Function queries system hostname and applies changes only when necessary. Also,
migrate all client of sethostname to sethostname_idempotent while at it.
---
src/core/hostname-setup.c | 2 +-
src/hostname/hostnamed.c | 2 +-
src/nspawn/nspawn.c | 2 +-
src/shared/util.c | 20 ++++++++++++++++++++
src/shared/util.h | 2 ++
5 files changed, 25 insertions(+), 3 deletions(-)
diff --git a/src/core/hostname-setup.c b/src/core/hostname-setup.c
index 8aa1cff..57baa79 100644
--- a/src/core/hostname-setup.c
+++ b/src/core/hostname-setup.c
@@ -82,7 +82,7 @@ int hostname_setup(void) {
hn = "localhost";
}
- if (sethostname(hn, strlen(hn)) < 0) {
+ if (sethostname_idempotent(hn) < 0) {
log_warning("Failed to set hostname to <%s>: %m", hn);
return -errno;
}
diff --git a/src/hostname/hostnamed.c b/src/hostname/hostnamed.c
index b6b5d52..3e5d434 100644
--- a/src/hostname/hostnamed.c
+++ b/src/hostname/hostnamed.c
@@ -287,7 +287,7 @@ static int context_update_kernel_hostname(Context *c) {
else
hn = "localhost";
- if (sethostname(hn, strlen(hn)) < 0)
+ if (sethostname_idempotent(hn) < 0)
return -errno;
return 0;
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index c567c8d..b6d9bc6 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -1289,7 +1289,7 @@ static int setup_hostname(void) {
if (arg_share_system)
return 0;
- if (sethostname(arg_machine, strlen(arg_machine)) < 0)
+ if (sethostname_idempotent(arg_machine) < 0)
return -errno;
return 0;
diff --git a/src/shared/util.c b/src/shared/util.c
index 5f6249e..cb3bd2f 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -7164,3 +7164,23 @@ int free_and_strdup(char **p, const char *s) {
return 0;
}
+
+int sethostname_idempotent(const char *s) {
+ int r = 0;
+ char buf[HOST_NAME_MAX + 1] = {};
+
+ assert(s);
+
+ r = gethostname(buf, sizeof(buf));
+ if (r < 0)
+ return -errno;
+
+ if (streq(buf, s))
+ return 0;
+
+ r = sethostname(buf, strlen(buf));
+ if (r < 0)
+ return -errno;
+
+ return 0;
+}
diff --git a/src/shared/util.h b/src/shared/util.h
index 21a90a4..10cdc7b 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -996,3 +996,5 @@ int unquote_first_word(const char **p, char **ret);
int unquote_many_words(const char **p, ...) _sentinel_;
int free_and_strdup(char **p, const char *s);
+
+int sethostname_idempotent(const char *s);
--
1.8.3.1
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