[libcamera-devel] [PATCH v2 02/27] libcamera: file_descriptor: Add a function to retrieve the inode

[paul.elder at ideasonboard.com]

Hi Laurent,

On Mon, Sep 06, 2021 at 05:00:35AM +0300, Laurent Pinchart wrote:
> The inode is useful to check if two file descriptors refer to the same
> file. Add a function to retrieve it.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

Reviewed-by: Paul Elder <paul.elder at ideasonboard.com>

> ---
> Changes since v1:
> 
> - Use isValid() instead of open-coding it
> - Print a message on error
> ---
>  include/libcamera/file_descriptor.h |  3 +++
>  src/libcamera/file_descriptor.cpp   | 26 ++++++++++++++++++++++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/include/libcamera/file_descriptor.h b/include/libcamera/file_descriptor.h
> index d514aac7697b..988f9b7a3d25 100644
> --- a/include/libcamera/file_descriptor.h
> +++ b/include/libcamera/file_descriptor.h
> @@ -8,6 +8,7 @@
>  #define __LIBCAMERA_FILE_DESCRIPTOR_H__
>  
>  #include <memory>
> +#include <sys/types.h>
>  
>  namespace libcamera {
>  
> @@ -27,6 +28,8 @@ public:
>  	int fd() const { return fd_ ? fd_->fd() : -1; }
>  	FileDescriptor dup() const;
>  
> +	ino_t inode() const;
> +
>  private:
>  	class Descriptor
>  	{
> diff --git a/src/libcamera/file_descriptor.cpp b/src/libcamera/file_descriptor.cpp
> index 9f9ebc81f738..0409c3e1758c 100644
> --- a/src/libcamera/file_descriptor.cpp
> +++ b/src/libcamera/file_descriptor.cpp
> @@ -8,6 +8,8 @@
>  #include <libcamera/file_descriptor.h>
>  
>  #include <string.h>
> +#include <sys/stat.h>
> +#include <sys/types.h>
>  #include <unistd.h>
>  #include <utility>
>  
> @@ -221,6 +223,30 @@ FileDescriptor FileDescriptor::dup() const
>  	return FileDescriptor(fd());
>  }
>  
> +/**
> + * \brief Retrieve the file descriptor inode
> + *
> + * \todo Should this move to the File class ?
> + *
> + * \return The file descriptor inode on success, or 0 on error
> + */
> +ino_t FileDescriptor::inode() const
> +{
> +	if (!isValid())
> +		return 0;
> +
> +	struct stat st;
> +	int ret = fstat(fd_->fd(), &st);
> +	if (ret < 0) {
> +		ret = -errno;
> +		LOG(FileDescriptor, Fatal)
> +			<< "Failed to fstat() fd: " << strerror(-ret);
> +		return 0;
> +	}
> +
> +	return st.st_ino;
> +}
> +
>  FileDescriptor::Descriptor::Descriptor(int fd, bool duplicate)
>  {
>  	if (!duplicate) {
> -- 
> Regards,
> 
> Laurent Pinchart
>