+
+int on_ac_power(void) {
+ bool found_offline = false, found_online = false;
+ _cleanup_closedir_ DIR *d = NULL;
+
+ d = opendir("/sys/class/power_supply");
+ if (!d)
+ return -errno;
+
+ for (;;) {
+ struct dirent *de;
+ union dirent_storage buf;
+ _cleanup_free_ char *p = NULL;
+ _cleanup_close_ int fd = -1, device = -1;
+ char contents[6];
+ ssize_t n;
+ int k;
+
+ k = readdir_r(d, &buf.de, &de);
+ if (k != 0)
+ return -k;
+
+ if (!de)
+ break;
+
+ if (ignore_file(de->d_name))
+ continue;
+
+ device = openat(dirfd(d), de->d_name, O_DIRECTORY|O_RDONLY|O_CLOEXEC|O_NOCTTY);
+ if (device < 0) {
+ if (errno == ENOENT || errno == ENOTDIR)
+ continue;
+
+ return -errno;
+ }
+
+ fd = openat(device, "type", O_RDONLY|O_CLOEXEC|O_NOCTTY);
+ if (fd < 0) {
+ if (errno == ENOENT)
+ continue;
+
+ return -errno;
+ }
+
+ n = read(fd, contents, sizeof(contents));
+ if (n < 0)
+ return -errno;
+
+ if (n != 6 || memcmp(contents, "Mains\n", 6))
+ continue;
+
+ close_nointr_nofail(fd);
+ fd = openat(device, "online", O_RDONLY|O_CLOEXEC|O_NOCTTY);
+ if (fd < 0) {
+ if (errno == ENOENT)
+ continue;
+
+ return -errno;
+ }
+
+ n = read(fd, contents, sizeof(contents));
+ if (n < 0)
+ return -errno;
+
+ if (n != 2 || contents[1] != '\n')
+ return -EIO;
+
+ if (contents[0] == '1') {
+ found_online = true;
+ break;
+ } else if (contents[0] == '0')
+ found_offline = true;
+ else
+ return -EIO;
+ }
+
+ return found_online || !found_offline;
+}
+
+static int search_and_fopen_internal(const char *path, const char *mode, char **search, FILE **_f) {
+ char **i;
+
+ assert(path);
+ assert(mode);
+ assert(_f);
+
+ if (!path_strv_canonicalize_uniq(search))
+ return -ENOMEM;
+
+ STRV_FOREACH(i, search) {
+ _cleanup_free_ char *p = NULL;
+ FILE *f;
+
+ p = strjoin(*i, "/", path, NULL);
+ if (!p)
+ return -ENOMEM;
+
+ f = fopen(p, mode);
+ if (f) {
+ *_f = f;
+ return 0;
+ }
+
+ if (errno != ENOENT)
+ return -errno;
+ }
+
+ return -ENOENT;
+}
+
+int search_and_fopen(const char *path, const char *mode, const char **search, FILE **_f) {
+ _cleanup_strv_free_ char **copy = NULL;
+
+ assert(path);
+ assert(mode);
+ assert(_f);
+
+ if (path_is_absolute(path)) {
+ FILE *f;
+
+ f = fopen(path, mode);
+ if (f) {
+ *_f = f;
+ return 0;
+ }
+
+ return -errno;
+ }
+
+ copy = strv_copy((char**) search);
+ if (!copy)
+ return -ENOMEM;
+
+ return search_and_fopen_internal(path, mode, copy, _f);
+}
+
+int search_and_fopen_nulstr(const char *path, const char *mode, const char *search, FILE **_f) {
+ _cleanup_strv_free_ char **s = NULL;
+
+ if (path_is_absolute(path)) {
+ FILE *f;
+
+ f = fopen(path, mode);
+ if (f) {
+ *_f = f;
+ return 0;
+ }
+
+ return -errno;
+ }
+
+ s = strv_split_nulstr(search);
+ if (!s)
+ return -ENOMEM;
+
+ return search_and_fopen_internal(path, mode, s, _f);
+}