[Qemu-block] [PATCH] qemu-pr-helper: check the return value of fcntl in do_pr_out

[Zhengui li]

The function fcntl maybe return -1, which is not a unsigned type. Unsigned type 
or Negative values should not do bitwise operator with O_ACCMODE.

Signed-off-by: Zhengui li <address@hidden>
---
 scsi/qemu-pr-helper.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/scsi/qemu-pr-helper.c b/scsi/qemu-pr-helper.c
index e7af637..da1f0f2 100644
--- a/scsi/qemu-pr-helper.c
+++ b/scsi/qemu-pr-helper.c
@@ -551,8 +551,13 @@ static int do_pr_out(int fd, const uint8_t *cdb, uint8_t 
*sense,
                      const uint8_t *param, int sz)
 {
     int resp_sz;
+    int flags;
 
-    if ((fcntl(fd, F_GETFL) & O_ACCMODE) == O_RDONLY) {
+    flags = fcntl(fd, F_GETFL);
+    if (flags < 0)
+        return -1;
+
+    if ((unsigned int) flags & O_ACCMODE) == O_RDONLY) {
         scsi_build_sense(sense, SENSE_CODE(INVALID_OPCODE));
         return CHECK_CONDITION;
     }
-- 
2.7.2.windows.1