| /* |
| * Copyright (C) 2005-2006 Kay Sievers <kay.sievers@vrfy.org> |
| * 2008 Jaroslav Kysela <perex@perex.cz> |
| * |
| * 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., |
| * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
| * |
| */ |
| |
| |
| static char sysfs_path[PATH_SIZE]; |
| |
| /* 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]; |
| }; |
| |
| static int sysfs_init(void) |
| { |
| const char *env; |
| char sysfs_test[PATH_SIZE]; |
| |
| 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); |
| |
| strlcpy(sysfs_test, sysfs_path, sizeof(sysfs_test)); |
| strlcat(sysfs_test, "/kernel/uevent_helper", sizeof(sysfs_test)); |
| if (access(sysfs_test, F_OK)) { |
| error("sysfs path '%s' is invalid\n", sysfs_path); |
| return -errno; |
| } |
| |
| INIT_LIST_HEAD(&attr_list); |
| return 0; |
| } |
| |
| static void sysfs_cleanup(void) |
| { |
| struct sysfs_attr *attr_loop; |
| struct sysfs_attr *attr_temp; |
| |
| list_for_each_entry_safe(attr_loop, attr_temp, &attr_list, node) { |
| list_del(&attr_loop->node); |
| free(attr_loop); |
| } |
| } |
| |
| static 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; |
| struct stat statbuf; |
| 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); |
| |
| if (lstat(path_full, &statbuf) != 0) { |
| dbg("stat '%s' failed: %s", path_full, strerror(errno)); |
| goto out; |
| } |
| |
| if (S_ISLNK(statbuf.st_mode)) { |
| /* links return the last element of the target path */ |
| char link_target[PATH_SIZE]; |
| int len; |
| const char *pos; |
| |
| len = readlink(path_full, link_target, sizeof(link_target)); |
| if (len > 0) { |
| link_target[len] = '\0'; |
| pos = strrchr(link_target, '/'); |
| if (pos != NULL) { |
| dbg("cache '%s' with link value '%s'", path_full, pos+1); |
| strlcpy(attr->value_local, &pos[1], sizeof(attr->value_local)); |
| attr->value = attr->value_local; |
| } |
| } |
| goto out; |
| } |
| |
| /* skip directories */ |
| if (S_ISDIR(statbuf.st_mode)) |
| goto out; |
| |
| /* skip non-readable files */ |
| if ((statbuf.st_mode & S_IRUSR) == 0) |
| goto out; |
| |
| /* 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 attribute value '%s'", path_full, value); |
| strlcpy(attr->value_local, value, sizeof(attr->value_local)); |
| attr->value = attr->value_local; |
| |
| out: |
| return attr->value; |
| } |