@@ -25,6 +25,7 @@ libcamera_internal_headers = files([
'process.h',
'pub_key.h',
'semaphore.h',
+ 'sysfs.h',
'thread.h',
'utils.h',
'v4l2_controls.h',
new file mode 100644
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2020, Google Inc.
+ *
+ * sysfs.h - Miscellaneous utility functions to access sysfs
+ */
+#ifndef __LIBCAMERA_INTERNAL_SYSFS_H__
+#define __LIBCAMERA_INTERNAL_SYSFS_H__
+
+#include <string>
+
+namespace libcamera {
+
+namespace sysfs {
+
+std::string charDevPath(const std::string &deviceNode);
+
+} /* namespace sysfs */
+
+} /* namespace libcamera */
+
+#endif /* __LIBCAMERA_INTERNAL_SYSFS_H__ */
@@ -41,6 +41,7 @@ libcamera_sources = files([
'semaphore.cpp',
'signal.cpp',
'stream.cpp',
+ 'sysfs.cpp',
'thread.cpp',
'timer.cpp',
'utils.cpp',
new file mode 100644
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2020, Google Inc.
+ *
+ * sysfs.cpp - Miscellaneous utility functions to access sysfs
+ */
+
+#include "libcamera/internal/sysfs.h"
+
+#include <sstream>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+
+#include "libcamera/internal/log.h"
+
+/**
+ * \file sysfs.h
+ * \brief Miscellaneous utility functions to access sysfs
+ */
+
+namespace libcamera {
+
+LOG_DEFINE_CATEGORY(SysFs);
+
+namespace sysfs {
+
+/**
+ * \brief Retrieve the sysfs path for a character device
+ * \param[in] deviceNode Path to character device node
+ * \return The sysfs path on success or an empty string on failure
+ */
+std::string charDevPath(const std::string &deviceNode)
+{
+ struct stat st;
+ int ret = stat(deviceNode.c_str(), &st);
+ if (ret < 0) {
+ ret = -errno;
+ LOG(SysFs, Error)
+ << "Unable to stat '" << deviceNode << "': "
+ << strerror(-ret);
+ return {};
+ }
+
+ std::ostringstream dev("/sys/dev/char/", std::ios_base::ate);
+ dev << major(st.st_rdev) << ":" << minor(st.st_rdev);
+
+ return dev.str();
+}
+
+} /* namespace sysfs */
+
+} /* namespace libcamera */