hostname-setup: send chosen hostname to supervisor via sd_notify()

once we decided on a hostname, let's tell the supervisor about it. This
is useful for example in order to recognize the system via mDNS/LLMNR or
in a DHCP lease.

diff --git a/src/shared/hostname-setup.c b/src/shared/hostname-setup.c
index 8e42c931170d9cabcd597b4fcd9f2df7d39606d8..6cfd4b54bf631c053fe84088b4223725218b887b 100644 (file)
--- a/src/shared/hostname-setup.c
+++ b/src/shared/hostname-setup.c
@@ -6,6 +6,8 @@
 #include <sys/utsname.h>
 #include <unistd.h>
 
+#include "sd-daemon.h"
+
 #include "alloc-util.h"
 #include "creds-util.h"
 #include "fd-util.h"
@@ -13,6 +15,7 @@
 #include "fs-util.h"
 #include "hostname-setup.h"
 #include "hostname-util.h"
+#include "initrd-util.h"
 #include "log.h"
 #include "macro.h"
 #include "proc-cmdline.h"
@@ -153,63 +156,54 @@ void hostname_update_source_hint(const char *hostname, HostnameSource source) {
 }
 
 int hostname_setup(bool really) {
-        _cleanup_free_ char *b = NULL;
-        const char *hn = NULL;
+        _cleanup_free_ char *hn = NULL;
         HostnameSource source;
         bool enoent = false;
         int r;
 
-        r = proc_cmdline_get_key("systemd.hostname", 0, &b);
+        r = proc_cmdline_get_key("systemd.hostname", 0, &hn);
         if (r < 0)
                 log_warning_errno(r, "Failed to retrieve system hostname from kernel command line, ignoring: %m");
         else if (r > 0) {
-                if (hostname_is_valid(b, VALID_HOSTNAME_TRAILING_DOT)) {
-                        hn = b;
+                if (hostname_is_valid(hn, VALID_HOSTNAME_TRAILING_DOT))
                         source = HOSTNAME_TRANSIENT;
-                } else  {
-                        log_warning("Hostname specified on kernel command line is invalid, ignoring: %s", b);
-                        b = mfree(b);
+                else  {
+                        log_warning("Hostname specified on kernel command line is invalid, ignoring: %s", hn);
+                        hn = mfree(hn);
                 }
         }
 
         if (!hn) {
-                r = read_etc_hostname(NULL, &b);
-                if (r < 0) {
-                        if (r == -ENOENT)
-                                enoent = true;
-                        else
-                                log_warning_errno(r, "Failed to read configured hostname, ignoring: %m");
-                } else {
-                        hn = b;
+                r = read_etc_hostname(NULL, &hn);
+                if (r == -ENOENT)
+                        enoent = true;
+                else if (r < 0)
+                        log_warning_errno(r, "Failed to read configured hostname, ignoring: %m");
+                else
                         source = HOSTNAME_STATIC;
-                }
         }
 
         if (!hn) {
-                r = acquire_hostname_from_credential(&b);
-                if (r >= 0) {
-                        hn = b;
+                r = acquire_hostname_from_credential(&hn);
+                if (r >= 0)
                         source = HOSTNAME_TRANSIENT;
-                }
         }
 
         if (!hn) {
-                _cleanup_free_ char *buf = NULL;
-
                 /* Don't override the hostname if it is already set and not explicitly configured */
 
-                r = gethostname_full(GET_HOSTNAME_ALLOW_LOCALHOST, &buf);
+                r = gethostname_full(GET_HOSTNAME_ALLOW_LOCALHOST, &hn);
                 if (r == -ENOMEM)
                         return log_oom();
                 if (r >= 0) {
-                        log_debug("No hostname configured, leaving existing hostname <%s> in place.", buf);
-                        return 0;
+                        log_debug("No hostname configured, leaving existing hostname <%s> in place.", hn);
+                        goto finish;
                 }
 
                 if (enoent)
                         log_info("No hostname configured, using default hostname.");
 
-                hn = b = get_default_hostname();
+                hn = get_default_hostname();
                 if (!hn)
                         return log_oom();
 
@@ -229,7 +223,11 @@ int hostname_setup(bool really) {
         if (really)
                 hostname_update_source_hint(hn, source);
 
-        return r;
+finish:
+        if (!in_initrd())
+                (void) sd_notifyf(/* unset_environment= */ false, "X_SYSTEMD_HOSTNAME=%s", hn);
+
+        return 0;
 }
 
 static const char* const hostname_source_table[] = {