From 5704cd733c08d4e8c3ec7a3da0c4385e97bdb545 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Tue, 28 Apr 2020 17:03:12 +0200
Subject: [PATCH] hostnamed: don't cache system UUID

There's no point in caching this. Let's always get this directly from
sysfs, so that we can never get out-of-date data here (after all this is
going to be cheap, and people might overmount it or so)
---
 src/hostname/hostnamed.c | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/src/hostname/hostnamed.c b/src/hostname/hostnamed.c
index e20e9f6dad..d5fa44a76d 100644
--- a/src/hostname/hostnamed.c
+++ b/src/hostname/hostnamed.c
@@ -52,8 +52,6 @@ enum {
 typedef struct Context {
         char *data[_PROP_MAX];
         Hashmap *polkit_registry;
-        sd_id128_t uuid;
-        bool has_uuid;
 } Context;
 
 static void context_reset(Context *c) {
@@ -104,17 +102,6 @@ static int context_read_data(Context *c) {
         if (r < 0 && r != -ENOENT)
                 return r;
 
-        r = id128_read("/sys/class/dmi/id/product_uuid", ID128_UUID, &c->uuid);
-        if (r == -ENOENT)
-                r = id128_read("/sys/firmware/devicetree/base/vm,uuid", ID128_UUID, &c->uuid);
-        if (r < 0)
-                log_full_errno(r == -ENOENT ? LOG_DEBUG : LOG_WARNING, r,
-                               "Failed to read product UUID, ignoring: %m");
-        else if (sd_id128_is_null(c->uuid) || sd_id128_is_allf(c->uuid))
-                log_debug("DMI product UUID " SD_ID128_FORMAT_STR " is all 0x00 or all 0xFF, ignoring.", SD_ID128_FORMAT_VAL(c->uuid));
-        else
-                c->has_uuid = true;
-
         return 0;
 }
 
@@ -631,13 +618,27 @@ static int method_set_location(sd_bus_message *m, void *userdata, sd_bus_error *
 static int method_get_product_uuid(sd_bus_message *m, void *userdata, sd_bus_error *error) {
         _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
         Context *c = userdata;
+        bool has_uuid = false;
         int interactive, r;
+        sd_id128_t uuid;
 
         assert(m);
         assert(c);
 
-        if (!c->has_uuid)
-                return sd_bus_error_set(error, BUS_ERROR_NO_PRODUCT_UUID, "Failed to read product UUID from /sys/class/dmi/id/product_uuid");
+        r = id128_read("/sys/class/dmi/id/product_uuid", ID128_UUID, &uuid);
+        if (r == -ENOENT)
+                r = id128_read("/sys/firmware/devicetree/base/vm,uuid", ID128_UUID, &uuid);
+        if (r < 0)
+                log_full_errno(r == -ENOENT ? LOG_DEBUG : LOG_WARNING, r,
+                               "Failed to read product UUID, ignoring: %m");
+        else if (sd_id128_is_null(uuid) || sd_id128_is_allf(uuid))
+                log_debug("DMI product UUID " SD_ID128_FORMAT_STR " is all 0x00 or all 0xFF, ignoring.", SD_ID128_FORMAT_VAL(uuid));
+        else
+                has_uuid = true;
+
+        if (!has_uuid)
+                return sd_bus_error_set(error, BUS_ERROR_NO_PRODUCT_UUID,
+                                        "Failed to read product UUID from firmware.");
 
         r = sd_bus_message_read(m, "b", &interactive);
         if (r < 0)
@@ -661,7 +662,7 @@ static int method_get_product_uuid(sd_bus_message *m, void *userdata, sd_bus_err
         if (r < 0)
                 return r;
 
-        r = sd_bus_message_append_array(reply, 'y', &c->uuid, sizeof(c->uuid));
+        r = sd_bus_message_append_array(reply, 'y', &uuid, sizeof(uuid));
         if (r < 0)
                 return r;