v4l2: v4l2_camera_file: Store file description

Create a string that describe the file from the path and file
descriptor. This will be used in log messages to clearly identify which
file an operation is related to.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>

src/v4l2/v4l2_camera_file.cpp

@@ -7,20 +7,46 @@
 
 #include "v4l2_camera_file.h"
 
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+
 #include <linux/videodev2.h>
 
 #include "v4l2_camera_proxy.h"
 
 using namespace libcamera;
 
-V4L2CameraFile::V4L2CameraFile(int efd, bool nonBlocking, V4L2CameraProxy *proxy)
+V4L2CameraFile::V4L2CameraFile(int dirfd, const char *path, int efd,
+			       bool nonBlocking, V4L2CameraProxy *proxy)
 	: proxy_(proxy), nonBlocking_(nonBlocking), efd_(efd),
 	  priority_(V4L2_PRIORITY_DEFAULT)
 {
 	proxy_->open(this);
+
+	if (path[0] != '/') {
+		if (dirfd == AT_FDCWD) {
+			char *cwd = getcwd(nullptr, 0);
+			if (cwd) {
+				description_ = std::string(cwd) + "/";
+				free(cwd);
+			} else {
+				description_ = std::string("(unreachable)/");
+			}
+		} else {
+			description_ = "(dirfd:" + std::to_string(dirfd) + ")/";
+		}
+	}
+
+	description_ += std::string(path) + " (fd:" + std::to_string(efd) + ")";
 }
 
 V4L2CameraFile::~V4L2CameraFile()
 {
 	proxy_->close(this);
 }
+
+const std::string &V4L2CameraFile::description() const
+{
+	return description_;
+}

src/v4l2/v4l2_camera_file.h

@@ -7,6 +7,8 @@
 
 #pragma once
 
+#include <string>
+
 #include <linux/videodev2.h>
 
 class V4L2CameraProxy;
@@ -14,7 +16,8 @@ class V4L2CameraProxy;
 class V4L2CameraFile
 {
 public:
-	V4L2CameraFile(int efd, bool nonBlocking, V4L2CameraProxy *proxy);
+	V4L2CameraFile(int dirfd, const char *path, int efd, bool nonBlocking,
+		       V4L2CameraProxy *proxy);
 	~V4L2CameraFile();
 
 	V4L2CameraProxy *proxy() const { return proxy_; }
@@ -25,9 +28,12 @@ public:
 	enum v4l2_priority priority() const { return priority_; }
 	void setPriority(enum v4l2_priority priority) { priority_ = priority; }
 
+	const std::string &description() const;
+
 private:
 	V4L2CameraProxy *proxy_;
 
+	std::string description_;
 	bool nonBlocking_;
 	int efd_;
 	enum v4l2_priority priority_;

src/v4l2/v4l2_compat_manager.cpp

@@ -156,7 +156,9 @@ int V4L2CompatManager::openat(int dirfd, const char *path, int oflag, mode_t mod
 		return efd;
 
 	V4L2CameraProxy *proxy = proxies_[ret].get();
-	files_.emplace(efd, std::make_shared<V4L2CameraFile>(efd, oflag & O_NONBLOCK, proxy));
+	files_.emplace(efd, std::make_shared<V4L2CameraFile>(dirfd, path, efd,
+							     oflag & O_NONBLOCK,
+							     proxy));
 
 	LOG(V4L2Compat, Debug) << "Opened " << path << " -> fd " << efd;
 	return efd;