Files
finit/keventd/sysfs.h
T
Paweł a22a5fae7c keventd: resolve $attr{} and %s{} through the parent chain
Attribute substitution only looked at the device's own sysfs directory,
while the matching key ATTRS{} walks parents. Devices without an
attribute of their own, partitions in particular whose serial lives in
the parent disk, therefore substituted to an empty string.
2026-10-14 10:30:17 +02:00

85 lines
3.0 KiB
C

/* sysfs attribute reader and parent-chain walker for keventd
*
* Copyright (c) 2025 Joachim Wiberg <troglobit@gmail.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef KEVENTD_SYSFS_H_
#define KEVENTD_SYSFS_H_
#include <stddef.h>
/*
* Read the first line from an absolute path.
* Returns 0 on success, -1 on failure.
*/
int sysfs_read_file(const char *path, char *buf, size_t len);
/*
* Read a sysfs attribute for the device at /sys{devpath}.
* attr may be a relative path like "device/vendor" or "../serial".
* Returns 0 on success, -1 if the attribute does not exist.
*/
int sysfs_read_attr(const char *devpath, const char *attr,
char *buf, size_t len);
/*
* Read a sysfs attribute for the device at /sys{devpath}, falling back
* to the parent chain, partitions have no "serial" of their own, it
* lives in the parent disk's sysfs directory.
* Returns 0 on success, -1 if no level of the chain has the attribute.
*/
int sysfs_read_attr_chain(const char *devpath, const char *attr,
char *buf, size_t len);
/*
* Walk the sysfs device tree upward from devpath toward /sys/devices,
* calling cb at each level. cb receives the absolute syspath and the
* caller-supplied data pointer. Walk stops when cb returns 0 (found)
* or the tree root is reached.
* Returns 0 if cb returned 0, -1 if nothing matched.
*/
int sysfs_parent_walk(const char *devpath,
int (*cb)(const char *syspath, void *data),
void *data);
/*
* Read the subsystem name at syspath by following the "subsystem"
* symlink and returning its basename.
* Returns 0 on success, -1 if there is no subsystem link.
*/
int sysfs_read_subsystem(const char *syspath, char *buf, size_t len);
/*
* Read the driver name at syspath by following the "driver" symlink
* and returning its basename.
* Returns 0 on success, -1 if there is no driver link.
*/
int sysfs_read_driver(const char *syspath, char *buf, size_t len);
#endif /* KEVENTD_SYSFS_H_ */
/**
* Local Variables:
* indent-tabs-mode: t
* c-file-style: "linux"
* End:
*/