libcamera: sysfs: Fix directory exists check

The scope of File::exists() was changed to only validate that a file
exists and is therefore not usable to check if a directory exists. This
breaks the persistent name generation for DT based systems as it uses
File::exists() to check for directories, fix this by using stat()
directly.

On Scarlet the persistent names of the cameras are impacted by this and
where incorrectly reported as:

    $ cam -l
    Available cameras:
    1: Internal front camera (platform/ff160000.i2c/i2c-7/7-003c ov2685)
    2: Internal front camera (platform/ff160000.i2c/i2c-7/7-0036 ov5695

While the expected ones are restored with this fix:

    $ cam -l
    Available cameras:
    1: Internal front camera (/base/i2c@ff160000/camera@3c)
    2: Internal front camera (/base/i2c@ff160000/camera@36)

Fixes: 8f4e16f014c820a0 ("test: file: Check that directories are not treated as files")
Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/libcamera/sysfs.cpp b/src/libcamera/sysfs.cpp
index 3ebe66f8..e9004b2b 100644
--- a/src/libcamera/sysfs.cpp
+++ b/src/libcamera/sysfs.cpp
@@ -70,10 +70,11 @@ std::string charDevPath(const std::string &deviceNode)
 std::string firmwareNodePath(const std::string &device)
 {
 	std::string fwPath, node;
+	struct stat st;
 
 	/* Lookup for DT-based systems */
 	node = device + "/of_node";
-	if (File::exists(node)) {
+	if (!stat(node.c_str(), &st)) {
 		char *ofPath = realpath(node.c_str(), nullptr);
 		if (!ofPath)
 			return {};