+#define HIBERNATION_SWAP_THRESHOLD 0.98
+
+static int hibernation_partition_size(size_t *size, size_t *used) {
+ _cleanup_fclose_ FILE *f;
+ int i;
+
+ assert(size);
+ assert(used);
+
+ f = fopen("/proc/swaps", "re");
+ if (!f) {
+ log_full(errno == ENOENT ? LOG_DEBUG : LOG_WARNING,
+ "Failed to retrieve open /proc/swaps: %m");
+ assert(errno > 0);
+ return -errno;
+ }
+
+ (void) fscanf(f, "%*s %*s %*s %*s %*s\n");
+
+ for (i = 1;; i++) {
+ _cleanup_free_ char *dev = NULL, *type = NULL;
+ size_t size_field, used_field;
+ int k;
+
+ k = fscanf(f,
+ "%ms " /* device/file */
+ "%ms " /* type of swap */
+ "%zd " /* swap size */
+ "%zd " /* used */
+ "%*i\n", /* priority */
+ &dev, &type, &size_field, &used_field);
+ if (k != 4) {
+ if (k == EOF)
+ break;
+
+ log_warning("Failed to parse /proc/swaps:%u", i);
+ continue;
+ }
+
+ if (streq(type, "partition") && endswith(dev, "\\040(deleted)")) {
+ log_warning("Ignoring deleted swapfile '%s'.", dev);
+ continue;
+ }
+
+ *size = size_field;
+ *used = used_field;
+ return 0;
+ }
+
+ log_debug("No swap partitions were found.");
+ return -ENOSYS;
+}
+
+static bool enough_memory_for_hibernation(void) {
+ _cleanup_free_ char *active = NULL;
+ unsigned long long act = 0;
+ size_t size = 0, used = 0;
+ int r;
+
+ r = hibernation_partition_size(&size, &used);
+ if (r < 0)
+ return false;
+
+ r = get_status_field("/proc/meminfo", "\nActive(anon):", &active);
+ if (r < 0) {
+ log_error("Failed to retrieve Active(anon) from /proc/meminfo: %s", strerror(-r));
+ return false;
+ }
+
+ r = safe_atollu(active, &act);
+ if (r < 0) {
+ log_error("Failed to parse Active(anon) from /proc/meminfo: %s: %s",
+ active, strerror(-r));
+ return false;
+ }
+
+ r = act <= (size - used) * HIBERNATION_SWAP_THRESHOLD;
+ log_debug("Hibernation is %spossible, Active(anon)=%llu kB, size=%zu kB, used=%zu kB, threshold=%.2g%%",
+ r ? "" : "im", act, size, used, 100*HIBERNATION_SWAP_THRESHOLD);
+
+ return r;
+}
+