core: optionally, accept a percentage value for MemoryLimit= and related settings

If a percentage is used, it is taken relative to the installed RAM size. This
should make it easier to write generic unit files that adapt to the local system.

1 files changed, 13 insertions, 3 deletions

diff --git a/src/core/load-fragment.c b/src/core/load-fragment.c
index fe60bee789..05852cc7e3 100644
--- a/src/core/load-fragment.c
+++ b/src/core/load-fragment.c
@@ -2812,9 +2812,19 @@ int config_parse_memory_limit(
         int r;
 
         if (!isempty(rvalue) && !streq(rvalue, "infinity")) {
-                r = parse_size(rvalue, 1024, &bytes);
-                if (r < 0 || bytes < 1) {
-                        log_syntax(unit, LOG_ERR, filename, line, r, "Memory limit '%s' invalid. Ignoring.", rvalue);
+
+                r = parse_percent(rvalue);
+                if (r < 0) {
+                        r = parse_size(rvalue, 1024, &bytes);
+                        if (r < 0) {
+                                log_syntax(unit, LOG_ERR, filename, line, r, "Memory limit '%s' invalid. Ignoring.", rvalue);
+                                return 0;
+                        }
+                } else
+                        bytes = (((physical_memory() / page_size()) * (uint64_t) r) / 100) * page_size();
+
+                if (bytes < 1) {
+                        log_syntax(unit, LOG_ERR, filename, line, 0, "Memory limit '%s' too small. Ignoring.", rvalue);
                         return 0;
                 }
         }