[gnome-control-center/wip/hadess/fix-ram-size: 2/2] info: Use udev to get the hardware RAM size

[Bastien Nocera <hadess src gnome org>]

commit 3ba3b028d542e98a0ba3f80df70935d6d57d749b
Author: Bastien Nocera <hadess hadess net>
Date:   Tue Jan 25 23:12:58 2022 +0100

    info: Use udev to get the hardware RAM size
    
    libgtop gets the RAM size as is visible to the OS, so the physical RAM
    size minus all the reserved areas listed at the top of your usual Linux
    dmesg output.
    
    Use systemd 248's MEMORY_ARRAY_* properties attached to the pseudo-DMI
    device to get the size of the RAM sticks/chips as the user expects.
    
    Closes: #1540

 panels/info-overview/cc-info-overview-panel.c | 31 +++++++++++++++++++++++++--
 panels/info-overview/meson.build              |  3 ++-
 2 files changed, 31 insertions(+), 3 deletions(-)
---
diff --git a/panels/info-overview/cc-info-overview-panel.c b/panels/info-overview/cc-info-overview-panel.c
index 88aea9900..257436395 100644
--- a/panels/info-overview/cc-info-overview-panel.c
+++ b/panels/info-overview/cc-info-overview-panel.c
@@ -38,6 +38,7 @@
 #include <glibtop/mem.h>
 #include <glibtop/sysinfo.h>
 #include <udisks/udisks.h>
+#include <gudev/gudev.h>
 
 #include <gdk/gdk.h>
 
@@ -724,7 +725,7 @@ get_windowing_system (void)
 }
 
 static guint64
-get_ram_size (void)
+get_ram_size_libgtop (void)
 {
   glibtop_mem mem;
 
@@ -732,6 +733,30 @@ get_ram_size (void)
   return mem.total;
 }
 
+static guint64
+get_ram_size_dmi (void)
+{
+  g_autoptr(GUdevClient) client = NULL;
+  g_autoptr(GUdevDevice) dmi = NULL;
+  const gchar * const subsystems[] = {"dmi", NULL };
+  guint64 ram_total = 0;
+  guint64 num_ram;
+  guint i;
+
+  client = g_udev_client_new (subsystems);
+  dmi = g_udev_client_query_by_sysfs_path (client, "/sys/devices/virtual/dmi/id");
+  if (!dmi)
+    return 0;
+  num_ram = g_udev_device_get_property_as_uint64 (dmi, "MEMORY_ARRAY_NUM_DEVICES");
+  for (i = 0; i < num_ram ; i++) {
+    g_autofree char *prop = NULL;
+
+    prop = g_strdup_printf ("MEMORY_DEVICE_%d_SIZE", i);
+    ram_total += g_udev_device_get_property_as_uint64 (dmi, prop);
+  }
+  return ram_total;
+}
+
 static void
 info_overview_panel_setup_overview (CcInfoOverviewPanel *self)
 {
@@ -751,7 +776,9 @@ info_overview_panel_setup_overview (CcInfoOverviewPanel *self)
 
   get_hardware_model (self);
 
-  ram_size = get_ram_size ();
+  ram_size = get_ram_size_dmi ();
+  if (ram_size == 0)
+    ram_size = get_ram_size_libgtop ();
   memory_text = g_format_size_full (ram_size, G_FORMAT_SIZE_IEC_UNITS);
   cc_list_row_set_secondary_label (self->memory_row, memory_text);
 
diff --git a/panels/info-overview/meson.build b/panels/info-overview/meson.build
index 1cc062eee..b465ada56 100644
--- a/panels/info-overview/meson.build
+++ b/panels/info-overview/meson.build
@@ -40,7 +40,8 @@ sources += gnome.compile_resources(
 
 deps = common_deps + [
   dependency('udisks2', version: '>= 2.8.2'),
-  dependency('libgtop-2.0')
+  dependency('libgtop-2.0'),
+  gudev_dep
 ]
 
 info_panel_lib = static_library(