdrs->x_private) != 1)
+	if (fread(&mycopy, sizeof(int32_t), 1, (FILE *)xdrs->x_private) != 1)
 		return (FALSE);
-	*lp = (long)ntohl((u_int32_t)*lp);
+
+	*lp = (long)ntohl(mycopy);
 	return (TRUE);
 }
 
@@ -115,8 +118,14 @@ xdrstdio_putlong(xdrs, lp)
 	XDR *xdrs;
 	const long *lp;
 {
-	long mycopy = (long)htonl((u_int32_t)*lp);
+	int32_t mycopy;
+
+#if defined(_LP64)
+	if ((*lp > UINT32_MAX) || (*lp < INT32_MIN))
+		return (FALSE);
+#endif
 
+	mycopy = (int32_t)htonl((int32_t)*lp);
 	if (fwrite(&mycopy, sizeof(int32_t), 1, (FILE *)xdrs->x_private) != 1)
 		return (FALSE);
 	return (TRUE);
-- 
2.17.1