systemctl: allow percent-based MemoryLimit= settings via systemctl set-property

The unit files already accept relative, percent-based memory limit
specification, let's make sure "systemctl set-property" support this too.

Since we want the physical memory size of the destination machine to apply we
pass the percentage in a new set of properties that only exist for this
purpose, and can only be set.

1 files changed, 28 insertions, 15 deletions

diff --git a/src/shared/bus-unit-util.c b/src/shared/bus-unit-util.c
index 778c79b3cf..6fc201b885 100644
--- a/src/shared/bus-unit-util.c
+++ b/src/shared/bus-unit-util.c
@@ -120,6 +120,34 @@ int bus_append_unit_property_assignment(sd_bus_message *m, const char *assignmen
                 strcpy(mempcpy(n, field, l - 3), "USec");
                 r = sd_bus_message_append(m, "sv", n, "t", t);
                 goto finish;
+
+        } else if (STR_IN_SET(field, "MemoryLow", "MemoryHigh", "MemoryMax", "MemoryLimit")) {
+                uint64_t bytes;
+
+                if (isempty(eq) || streq(eq, "infinity"))
+                        bytes = CGROUP_LIMIT_MAX;
+                else {
+                        r = parse_percent(eq);
+                        if (r >= 0) {
+                                char *n;
+
+                                /* When this is a percentage we'll convert this into a relative value in the range
+                                 * 0…UINT32_MAX and pass it in the MemoryLowByPhysicalMemory property (and related
+                                 * ones). This way the physical memory size can be determined server-side */
+
+                                n = strjoina(field, "ByPhysicalMemory");
+                                r = sd_bus_message_append(m, "sv", n, "u", (uint32_t) (((uint64_t) UINT32_MAX * r) / 100U));
+                                goto finish;
+
+                        } else {
+                                r = parse_size(eq, 1024, &bytes);
+                                if (r < 0)
+                                        return log_error_errno(r, "Failed to parse bytes specification %s", assignment);
+                        }
+                }
+
+                r = sd_bus_message_append(m, "sv", field, "t", bytes);
+                goto finish;
         }
 
         r = sd_bus_message_append_basic(m, SD_BUS_TYPE_STRING, field);
@@ -163,21 +191,6 @@ int bus_append_unit_property_assignment(sd_bus_message *m, const char *assignmen
 
                 r = sd_bus_message_append(m, "v", "b", r);
 
-        } else if (STR_IN_SET(field, "MemoryLow", "MemoryHigh", "MemoryMax", "MemoryLimit")) {
-                uint64_t bytes;
-
-                if (isempty(eq) || streq(eq, "infinity"))
-                        bytes = CGROUP_LIMIT_MAX;
-                else {
-                        r = parse_size(eq, 1024, &bytes);
-                        if (r < 0) {
-                                log_error("Failed to parse bytes specification %s", assignment);
-                                return -EINVAL;
-                        }
-                }
-
-                r = sd_bus_message_append(m, "v", "t", bytes);
-
         } else if (streq(field, "TasksMax")) {
                 uint64_t n;