[1/2] v4l-helpers: Don't close the fd in {}_s_fd

Commit Message

Ezequiel Garcia June 29, 2018, 6:07 p.m. UTC

Hey Hans,

On Fri, 2018-06-29 at 09:03 +0200, Hans Verkuil wrote:
> On 06/28/2018 09:25 PM, Ezequiel Garcia wrote:
> > When creating a second node via copy or assignment:
> > 
> >     node2 = node
> > 
> > The node being assigned to, i.e. node2, obtains the fd.
> > This causes a later call to node2.media_open to close()
> > the fd, thus unintendenly closing the original node fd,
> > via the call path (e.g. for media devices):
> > 
> >   node2.media_open
> >      v4l_media_open
> >         v4l_media_s_fd
> > 
> > Similar call paths apply for other device types.
> > Fix this by removing the close in xxx_s_fd.
> 
> I fixed this in a different way by overloading the assignment
> operator
> and calling dup(fd). That solves this as well.
> 

This patch is also needed to prevent the compliance tool
from unintendenly closing a descriptor.

 static inline ssize_t v4l_wrap_read(struct v4l_fd *f, void *buffer,
size_t n)

Regards,
Eze

Patch

diff --git a/utils/common/v4l-helpers.h b/utils/common/v4l-helpers.h
index 27683a3d286d..45ed997379a1 100644
--- a/utils/common/v4l-helpers.h
+++ b/utils/common/v4l-helpers.h
@@ -118,7 +118,11 @@  static inline int v4l_wrap_open(struct v4l_fd *f,
const char *file, int oflag, .
 
 static inline int v4l_wrap_close(struct v4l_fd *f)
 {
-       return close(f->fd);
+       int ret;
+
+       ret = close(f->fd);
+       f->fd = -1;
+       return ret;
 }