nfs-server-generator: avoid using external services.

nfs-server-generator is run very early when a lot of services are not
yet started, so it mustn't depend on them.  Currently it can try to
use hostname lookup and syslog.  Using hostname lookup can cause
errors and when these are logged via syslog, it can cause the
generator to block indefinitely

Hostname-lookup is not needed, as we don't use the host issue,
and sending message to stderr is sufficient for the generator.

Disabling syslog is easy - call a function that sets a static variable.

Disabling hostname lookup requires adding an "ignore_hosts" flags to
export_read and export_d_read().

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Steve Dickson <steved@redhat.com>

4 files changed, 15 insertions, 10 deletions

diff --git a/support/export/export.c b/support/export/export.c
index 0b8a858..15e91cb 100644
--- a/support/export/export.c
+++ b/support/export/export.c
@@ -70,11 +70,15 @@ static void warn_duplicated_exports(nfs_export *exp, struct exportent *eep)
 /**
  * export_read - read entries from /etc/exports
  * @fname: name of file to read from
+ * @ignore_hosts: don't check validity of host names
  *
  * Returns number of read entries.
+ * @ignore_hosts can be set when the host names won't be used
+ * and when getting delays or errors due to problems with
+ * hostname looking is not acceptable.
  */
 int
-export_read(char *fname)
+export_read(char *fname, int ignore_hosts)
 {
 	struct exportent	*eep;
 	nfs_export		*exp;
@@ -83,7 +87,7 @@ export_read(char *fname)
 
 	setexportent(fname, "r");
 	while ((eep = getexportent(0,1)) != NULL) {
-		exp = export_lookup(eep->e_hostname, eep->e_path, 0);
+		exp = export_lookup(eep->e_hostname, eep->e_path, ignore_hosts);
 		if (!exp) {
 			if (export_create(eep, 0))
 				/* possible complaints already logged */
@@ -100,13 +104,14 @@ export_read(char *fname)
 /**
  * export_d_read - read entries from /etc/exports.
  * @fname: name of directory to read from
+ * @ignore_hosts: don't check validity of host names
  *
  * Returns number of read entries.
  * Based on mnt_table_parse_dir() in
  *  util-linux-ng/shlibs/mount/src/tab_parse.c
  */
 int
-export_d_read(const char *dname)
+export_d_read(const char *dname, int ignore_hosts)
 {
 	int n = 0, i;
 	struct dirent **namelist = NULL;
@@ -150,7 +155,7 @@ export_d_read(const char *dname)
 			continue;
 		}
 
-		volumes += export_read(fname);
+		volumes += export_read(fname, ignore_hosts);
 	}
 
 	for (i = 0; i < n; i++)
diff --git a/support/include/exportfs.h b/support/include/exportfs.h
index f033329..32d4fe9 100644
--- a/support/include/exportfs.h
+++ b/support/include/exportfs.h
@@ -134,8 +134,8 @@ struct addrinfo *		client_resolve(const struct sockaddr *sap);
 int 				client_member(const char *client,
 						const char *name);
 
-int				export_read(char *fname);
-int				export_d_read(const char *dname);
+int				export_read(char *fname, int ignore_hosts);
+int				export_d_read(const char *dname, int ignore_hosts);
 void				export_reset(nfs_export *);
 nfs_export *			export_lookup(char *hname, char *path, int caconical);
 nfs_export *			export_find(const struct addrinfo *ai,
diff --git a/systemd/nfs-server-generator.c b/systemd/nfs-server-generator.c
index f47718e..7c40b3f 100644
--- a/systemd/nfs-server-generator.c
+++ b/systemd/nfs-server-generator.c
@@ -104,8 +104,8 @@ int main(int argc, char *argv[])
 	path = malloc(strlen(argv[1]) + sizeof(dirbase) + sizeof(filebase));
 	if (!path)
 		exit(2);
-	if (export_read(_PATH_EXPORTS) +
-	    export_d_read(_PATH_EXPORTS_D) == 0)
+	if (export_read(_PATH_EXPORTS, 1) +
+	    export_d_read(_PATH_EXPORTS_D, 1) == 0)
 		/* Nothing is exported, so nothing to do */
 		exit(0);
 
diff --git a/utils/exportfs/exportfs.c b/utils/exportfs/exportfs.c
index 4ac2c15..5136810 100644
--- a/utils/exportfs/exportfs.c
+++ b/utils/exportfs/exportfs.c
@@ -183,8 +183,8 @@ main(int argc, char **argv)
 	atexit(release_lockfile);
 
 	if (f_export && ! f_ignore) {
-		if (! (export_read(_PATH_EXPORTS) +
-		       export_d_read(_PATH_EXPORTS_D))) {
+		if (! (export_read(_PATH_EXPORTS, 0) +
+		       export_d_read(_PATH_EXPORTS_D, 0))) {
 			if (f_verbose)
 				xlog(L_WARNING, "No file systems exported!");
 		}