lib: set errno when buf points to NULL in common.c:pqos_read()

There is little need for the check, as the first read() call is supposed
to fail with EFAULT in case buf is NULL, but if this check is done,
it would be nice if it matches the error code the call it wraps.

Signed-off-by: Eugene Syromiatnikov <[email protected]>

Author: esyr-rh

lib/common.c

@@ -382,8 +382,10 @@ pqos_read(int fd, void *buf, size_t count)
         char *byte_ptr = (char *)buf;
         ssize_t ret;
 
-        if (buf == NULL)
+        if (buf == NULL) {
+                errno = EFAULT;
                 return -1;
+        }
 
         while (len != 0 && (ret = read(fd, byte_ptr, len)) != 0) {
                 if (ret == -1) {