libcamera: base: file_descriptor: Move inode() function to frame_buffer.cpp

The inode() function has always been a bit of an outcast in the
FileDescriptor class, as it's not related to the core feature provided
by FileDescriptor, a shared ownership wrapper around file descriptors.
As it's only used in the FrameBuffer implementation, move it to
frame_buffer.cpp as a static function.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>

src/libcamera/base/file_descriptor.cpp

@@ -8,7 +8,6 @@
 #include <libcamera/base/file_descriptor.h>
 
 #include <string.h>
-#include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
 #include <utility>
@@ -223,30 +222,6 @@ 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) {

src/libcamera/framebuffer.cpp

@@ -8,6 +8,9 @@
 #include <libcamera/framebuffer.h>
 #include "libcamera/internal/framebuffer.h"
 
+#include <sys/stat.h>
+
+#include <libcamera/base/file_descriptor.h>
 #include <libcamera/base/log.h>
 
 /**
@@ -207,6 +210,27 @@ FrameBuffer::Private::Private()
  * \brief The plane length in bytes
  */
 
+namespace {
+
+ino_t fileDescriptorInode(const FileDescriptor &fd)
+{
+	if (!fd.isValid())
+		return 0;
+
+	struct stat st;
+	int ret = fstat(fd.fd(), &st);
+	if (ret < 0) {
+		ret = -errno;
+		LOG(Buffer, Fatal)
+			<< "Failed to fstat() fd: " << strerror(-ret);
+		return 0;
+	}
+
+	return st.st_ino;
+}
+
+} /* namespace */
+
 /**
  * \brief Construct a FrameBuffer with an array of planes
  * \param[in] planes The frame memory planes
@@ -236,8 +260,8 @@ FrameBuffer::FrameBuffer(const std::vector<Plane> &planes, unsigned int cookie)
 		 */
 		if (plane.fd.fd() != planes_[0].fd.fd()) {
 			if (!inode)
-				inode = planes_[0].fd.inode();
-			if (plane.fd.inode() != inode) {
+				inode = fileDescriptorInode(planes_[0].fd);
+			if (fileDescriptorInode(plane.fd) != inode) {
 				isContiguous = false;
 				break;
 			}