Advertise hibernation only if there's enough free swap

Condition that is checked is taken from upower:
  active(anon) < free swap * 0.98

This is really stupid, because the kernel knows the situation better,
e.g. there could be two swap files, and then hibernation would be
impossible despite passing this check, or the kernel could start
supporting compressed swap and/or compressed hibernation images, and
then this this check would be too stringent. Nevertheless, until
we have something better, this should at least return a true negative
if there's no swap.

Logging of capabilities in the journal is changed to not strip leading
zeros. I consider this more readable anyway.

http://cgit.freedesktop.org/upower/tree/src/up-daemon.c#n613
https://bugzilla.redhat.com/show_bug.cgi?id=1007059

1 files changed, 44 insertions, 1 deletions

diff --git a/src/shared/sleep-config.c b/src/shared/sleep-config.c
index cd3238b405..5ec7cce458 100644
--- a/src/shared/sleep-config.c
+++ b/src/shared/sleep-config.c
@@ -163,6 +163,46 @@ int can_sleep_disk(char **types) {
         return false;
 }
 
+#define HIBERNATION_SWAP_THRESHOLD 0.98
+
+static bool enough_memory_for_hibernation(void) {
+        _cleanup_free_ char *active = NULL, *swapfree = NULL;
+        unsigned long long act, swap;
+        int r;
+
+        r = get_status_field("/proc/meminfo", "\nSwapFree:", &swapfree);
+        if (r < 0) {
+                log_error("Failed to retrieve SwapFree from /proc/meminfo: %s", strerror(-r));
+                return false;
+        }
+
+        r = safe_atollu(swapfree, &swap);
+        if (r < 0) {
+                log_error("Failed to parse SwapFree from /proc/meminfo: %s: %s",
+                          swapfree, strerror(-r));
+                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 <= swap * HIBERNATION_SWAP_THRESHOLD;
+        log_debug("Hibernation is %spossible, Active(anon)=%llu kB, SwapFree=%llu kB, threshold=%.2g%%",
+                  r ? "" : "im", act, swap, 100*HIBERNATION_SWAP_THRESHOLD);
+
+        return r;
+}
+
 int can_sleep(const char *verb) {
         _cleanup_strv_free_ char **modes = NULL, **states = NULL;
         int r;
@@ -175,5 +215,8 @@ int can_sleep(const char *verb) {
         if (r < 0)
                 return false;
 
-        return can_sleep_state(states) && can_sleep_disk(modes);
+        if (!can_sleep_state(states) || !can_sleep_disk(modes))
+                return false;
+
+        return streq(verb, "suspend") || enough_memory_for_hibernation();
 }