| /* |
| * udev_sysfs.c - sysfs access |
| * |
| * Copyright (C) 2005 Kay Sievers <kay.sievers@vrfy.org> |
| * |
| * This program is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License as published by the |
| * Free Software Foundation version 2 of the License. |
| * |
| * This program is distributed in the hope that it will be useful, but |
| * WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License along |
| * with this program; if not, write to the Free Software Foundation, Inc., |
| * 675 Mass Ave, Cambridge, MA 02139, USA. |
| * |
| */ |
| |
| |
| #include <stdlib.h> |
| #include <stdio.h> |
| #include <stddef.h> |
| #include <unistd.h> |
| #include <fcntl.h> |
| #include <ctype.h> |
| #include <errno.h> |
| #include <sys/stat.h> |
| |
| #include "udev.h" |
| |
| char sysfs_path[PATH_SIZE]; |
| |
| /* device cache */ |
| static LIST_HEAD(dev_list); |
| |
| /* attribute value cache */ |
| static LIST_HEAD(attr_list); |
| struct sysfs_attr { |
| struct list_head node; |
| char path[PATH_SIZE]; |
| char *value; /* points to value_local if value is cached */ |
| char value_local[NAME_SIZE]; |
| }; |
| |
| int sysfs_init(void) |
| { |
| const char *env; |
| |
| env = getenv("SYSFS_PATH"); |
| if (env) { |
| strlcpy(sysfs_path, env, sizeof(sysfs_path)); |
| remove_trailing_chars(sysfs_path, '/'); |
| } else |
| strlcpy(sysfs_path, "/sys", sizeof(sysfs_path)); |
| dbg("sysfs_path='%s'", sysfs_path); |
| |
| INIT_LIST_HEAD(&dev_list); |
| INIT_LIST_HEAD(&attr_list); |
| return 0; |
| } |
| |
| void sysfs_cleanup(void) |
| { |
| struct sysfs_attr *attr_loop; |
| struct sysfs_attr *attr_temp; |
| struct sysfs_device *dev_loop; |
| struct sysfs_device *dev_temp; |
| |
| list_for_each_entry_safe(attr_loop, attr_temp, &attr_list, node) { |
| list_del(&attr_loop->node); |
| free(attr_loop); |
| } |
| |
| list_for_each_entry_safe(dev_loop, dev_temp, &dev_list, node) { |
| list_del(&dev_loop->node); |
| free(dev_loop); |
| } |
| } |
| |
| void sysfs_device_set_values(struct sysfs_device *dev, const char *devpath, const char *subsystem) |
| { |
| char *pos; |
| |
| strlcpy(dev->devpath, devpath, sizeof(dev->devpath)); |
| if (subsystem != NULL) |
| strlcpy(dev->subsystem, subsystem, sizeof(dev->subsystem)); |
| |
| /* set kernel name */ |
| pos = strrchr(dev->devpath, '/'); |
| if (pos == NULL) |
| return; |
| |
| strlcpy(dev->kernel_name, &pos[1], sizeof(dev->kernel_name)); |
| dbg("kernel_name='%s'", dev->kernel_name); |
| |
| /* some devices have '!' in their name, change that to '/' */ |
| pos = dev->kernel_name; |
| while (pos[0] != '\0') { |
| if (pos[0] == '!') |
| pos[0] = '/'; |
| pos++; |
| } |
| |
| /* get kernel number */ |
| pos = &dev->kernel_name[strlen(dev->kernel_name)]; |
| while (isdigit(pos[-1])) |
| pos--; |
| strlcpy(dev->kernel_number, pos, sizeof(dev->kernel_number)); |
| dbg("kernel_number='%s'", dev->kernel_number); |
| } |
| |
| struct sysfs_device *sysfs_device_get(const char *devpath) |
| { |
| char path[PATH_SIZE]; |
| char devpath_real[PATH_SIZE]; |
| struct sysfs_device *dev; |
| struct sysfs_device *dev_loop; |
| struct stat statbuf; |
| char link_path[PATH_SIZE]; |
| char link_target[PATH_SIZE]; |
| int len; |
| char *pos; |
| |
| dbg("open '%s'", devpath); |
| strlcpy(devpath_real, devpath, sizeof(devpath_real)); |
| remove_trailing_chars(devpath_real, '/'); |
| |
| /* look for device already in cache (we never put an untranslated path in the cache) */ |
| list_for_each_entry(dev_loop, &dev_list, node) { |
| if (strcmp(dev_loop->devpath, devpath_real) == 0) { |
| dbg("found in cache '%s'", dev_loop->devpath); |
| return dev_loop; |
| } |
| } |
| |
| /* if we got a link, resolve it to the real device */ |
| strlcpy(path, sysfs_path, sizeof(path)); |
| strlcat(path, devpath_real, sizeof(path)); |
| if (lstat(path, &statbuf) != 0) { |
| dbg("stat '%s' failed: %s", path, strerror(errno)); |
| return NULL; |
| } |
| if (S_ISLNK(statbuf.st_mode)) { |
| int i; |
| int back; |
| |
| len = readlink(path, link_target, sizeof(link_target)); |
| if (len <= 0) |
| return NULL; |
| link_target[len] = '\0'; |
| dbg("devpath link '%s' points to '%s'", path, link_target); |
| |
| for (back = 0; strncmp(&link_target[back * 3], "../", 3) == 0; back++) |
| ; |
| dbg("base '%s', tail '%s', back %i", devpath_real, &link_target[back * 3], back); |
| for (i = 0; i <= back; i++) { |
| pos = strrchr(devpath_real, '/'); |
| if (pos == NULL) |
| return NULL; |
| pos[0] = '\0'; |
| } |
| dbg("after moving back '%s'", devpath_real); |
| strlcat(devpath_real, "/", sizeof(devpath_real)); |
| strlcat(devpath_real, &link_target[back * 3], sizeof(devpath_real)); |
| |
| /* now look for device in cache after path translation */ |
| list_for_each_entry(dev_loop, &dev_list, node) { |
| if (strcmp(dev_loop->devpath, devpath_real) == 0) { |
| dbg("found in cache '%s'", dev_loop->devpath); |
| return dev_loop; |
| } |
| } |
| } |
| |
| /* it is a new device */ |
| dbg("new uncached device '%s'", devpath_real); |
| dev = malloc(sizeof(struct sysfs_device)); |
| if (dev == NULL) |
| return NULL; |
| memset(dev, 0x00, sizeof(struct sysfs_device)); |
| |
| sysfs_device_set_values(dev, devpath_real, NULL); |
| |
| /* get subsystem */ |
| if (strncmp(dev->devpath, "/class/", 7) == 0) { |
| strlcpy(dev->subsystem, &dev->devpath[7], sizeof(dev->subsystem)); |
| pos = strchr(dev->subsystem, '/'); |
| if (pos != NULL) |
| pos[0] = '\0'; |
| else |
| dev->subsystem[0] = '\0'; |
| } else if (strncmp(dev->devpath, "/block/", 7) == 0) { |
| strlcpy(dev->subsystem, "block", sizeof(dev->subsystem)); |
| } else if (strncmp(dev->devpath, "/devices/", 9) == 0) { |
| /* get subsystem from "bus" link */ |
| strlcpy(link_path, sysfs_path, sizeof(link_path)); |
| strlcat(link_path, dev->devpath, sizeof(link_path)); |
| strlcat(link_path, "/bus", sizeof(link_path)); |
| len = readlink(link_path, link_target, sizeof(link_target)); |
| if (len > 0) { |
| link_target[len] = '\0'; |
| dbg("bus link '%s' points to '%s'", link_path, link_target); |
| pos = strrchr(link_target, '/'); |
| if (pos != NULL) |
| strlcpy(dev->subsystem, &pos[1], sizeof(dev->subsystem)); |
| } else { |
| /* get subsystem from "subsystem" link */ |
| strlcpy(link_path, sysfs_path, sizeof(link_path)); |
| strlcat(link_path, dev->devpath, sizeof(link_path)); |
| strlcat(link_path, "/subsystem", sizeof(link_path)); |
| len = readlink(link_path, link_target, sizeof(link_target)); |
| if (len > 0) { |
| link_target[len] = '\0'; |
| dbg("subsystem link '%s' points to '%s'", link_path, link_target); |
| pos = strrchr(link_target, '/'); |
| if (pos != NULL) |
| strlcpy(dev->subsystem, &pos[1], sizeof(dev->subsystem)); |
| } |
| } |
| /* get driver name */ |
| strlcpy(link_path, sysfs_path, sizeof(link_path)); |
| strlcat(link_path, dev->devpath, sizeof(link_path)); |
| strlcat(link_path, "/driver", sizeof(link_path)); |
| len = readlink(link_path, link_target, sizeof(link_target)); |
| if (len > 0) { |
| link_target[len] = '\0'; |
| dbg("driver link '%s' points to '%s'", link_path, link_target); |
| pos = strrchr(link_target, '/'); |
| if (pos != NULL) |
| strlcpy(dev->driver, &pos[1], sizeof(dev->driver)); |
| } |
| } else if (strncmp(dev->devpath, "/bus/", 5) == 0 && strstr(dev->devpath, "/drivers/")) { |
| strlcpy(dev->subsystem, "drivers", sizeof(dev->subsystem)); |
| } else if (strncmp(dev->devpath, "/module/", 8) == 0) { |
| strlcpy(dev->subsystem, "module", sizeof(dev->subsystem)); |
| } |
| |
| dbg("add to cache 'devpath=%s', subsystem='%s', driver='%s'", dev->devpath, dev->subsystem, dev->driver); |
| list_add(&dev->node, &dev_list); |
| |
| return dev; |
| } |
| |
| struct sysfs_device *sysfs_device_get_parent(struct sysfs_device *dev) |
| { |
| char parent_devpath[PATH_SIZE]; |
| char device_link[PATH_SIZE]; |
| char device_link_target[PATH_SIZE]; |
| char *pos; |
| int i; |
| int len; |
| int back; |
| |
| dbg("open '%s'", dev->devpath); |
| |
| /* look if we already know the parent */ |
| if (dev->parent != NULL) |
| return dev->parent; |
| |
| /* requesting a parent is only valid for devices */ |
| if ((strncmp(dev->devpath, "/devices/", 9) != 0) && |
| (strncmp(dev->devpath, "/class/", 7) != 0) && |
| (strncmp(dev->devpath, "/block/", 7) != 0)) |
| return NULL; |
| |
| strlcpy(parent_devpath, dev->devpath, sizeof(parent_devpath)); |
| dbg("'%s'", parent_devpath); |
| |
| /* strip last element */ |
| pos = strrchr(parent_devpath, '/'); |
| if (pos == NULL || pos == parent_devpath) |
| return NULL; |
| pos[0] = '\0'; |
| |
| /* are we at the top level of /devices */ |
| if (strcmp(parent_devpath, "/devices") == 0) { |
| dbg("/devices top level"); |
| return NULL; |
| } |
| |
| /* at the top level of class/block we want to follow the "device" link */ |
| if (strcmp(parent_devpath, "/block") == 0) { |
| dbg("/block top level, look for device link"); |
| goto device_link; |
| } |
| if (strncmp(parent_devpath, "/class", 6) == 0) { |
| pos = strrchr(parent_devpath, '/'); |
| if (pos == &parent_devpath[6] || pos == parent_devpath) { |
| dbg("/class top level, look for device link"); |
| goto device_link; |
| } |
| } |
| /* get parent and remember it */ |
| dev->parent = sysfs_device_get(parent_devpath); |
| return dev->parent; |
| |
| device_link: |
| strlcpy(device_link, sysfs_path, sizeof(device_link)); |
| strlcat(device_link, dev->devpath, sizeof(device_link)); |
| strlcat(device_link, "/device", sizeof(device_link)); |
| len = readlink(device_link, device_link_target, sizeof(device_link_target)); |
| if (len < 0) |
| return NULL; |
| device_link_target[len] = '\0'; |
| dbg("device link '%s' points to '%s'", device_link, device_link_target); |
| |
| for (back = 0; strncmp(&device_link_target[back * 3], "../", 3) == 0; back++) |
| ; |
| strlcpy(parent_devpath, dev->devpath, sizeof(parent_devpath)); |
| dbg("base='%s', tail='%s', back=%i", parent_devpath, &device_link_target[back * 3], back); |
| for (i = 0; i < back; i++) { |
| pos = strrchr(parent_devpath, '/'); |
| if (pos == NULL) |
| return NULL; |
| pos[0] = '\0'; |
| } |
| dbg("after moving back '%s'", parent_devpath); |
| strlcat(parent_devpath, "/", sizeof(parent_devpath)); |
| strlcat(parent_devpath, &device_link_target[back * 3], sizeof(parent_devpath)); |
| |
| /* get parent and remember it */ |
| dev->parent = sysfs_device_get(parent_devpath); |
| return dev->parent; |
| } |
| |
| struct sysfs_device *sysfs_device_get_parent_with_subsystem(struct sysfs_device *dev, const char *subsystem) |
| { |
| struct sysfs_device *dev_parent; |
| |
| dev_parent = sysfs_device_get_parent(dev); |
| while (dev_parent != NULL) { |
| if (strcmp(dev_parent->subsystem, subsystem) == 0) |
| return dev_parent; |
| dev_parent = sysfs_device_get_parent(dev_parent); |
| } |
| return NULL; |
| } |
| |
| char *sysfs_attr_get_value(const char *devpath, const char *attr_name) |
| { |
| char path_full[PATH_SIZE]; |
| const char *path; |
| char value[NAME_SIZE]; |
| struct sysfs_attr *attr_loop; |
| struct sysfs_attr *attr; |
| int fd; |
| ssize_t size; |
| size_t sysfs_len; |
| |
| dbg("open '%s'/'%s'", devpath, attr_name); |
| sysfs_len = strlcpy(path_full, sysfs_path, sizeof(path_full)); |
| path = &path_full[sysfs_len]; |
| strlcat(path_full, devpath, sizeof(path_full)); |
| strlcat(path_full, "/", sizeof(path_full)); |
| strlcat(path_full, attr_name, sizeof(path_full)); |
| |
| /* look for attribute in cache */ |
| list_for_each_entry(attr_loop, &attr_list, node) { |
| if (strcmp(attr_loop->path, path) == 0) { |
| dbg("found in cache '%s'", attr_loop->path); |
| return attr_loop->value; |
| } |
| } |
| |
| /* store attribute in cache (also negatives are kept in cache) */ |
| dbg("new uncached attribute '%s'", path_full); |
| attr = malloc(sizeof(struct sysfs_attr)); |
| if (attr == NULL) |
| return NULL; |
| memset(attr, 0x00, sizeof(struct sysfs_attr)); |
| strlcpy(attr->path, path, sizeof(attr->path)); |
| dbg("add to cache '%s'", path_full); |
| list_add(&attr->node, &attr_list); |
| |
| /* read attribute value */ |
| fd = open(path_full, O_RDONLY); |
| if (fd < 0) { |
| dbg("attribute '%s' does not exist", path_full); |
| goto out; |
| } |
| size = read(fd, value, sizeof(value)); |
| close(fd); |
| if (size < 0) |
| goto out; |
| if (size == sizeof(value)) |
| goto out; |
| |
| /* got a valid value, store and return it */ |
| value[size] = '\0'; |
| remove_trailing_chars(value, '\n'); |
| dbg("cache '%s' with value '%s'", path_full, value); |
| strlcpy(attr->value_local, value, sizeof(attr->value_local)); |
| attr->value = attr->value_local; |
| |
| out: |
| return attr->value; |
| } |